QImage 类

QImage class provides a hardware-independent image representation that allows direct access to the pixel data, and can be used as a paint device. 更多...

Header: #include <QImage>
qmake: QT += gui
继承: QPaintDevice

注意: 此类的所有函数 可重入 .

公共类型

enum Format { Format_Invalid, Format_Mono, Format_MonoLSB, Format_Indexed8, ..., Format_RGBA64_Premultiplied }
enum InvertMode { InvertRgb, InvertRgba }

公共函数

QImage ()
QImage (const QSize & size , QImage::Format format )
QImage (int width , int height , QImage::Format format )
QImage (uchar * data , int width , int height , QImage::Format format , QImageCleanupFunction cleanupFunction = nullptr, void * cleanupInfo = nullptr)
QImage (const uchar * data , int width , int height , QImage::Format format , QImageCleanupFunction cleanupFunction = nullptr, void * cleanupInfo = nullptr)
QImage (uchar * data , int width , int height , int bytesPerLine , QImage::Format format , QImageCleanupFunction cleanupFunction = nullptr, void * cleanupInfo = nullptr)
QImage (const uchar * data , int width , int height , int bytesPerLine , QImage::Format format , QImageCleanupFunction cleanupFunction = nullptr, void * cleanupInfo = nullptr)
QImage (const char *const [] xpm )
QImage (const QString & fileName , const char * format = nullptr)
QImage (const QImage & image )
QImage (QImage && other )
virtual ~QImage ()
bool allGray () const
int bitPlaneCount () const
uchar * bits ()
const uchar * bits () const
int bytesPerLine () const
qint64 cacheKey () const
QRgb color (int i ) const
int colorCount () const
QVector<QRgb> colorTable () const
const uchar * constBits () const
const uchar * constScanLine (int i ) const
QImage convertToFormat (QImage::Format format , Qt::ImageConversionFlags flags = Qt::AutoColor) const &
QImage convertToFormat (QImage::Format format , Qt::ImageConversionFlags flags = Qt::AutoColor) &&
QImage convertToFormat (QImage::Format format , const QVector<QRgb> & colorTable , Qt::ImageConversionFlags flags = Qt::AutoColor) const
QImage copy (const QRect & rectangle = QRect()) const
QImage copy (int x , int y , int width , int height ) const
QImage createAlphaMask (Qt::ImageConversionFlags flags = Qt::AutoColor) const
QImage createHeuristicMask (bool clipTight = true) const
QImage createMaskFromColor (QRgb color , Qt::MaskMode mode = Qt::MaskInColor) const
int depth () const
qreal devicePixelRatio () const
int dotsPerMeterX () const
int dotsPerMeterY () const
void fill (uint pixelValue )
void fill (const QColor & color )
void fill (Qt::GlobalColor color )
QImage::Format format () const
bool hasAlphaChannel () const
int height () const
void invertPixels (QImage::InvertMode mode = InvertRgb)
bool isGrayscale () const
bool isNull () const
bool load (const QString & fileName , const char * format = nullptr)
bool load (QIODevice * device , const char * format )
bool loadFromData (const uchar * data , int len , const char * format = nullptr)
bool loadFromData (const QByteArray & data , const char * format = nullptr)
QImage mirrored (bool horizontal = ..., bool vertical = ...) const &
QImage && mirrored (bool horizontal = ..., bool vertical = ...) &&
QPoint offset () const
QRgb pixel (const QPoint & position ) const
QRgb pixel (int x , int y ) const
QColor pixelColor (const QPoint & position ) const
QColor pixelColor (int x , int y ) const
QPixelFormat pixelFormat () const
int pixelIndex (const QPoint & position ) const
int pixelIndex (int x , int y ) const
QRect rect () const
bool reinterpretAsFormat (QImage::Format format )
QImage rgbSwapped () const &
QImage && rgbSwapped () &&
bool save (const QString & fileName , const char * format = nullptr, int quality = -1) const
bool save (QIODevice * device , const char * format = nullptr, int quality = -1) const
QImage scaled (const QSize & size , Qt::AspectRatioMode aspectRatioMode = Qt::IgnoreAspectRatio, Qt::TransformationMode transformMode = Qt::FastTransformation) const
QImage scaled (int width , int height , Qt::AspectRatioMode aspectRatioMode = Qt::IgnoreAspectRatio, Qt::TransformationMode transformMode = Qt::FastTransformation) const
QImage scaledToHeight (int height , Qt::TransformationMode mode = Qt::FastTransformation) const
QImage scaledToWidth (int width , Qt::TransformationMode mode = Qt::FastTransformation) const
uchar * scanLine (int i )
const uchar * scanLine (int i ) const
void setColor (int index , QRgb colorValue )
void setColorCount (int colorCount )
void setColorTable (const QVector<QRgb> colors )
void setDevicePixelRatio (qreal scaleFactor )
void setDotsPerMeterX (int x )
void setDotsPerMeterY (int y )
void setOffset (const QPoint & offset )
void setPixel (const QPoint & position , uint index_or_rgb )
void setPixel (int x , int y , uint index_or_rgb )
void setPixelColor (const QPoint & position , const QColor & color )
void setPixelColor (int x , int y , const QColor & color )
void setText (const QString & key , const QString & text )
QSize size () const
qsizetype sizeInBytes () const
void swap (QImage & other )
QString text (const QString & key = QString()) const
QStringList textKeys () const
CGImageRef toCGImage () const
QImage transformed (const QMatrix & matrix , Qt::TransformationMode mode = Qt::FastTransformation) const
QImage transformed (const QTransform & matrix , Qt::TransformationMode mode = Qt::FastTransformation) const
bool valid (const QPoint & pos ) const
bool valid (int x , int y ) const
int width () const
QVariant operator QVariant () const
bool operator!= (const QImage & image ) const
QImage & operator= (const QImage & image )
QImage & operator= (QImage && other )
bool operator== (const QImage & image ) const

静态公共成员

QImage fromData (const uchar * data , int size , const char * format = nullptr)
QImage fromData (const QByteArray & data , const char * format = nullptr)
const QMetaObject staticMetaObject
QImage::Format toImageFormat (QPixelFormat format )
QPixelFormat toPixelFormat (QImage::Format format )
QMatrix trueMatrix (const QMatrix & matrix , int width , int height )
QTransform trueMatrix (const QTransform & matrix , int width , int height )

保护函数

QImage smoothScaled (int w , int h ) const
typedef QImageCleanupFunction
QDataStream & operator<< (QDataStream & stream , const QImage & image )
QDataStream & operator>> (QDataStream & stream , QImage & image )

详细描述

QImage class provides a hardware-independent image representation that allows direct access to the pixel data, and can be used as a paint device.

Qt 为处理图像数据提供了 4 个类: QImage , QPixmap , QBitmap and QPicture . QImage is designed and optimized for I/O, and for direct pixel access and manipulation, while QPixmap is designed and optimized for showing images on screen. QBitmap is only a convenience class that inherits QPixmap , ensuring a depth of 1. Finally, the QPicture 类是描绘设备,它记录并重演 QPainter 命令。

因为 QImage QPaintDevice subclass, QPainter can be used to draw directly onto images. When using QPainter on a QImage , the painting can be performed in another thread than the current GUI thread.

QImage class supports several image formats described by the Format enum. These include monochrome, 8-bit, 32-bit and alpha-blended images which are available in all versions of Qt 4.x.

QImage provides a collection of functions that can be used to obtain a variety of information about the image. There are also several functions that enables transformation of the image.

QImage objects can be passed around by value since the QImage class uses implicit data sharing . QImage objects can also be streamed and compared.

注意: If you would like to load QImage objects in a static build of Qt, refer to the Plugin HowTo .

警告: Painting on a QImage with the format QImage::Format_Indexed8 is not supported.

读写图像文件

QImage provides several ways of loading an image file: The file can be loaded when constructing the QImage object, or by using the load () 或 loadFromData () functions later on. QImage also provides the static fromData () function, constructing a QImage from the given data. When loading an image, the file name can either refer to an actual file on disk or to one of the application's embedded resources. See Qt 资源系统 overview for details on how to embed images and other resource files in the application's executable.

Simply call the save () function to save a QImage 对象。

The complete list of supported file formats are available through the QImageReader::supportedImageFormats () 和 QImageWriter::supportedImageFormats () functions. New file formats can be added as plugins. By default, Qt supports the following formats:

Format 描述 Qt 支持
BMP Windows Bitmap 读/写
GIF Graphic Interchange Format (optional)
JPG Joint Photographic Experts Group 读/写
JPEG Joint Photographic Experts Group 读/写
PNG Portable Network Graphics 读/写
PBM Portable Bitmap
PGM Portable Graymap
PPM Portable Pixmap 读/写
XBM X11 Bitmap 读/写
XPM X11 Pixmap 读/写

图像信息

QImage provides a collection of functions that can be used to obtain a variety of information about the image:

Available Functions
Geometry size (), width (), height (), dotsPerMeterX (),和 dotsPerMeterY () functions provide information about the image size and aspect ratio.

rect () function returns the image's enclosing rectangle. The valid () function tells if a given pair of coordinates is within this rectangle. The offset () function returns the number of pixels by which the image is intended to be offset by when positioned relative to other images, which also can be manipulated using the setOffset () 函数。

Colors The color of a pixel can be retrieved by passing its coordinates to the pixel () function. The pixel () function returns the color as a QRgb value indepedent of the image's format.

In case of monochrome and 8-bit images, the colorCount () 和 colorTable () functions provide information about the color components used to store the image data: The colorTable () function returns the image's entire color table. To obtain a single entry, use the pixelIndex () function to retrieve the pixel index for a given pair of coordinates, then use the color () function to retrieve the color. Note that if you create an 8-bit image manually, you have to set a valid color table on the image as well.

hasAlphaChannel () function tells if the image's format respects the alpha channel, or not. The allGray () 和 isGrayscale () functions tell whether an image's colors are all shades of gray.

另请参阅 像素操纵 and 图像变换 sections.

文本 text () function returns the image text associated with the given text key. An image's text keys can be retrieved using the textKeys () function. Use the setText () function to alter an image's text.
Low-level information depth () function returns the depth of the image. The supported depths are 1 (monochrome), 8, 16, 24 and 32 bits. The bitPlaneCount () function tells how many of those bits that are used. For more information see the 图像格式 章节。

format (), bytesPerLine (),和 sizeInBytes () functions provide low-level information about the data stored in the image.

cacheKey () function returns a number that uniquely identifies the contents of this QImage 对象。

像素操纵

The functions used to manipulate an image's pixels depend on the image format. The reason is that monochrome and 8-bit images are index-based and use a color lookup table, while 32-bit images store ARGB values directly. For more information on image formats, see the 图像格式 章节。

In case of a 32-bit image, the setPixel () function can be used to alter the color of the pixel at the given coordinates to any other color specified as an ARGB quadruplet. To make a suitable QRgb value, use the qRgb () (adding a default alpha component to the given RGB values, i.e. creating an opaque color) or qRgba () function. For example:

32-bit
QImage image(3, 3, QImage::Format_RGB32);
QRgb value;
value = qRgb(189, 149, 39); // 0xffbd9527
image.setPixel(1, 1, value);
value = qRgb(122, 163, 39); // 0xff7aa327
image.setPixel(0, 1, value);
image.setPixel(1, 0, value);
value = qRgb(237, 187, 51); // 0xffedba31
image.setPixel(2, 1, value);
										

In case of a 8-bit and monchrome images, the pixel value is only an index from the image's color table. So the setPixel () function can only be used to alter the color of the pixel at the given coordinates to a predefined color from the image's color table, i.e. it can only change the pixel's index value. To alter or add a color to an image's color table, use the setColor () 函数。

An entry in the color table is an ARGB quadruplet encoded as an QRgb value. Use the qRgb () 和 qRgba () functions to make a suitable QRgb value for use with the setColor () function. For example:

8-bit
QImage image(3, 3, QImage::Format_Indexed8);
QRgb value;
value = qRgb(122, 163, 39); // 0xff7aa327
image.setColor(0, value);
value = qRgb(237, 187, 51); // 0xffedba31
image.setColor(1, value);
value = qRgb(189, 149, 39); // 0xffbd9527
image.setColor(2, value);
image.setPixel(0, 1, 0);
image.setPixel(1, 0, 0);
image.setPixel(1, 1, 2);
image.setPixel(2, 1, 1);
										

For images with more than 8-bit per color-channel. The methods setPixelColor () 和 pixelColor () can be used to set and get with QColor 值。

QImage also provide the scanLine () function which returns a pointer to the pixel data at the scanline with the given index, and the bits () function which returns a pointer to the first pixel data (this is equivalent to scanLine(0) ).

图像格式

Each pixel stored in a QImage is represented by an integer. The size of the integer varies depending on the format. QImage supports several image formats described by the Format 枚举。

Monochrome images are stored using 1-bit indexes into a color table with at most two colors. There are two different types of monochrome images: big endian (MSB first) or little endian (LSB first) bit order.

8-bit images are stored using 8-bit indexes into a color table, i.e. they have a single byte per pixel. The color table is a QVector < QRgb >, and the QRgb typedef is equivalent to an unsigned int containing an ARGB quadruplet on the format 0xAARRGGBB.

32-bit images have no color table; instead, each pixel contains an QRgb value. There are three different types of 32-bit images storing RGB (i.e. 0xffRRGGBB), ARGB and premultiplied ARGB values respectively. In the premultiplied format the red, green, and blue channels are multiplied by the alpha component divided by 255.

An image's format can be retrieved using the format () function. Use the convertToFormat () functions to convert an image into another format. The allGray () 和 isGrayscale () functions tell whether a color image can safely be converted to a grayscale image.

图像变换

QImage supports a number of functions for creating a new image that is a transformed version of the original: The createAlphaMask () function builds and returns a 1-bpp mask from the alpha buffer in this image, and the createHeuristicMask () function creates and returns a 1-bpp heuristic mask for this image. The latter function works by selecting a color from one of the corners, then chipping away pixels of that color starting at all the edges.

mirrored () 函数返回期望方向的图像镜像, scaled () returns a copy of the image scaled to a rectangle of the desired measures, and the rgbSwapped () function constructs a BGR image from a RGB image.

scaledToWidth () 和 scaledToHeight () functions return scaled copies of the image.

transformed () function returns a copy of the image that is transformed with the given transformation matrix and transformation mode: Internally, the transformation matrix is adjusted to compensate for unwanted translation, i.e. transformed () returns the smallest image containing all transformed points of the original image. The static trueMatrix () function returns the actual matrix used for transforming the image.

There are also functions for changing attributes of an image in-place:

函数 描述
setDotsPerMeterX () Defines the aspect ratio by setting the number of pixels that fit horizontally in a physical meter.
setDotsPerMeterY () Defines the aspect ratio by setting the number of pixels that fit vertically in a physical meter.
fill () Fills the entire image with the given pixel value.
invertPixels () Inverts all pixel values in the image using the given InvertMode value.
setColorTable () Sets the color table used to translate color indexes. Only monochrome and 8-bit formats.
setColorCount () Resizes the color table. Only monochrome and 8-bit formats.

另请参阅 QImageReader , QImageWriter , QPixmap , QSvgRenderer , 图像合成范例 , 图像查看器范例 , 涂鸦范例 ,和 像素器范例 .

成员类型文档编制

enum QImage:: Format

The following image formats are available in Qt. See the notes after the table.

常量 描述
QImage::Format_Invalid 0 The image is invalid.
QImage::Format_Mono 1 The image is stored using 1-bit per pixel. Bytes are packed with the most significant bit (MSB) first.
QImage::Format_MonoLSB 2 The image is stored using 1-bit per pixel. Bytes are packed with the less significant bit (LSB) first.
QImage::Format_Indexed8 3 The image is stored using 8-bit indexes into a colormap.
QImage::Format_RGB32 4 The image is stored using a 32-bit RGB format (0xffRRGGBB).
QImage::Format_ARGB32 5 The image is stored using a 32-bit ARGB format (0xAARRGGBB).
QImage::Format_ARGB32_Premultiplied 6 The image is stored using a premultiplied 32-bit ARGB format (0xAARRGGBB), i.e. the red, green, and blue channels are multiplied by the alpha component divided by 255. (If RR, GG, or BB has a higher value than the alpha channel, the results are undefined.) Certain operations (such as image composition using alpha blending) are faster using premultiplied ARGB32 than with plain ARGB32.
QImage::Format_RGB16 7 The image is stored using a 16-bit RGB format (5-6-5).
QImage::Format_ARGB8565_Premultiplied 8 The image is stored using a premultiplied 24-bit ARGB format (8-5-6-5).
QImage::Format_RGB666 9 The image is stored using a 24-bit RGB format (6-6-6). The unused most significant bits is always zero.
QImage::Format_ARGB6666_Premultiplied 10 The image is stored using a premultiplied 24-bit ARGB format (6-6-6-6).
QImage::Format_RGB555 11 The image is stored using a 16-bit RGB format (5-5-5). The unused most significant bit is always zero.
QImage::Format_ARGB8555_Premultiplied 12 The image is stored using a premultiplied 24-bit ARGB format (8-5-5-5).
QImage::Format_RGB888 13 The image is stored using a 24-bit RGB format (8-8-8).
QImage::Format_RGB444 14 The image is stored using a 16-bit RGB format (4-4-4). The unused bits are always zero.
QImage::Format_ARGB4444_Premultiplied 15 The image is stored using a premultiplied 16-bit ARGB format (4-4-4-4).
QImage::Format_RGBX8888 16 The image is stored using a 32-bit byte-ordered RGB(x) format (8-8-8-8). This is the same as the Format_RGBA8888 except alpha must always be 255. (added in Qt 5.2)
QImage::Format_RGBA8888 17 The image is stored using a 32-bit byte-ordered RGBA format (8-8-8-8). Unlike ARGB32 this is a byte-ordered format, which means the 32bit encoding differs between big endian and little endian architectures, being respectively (0xRRGGBBAA) and (0xAABBGGRR). The order of the colors is the same on any architecture if read as bytes 0xRR,0xGG,0xBB,0xAA. (added in Qt 5.2)
QImage::Format_RGBA8888_Premultiplied 18 The image is stored using a premultiplied 32-bit byte-ordered RGBA format (8-8-8-8). (added in Qt 5.2)
QImage::Format_BGR30 19 The image is stored using a 32-bit BGR format (x-10-10-10). (added in Qt 5.4)
QImage::Format_A2BGR30_Premultiplied 20 The image is stored using a 32-bit premultiplied ABGR format (2-10-10-10). (added in Qt 5.4)
QImage::Format_RGB30 21 The image is stored using a 32-bit RGB format (x-10-10-10). (added in Qt 5.4)
QImage::Format_A2RGB30_Premultiplied 22 The image is stored using a 32-bit premultiplied ARGB format (2-10-10-10). (added in Qt 5.4)
QImage::Format_Alpha8 23 The image is stored using an 8-bit alpha only format. (added in Qt 5.5)
QImage::Format_Grayscale8 24 The image is stored using an 8-bit grayscale format. (added in Qt 5.5)
QImage::Format_RGBX64 25 The image is stored using a 64-bit halfword-ordered RGB(x) format (16-16-16-16). This is the same as the Format_RGBX64 except alpha must always be 65535. (added in Qt 5.12)
QImage::Format_RGBA64 26 The image is stored using a 64-bit halfword-ordered RGBA format (16-16-16-16). (added in Qt 5.12)
QImage::Format_RGBA64_Premultiplied 27 The image is stored using a premultiplied 64-bit halfword-ordered RGBA format (16-16-16-16). (added in Qt 5.12)

注意: Drawing into a QImage with QImage::Format_Indexed8 is not supported.

注意: Avoid most rendering directly to most of these formats using QPainter . Rendering is best optimized to the Format_RGB32 and Format_ARGB32_Premultiplied formats, and secondarily for rendering to the Format_RGB16 , Format_RGBX8888 , Format_RGBA8888_Premultiplied , Format_RGBX64 and Format_RGBA64_Premultiplied formats

另请参阅 format () 和 convertToFormat ().

enum QImage:: InvertMode

This enum type is used to describe how pixel values should be inverted in the invertPixels () 函数。

常量 描述
QImage::InvertRgb 0 Invert only the RGB values and leave the alpha channel unchanged.
QImage::InvertRgba 1 Invert all channels, including the alpha channel.

另请参阅 invertPixels ().

成员函数文档编制

QImage QImage:: rgbSwapped () const &

QImage &&QImage:: rgbSwapped () &&

返回 QImage in which the values of the red and blue components of all pixels have been swapped, effectively converting an RGB image to an BGR image.

The original QImage is not changed.

另请参阅 图像变换 .

QImage QImage:: mirrored ( bool horizontal = ..., bool vertical = ...) const &

QImage &&QImage:: mirrored ( bool horizontal = ..., bool vertical = ...) &&

Returns a mirror of the image, mirrored in the horizontal and/or the vertical direction depending on whether horizontal and vertical are set to true or false.

Note that the original image is not changed.

另请参阅 图像变换 .

QImage QImage:: convertToFormat ( QImage::Format format , Qt::ImageConversionFlags flags = Qt::AutoColor) const &

QImage QImage:: convertToFormat ( QImage::Format format , Qt::ImageConversionFlags flags = Qt::AutoColor) &&

Returns a copy of the image in the given format .

The specified image conversion flags control how the image data is handled during the conversion process.

另请参阅 图像格式 .

QImage:: QImage ()

构造空图像。

另请参阅 isNull ().

QImage:: QImage (const QSize & size , QImage::Format format )

Constructs an image with the given size and format .

A null image is returned if memory cannot be allocated.

警告: This will create a QImage with uninitialized data. Call fill () to fill the image with an appropriate pixel value before drawing onto it with QPainter .

QImage:: QImage ( int width , int height , QImage::Format format )

Constructs an image with the given width , height and format .

A null image will be returned if memory cannot be allocated.

警告: This will create a QImage with uninitialized data. Call fill () to fill the image with an appropriate pixel value before drawing onto it with QPainter .

QImage:: QImage ( uchar * data , int width , int height , QImage::Format format , QImageCleanupFunction cleanupFunction = nullptr, void * cleanupInfo = nullptr)

Constructs an image with the given width , height and format , that uses an existing memory buffer, data width and height must be specified in pixels, data must be 32-bit aligned, and each scanline of data in the image must also be 32-bit aligned.

The buffer must remain valid throughout the life of the QImage and all copies that have not been modified or otherwise detached from the original buffer. The image does not delete the buffer at destruction. You can provide a function pointer cleanupFunction along with an extra pointer cleanupInfo that will be called when the last copy is destroyed.

format is an indexed color format, the image color table is initially empty and must be sufficiently expanded with setColorCount () 或 setColorTable () before the image is used.

QImage:: QImage (const uchar * data , int width , int height , QImage::Format format , QImageCleanupFunction cleanupFunction = nullptr, void * cleanupInfo = nullptr)

Constructs an image with the given width , height and format , that uses an existing read-only memory buffer, data width and height must be specified in pixels, data must be 32-bit aligned, and each scanline of data in the image must also be 32-bit aligned.

The buffer must remain valid throughout the life of the QImage and all copies that have not been modified or otherwise detached from the original buffer. The image does not delete the buffer at destruction. You can provide a function pointer cleanupFunction along with an extra pointer cleanupInfo that will be called when the last copy is destroyed.

format is an indexed color format, the image color table is initially empty and must be sufficiently expanded with setColorCount () 或 setColorTable () before the image is used.

Unlike the similar QImage constructor that takes a non-const data buffer, this version will never alter the contents of the buffer. For example, calling QImage::bits () will return a deep copy of the image, rather than the buffer passed to the constructor. This allows for the efficiency of constructing a QImage from raw data, without the possibility of the raw data being changed.

QImage:: QImage ( uchar * data , int width , int height , int bytesPerLine , QImage::Format format , QImageCleanupFunction cleanupFunction = nullptr, void * cleanupInfo = nullptr)

Constructs an image with the given width , height and format , that uses an existing memory buffer, data width and height must be specified in pixels. bytesPerLine specifies the number of bytes per line (stride).

The buffer must remain valid throughout the life of the QImage and all copies that have not been modified or otherwise detached from the original buffer. The image does not delete the buffer at destruction. You can provide a function pointer cleanupFunction along with an extra pointer cleanupInfo that will be called when the last copy is destroyed.

format is an indexed color format, the image color table is initially empty and must be sufficiently expanded with setColorCount () 或 setColorTable () before the image is used.

QImage:: QImage (const uchar * data , int width , int height , int bytesPerLine , QImage::Format format , QImageCleanupFunction cleanupFunction = nullptr, void * cleanupInfo = nullptr)

Constructs an image with the given width , height and format , that uses an existing memory buffer, data width and height must be specified in pixels. bytesPerLine specifies the number of bytes per line (stride).

The buffer must remain valid throughout the life of the QImage and all copies that have not been modified or otherwise detached from the original buffer. The image does not delete the buffer at destruction. You can provide a function pointer cleanupFunction along with an extra pointer cleanupInfo that will be called when the last copy is destroyed.

format is an indexed color format, the image color table is initially empty and must be sufficiently expanded with setColorCount () 或 setColorTable () before the image is used.

Unlike the similar QImage constructor that takes a non-const data buffer, this version will never alter the contents of the buffer. For example, calling QImage::bits () will return a deep copy of the image, rather than the buffer passed to the constructor. This allows for the efficiency of constructing a QImage from raw data, without the possibility of the raw data being changed.

QImage:: QImage (const char *const [] xpm )

Constructs an image from the given xpm image.

Make sure that the image is a valid XPM image. Errors are silently ignored.

Note that it's possible to squeeze the XPM variable a little bit by using an unusual declaration:

static const char * const start_xpm[] = {
    "16 15 8 1",
    "a c #cec6bd",
....
							

The extra const makes the entire definition read-only, which is slightly more efficient (e.g., when the code is in a shared library) and able to be stored in ROM with the application.

QImage:: QImage (const QString & fileName , const char * format = nullptr)

Constructs an image and tries to load the image from the file with the given fileName .

The loader attempts to read the image using the specified format 。若 format is not specified (which is the default), it is auto-detected based on the file's suffix and header. For details, see { QImageReader::setAutoDetectImageFormat ()}{ QImageReader }.

If the loading of the image failed, this object is a null image.

The file name can either refer to an actual file on disk or to one of the application's embedded resources. See the Resource System overview for details on how to embed images and other resource files in the application's executable.

另请参阅 isNull () 和 读写图像文件 .

QImage:: QImage (const QImage & image )

Constructs a shallow copy of the given image .

For more information about shallow copies, see the Implicit Data Sharing 文档编制。

另请参阅 copy ().

QImage:: QImage ( QImage && other )

Move-constructs a QImage instance, making it point at the same object that other 所指向的。

This function was introduced in Qt 5.2.

[virtual] QImage:: ~QImage ()

Destroys the image and cleans up.

bool QImage:: allGray () const

返回 true if all the colors in the image are shades of gray (i.e. their red, green and blue components are equal); otherwise false.

Note that this function is slow for images without color table.

另请参阅 isGrayscale ().

int QImage:: bitPlaneCount () const

Returns the number of bit planes in the image.

The number of bit planes is the number of bits of color and transparency information for each pixel. This is different from (i.e. smaller than) the depth when the image format contains unused bits.

This function was introduced in Qt 4.7.

另请参阅 depth (), format (),和 图像格式 .

uchar *QImage:: bits ()

Returns a pointer to the first pixel data. This is equivalent to scanLine (0).

注意: QImage 使用 implicit data sharing . This function performs a deep copy of the shared pixel data, thus ensuring that this QImage is the only one using the current return value.

另请参阅 scanLine (), sizeInBytes (),和 constBits ().

const uchar *QImage:: bits () const

这是重载函数。

注意: QImage 使用 implicit data sharing , but this function does not perform a deep copy of the shared pixel data, because the returned data is const.

int QImage:: bytesPerLine () const

Returns the number of bytes per image scanline.

这相当于 sizeInBytes () / height () if height () is non-zero.

另请参阅 scanLine ().

qint64 QImage:: cacheKey () const

Returns a number that identifies the contents of this QImage object. Distinct QImage objects can only have the same key if they refer to the same contents.

The key will change when the image is altered.

QRgb QImage:: color ( int i ) const

Returns the color in the color table at index i . The first color is at index 0.

The colors in an image's color table are specified as ARGB quadruplets ( QRgb ). Use the qAlpha (), qRed (), qGreen (),和 qBlue () functions to get the color value components.

另请参阅 setColor (), pixelIndex (),和 像素操纵 .

int QImage:: colorCount () const

Returns the size of the color table for the image.

Notice that colorCount() returns 0 for 32-bpp images because these images do not use color tables, but instead encode pixel values as ARGB quadruplets.

This function was introduced in Qt 4.6.

另请参阅 setColorCount () 和 图像信息 .

QVector < QRgb > QImage:: colorTable () const

Returns a list of the colors contained in the image's color table, or an empty list if the image does not have a color table

另请参阅 setColorTable (), colorCount (),和 color ().

const uchar *QImage:: constBits () const

Returns a pointer to the first pixel data.

注意: QImage 使用 implicit data sharing , but this function does not perform a deep copy of the shared pixel data, because the returned data is const.

This function was introduced in Qt 4.7.

另请参阅 bits () 和 constScanLine ().

const uchar *QImage:: constScanLine ( int i ) const

Returns a pointer to the pixel data at the scanline with index i . The first scanline is at index 0.

The scanline data is aligned on a 32-bit boundary.

注意: QImage 使用 implicit data sharing , but this function does not perform a deep copy of the shared pixel data, because the returned data is const.

This function was introduced in Qt 4.7.

另请参阅 scanLine () 和 constBits ().

QImage QImage:: convertToFormat ( QImage::Format format , const QVector < QRgb > & colorTable , Qt::ImageConversionFlags flags = Qt::AutoColor) const

这是重载函数。

Returns a copy of the image converted to the given format , using the specified colorTable .

Conversion from RGB formats to indexed formats is a slow operation and will use a straightforward nearest color approach, with no dithering.

QImage QImage:: copy (const QRect & rectangle = QRect()) const

Returns a sub-area of the image as a new image.

The returned image is copied from the position ( rectangle .x(), rectangle .y()) in this image, and will always have the size of the given rectangle .

In areas beyond this image, pixels are set to 0. For 32-bit RGB images, this means black; for 32-bit ARGB images, this means transparent black; for 8-bit images, this means the color with index 0 in the color table which can be anything; for 1-bit images, this means Qt::color0 .

若给定 rectangle is a null rectangle the entire image is copied.

另请参阅 QImage ().

QImage QImage:: copy ( int x , int y , int width , int height ) const

这是重载函数。

The returned image is copied from the position ( x , y ) in this image, and will always have the given width and height . In areas beyond this image, pixels are set to 0.

QImage QImage:: createAlphaMask ( Qt::ImageConversionFlags flags = Qt::AutoColor) const

Builds and returns a 1-bpp mask from the alpha buffer in this image. Returns a null image if the image's format is QImage::Format_RGB32 .

flags argument is a bitwise-OR of the Qt::ImageConversionFlags , and controls the conversion process. Passing 0 for flags sets all the default options.

The returned image has little-endian bit order (i.e. the image's format is QImage::Format_MonoLSB ), which you can convert to big-endian ( QImage::Format_Mono ) using the convertToFormat () 函数。

另请参阅 createHeuristicMask () 和 图像变换 .

QImage QImage:: createHeuristicMask ( bool clipTight = true) const

Creates and returns a 1-bpp heuristic mask for this image.

The function works by selecting a color from one of the corners, then chipping away pixels of that color starting at all the edges. The four corners vote for which color is to be masked away. In case of a draw (this generally means that this function is not applicable to the image), the result is arbitrary.

The returned image has little-endian bit order (i.e. the image's format is QImage::Format_MonoLSB ), which you can convert to big-endian ( QImage::Format_Mono ) using the convertToFormat () 函数。

clipTight is true (the default) the mask is just large enough to cover the pixels; otherwise, the mask is larger than the data pixels.

Note that this function disregards the alpha buffer.

另请参阅 createAlphaMask () 和 图像变换 .

QImage QImage:: createMaskFromColor ( QRgb color , Qt::MaskMode mode = Qt::MaskInColor) const

Creates and returns a mask for this image based on the given color value. If the mode is MaskInColor (the default value), all pixels matching color will be opaque pixels in the mask. If mode is MaskOutColor, all pixels matching the given color will be transparent.

另请参阅 createAlphaMask () 和 createHeuristicMask ().

int QImage:: depth () const

Returns the depth of the image.

The image depth is the number of bits used to store a single pixel, also called bits per pixel (bpp).

The supported depths are 1, 8, 16, 24, 32 and 64.

另请参阅 bitPlaneCount (), convertToFormat (), 图像格式 ,和 图像信息 .

qreal QImage:: devicePixelRatio () const

Returns the device pixel ratio for the image. This is the ratio between device pixels and device independent pixels .

Use this function when calculating layout geometry based on the image size: QSize layoutSize = image. size () / image.devicePixelRatio()

默认值为 1.0。

另请参阅 setDevicePixelRatio () 和 QImageReader .

int QImage:: dotsPerMeterX () const

Returns the number of pixels that fit horizontally in a physical meter. Together with dotsPerMeterY (), this number defines the intended scale and aspect ratio of the image.

另请参阅 setDotsPerMeterX () 和 图像信息 .

int QImage:: dotsPerMeterY () const

Returns the number of pixels that fit vertically in a physical meter. Together with dotsPerMeterX (), this number defines the intended scale and aspect ratio of the image.

另请参阅 setDotsPerMeterY () 和 图像信息 .

void QImage:: fill ( uint pixelValue )

Fills the entire image with the given pixelValue .

If the depth of this image is 1, only the lowest bit is used. If you say fill(0), fill(2), etc., the image is filled with 0s. If you say fill(1), fill(3), etc., the image is filled with 1s. If the depth is 8, the lowest 8 bits are used and if the depth is 16 the lowest 16 bits are used.

注意: QImage::pixel () returns the color of the pixel at the given coordinates while QColor::pixel() returns the pixel value of the underlying window system (essentially an index value), so normally you will want to use QImage::pixel () to use a color from an existing image or QColor::rgb () to use a specific color.

另请参阅 depth () 和 图像变换 .

void QImage:: fill (const QColor & color )

这是重载函数。

Fills the entire image with the given color .

If the depth of the image is 1, the image will be filled with 1 if color equals Qt::color1 ; it will otherwise be filled with 0.

If the depth of the image is 8, the image will be filled with the index corresponding the color in the color table if present; it will otherwise be filled with 0.

This function was introduced in Qt 4.8.

void QImage:: fill ( Qt::GlobalColor color )

这是重载函数。

Fills the image with the given color , described as a standard global color.

This function was introduced in Qt 4.8.

QImage::Format QImage:: format () const

Returns the format of the image.

另请参阅 图像格式 .

[static] QImage QImage:: fromData (const uchar * data , int size , const char * format = nullptr)

构造 QImage from the first size bytes of the given binary data . The loader attempts to read the image using the specified format 。若 format is not specified (which is the default), the loader probes the data for a header to guess the file format.

format is specified, it must be one of the values returned by QImageReader::supportedImageFormats ().

If the loading of the image fails, the image returned will be a null image.

另请参阅 load (), save (),和 读写图像文件 .

[static] QImage QImage:: fromData (const QByteArray & data , const char * format = nullptr)

这是重载函数。

Loads an image from the given QByteArray data .

bool QImage:: hasAlphaChannel () const

返回 true if the image has a format that respects the alpha channel, otherwise returns false .

另请参阅 图像信息 .

int QImage:: height () const

Returns the height of the image.

另请参阅 图像信息 .

void QImage:: invertPixels ( QImage::InvertMode mode = InvertRgb)

Inverts all pixel values in the image.

The given invert mode only have a meaning when the image's depth is 32. The default mode is InvertRgb , which leaves the alpha channel unchanged. If the mode is InvertRgba , the alpha bits are also inverted.

Inverting an 8-bit image means to replace all pixels using color index i with a pixel using color index 255 minus i . The same is the case for a 1-bit image. Note that the color table is not changed.

If the image has a premultiplied alpha channel, the image is first converted to an unpremultiplied image format to be inverted and then converted back.

另请参阅 图像变换 .

bool QImage:: isGrayscale () const

For 32-bit images, this function is equivalent to allGray ().

For color indexed images, this function returns true if color(i) is QRgb (i, i, i) for all indexes of the color table; otherwise returns false .

另请参阅 allGray () 和 图像格式 .

bool QImage:: isNull () const

返回 true if it is a null image, otherwise returns false .

A null image has all parameters set to zero and no allocated data.

bool QImage:: load (const QString & fileName , const char * format = nullptr)

Loads an image from the file with the given fileName 。返回 true if the image was successfully loaded; otherwise invalidates the image and returns false .

The loader attempts to read the image using the specified format , e.g., PNG or JPG. If format is not specified (which is the default), it is auto-detected based on the file's suffix and header. For details, see QImageReader::setAutoDetectImageFormat ().

The file name can either refer to an actual file on disk or to one of the application's embedded resources. See the Resource System overview for details on how to embed images and other resource files in the application's executable.

另请参阅 读写图像文件 .

bool QImage:: load ( QIODevice * device , const char * format )

这是重载函数。

This function reads a QImage from the given device . This can, for example, be used to load an image directly into a QByteArray .

bool QImage:: loadFromData (const uchar * data , int len , const char * format = nullptr)

Loads an image from the first len bytes of the given binary data 。返回 true if the image was successfully loaded; otherwise invalidates the image and returns false .

The loader attempts to read the image using the specified format , e.g., PNG or JPG. If format is not specified (which is the default), the loader probes the file for a header to guess the file format.

另请参阅 读写图像文件 .

bool QImage:: loadFromData (const QByteArray & data , const char * format = nullptr)

这是重载函数。

Loads an image from the given QByteArray data .

QPoint QImage:: offset () const

Returns the number of pixels by which the image is intended to be offset by when positioning relative to other images.

另请参阅 setOffset () 和 图像信息 .

QRgb QImage:: pixel (const QPoint & position ) const

Returns the color of the pixel at the given position .

position is not valid, the results are undefined.

警告: This function is expensive when used for massive pixel manipulations. Use constBits () 或 constScanLine () when many pixels needs to be read.

另请参阅 setPixel (), valid (), constBits (), constScanLine (),和 像素操纵 .

QRgb QImage:: pixel ( int x , int y ) const

这是重载函数。

Returns the color of the pixel at coordinates ( x , y ).

QColor QImage:: pixelColor (const QPoint & position ) const

Returns the color of the pixel at the given position as a QColor .

position is not valid, an invalid QColor 被返回。

警告: This function is expensive when used for massive pixel manipulations. Use constBits () 或 constScanLine () when many pixels needs to be read.

This function was introduced in Qt 5.6.

另请参阅 setPixelColor (), setPixel (), valid (), constBits (), constScanLine (),和 像素操纵 .

QColor QImage:: pixelColor ( int x , int y ) const

这是重载函数。

Returns the color of the pixel at coordinates ( x , y ) as a QColor .

This function was introduced in Qt 5.6.

QPixelFormat QImage:: pixelFormat () const

返回 QImage::Format as a QPixelFormat

int QImage:: pixelIndex (const QPoint & position ) const

Returns the pixel index at the given position .

position is not valid, or if the image is not a paletted image ( depth () > 8), the results are undefined.

另请参阅 valid (), depth (),和 像素操纵 .

int QImage:: pixelIndex ( int x , int y ) const

这是重载函数。

Returns the pixel index at ( x , y ).

QRect QImage:: rect () const

Returns the enclosing rectangle (0, 0, width (), height ()) of the image.

另请参阅 图像信息 .

bool QImage:: reinterpretAsFormat ( QImage::Format format )

Changes the format of the image to format without changing the data. Only works between formats of the same depth.

返回 true if successful.

This function can be used to change images with alpha-channels to their corresponding opaque formats if the data is known to be opaque-only, or to change the format of a given image buffer before overwriting it with new data.

警告: The function does not check if the image data is valid in the new format and will still return true if the depths are compatible. Operations on an image with invalid data are undefined.

警告: If the image is not detached, this will cause the data to be copied.

This function was introduced in Qt 5.9.

另请参阅 hasAlphaChannel () 和 convertToFormat ().

bool QImage:: save (const QString & fileName , const char * format = nullptr, int quality = -1) const

Saves the image to the file with the given fileName , using the given image file format and quality factor. If format is 0, QImage will attempt to guess the format by looking at fileName 的后缀。

quality factor must be in the range 0 to 100 or -1. Specify 0 to obtain small compressed files, 100 for large uncompressed files, and -1 (the default) to use the default settings.

返回 true if the image was successfully saved; otherwise returns false .

另请参阅 读写图像文件 .

bool QImage:: save ( QIODevice * device , const char * format = nullptr, int quality = -1) const

这是重载函数。

此函数写入 QImage 到给定 device .

This can, for example, be used to save an image directly into a QByteArray :

        QImage image;
        QByteArray ba;
        QBuffer buffer(&ba);
        buffer.open(QIODevice::WriteOnly);
        image.save(&buffer, "PNG"); // writes image into ba in PNG format
							

QImage QImage:: scaled (const QSize & size , Qt::AspectRatioMode aspectRatioMode = Qt::IgnoreAspectRatio, Qt::TransformationMode transformMode = Qt::FastTransformation) const

Returns a copy of the image scaled to a rectangle defined by the given size according to the given aspectRatioMode and transformMode .

若给定 size is empty, this function returns a null image.

另请参阅 isNull () 和 图像变换 .

QImage QImage:: scaled ( int width , int height , Qt::AspectRatioMode aspectRatioMode = Qt::IgnoreAspectRatio, Qt::TransformationMode transformMode = Qt::FastTransformation) const

这是重载函数。

Returns a copy of the image scaled to a rectangle with the given width and height according to the given aspectRatioMode and transformMode .

If either the width height is zero or negative, this function returns a null image.

QImage QImage:: scaledToHeight ( int height , Qt::TransformationMode mode = Qt::FastTransformation) const

Returns a scaled copy of the image. The returned image is scaled to the given height using the specified transformation mode .

This function automatically calculates the width of the image so that the ratio of the image is preserved.

若给定 height is 0 or negative, a null image is returned.

另请参阅 图像变换 .

QImage QImage:: scaledToWidth ( int width , Qt::TransformationMode mode = Qt::FastTransformation) const

Returns a scaled copy of the image. The returned image is scaled to the given width using the specified transformation mode .

This function automatically calculates the height of the image so that its aspect ratio is preserved.

若给定 width is 0 or negative, a null image is returned.

另请参阅 图像变换 .

uchar *QImage:: scanLine ( int i )

Returns a pointer to the pixel data at the scanline with index i . The first scanline is at index 0.

The scanline data is as minimum 32-bit aligned. For 64-bit formats it follows the native alignment of 64-bit integers (64-bit for most platforms, but notably 32-bit on i386).

警告: If you are accessing 32-bpp image data, cast the returned pointer to QRgb* ( QRgb has a 32-bit size) and use it to read/write the pixel value. You cannot use the uchar* pointer directly, because the pixel format depends on the byte order on the underlying platform. Use qRed (), qGreen (), qBlue (),和 qAlpha () to access the pixels.

另请参阅 bytesPerLine (), bits (), 像素操纵 ,和 constScanLine ().

const uchar *QImage:: scanLine ( int i ) const

这是重载函数。

void QImage:: setColor ( int index , QRgb colorValue )

Sets the color at the given index in the color table, to the given to colorValue . The color value is an ARGB quadruplet.

index is outside the current size of the color table, it is expanded with setColorCount ().

另请参阅 color (), colorCount (), setColorTable (),和 像素操纵 .

void QImage:: setColorCount ( int colorCount )

Resizes the color table to contain colorCount entries.

If the color table is expanded, all the extra colors will be set to transparent (i.e qRgba (0, 0, 0, 0)).

When the image is used, the color table must be large enough to have entries for all the pixel/index values present in the image, otherwise the results are undefined.

This function was introduced in Qt 4.6.

另请参阅 colorCount (), colorTable (), setColor (),和 图像变换 .

void QImage:: setColorTable (const QVector < QRgb > colors )

Sets the color table used to translate color indexes to QRgb values, to the specified colors .

When the image is used, the color table must be large enough to have entries for all the pixel/index values present in the image, otherwise the results are undefined.

另请参阅 colorTable (), setColor (),和 图像变换 .

void QImage:: setDevicePixelRatio ( qreal scaleFactor )

Sets the device pixel ratio for the image. This is the ratio between image pixels and device-independent pixels.

默认 scaleFactor is 1.0. Setting it to something else has two effects:

QPainters that are opened on the image will be scaled. For example, painting on a 200x200 image if with a ratio of 2.0 will result in effective (device-independent) painting bounds of 100x100.

Code paths in Qt that calculate layout geometry based on the image size will take the ratio into account: QSize layoutSize = image. size () / image. devicePixelRatio () The net effect of this is that the image is displayed as high-DPI image rather than a large image (see 绘制高分辨率版本的像素图和图像 ).

另请参阅 devicePixelRatio ().

void QImage:: setDotsPerMeterX ( int x )

Sets the number of pixels that fit horizontally in a physical meter, to x .

Together with dotsPerMeterY (), this number defines the intended scale and aspect ratio of the image, and determines the scale at which QPainter will draw graphics on the image. It does not change the scale or aspect ratio of the image when it is rendered on other paint devices.

另请参阅 dotsPerMeterX () 和 图像信息 .

void QImage:: setDotsPerMeterY ( int y )

Sets the number of pixels that fit vertically in a physical meter, to y .

Together with dotsPerMeterX (), this number defines the intended scale and aspect ratio of the image, and determines the scale at which QPainter will draw graphics on the image. It does not change the scale or aspect ratio of the image when it is rendered on other paint devices.

另请参阅 dotsPerMeterY () 和 图像信息 .

void QImage:: setOffset (const QPoint & offset )

Sets the number of pixels by which the image is intended to be offset by when positioning relative to other images, to offset .

另请参阅 offset () 和 图像信息 .

void QImage:: setPixel (const QPoint & position , uint index_or_rgb )

Sets the pixel index or color at the given position to index_or_rgb .

If the image's format is either monochrome or paletted, the given index_or_rgb value must be an index in the image's color table, otherwise the parameter must be a QRgb value.

position is not a valid coordinate pair in the image, or if index_or_rgb >= colorCount () in the case of monochrome and paletted images, the result is undefined.

警告: This function is expensive due to the call of the internal detach() function called within; if performance is a concern, we recommend the use of scanLine () 或 bits () to access pixel data directly.

另请参阅 pixel () 和 像素操纵 .

void QImage:: setPixel ( int x , int y , uint index_or_rgb )

这是重载函数。

Sets the pixel index or color at ( x , y ) to index_or_rgb .

void QImage:: setPixelColor (const QPoint & position , const QColor & color )

Sets the color at the given position to color .

position is not a valid coordinate pair in the image, or the image's format is either monochrome or paletted, the result is undefined.

警告: This function is expensive due to the call of the internal detach() function called within; if performance is a concern, we recommend the use of scanLine () 或 bits () to access pixel data directly.

This function was introduced in Qt 5.6.

另请参阅 pixelColor (), pixel (), bits (), scanLine (),和 像素操纵 .

void QImage:: setPixelColor ( int x , int y , const QColor & color )

这是重载函数。

Sets the pixel color at ( x , y ) to color .

This function was introduced in Qt 5.6.

void QImage:: setText (const QString & key , const QString & text )

Sets the image text to the given text and associate it with the given key .

If you just want to store a single text block (i.e., a "comment" or just a description), you can either pass an empty key, or use a generic key like "Description".

The image text is embedded into the image data when you call save () 或 QImageWriter::write ().

Not all image formats support embedded text. You can find out if a specific image or format supports embedding text by using QImageWriter::supportsOption (). We give an example:

    QImageWriter writer;
    writer.setFormat("png");
    if (writer.supportsOption(QImageIOHandler::Description))
        qDebug() << "Png supports embedded text";
							

可以使用 QImageWriter::supportedImageFormats () to find out which image formats are available to you.

另请参阅 text () 和 textKeys ().

QSize QImage:: size () const

Returns the size of the image, i.e. its width () 和 height ().

另请参阅 图像信息 .

qsizetype QImage:: sizeInBytes () const

Returns the image data size in bytes.

This function was introduced in Qt 5.10.

另请参阅 byteCount (), bytesPerLine (), bits (),和 图像信息 .

[protected] QImage QImage:: smoothScaled ( int w , int h ) const

Returns a smoothly scaled copy of the image. The returned image has a size of width w by height h pixels.

void QImage:: swap ( QImage & other )

Swaps image other with this image. This operation is very fast and never fails.

This function was introduced in Qt 4.8.

QString QImage:: text (const QString & key = QString()) const

Returns the image text associated with the given key . If the specified key is an empty string, the whole image text is returned, with each key-text pair separated by a newline.

另请参阅 setText () 和 textKeys ().

QStringList QImage:: textKeys () const

Returns the text keys for this image.

You can use these keys with text () to list the image text for a certain key.

另请参阅 text ().

CGImageRef QImage:: toCGImage () const

创建 CGImage equivalent to this QImage . Returns a CGImageRef handle.

The returned CGImageRef partakes in the QImage implicit sharing, and holds a reference to the QImage data. CGImage is immutable and will never detach the QImage . Writing to the QImage will detach as usual.

This function is fast, and does not copy or convert image data.

The following image formats are supported, and will be mapped to a corresponding native image type:

Qt CoreGraphics
Format_ARGB32 kCGImageAlphaFirst | kCGBitmapByteOrder32Host
Format_RGB32 kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Host
Format_RGBA8888_Premultiplied kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big
Format_RGBA8888 kCGImageAlphaLast | kCGBitmapByteOrder32Big
Format_RGBX8888 kCGImageAlphaNoneSkipLast | kCGBitmapByteOrder32Big
Format_ARGB32_Premultiplied kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host

Other formats are not supported; this function returns a null CGImageRef for those cases. Users of this function may then convert the QImage to a supported formate first, for example Format_ARGB32_Premultiplied .

The CGImageRef color space is set to the sRGB color space.

另请参阅 QtMac::toNSImage ().

[static] QImage::Format QImage:: toImageFormat ( QPixelFormat format )

转换 format into a QImage::Format

[static] QPixelFormat QImage:: toPixelFormat ( QImage::Format format )

转换 format into a QPixelFormat

QImage QImage:: transformed (const QMatrix & matrix , Qt::TransformationMode mode = Qt::FastTransformation) const

Returns a copy of the image that is transformed using the given transformation matrix and transformation mode .

The returned image will normally have the same {Image Formats}{format} as the original image. However, a complex transformation may result in an image where not all pixels are covered by the transformed pixels of the original image. In such cases, those background pixels will be assigned a transparent color value, and the transformed image will be given a format with an alpha channel, even if the orginal image did not have that.

The transformation matrix is internally adjusted to compensate for unwanted translation; i.e. the image produced is the smallest image that contains all the transformed points of the original image. Use the trueMatrix () function to retrieve the actual matrix used for transforming an image.

另请参阅 trueMatrix () 和 图像变换 .

QImage QImage:: transformed (const QTransform & matrix , Qt::TransformationMode mode = Qt::FastTransformation) const

Returns a copy of the image that is transformed using the given transformation matrix and transformation mode .

The returned image will normally have the same {Image Formats}{format} as the original image. However, a complex transformation may result in an image where not all pixels are covered by the transformed pixels of the original image. In such cases, those background pixels will be assigned a transparent color value, and the transformed image will be given a format with an alpha channel, even if the orginal image did not have that.

The transformation matrix is internally adjusted to compensate for unwanted translation; i.e. the image produced is the smallest image that contains all the transformed points of the original image. Use the trueMatrix () function to retrieve the actual matrix used for transforming an image.

Unlike the other overload, this function can be used to perform perspective transformations on images.

另请参阅 trueMatrix () 和 图像变换 .

[static] QMatrix QImage:: trueMatrix (const QMatrix & matrix , int width , int height )

Returns the actual matrix used for transforming an image with the given width , height and matrix .

When transforming an image using the transformed () function, the transformation matrix is internally adjusted to compensate for unwanted translation, i.e. transformed () returns the smallest image containing all transformed points of the original image. This function returns the modified matrix, which maps points correctly from the original image into the new image.

另请参阅 transformed () 和 图像变换 .

[static] QTransform QImage:: trueMatrix (const QTransform & matrix , int width , int height )

Returns the actual matrix used for transforming an image with the given width , height and matrix .

When transforming an image using the transformed () function, the transformation matrix is internally adjusted to compensate for unwanted translation, i.e. transformed () returns the smallest image containing all transformed points of the original image. This function returns the modified matrix, which maps points correctly from the original image into the new image.

Unlike the other overload, this function creates transformation matrices that can be used to perform perspective transformations on images.

另请参阅 transformed () 和 图像变换 .

bool QImage:: valid (const QPoint & pos ) const

返回 true if pos is a valid coordinate pair within the image; otherwise returns false .

另请参阅 rect () 和 QRect::contains ().

bool QImage:: valid ( int x , int y ) const

这是重载函数。

返回 true if QPoint ( x , y ) is a valid coordinate pair within the image; otherwise returns false .

int QImage:: width () const

返回图像宽度。

另请参阅 图像信息 .

QVariant QImage:: operator QVariant () const

Returns the image as a QVariant .

bool QImage:: operator!= (const QImage & image ) const

返回 true if this image and the given image have different contents; otherwise returns false .

The comparison can be slow, unless there is some obvious difference, such as different widths, in which case the function will return quickly.

另请参阅 operator= ().

QImage &QImage:: operator= (const QImage & image )

Assigns a shallow copy of the given image to this image and returns a reference to this image.

For more information about shallow copies, see the Implicit Data Sharing 文档编制。

另请参阅 copy () 和 QImage ().

QImage &QImage:: operator= ( QImage && other )

移动赋值 other 到此 QImage 实例。

This function was introduced in Qt 5.2.

bool QImage:: operator== (const QImage & image ) const

返回 true if this image and the given image have the same contents; otherwise returns false .

The comparison can be slow, unless there is some obvious difference (e.g. different size or format), in which case the function will return quickly.

另请参阅 operator= ().

相关非成员

typedef QImageCleanupFunction

A function with the following signature that can be used to implement basic image memory management:

void myImageCleanupHandler(void *info);
							

This typedef was introduced in Qt 5.0.

QDataStream & operator<< ( QDataStream & stream , const QImage & image )

写入给定 image 到给定 stream as a PNG image, or as a BMP image if the stream's version is 1. Note that writing the stream to a file will not produce a valid image file.

另请参阅 QImage::save () 和 序列化 Qt 数据类型 .

QDataStream & operator>> ( QDataStream & stream , QImage & image )

Reads an image from the given stream and stores it in the given image .

另请参阅 QImage::load () 和 序列化 Qt 数据类型 .