QDial 類提供四捨五入範圍控製 (像速度計或電位計)。 更多...
| 頭： | #include <QDial> |
| qmake: | QT += widgets |
| 繼承： | QAbstractSlider |
| QDial (QWidget * parent = nullptr) | |
| virtual | ~QDial () |
| int | notchSize () const |
| qreal | notchTarget () const |
| bool | notchesVisible () const |
| void | setNotchTarget (double target ) |
| bool | wrapping () const |
| virtual QSize | minimumSizeHint () const override |
| virtual QSize | sizeHint () const override |
| void | setNotchesVisible (bool visible ) |
| void | setWrapping (bool on ) |
| void | initStyleOption (QStyleOptionSlider * option ) const |
| virtual bool | event (QEvent * e ) override |
| virtual void | mouseMoveEvent (QMouseEvent * e ) override |
| virtual void | mousePressEvent (QMouseEvent * e ) override |
| virtual void | mouseReleaseEvent (QMouseEvent * e ) override |
| virtual void | paintEvent (QPaintEvent * pe ) override |
| virtual void | resizeEvent (QResizeEvent * e ) override |
| virtual void | sliderChange (QAbstractSlider::SliderChange change ) override |
QDial is used when the user needs to control a value within a program-definable range, and the range either wraps around (for example, with angles measured from 0 to 359 degrees) or the dialog layout needs a square widget.
由於 QDial 繼承自 QAbstractSlider , the dial behaves in a similar way to a slider 。當 wrapping () is false (the default setting) there is no real difference between a slider and a dial. They both share the same signals, slots and member functions. Which one you use depends on the expectations of your users and on the type of application.
The dial initially emits valueChanged () signals continuously while the slider is being moved; you can make it emit the signal less often by disabling the tracking property. The sliderMoved () signal is emitted continuously even when tracking is disabled.
The dial also emits sliderPressed () 和 sliderReleased () signals when the mouse button is pressed and released. Note that the dial's value can change without these signals being emitted since the keyboard and wheel can also be used to change the value.
Unlike the slider, QDial attempts to draw a "nice" number of notches rather than one per line step. If possible, the number of notches drawn is one per line step, but if there aren't enough pixels to draw every one, QDial will skip notches to try and draw a uniform set (e.g. by drawing every second or third notch).
Like the slider, the dial makes the QAbstractSlider function setValue () available as a slot.
The dial's keyboard interface is fairly simple: The left / up and right / down arrow keys adjust the dial's value by the defined singleStep , Page Up and Page Down by the defined pageStep ，和 首頁 and End keys set the value to the defined minimum and maximum 值。
If you are using the mouse wheel to adjust the dial, the increment value is determined by the lesser value of wheelScrollLines multiplied by singleStep ，和 pageStep .
另請參閱 QScrollBar , QSpinBox , QSlider , GUI 設計手冊：滑塊 ，和 滑塊範例 .
This property holds the current notch size
The notch size is in range control units, not pixels, and if possible it is a multiple of singleStep () that results in an on-screen notch size near notchTarget ().
默認情況下，此特性擁有 1 值。
訪問函數：
| int | notchSize () const |
另請參閱 notchTarget () 和 singleStep ().
This property holds the target number of pixels between notches
The notch target is the number of pixels QDial attempts to put between each notch.
The actual size may differ from the target size.
The default notch target is 3.7 pixels.
訪問函數：
| qreal | notchTarget () const |
| void | setNotchTarget (double target ) |
This property holds whether the notches are shown
若特性為
true
, a series of notches are drawn around the dial to indicate the range of values available; otherwise no notches are shown.
By default, this property is disabled.
訪問函數：
| bool | notchesVisible () const |
| void | setNotchesVisible (bool visible ) |
This property holds whether wrapping is enabled
If true, wrapping is enabled; otherwise some space is inserted at the bottom of the dial to separate the ends of the range of valid values.
If enabled, the arrow can be oriented at any angle on the dial. If disabled, the arrow will be restricted to the upper part of the dial; if it is rotated into the space at the bottom of the dial, it will be clamped to the closest end of the valid range of values.
默認情況下此特性為
false
.
訪問函數：
| bool | wrapping () const |
| void | setWrapping (bool on ) |
Constructs a dial.
The parent 自變量被發送給 QAbstractSlider 構造函數。
[虛擬]
QDial::
~QDial
()
Destroys the dial.
[override virtual protected]
bool
QDial::
event
(
QEvent
*
e
)
重實現： QAbstractSlider::event (QEvent *e).
[protected]
void
QDial::
initStyleOption
(
QStyleOptionSlider
*
option
) const
初始化 option 采用值來自此 QDial 。此方法對子類是有用的，當需要 QStyleOptionSlider ，但不希望自己填充所有信息。
另請參閱 QStyleOption::initFrom ().
[override virtual]
QSize
QDial::
minimumSizeHint
() const
重實現訪問函數為特性： QWidget::minimumSizeHint .
[override virtual protected]
void
QDial::
mouseMoveEvent
(
QMouseEvent
*
e
)
重實現： QWidget::mouseMoveEvent (QMouseEvent *event).
[override virtual protected]
void
QDial::
mousePressEvent
(
QMouseEvent
*
e
)
重實現： QWidget::mousePressEvent (QMouseEvent *event).
[override virtual protected]
void
QDial::
mouseReleaseEvent
(
QMouseEvent
*
e
)
重實現： QWidget::mouseReleaseEvent (QMouseEvent *event).
[override virtual protected]
void
QDial::
paintEvent
(
QPaintEvent
*
pe
)
重實現： QWidget::paintEvent (QPaintEvent *event).
[override virtual protected]
void
QDial::
resizeEvent
(
QResizeEvent
*
e
)
重實現： QWidget::resizeEvent (QResizeEvent *event).
[override virtual]
QSize
QDial::
sizeHint
() const
重實現訪問函數為特性： QWidget::sizeHint .
[override virtual protected]
void
QDial::
sliderChange
(
QAbstractSlider::SliderChange
change
)
重實現： QAbstractSlider::sliderChange (QAbstractSlider::SliderChange change).