QQuickFramebufferObject Class

QQuickFramebufferObject class is a convenience class for integrating OpenGL rendering using a framebuffer object (FBO) with Qt Quick. 更多...

Header: #include <QQuickFramebufferObject>
qmake: QT += quick
Since: Qt 5.2
继承: QQuickItem

公共类型

特性

公共函数

QQuickFramebufferObject (QQuickItem * parent = nullptr)
virtual QQuickFramebufferObject::Renderer * createRenderer () const = 0
bool mirrorVertically () const
void setMirrorVertically (bool enable )
void setTextureFollowsItemSize (bool follows )
bool textureFollowsItemSize () const

重实现公共函数

virtual bool isTextureProvider () const override
virtual void releaseResources () override
virtual QSGTextureProvider * textureProvider () const override

信号

静态公共成员

const QMetaObject staticMetaObject

额外继承成员

详细描述

QQuickFramebufferObject class is a convenience class for integrating OpenGL rendering using a framebuffer object (FBO) with Qt Quick.

On most platforms, the rendering will occur on a dedicated thread . For this reason, the QQuickFramebufferObject class enforces a strict separation between the item implementation and the FBO rendering. All item logic, such as properties and UI-related helper functions needed by QML should be located in a QQuickFramebufferObject class subclass. Everything that relates to rendering must be located in the QQuickFramebufferObject::Renderer 类。

To avoid race conditions and read/write issues from two threads it is important that the renderer and the item never read or write shared variables. Communication between the item and the renderer should primarily happen via the QQuickFramebufferObject::Renderer::synchronize () function. This function will be called on the render thread while the GUI thread is blocked.

Using queued connections or events for communication between item and renderer is also possible.

Both the Renderer and the FBO are memory managed internally.

To render into the FBO, the user should subclass the Renderer class and reimplement its Renderer::render () function. The Renderer subclass is returned from createRenderer ().

The size of the FBO will by default adapt to the size of the item. If a fixed size is preferred, set textureFollowsItemSize to false and return a texture of your choosing from QQuickFramebufferObject::Renderer::createFramebufferObject ().

Starting Qt 5.4, the QQuickFramebufferObject class is a texture provider and can be used directly in ShaderEffects and other classes that consume texture providers.

另请参阅 场景图形 - 渲染 FBO (帧缓冲对象) and 场景图形和渲染 .

特性文档编制

mirrorVertically : bool

This property controls if the size of the FBO's contents should be mirrored vertically when drawing. This allows easy integration of third-party rendering code that does not follow the standard expectations.

默认值为 false .

This property was introduced in Qt 5.6.

访问函数:

bool mirrorVertically () const
void setMirrorVertically (bool enable )

通知信号:

void mirrorVerticallyChanged ( bool )

textureFollowsItemSize : bool

This property controls if the size of the FBO's texture should follow the dimensions of the QQuickFramebufferObject item. When this property is false, the FBO will be created once the first time it is displayed. If it is set to true, the FBO will be recreated every time the dimensions of the item change.

默认值为 true .

访问函数:

bool textureFollowsItemSize () const
void setTextureFollowsItemSize (bool follows )

通知信号:

void textureFollowsItemSizeChanged ( bool )

成员函数文档编制

QQuickFramebufferObject:: QQuickFramebufferObject ( QQuickItem * parent = nullptr)

构造新 QQuickFramebufferObject 采用父级 parent .

[pure virtual] QQuickFramebufferObject::Renderer *QQuickFramebufferObject:: createRenderer () const

Reimplement this function to create a renderer used to render into the FBO.

This function will be called on the rendering thread while the GUI thread is blocked.

[override virtual] bool QQuickFramebufferObject:: isTextureProvider () const

Reimplemented from QQuickItem::isTextureProvider ().

[override virtual] void QQuickFramebufferObject:: releaseResources ()

Reimplemented from QQuickItem::releaseResources ().

[override virtual] QSGTextureProvider *QQuickFramebufferObject:: textureProvider () const

Reimplemented from QQuickItem::textureProvider ().