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QQuickWindow 类

QQuickWindow 类提供用于显示图形 QML 场景的窗口。 更多...

头： #include <QQuickWindow>
CMake: find_package(Qt6 REQUIRED COMPONENTS Quick)
target_link_libraries(mytarget PRIVATE Qt6::Quick)
qmake: QT += quick
实例化： Window
继承： QWindow
继承者： QQuickView

公共类型

struct GraphicsStateInfo
enum CreateTextureOption { TextureHasAlphaChannel, TextureHasMipmaps, TextureOwnsGLTexture, TextureCanUseAtlas, TextureIsOpaque }
flags CreateTextureOptions
enum RenderStage { BeforeSynchronizingStage, AfterSynchronizingStage, BeforeRenderingStage, AfterRenderingStage, AfterSwapStage, NoStage }
enum SceneGraphError { ContextNotAvailable }
enum TextRenderType { QtTextRendering, NativeTextRendering }

特性

公共函数

QQuickWindow (QWindow * parent = nullptr)
QQuickWindow (QQuickRenderControl * control )
virtual ~QQuickWindow () override
QQuickItem * activeFocusItem () const
void beginExternalCommands ()
QColor color () const
QQuickItem * contentItem () const
QSGImageNode * createImageNode () const
QSGNinePatchNode * createNinePatchNode () const
QSGRectangleNode * createRectangleNode () const
QSGTexture * createTextureFromImage (const QImage & image , QQuickWindow::CreateTextureOptions options ) const
QSGTexture * createTextureFromImage (const QImage & image ) const
qreal effectiveDevicePixelRatio () const
void endExternalCommands ()
QImage grabWindow ()
QQuickGraphicsConfiguration graphicsConfiguration () const
QQuickGraphicsDevice graphicsDevice () const
const QQuickWindow::GraphicsStateInfo & graphicsStateInfo ()
QQmlIncubationController * incubationController () const
bool isPersistentGraphics () const
bool isPersistentSceneGraph () const
bool isSceneGraphInitialized () const
QQuickRenderTarget renderTarget () const
QSGRendererInterface * rendererInterface () const
void scheduleRenderJob (QRunnable * job , QQuickWindow::RenderStage stage )
void setColor (const QColor & color )
void setGraphicsConfiguration (const QQuickGraphicsConfiguration & config )
void setGraphicsDevice (const QQuickGraphicsDevice & device )
void setPersistentGraphics (bool persistent )
void setPersistentSceneGraph (bool persistent )
void setRenderTarget (const QQuickRenderTarget & target )

重实现公共函数

virtual QAccessibleInterface * accessibleRoot () const override

公共槽

void releaseResources ()
void update ()

信号

void activeFocusItemChanged ()
void afterAnimating ()
void afterFrameEnd ()
void afterRenderPassRecording ()
void afterRendering ()
void afterSynchronizing ()
void beforeFrameBegin ()
void beforeRenderPassRecording ()
void beforeRendering ()
void beforeSynchronizing ()
void colorChanged (const QColor &)
void frameSwapped ()
void sceneGraphAboutToStop ()
void sceneGraphError (QQuickWindow::SceneGraphError error , const QString & message )
void sceneGraphInitialized ()
void sceneGraphInvalidated ()

静态公共成员

QSGRendererInterface::GraphicsApi graphicsApi ()
bool hasDefaultAlphaBuffer ()
QString sceneGraphBackend ()
void setDefaultAlphaBuffer (bool useAlpha )
void setGraphicsApi (QSGRendererInterface::GraphicsApi api )
void setSceneGraphBackend (const QString & backend )
void setTextRenderType (QQuickWindow::TextRenderType renderType )
QQuickWindow::TextRenderType textRenderType ()

重实现保护函数

virtual void closeEvent (QCloseEvent * e ) override
virtual bool event (QEvent * event ) override
virtual void exposeEvent (QExposeEvent *) override
virtual void focusInEvent (QFocusEvent * ev ) override
virtual void focusOutEvent (QFocusEvent * ev ) override
virtual void hideEvent (QHideEvent *) override
virtual void keyPressEvent (QKeyEvent * e ) override
virtual void keyReleaseEvent (QKeyEvent * e ) override
virtual void mouseDoubleClickEvent (QMouseEvent * event ) override
virtual void mouseMoveEvent (QMouseEvent * event ) override
virtual void mousePressEvent (QMouseEvent * event ) override
virtual void mouseReleaseEvent (QMouseEvent * event ) override
virtual void resizeEvent (QResizeEvent * ev ) override
virtual void showEvent (QShowEvent *) override
virtual void tabletEvent (QTabletEvent * event ) override
virtual void wheelEvent (QWheelEvent * event ) override

详细描述

QQuickWindow 提供与 QQuickItems 场景交互和显示，所需的图形场景管理。

QQuickWindow 始终拥有单个不可见根项。要把项添加到此窗口，将项表示成根项 (或场景中的现有项)。

为轻松从 QML 文件显示场景，见 QQuickView .

渲染

QQuickWindow uses a scene graph to represent what needs to be rendered. This scene graph is disconnected from the QML scene and potentially lives in another thread, depending on the platform implementation. Since the rendering scene graph lives independently from the QML scene, it can also be completely released without affecting the state of the QML scene.

The sceneGraphInitialized () signal is emitted on the rendering thread before the QML scene is rendered to the screen for the first time. If the rendering scene graph has been released, the signal will be emitted again before the next frame is rendered. A visible, on-screen QQuickWindow is driven internally by a render loop , of which there are multiple implementations provided in the scene graph. For details on the scene graph rendering process, see Qt Quick 场景图形 .

By default, a QQuickWindow renders using an accelerated 3D graphics API, such as OpenGL or Vulkan. See 场景图形适配 for a detailed overview of scene graph backends and the supported graphics APIs.

警告： It is crucial that graphics operations and interaction with the scene graph happens exclusively on the rendering thread, primarily during the updatePaintNode() phase.

警告： As many of the signals related to rendering are emitted from the rendering thread, connections should be made using Qt::DirectConnection .

Integration with Accelerated 3D Graphics APIs

It is possible to integrate OpenGL, Vulkan, Metal, or Direct3D 11 calls directly into the QQuickWindow, as long as the QQuickWindow and the underlying scene graph is rendering using the same API. To access native graphics objects, such as device or context object handles, use QSGRendererInterface . An instance of QSGRendererInterface is queriable from QQuickWindow by calling rendererInterface (). The enablers for this integration are the beforeRendering (), beforeRenderPassRecording (), afterRenderPassRecording (), and related signals. These allow rendering underlays or overlays. Alternatively, QNativeInterface::QSGOpenGLTexture , QNativeInterface::QSGVulkanTexture , and other similar classes allow wrapping an existing native texture or image object in a QSGTexture that can then be used with the scene graph.

Rendering without Acceleration

A limited, pure software based rendering path is available as well. With the software backend, a number of Qt Quick features are not available, QML items relying on these will not be rendered at all. At the same time, this allows QQuickWindow to be functional even on systems where there is no 3D graphics API available at all. See Qt Quick Software Adaptation 了解更多细节。

Redirected Rendering

A QQuickWindow is not necessarily backed by a native window on screen. The rendering can be redirected to target a custom render target, such as a given native texture. This is achieved in combination with the QQuickRenderControl class, and functions such as setRenderTarget (), setGraphicsDevice ()，和 setGraphicsConfiguration ().

In this case, the QQuickWindow represents the scene, and provides the intrastructure for rendering a frame. It will not be backed by a render loop and a native window. Instead, in this case the application drives rendering, effectively substituting for the render loops. This allows generating image sequences, rendering into textures for use in external 3D engines, or rendering Qt Quick content within a VR environment.

资源管理

QML will try to cache images and scene graph nodes to improve performance, but in some low-memory scenarios it might be required to aggressively release these resources. The releaseResources () function can be used to force the clean up of certain resources, especially resource that are cached and can be recreated later when needed again.

Additionally, calling releaseResources () may result in releasing the entire scene graph and the associated graphics resources. The sceneGraphInvalidated () signal will be emitted when this happens. This behavior is controlled by the setPersistentGraphics () 和 setPersistentSceneGraph () 函数。

注意： 所有带有 QSG 前缀的类只应用于场景图形渲染线程。见 场景图形和渲染 了解更多信息。

曝光和可见性

When a QQuickWindow instance is deliberately hidden with hide () or setVisible(false), it will stop rendering and its scene graph and graphics context might be released as well. This depends on the settings configured by setPersistentGraphics () 和 setPersistentSceneGraph (). The behavior in this respect is identical to explicitly calling the releaseResources () function. A window can become not exposed, in other words non-renderable, by other means as well. This depends on the platform and windowing system. For example, on Windows minimizing a window makes it stop rendering. On macOS fully obscuring a window by other windows on top triggers the same. On Linux/X11, the behavior is dependent on the window manager.

OpenGL Context and Surface Formats

While it is possible to specify a QSurfaceFormat for every QQuickWindow by calling the member function setFormat (), windows may also be created from QML by using the Window and ApplicationWindow elements. In this case there is no C++ code involved in the creation of the window instance, yet applications may still wish to set certain surface format values, for example to request a given OpenGL version or profile. Such applications can call the static function QSurfaceFormat::setDefaultFormat () at startup. The specified format will be used for all Quick windows created afterwards.

Vulkan Instance

When using Vulkan, a QQuickWindow is automatically associated with a QVulkanInstance that is created and managed internally by the scene graph. This way most applications do not need to worry about having a VkInstance available since it all happens automatically. In advanced cases an application may wish to create its own QVulkanInstance , in order to configure it in a specific way. That is possible as well. Calling setVulkanInstance () on the QQuickWindow right after construction, before making it visible, leads to using the application-supplied QVulkanInstance (and the underlying VkInstance ). When redirecting via QQuickRenderControl , there is no QVulkanInstance provided automatically, but rather the application is expected to provide its own and associate it with the QQuickWindow.

Graphics Contexts and Devices

When the scene graph is initialized, which typically happens when the window becomes exposed or, in case of redirected rendering, initialization is performed via QQuickRenderControl , the context or device objects necessary for rendering are created automatically. This includes OpenGL contexts, Direct3D devices and device contexts, Vulkan and Metal devices. These are also queriable by application code afterwards via QSGRendererInterface . When using the basic render loop, which performs all rendering on the GUI thread, the same context or device is used with all visible QQuickWindows. The threaded render loop uses a dedicated context or device object for each rendering thread, and so for each QQuickWindow. With some graphics APIs, there is a degree of customizability provided via setGraphicsConfiguration (). This makes it possible, for example, to specify the list of Vulkan extensions to enable on the VkDevice . Alternatively, it is also possible to provide a set of existing context or device objects for use by the QQuickWindow, instead of letting it construct its own. This is achieved through setGraphicsDevice ().

另请参阅 QQuickView , QQuickRenderControl , QQuickRenderTarget , QQuickGraphicsDevice , QQuickGraphicsConfiguration ，和 QSGRendererInterface .

成员类型文档编制

enum QQuickWindow:: CreateTextureOption
flags QQuickWindow:: CreateTextureOptions

The CreateTextureOption enums are used to customize a texture is wrapped.

常量 值 描述
QQuickWindow::TextureHasAlphaChannel 0x0001 The texture has an alpha channel and should be drawn using blending.
QQuickWindow::TextureHasMipmaps 0x0002 The texture has mipmaps and can be drawn with mipmapping enabled.
QQuickWindow::TextureOwnsGLTexture 0x0004 As of Qt 6.0, this flag is not used in practice and is ignored. Native graphics resource ownership is not transferable to the wrapping QSGTexture , because Qt Quick may not have the necessary details on how such an object and the associated memory should be freed.
QQuickWindow::TextureCanUseAtlas 0x0008 The image can be uploaded into a texture atlas.
QQuickWindow::TextureIsOpaque 0x0010 The texture will return false for QSGTexture::hasAlphaChannel () and will not be blended. This flag was added in Qt 5.6.

CreateTextureOptions 类型是 typedef 对于 QFlags <CreateTextureOption>. It stores an OR combination of CreateTextureOption values.

enum QQuickWindow:: RenderStage

常量 值 描述
QQuickWindow::BeforeSynchronizingStage 0 在同步前。
QQuickWindow::AfterSynchronizingStage 1 在同步后。
QQuickWindow::BeforeRenderingStage 2 在渲染前。
QQuickWindow::AfterRenderingStage 3 在渲染后。
QQuickWindow::AfterSwapStage 4 在帧交换后。
QQuickWindow::NoStage 5 尽快。该值在 Qt 5.6 添加。

另请参阅 场景图形和渲染 .

enum QQuickWindow:: SceneGraphError

此枚举描述的错误在 sceneGraphError () 信号。

常量 值 描述
QQuickWindow::ContextNotAvailable 1 graphics context creation failed. This typically means that no suitable OpenGL implementation was found, for example because no graphics drivers are installed and so no OpenGL 2 support is present. On mobile and embedded boards that use OpenGL ES such an error is likely to indicate issues in the windowing system integration and possibly an incorrect configuration of Qt.

enum QQuickWindow:: TextRenderType

此枚举描述 Qt Quick 中像文本元素的默认渲染类型 ( Text , TextInput ，等)。

Select NativeTextRendering if you prefer text to look native on the target platform and do not require advanced features such as transformation of the text. Using such features in combination with the NativeTextRendering render type will lend poor and sometimes pixelated results.

常量 值 描述
QQuickWindow::QtTextRendering 0 使用 Qt 自己的光栅化算法。
QQuickWindow::NativeTextRendering 1 对文本使用 OS (操作系统) 的本机光栅化器。

特性文档编制

[read-only] activeFocusItem : QQuickItem * const

此特性保持的项目前拥有活动聚焦或 null 若没有项具有活动聚焦。

访问函数：

QQuickItem * activeFocusItem () const

通知程序信号：

void activeFocusItemChanged ()

另请参阅 QQuickItem::forceActiveFocus () 和 Qt Quick 中的键盘聚焦 .

color : QColor

This property holds the color used to clear the color buffer at the beginning of each frame.

By default, the clear color is white.

访问函数：

QColor color () const
void setColor (const QColor & color )

通知程序信号：

void colorChanged (const QColor &)

另请参阅 setDefaultAlphaBuffer ().

[read-only] contentItem : QQuickItem * const

此特性保持场景的不可见根项。

A QQuickWindow always has a single invisible root item containing all of its content. To add items to this window, reparent the items to the contentItem or to an existing item in the scene.

访问函数：

QQuickItem * contentItem () const

transientParent : QWindow * const

This property holds the window for which this window is a transient pop-up.

This is a hint to the window manager that this window is a dialog or pop-up on behalf of the transient parent, which may be any kind of QWindow .

In order to cause the window to be centered above its transient parent by default, depending on the window manager, it may also be necessary to set the flags property with a suitable Qt::WindowType (譬如 Qt::Dialog ).

另请参阅 parent ().

成员函数文档编制

[explicit] QQuickWindow:: QQuickWindow ( QWindow * parent = nullptr)

构造窗口为显示 QML 场景采用父级窗口 parent .

[explicit] QQuickWindow:: QQuickWindow ( QQuickRenderControl * control )

构造窗口为显示 QML 场景，渲染的控制是通过 control 对象。请参考 QQuickRenderControl 文档编制了解更多信息。

[override virtual] QQuickWindow:: ~QQuickWindow ()

销毁窗口。

[override virtual] QAccessibleInterface *QQuickWindow:: accessibleRoot () const

返回此窗口的可访问接口，或 0 若无法创建这种接口。

[signal] void QQuickWindow:: afterAnimating ()

此信号在 GUI 线程中发射，在请求渲染线程以履行场景图形的同步前。

Unlike the other similar signals, this one is emitted on the GUI thread instead of the render thread. It can be used to synchronize external animation systems with the QML content. At the same time this means that this signal is not suitable for triggering graphics operations.

[signal, since 6.0] void QQuickWindow:: afterFrameEnd ()

This signal is emitted when the scene graph has submitted a frame. This is emitted after all other related signals, such as afterRendering (). It is the last signal that is emitted by the scene graph rendering thread when rendering a frame.

注意： 不像 frameSwapped (), this signal is guaranteed to be emitted also when the Qt Quick output is redirected via QQuickRenderControl .

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

该函数在 Qt 6.0 引入。

另请参阅 beforeFrameBegin () 和 rendererInterface ().

[signal] void QQuickWindow:: afterRenderPassRecording ()

This signal is emitted after the scenegraph has recorded the commands for its main render pass, but the pass is not yet finalized on the command buffer.

This signal is emitted earlier than afterRendering (), and it guarantees that not just the frame but also the recording of the scenegraph's main render pass is still active. This allows inserting commands without having to generate an entire, separate render pass (which would typically clear the attached images). The native graphics objects can be queried via QSGRendererInterface .

注意： Resource updates (uploads, copies) typically cannot be enqueued from within a render pass. Therefore, more complex user rendering will need to connect to both beforeRendering () 和此信号。

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

另请参阅 rendererInterface ().

[signal] void QQuickWindow:: afterRendering ()

The signal is emitted after scene graph has added its commands to the command buffer, which is not yet submitted to the graphics queue. If desired, the slot function connected to this signal can query native resources, like the command buffer, before via QSGRendererInterface . Note however that the render pass (or passes) are already recorded at this point and it is not possible to add more commands within the scenegraph's pass. Instead, use afterRenderPassRecording () for that. This signal has therefore limited use in Qt 6, unlike in Qt 5. Rather, it is the combination of beforeRendering () 和 beforeRenderPassRecording ()，或 beforeRendering () 和 afterRenderPassRecording (), that is typically used to achieve under- or overlaying of the custom rendering.

When using OpenGL, the QOpenGLContext used for rendering by the scene graph will be bound at this point.

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

警告： When using OpenGL, be aware that setting OpenGL 3.x or 4.x specific states and leaving these enabled or set to non-default values when returning from the connected slot can interfere with the scene graph's rendering.

另请参阅 rendererInterface (), 场景图形 - QML 下的 OpenGL , 场景图形 - 在 QML 下的 Metal , 场景图形 - 在 QML 下的 Vulkan ，和 场景图形 - 在 QML 下的 Direct3D 11 .

[signal] void QQuickWindow:: afterSynchronizing ()

此信号被发射，在场景图形与 QML 状态同步后。

This signal can be used to do preparation required after calls to QQuickItem::updatePaintNode (), while the GUI thread is still locked.

When using OpenGL, the QOpenGLContext used for rendering by the scene graph will be bound at this point.

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

警告： When using OpenGL, be aware that setting OpenGL 3.x or 4.x specific states and leaving these enabled or set to non-default values when returning from the connected slot can interfere with the scene graph's rendering.

[signal, since 6.0] void QQuickWindow:: beforeFrameBegin ()

This signal is emitted before the scene graph starts preparing the frame. This precedes signals like beforeSynchronizing () 或 beforeRendering (). It is the earliest signal that is emitted by the scene graph rendering thread when starting to prepare a new frame.

This signal is relevant for lower level graphics frameworks that need to execute certain operations, such as resource cleanup, at a stage where Qt Quick has not initiated the recording of a new frame via the underlying rendering hardware interface APIs.

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

该函数在 Qt 6.0 引入。

另请参阅 afterFrameEnd () 和 rendererInterface ().

[signal] void QQuickWindow:: beforeRenderPassRecording ()

This signal is emitted before the scenegraph starts recording commands for the main render pass. (Layers have their own passes and are fully recorded by the time this signal is emitted.) The render pass is already active on the command buffer when the signal is emitted.

This signal is emitted later than beforeRendering () and it guarantees that not just the frame, but also the recording of the scenegraph's main render pass is active. This allows inserting commands without having to generate an entire, separate render pass (which would typically clear the attached images). The native graphics objects can be queried via QSGRendererInterface .

注意： Resource updates (uploads, copies) typically cannot be enqueued from within a render pass. Therefore, more complex user rendering will need to connect to both beforeRendering () 和此信号。

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

另请参阅 rendererInterface ().

[signal] void QQuickWindow:: beforeRendering ()

This signal is emitted after the preparations for the frame have been done, meaning there is a command buffer in recording mode, where applicable. If desired, the slot function connected to this signal can query native resources like the command before via QSGRendererInterface . Note however that the recording of the main render pass is not yet started at this point and it is not possible to add commands within that pass. Starting a pass means clearing the color, depth, and stencil buffers so it is not possible to achieve an underlay type of rendering by just connecting to this signal. Rather, connect to beforeRenderPassRecording (). However, connecting to this signal is still important if the recording of copy type of commands is desired since those cannot be enqueued within a render pass.

When using OpenGL, the QOpenGLContext used for rendering by the scene graph will be bound at this point.

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

警告： When using OpenGL, be aware that setting OpenGL 3.x or 4.x specific states and leaving these enabled or set to non-default values when returning from the connected slot can interfere with the scene graph's rendering.

另请参阅 rendererInterface (), 场景图形 - QML 下的 OpenGL , 场景图形 - 在 QML 下的 Metal , 场景图形 - 在 QML 下的 Vulkan ，和 场景图形 - 在 QML 下的 Direct3D 11 .

[signal] void QQuickWindow:: beforeSynchronizing ()

This signal is emitted before the scene graph is synchronized with the QML state.

Even though the signal is emitted from the scene graph rendering thread, the GUI thread is guaranteed to be blocked, like it is in QQuickItem::updatePaintNode (). Therefore, it is safe to access GUI thread thread data in a slot or lambda that is connected with Qt::DirectConnection .

This signal can be used to do any preparation required before calls to QQuickItem::updatePaintNode ().

When using OpenGL, the QOpenGLContext used for rendering by the scene graph will be bound at this point.

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

警告： When using OpenGL, be aware that setting OpenGL 3.x or 4.x specific states and leaving these enabled or set to non-default values when returning from the connected slot can interfere with the scene graph's rendering.

void QQuickWindow:: beginExternalCommands ()

When mixing raw graphics (OpenGL, Vulkan, Metal, etc.) commands with scene graph rendering, it is necessary to call this function before recording commands to the command buffer used by the scene graph to render its main render pass. This is to avoid clobbering state.

在实践中，此函数的调用经常是从槽连接到 beforeRenderPassRecording () 或 afterRenderPassRecording () 信号。

The function does not need to be called when recording commands to the application's own command buffer (such as, a VkCommandBuffer or MTLCommandBuffer + MTLRenderCommandEncoder created and managed by the application, not retrieved from the scene graph). With graphics APIs where no native command buffer concept is exposed (OpenGL, Direct 3D 11), beginExternalCommands() and endExternalCommands () together provide a replacement for the Qt 5 resetOpenGLState() function.

调用此函数和 endExternalCommands () 没有必要在 render () implementation of a QSGRenderNode 因为场景图形会为渲染节点，隐式履行必要步骤。

Native graphics objects (such as, graphics device, command buffer or encoder) are accessible via QSGRendererInterface::getResource ().

警告： Watch out for the fact that QSGRendererInterface::CommandListResource may return a different object between beginExternalCommands() - endExternalCommands (). This can happen when the underlying implementation provides a dedicated secondary command buffer for recording external graphics commands within a render pass. Therefore, always query CommandListResource after calling this function. Do not attempt to reuse an object from an earlier query.

注意： When the scenegraph is using OpenGL, pay attention to the fact that the OpenGL state in the context can have arbitrary settings, and this function does not perform any resetting of the state back to defaults.

另请参阅 endExternalCommands () 和 QQuickOpenGLUtils::resetOpenGLState ().

[override virtual protected] void QQuickWindow:: closeEvent ( QCloseEvent * e )

重实现： QWindow::closeEvent (QCloseEvent *ev).

QSGImageNode *QQuickWindow:: createImageNode () const

创建简单图像节点。当场景图形未初始化时，返回值为 null。

This is cross-backend alternative to constructing a QSGSimpleTextureNode 直接。

另请参阅 QSGImageNode .

QSGNinePatchNode *QQuickWindow:: createNinePatchNode () const

创建 9 个补丁节点。当场景图形未初始化时，返回值为 null。

QSGRectangleNode *QQuickWindow:: createRectangleNode () const

创建简单矩形节点。当场景图形未初始化时，返回值为 null。

This is cross-backend alternative to constructing a QSGSimpleRectNode 直接。

另请参阅 QSGRectangleNode .

QSGTexture *QQuickWindow:: createTextureFromImage (const QImage & image , QQuickWindow::CreateTextureOptions options ) const

创建新的 QSGTexture 从供给 image 。若图像拥有 Alpha 通道，相应纹理将拥有 Alpha 通道。

The caller of the function is responsible for deleting the returned texture. The underlying native texture object is then destroyed together with the QSGTexture .

当 options 包含 TextureCanUseAtlas ，引擎可以将图像放入纹理图集。图集中的纹理需要依赖 QSGTexture::normalizedTextureSubRect () 为它们的几何体且不支持 QSGTexture::Repeat 。其它值来自 CreateTextureOption 被忽略。

当 options 包含 TextureIsOpaque , the engine will create an RGB texture which returns false for QSGTexture::hasAlphaChannel (). Opaque textures will in most cases be faster to render. When this flag is not set, the texture will have an alpha channel based on the image's format.

当 options 包含 TextureHasMipmaps , the engine will create a texture which can use mipmap filtering. Mipmapped textures can not be in an atlas.

When the scene graph uses OpenGL, the returned texture will be using GL_TEXTURE_2D 作纹理目标和 GL_RGBA as internal format. With other graphics APIs, the texture format is typically RGBA8 。重实现 QSGTexture 能创建具有不同参数的纹理。

警告： 此函数将返回 0 若场景图形尚未初始化。

警告： The returned texture is not memory managed by the scene graph and must be explicitly deleted by the caller on the rendering thread. This is achieved by deleting the texture from a QSGNode destructor or by using deleteLater () in the case where the texture already has affinity to the rendering thread.

可以从任何线程中调用此函数。

另请参阅 sceneGraphInitialized () 和 QSGTexture .

QSGTexture *QQuickWindow:: createTextureFromImage (const QImage & image ) const

这是重载函数。

qreal QQuickWindow:: effectiveDevicePixelRatio () const

返回用于此窗口的设备像素比率。

这不同于 QWindow::devicePixelRatio () in that it supports redirected rendering via QQuickRenderControl and QQuickRenderTarget 。当使用 QQuickRenderControl ， QQuickWindow is often not fully created, meaning it is never shown and there is no underlying native window created in the windowing system. As a result, querying properties like the device pixel ratio cannot give correct results. This function takes into account both QQuickRenderControl::renderWindowFor () 和 QQuickRenderTarget::devicePixelRatio (). When no redirection is in effect, the result is same as QWindow::devicePixelRatio ().

另请参阅 QQuickRenderControl , QQuickRenderTarget , setRenderTarget ()，和 QWindow::devicePixelRatio ().

void QQuickWindow:: endExternalCommands ()

When mixing raw graphics (OpenGL, Vulkan, Metal, etc.) commands with scene graph rendering, it is necessary to call this function after recording commands to the command buffer used by the scene graph to render its main render pass. This is to avoid clobbering state.

在实践中，此函数的调用经常是从槽连接到 beforeRenderPassRecording () 或 afterRenderPassRecording () 信号。

The function does not need to be called when recording commands to the application's own command buffer (such as, a VkCommandBuffer or MTLCommandBuffer + MTLRenderCommandEncoder created and managed by the application, not retrieved from the scene graph). With graphics APIs where no native command buffer concept is exposed (OpenGL, Direct 3D 11), beginExternalCommands () and endExternalCommands() together provide a replacement for the Qt 5 resetOpenGLState() function.

调用此函数和 beginExternalCommands () 没有必要在 render () implementation of a QSGRenderNode 因为场景图形会为渲染节点，隐式履行必要步骤。

另请参阅 beginExternalCommands () 和 QQuickOpenGLUtils::resetOpenGLState ().

[override virtual protected] bool QQuickWindow:: event ( QEvent * event )

重实现： QWindow::event (QEvent *ev).

[override virtual protected] void QQuickWindow:: exposeEvent ( QExposeEvent *)

重实现： QWindow::exposeEvent (QExposeEvent *ev).

[override virtual protected] void QQuickWindow:: focusInEvent ( QFocusEvent * ev )

重实现： QWindow::focusInEvent (QFocusEvent *ev).

[override virtual protected] void QQuickWindow:: focusOutEvent ( QFocusEvent * ev )

重实现： QWindow::focusOutEvent (QFocusEvent *ev).

[signal] void QQuickWindow:: frameSwapped ()

This signal is emitted when a frame has been queued for presenting. With vertical synchronization enabled the signal is emitted at most once per vsync interval in a continuously animating scene.

此信号将从场景图形渲染线程中发射。

QImage QQuickWindow:: grabWindow ()

Grabs the contents of the window and returns it as an image.

It is possible to call the grabWindow() function when the window is not visible. This requires that the window is created and has a valid size and that no other QQuickWindow instances are rendering in the same process.

注意： When using this window in combination with QQuickRenderControl , the result of this function is an empty image, unless the software backend is in use. This is because when redirecting the output to an application-managed graphics resource (such as, a texture) by using QQuickRenderControl and setRenderTarget (), the application is better suited for managing and executing an eventual read back operation, since it is in full control of the resource to begin with.

警告： Calling this function will cause performance problems.

警告： 只可以从 GUI 线程是调用此函数。

[static, since 6.0] QSGRendererInterface::GraphicsApi QQuickWindow:: graphicsApi ()

Returns the graphics API that would be used by the scene graph if it was initialized at this point in time.

The standard way to query the API used by the scene graph is to use QSGRendererInterface::graphicsApi () once the scene graph has initialized, for example when or after the sceneGraphInitialized () signal is emitted. In that case one gets the true, real result, because then it is known that everything was initialized correctly using that graphics API.

This is not always convenient. If the application needs to set up external frameworks, or needs to work with setGraphicsDevice () in a manner that depends on the scene graph's built in API selection logic, it is not always feasiable to defer such operations until after the QQuickWindow has been made visible or QQuickRenderControl::initialize () 被调用。

Therefore, this static function is provided as a counterpart to setGraphicsApi (): it can be called at any time, and the result reflects what API the scene graph would choose if it was initialized at the point of the call.

注意： This static function is intended to be called on the main (GUI) thread only. For querying the API when rendering, use QSGRendererInterface since that object lives on the render thread.

注意： This function does not take scene graph backends into account.

该函数在 Qt 6.0 引入。

另请参阅 setGraphicsApi ().

[since 6.0] QQuickGraphicsConfiguration QQuickWindow:: graphicsConfiguration () const

返回 QQuickGraphicsDevice passed to setGraphicsDevice (), or a default constructed one otherwise

该函数在 Qt 6.0 引入。

另请参阅 setGraphicsConfiguration ().

[since 6.0] QQuickGraphicsDevice QQuickWindow:: graphicsDevice () const

返回 QQuickGraphicsDevice passed to setGraphicsDevice (), or a default constructed one otherwise

该函数在 Qt 6.0 引入。

另请参阅 setGraphicsDevice ().

const QQuickWindow::GraphicsStateInfo &QQuickWindow:: graphicsStateInfo ()

返回引用针对 GraphicsStateInfo struct describing some of the RHI's internal state, in particular, the double or tripple buffering status of the backend (such as, the Vulkan or Metal integrations). This is relevant when the underlying graphics APIs is Vulkan or Metal, and the external rendering code wishes to perform double or tripple buffering of its own often-changing resources, such as, uniform buffers, in order to avoid stalling the pipeline.

[static] bool QQuickWindow:: hasDefaultAlphaBuffer ()

Returns whether to use alpha transparency on newly created windows.

另请参阅 setDefaultAlphaBuffer ().

[override virtual protected] void QQuickWindow:: hideEvent ( QHideEvent *)

重实现： QWindow::hideEvent (QHideEvent *ev).

QQmlIncubationController *QQuickWindow:: incubationController () const

Returns an incubation controller that splices incubation between frames for this window. QQuickView automatically installs this controller for you, otherwise you will need to install it yourself using QQmlEngine::setIncubationController ().

The controller is owned by the window and will be destroyed when the window is deleted.

bool QQuickWindow:: isPersistentGraphics () const

Returns whether essential graphics resources can be released during the lifetime of the QQuickWindow .

注意： This is a hint, and is not guaranteed that it is taken into account.

另请参阅 setPersistentGraphics ().

bool QQuickWindow:: isPersistentSceneGraph () const

Returns whether the scene graph nodes and resources can be released during the lifetime of this QQuickWindow .

注意： This is a hint. When and how this happens is implementation specific.

bool QQuickWindow:: isSceneGraphInitialized () const

Returns true if the scene graph has been initialized; otherwise returns false.

[override virtual protected] void QQuickWindow:: keyPressEvent ( QKeyEvent * e )

重实现： QWindow::keyPressEvent (QKeyEvent *ev).

[override virtual protected] void QQuickWindow:: keyReleaseEvent ( QKeyEvent * e )

重实现： QWindow::keyReleaseEvent (QKeyEvent *ev).

[override virtual protected] void QQuickWindow:: mouseDoubleClickEvent ( QMouseEvent * event )

重实现： QWindow::mouseDoubleClickEvent (QMouseEvent *ev).

[override virtual protected] void QQuickWindow:: mouseMoveEvent ( QMouseEvent * event )

重实现： QWindow::mouseMoveEvent (QMouseEvent *ev).

[override virtual protected] void QQuickWindow:: mousePressEvent ( QMouseEvent * event )

重实现： QWindow::mousePressEvent (QMouseEvent *ev).

[override virtual protected] void QQuickWindow:: mouseReleaseEvent ( QMouseEvent * event )

重实现： QWindow::mouseReleaseEvent (QMouseEvent *ev).

[slot] void QQuickWindow:: releaseResources ()

此函数会试着释放目前由 QML 场景保持的冗余资源。

Calling this function requests the scene graph to release cached graphics resources, such as graphics pipeline objects, shader programs, or image data.

Additionally, depending on the render loop in use, this function may also result in the scene graph and all window-related rendering resources to be released. If this happens, the sceneGraphInvalidated () signal will be emitted, allowing users to clean up their own graphics resources. The setPersistentGraphics () 和 setPersistentSceneGraph () functions can be used to prevent this from happening, if handling the cleanup is not feasible in the application, at the cost of higher memory usage.

注意： The releasing of cached graphics resources, such as graphics pipelines or shader programs is not dependent on the persistency hints. The releasing of those will happen regardless of the values of the persistent graphics and scenegraph hints.

注意： This function is not related to the QQuickItem::releaseResources () virtual function.

另请参阅 sceneGraphInvalidated (), setPersistentGraphics ()，和 setPersistentSceneGraph ().

[since 6.0] QQuickRenderTarget QQuickWindow:: renderTarget () const

返回 QQuickRenderTarget passed to setRenderTarget (), or a default constructed one otherwise

该函数在 Qt 6.0 引入。

另请参阅 setRenderTarget ().

QSGRendererInterface *QQuickWindow:: rendererInterface () const

返回当前渲染器接口。值始终有效且从不为 null。

注意： 可以在任何时候调用此函数，后于构造 QQuickWindow ，即使 isSceneGraphInitialized () 仍为 false。不管怎样，某些渲染器接口函数，尤其 QSGRendererInterface::getResource () will not be functional until the scenegraph is up and running. Backend queries, like QSGRendererInterface::graphicsApi () 或 QSGRendererInterface::shaderType (), will always be functional on the other hand.

注意： The ownership of the returned pointer stays with Qt. The returned instance may or may not be shared between different QQuickWindow instances, depending on the scenegraph backend in use. Therefore applications are expected to query the interface object for each QQuickWindow instead of reusing the already queried pointer.

另请参阅 QSGRenderNode and QSGRendererInterface .

[override virtual protected] void QQuickWindow:: resizeEvent ( QResizeEvent * ev )

重实现： QWindow::resizeEvent (QResizeEvent *ev).

[signal] void QQuickWindow:: sceneGraphAboutToStop ()

This signal is emitted on the render thread when the scene graph is about to stop rendering. This happens usually because the window has been hidden.

Applications may use this signal to release resources, but should be prepared to reinstantiated them again fast. The scene graph and the graphics context are not released at this time.

警告： This signal is emitted from the scene graph rendering thread. If your slot function needs to finish before execution continues, you must make sure that the connection is direct (see Qt::ConnectionType ).

警告： Make very sure that a signal handler for sceneGraphAboutToStop() leaves the graphics context in the same state as it was when the signal handler was entered. Failing to do so can result in the scene not rendering properly.

另请参阅 sceneGraphInvalidated ().

[static] QString QQuickWindow:: sceneGraphBackend ()

返回请求的 Qt Quick 场景图形后端。

注意： 此函数的返回值可能仍过时通过后续调用 setSceneGraphBackend () 直到第一 QQuickWindow 在应用程序中已构造。

注意： The value only reflects the request in the QT_QUICK_BACKEND environment variable after a QQuickWindow has been constructed.

另请参阅 setSceneGraphBackend ().

[signal] void QQuickWindow:: sceneGraphError ( QQuickWindow::SceneGraphError error , const QString & message )

此信号被发射当 error 出现在场景图形初始化期间。

Applications should connect to this signal if they wish to handle errors, like graphics context creation failures, in a custom way. When no slot is connected to the signal, the behavior will be different: Quick will print the message , or show a message box, and terminate the application.

此信号将从 GUI 线程中发射。

[signal] void QQuickWindow:: sceneGraphInitialized ()

此信号被发射，当场景图形已初始化。

此信号将从场景图形渲染线程中发射。

[signal] void QQuickWindow:: sceneGraphInvalidated ()

此信号被发射，当场景图形已无效。

This signal implies that the graphics rendering context used has been invalidated and all user resources tied to that context should be released.

When rendering with OpenGL, the QOpenGLContext of this window will be bound when this function is called. The only exception is if the native OpenGL has been destroyed outside Qt's control, for instance through EGL_CONTEXT_LOST.

此信号将从场景图形渲染线程中发射。

void QQuickWindow:: scheduleRenderJob ( QRunnable * job , QQuickWindow::RenderStage stage )

调度 job to run when the rendering of this window reaches the given stage .

这很方便对于等价信号在 QQuickWindow for "one shot" tasks.

窗口拥有所有权对于 job 且会删除它当 job 完成时。

If rendering is shut down before job has a chance to run, the job will be run and then deleted as part of the scene graph cleanup. If the window is never shown and no rendering happens before the QQuickWindow is destroyed, all pending jobs will be destroyed without their run() method being called.

若渲染发生在不同线程，那么 job 将发生在渲染线程。

若 stage is NoStage , job will be run at the earliest opportunity whenever the render thread is not busy rendering a frame. If the window is not exposed, and is not renderable, at the time the job is either posted or handled, the job is deleted without executing the run() method. If a non-threaded renderer is in use, the run() method of the job is executed synchronously. When rendering with OpenGL, the OpenGL context is changed to the renderer's context before executing any job, including NoStage jobs.

注意： This function does not trigger rendering; the jobs targeting any other stage than NoStage will be stored run until rendering is triggered elsewhere. To force the job to run earlier, call QQuickWindow::update ();

另请参阅 beforeRendering (), afterRendering (), beforeSynchronizing (), afterSynchronizing (), frameSwapped ()，和 sceneGraphInvalidated ().

[static] void QQuickWindow:: setDefaultAlphaBuffer ( bool useAlpha )

useAlpha 指定是否在新近创建的窗口中使用 Alpha 透明度。

在任何期望创建半透明窗口的应用程序中，有必要将此设为 true 先于创建第一 QQuickWindow 。默认值为 false。

另请参阅 hasDefaultAlphaBuffer ().

[static, since 6.0] void QQuickWindow:: setGraphicsApi ( QSGRendererInterface::GraphicsApi api )

Requests the specified graphics api .

When the built-in, default graphics adaptation is used, api specifies which graphics API (OpenGL, Vulkan, Metal, or Direct3D) the scene graph should use to render. In addition, the software backend is built-in as well, and can be requested by setting api to QSGRendererInterface::Software .

不像 setSceneGraphBackend (), which can only be used to request a given backend (shipped either built-in or installed as dynamically loaded plugins), this function works with the higher level concept of graphics APIs. It covers the backends that ship with Qt Quick, and thus have corresponding values in the QSGRendererInterface::GraphicsApi 枚举。

When this function is not called at all, and the equivalent environment variable QSG_RHI_BACKEND is not set either, the scene graph will choose the graphics API to use based on the platform.

This function becomes important in applications that are only prepared for rendering with a given API. For example, if there is native OpenGL or Vulkan rendering done by the application, it will want to ensure Qt Quick is rendering using OpenGL or Vulkan too. Such applications are expected to call this function early in their main() function.

注意： 函数调用的发生必须先于构造第一 QQuickWindow in the application. The graphics API cannot be changed afterwards.

注意： 当组合使用同 QQuickRenderControl , this rule is relaxed: it is possible to change the graphics API, but only when all existing QQuickRenderControl and QQuickWindow instances have been destroyed.

To query what graphics API the scene graph is using to render, QSGRendererInterface::graphicsApi () after the scene graph has initialized , which typically happens either when the window becomes visible for the first time, or when QQuickRenderControl::initialize () 被调用。

To switch back to the default behavior, where the scene graph chooses a graphics API based on the platform and other conditions, set api to QSGRendererInterface::Unknown .

该函数在 Qt 6.0 引入。

另请参阅 graphicsApi ().

[since 6.0] void QQuickWindow:: setGraphicsConfiguration (const QQuickGraphicsConfiguration & config )

Sets the graphics configuration for this window. config contains various settings that may be taken into account by the scene graph when initializing the underlying graphics devices and contexts.

Such additional configuration, specifying for example what device extensions to enable for Vulkan, becomes relevant and essential when integrating native graphics rendering code that relies on certain extensions. The same is true when integrating with an external 3D or VR engines, such as OpenXR.

注意： The configuration is ignored when adopting existing graphics devices via setGraphicsDevice () since the scene graph is then not in control of the actual construction of those objects.

QQuickGraphicsConfiguration instances are implicitly shared, copyable, and can be passed by value.

警告： Setting a QQuickGraphicsConfiguration 在 QQuickWindow must happen early enough, before the scene graph is initialized for the first time for that window. With on-screen windows this means the call must be done before invoking show () on the QQuickWindow or QQuickView 。采用 QQuickRenderControl the configuration must be finalized before calling initialize ().

该函数在 Qt 6.0 引入。

另请参阅 graphicsConfiguration ().

[since 6.0] void QQuickWindow:: setGraphicsDevice (const QQuickGraphicsDevice & device )

Sets the graphics device objects for this window. The scenegraph will use existing device, physical device, and other objects specified by device instead of creating new ones.

This function is very often used in combination with QQuickRenderControl and setRenderTarget (), in order to redirect Qt Quick rendering into a texture.

A default constructed QQuickGraphicsDevice does not change the default behavior in any way. Once a device created via one of the QQuickGraphicsDevice factory functions, such as, QQuickGraphicsDevice::fromDeviceObjects (), is passed in, and the scenegraph uses a matching graphics API (with the example of fromDeviceObjects(), that would be Vulkan), the scenegraph will use the existing device objects (such as, the VkPhysicalDevice , VkDevice , and graphics queue family index, in case of Vulkan) encapsulated by the QQuickGraphicsDevice . This allows using the same device, and so sharing resources, such as buffers and textures, between Qt Quick and native rendering engines.

警告： This function can only be called before initializing the scenegraph and will have no effect if called afterwards. In practice this typically means calling it right before QQuickRenderControl::initialize ().

As an example, this time with Direct3D, the typical usage is expected to be the following: 

// native graphics resources set up by a custom D3D rendering engine
ID3D11Device *device;
ID3D11DeviceContext *context;
ID3D11Texture2D *texture;
...
// now to redirect Qt Quick content into 'texture' we could do the following:
QQuickRenderControl *renderControl = new QQuickRenderControl;
QQuickWindow *window = new QQuickWindow(renderControl); // this window will never be shown on-screen
...
window->setGraphicsDevice(QQuickGraphicsDevice::fromDeviceAndContext(device, context));
renderControl->initialize();
window->setRenderTarget(QQuickRenderTarget::fromD3D11Texture(texture, textureSize);
...

The key aspect of using this function is to ensure that resources or handles to resources, such as texture in the above example, are visible to and usable by both the external rendering engine and the scenegraph renderer. This requires using the same graphics device (or with OpenGL, OpenGL context).

QQuickGraphicsDevice instances are implicitly shared, copyable, and can be passed by value. They do not own the associated native objects (such as, the ID3D11Device in the example).

注意： 使用 QQuickRenderControl does not always imply having to call this function. When adopting an existing device or context is not needed, this function should not be called, and the scene graph will then initialize its own devices and contexts normally, just as it would with an on-screen QQuickWindow .

该函数在 Qt 6.0 引入。

另请参阅 graphicsDevice (), QQuickRenderControl , setRenderTarget ()，和 setGraphicsApi ().

void QQuickWindow:: setPersistentGraphics ( bool persistent )

Sets whether the graphics resources (graphics device or context, swapchain, buffers, textures) should be preserved, and cannot be released until the last window is deleted, to persistent 。默认值为 true。

When calling releaseResources (), or when the window gets hidden (more specifically, not renderable), some render loops have the possibility to release all, not just the cached, graphics resources. This can free up memory temporarily, but it also means the rendering engine will have to do a full, potentially costly reinitialization of the resources when the window needs to render again.

注意： The rules for when a window is not renderable are platform and window manager specific.

注意： All graphics resources are released when the last QQuickWindow is deleted, regardless of this setting.

注意： This is a hint, and is not guaranteed that it is taken into account.

注意： This hint does not apply to cached resources, that are relatively cheap to drop and then recreate later. Therefore, calling releaseResources () will typically lead to releasing those regardless of the value of this hint.

另请参阅 isPersistentGraphics (), setPersistentSceneGraph (), sceneGraphInitialized (), sceneGraphInvalidated ()，和 releaseResources ().

void QQuickWindow:: setPersistentSceneGraph ( bool persistent )

Sets whether the scene graph nodes and resources are persistent . Persistent means the nodes and resources cannot be released. The default value is true .

When calling releaseResources (), when the window gets hidden (more specifically, not renderable), some render loops have the possibility to release the scene graph nodes and related graphics resources. This frees up memory temporarily, but will also mean the scene graph has to be rebuilt when the window renders next time.

注意： The rules for when a window is not renderable are platform and window manager specific.

注意： The scene graph nodes and resources are always released when the last QQuickWindow is deleted, regardless of this setting.

注意： This is a hint, and is not guaranteed that it is taken into account.

另请参阅 isPersistentSceneGraph (), setPersistentGraphics (), sceneGraphInvalidated (), sceneGraphInitialized ()，和 releaseResources ().

[since 6.0] void QQuickWindow:: setRenderTarget (const QQuickRenderTarget & target )

将用于此窗口的渲染目标设为 target .

A QQuickRenderTarget serves as an opaque handle for a renderable native object, most commonly a 2D texture, and associated metadata, such as the size in pixels.

A default constructed QQuickRenderTarget means no redirection. A valid target , created via one of the static QQuickRenderTarget factory functions, on the other hand, enables redirection of the rendering of the Qt Quick scene: it will no longer target the color buffers for the surface associated with the window, but rather the textures or other graphics objects specified in target .

For example, assuming the scenegraph is using Vulkan to render, one can redirect its output into a VkImage . For graphics APIs like Vulkan, the image layout must be provided as well. QQuickRenderTarget instances are implicitly shared and are copyable and can be passed by value. They do not own the associated native objects (such as, the VkImage in the example), however. 

QQuickRenderTarget rt = QQuickRenderTarget::fromVulkanImage(vulkanImage, VK_IMAGE_LAYOUT_PREINITIALIZED, pixelSize);
quickWindow->setRenderTarget(rt);

This function is very often used in combination with QQuickRenderControl and an invisible QQuickWindow , in order to render Qt Quick content into a texture, without creating an on-screen native window for this QQuickWindow .

When the desired target, or associated data, such as the size, changes, call this function with a new QQuickRenderTarget . Constructing QQuickRenderTarget instances and calling this function is cheap, but be aware that setting a new target with a different native object or other data may lead to potentially expensive initialization steps when the scenegraph is about to render the next frame. Therefore change the target only when necessary.

注意： The window does not take ownership of any native objects referenced in target .

注意： It is the caller's responsibility to ensure the native objects referred to in target are valid for the scenegraph renderer too. For instance, with Vulkan, Metal, and Direct3D this implies that the texture or image is created on the same graphics device that is used by the scenegraph internally. Therefore, when texture objects created on an already existing device or context are involved, this function is often used in combination with setGraphicsDevice ().

注意： With graphics APIs where relevant, the application must pay attention to image layout transitions performed by the scenegraph. For example, once a VkImage is associated with the scenegraph by calling this function, its layout will transition to VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL when rendering a frame.

警告： 只可以从做渲染的线程中调用此函数。

该函数在 Qt 6.0 引入。

另请参阅 renderTarget (), QQuickRenderControl , setGraphicsDevice ()，和 setGraphicsApi ().

[static] void QQuickWindow:: setSceneGraphBackend (const QString & backend )

Requests a Qt Quick scenegraph backend 。后端要么可以是内置的，要么以动态加载插件的形式安装。

这是重载函数。

注意： 函数调用的发生必须先于构造第一 QQuickWindow 在应用程序中。之后无法改变。

见 Switch Between Adaptations in Your Application for more information about the list of backends. If backend is invalid or an error occurs, the request is ignored.

注意： 调用此函数相当于设置 QT_QUICK_BACKEND or QMLSCENE_DEVICE 环境变量。不管怎样，在卵生其它进程的应用程序中使用此 API 更安全，因为不需要担心环境继承。

另请参阅 sceneGraphBackend ().

[static] void QQuickWindow:: setTextRenderType ( QQuickWindow::TextRenderType renderType )

将 Qt Quick 中像文本元素的默认渲染类型设为 renderType .

注意： 设置渲染类型仅影响之后创建的元素；不会修改现有元素的渲染类型。

另请参阅 textRenderType ().

[override virtual protected] void QQuickWindow:: showEvent ( QShowEvent *)

重实现： QWindow::showEvent (QShowEvent *ev).

[override virtual protected] void QQuickWindow:: tabletEvent ( QTabletEvent * event )

重实现： QWindow::tabletEvent (QTabletEvent *ev).

[static] QQuickWindow::TextRenderType QQuickWindow:: textRenderType ()

返回 Qt Quick 中像文本元素的渲染类型。默认为 QQuickWindow::QtTextRendering .

另请参阅 setTextRenderType ().

[slot] void QQuickWindow:: update ()

调度窗口以渲染另一帧。

调用 QQuickWindow::update() 不同于 QQuickItem::update () in that it always triggers a repaint, regardless of changes in the underlying scene graph or not.

[override virtual protected] void QQuickWindow:: wheelEvent ( QWheelEvent * event )

重实现： QWindow::wheelEvent (QWheelEvent *ev).

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