QSurfaceFormat Class
The QSurfaceFormat class represents the format of a QSurface. More...
| Header: | #include <QSurfaceFormat> |
| qmake: | QT += gui |
| Since: | Qt 5.0 |
This class was introduced in Qt 5.0.
Public Types
| enum | ColorSpace { DefaultColorSpace, sRGBColorSpace } |
| enum | FormatOption { StereoBuffers, DebugContext, DeprecatedFunctions, ResetNotification } |
| flags | FormatOptions |
| enum | OpenGLContextProfile { NoProfile, CoreProfile, CompatibilityProfile } |
| enum | RenderableType { DefaultRenderableType, OpenGL, OpenGLES, OpenVG } |
| enum | SwapBehavior { DefaultSwapBehavior, SingleBuffer, DoubleBuffer, TripleBuffer } |
Public Functions
| QSurfaceFormat(const QSurfaceFormat &other) | |
| QSurfaceFormat(FormatOptions options) | |
| QSurfaceFormat() | |
| QSurfaceFormat & | operator=(const QSurfaceFormat &other) |
| ~QSurfaceFormat() | |
| int | alphaBufferSize() const |
| int | blueBufferSize() const |
| ColorSpace | colorSpace() const |
| int | depthBufferSize() const |
| int | greenBufferSize() const |
| bool | hasAlpha() const |
| int | majorVersion() const |
| int | minorVersion() const |
| QSurfaceFormat::FormatOptions | options() const |
| OpenGLContextProfile | profile() const |
| int | redBufferSize() const |
| RenderableType | renderableType() const |
| int | samples() const |
| void | setAlphaBufferSize(int size) |
| void | setBlueBufferSize(int size) |
| void | setColorSpace(ColorSpace colorSpace) |
| void | setDepthBufferSize(int size) |
| void | setGreenBufferSize(int size) |
| void | setMajorVersion(int major) |
| void | setMinorVersion(int minor) |
| void | setOption(FormatOption option, bool on = true) |
| void | setOptions(QSurfaceFormat::FormatOptions options) |
| void | setProfile(OpenGLContextProfile profile) |
| void | setRedBufferSize(int size) |
| void | setRenderableType(RenderableType type) |
| void | setSamples(int numSamples) |
| void | setStencilBufferSize(int size) |
| void | setStereo(bool enable) |
| void | setSwapBehavior(SwapBehavior behavior) |
| void | setSwapInterval(int interval) |
| void | setVersion(int major, int minor) |
| int | stencilBufferSize() const |
| bool | stereo() const |
| SwapBehavior | swapBehavior() const |
| int | swapInterval() const |
| bool | testOption(FormatOption option) const |
| QPair<int, int> | version() const |
Static Public Members
| QSurfaceFormat | defaultFormat() |
| void | setDefaultFormat(const QSurfaceFormat &format) |
Related Non-Members
| bool | operator!=(const QSurfaceFormat &a, const QSurfaceFormat &b) |
| bool | operator==(const QSurfaceFormat &a, const QSurfaceFormat &b) |
Detailed Description
The format includes the size of the color buffers, red, green, and blue; the size of the alpha buffer; the size of the depth and stencil buffers; and number of samples per pixel for multisampling. In addition, the format contains surface configuration parameters such as OpenGL profile and version for rendering, whether or not to enable stereo buffers, and swap behaviour.
Note: When troubleshooting context or window format issues, it can be helpful to enable the logging category qt.qpa.gl. Depending on the platform, this may print useful debug information when it comes to OpenGL initialization and the native visual or framebuffer configurations which QSurfaceFormat gets mapped to.
Member Type Documentation
enum QSurfaceFormat::ColorSpace
This enum is used to specify the preferred color space, controlling if the window's associated default framebuffer is able to do updates and blending in a given encoding instead of the standard linear operations.
| Constant | Value | Description |
|---|---|---|
QSurfaceFormat::DefaultColorSpace | 0 | The default, unspecified color space. |
QSurfaceFormat::sRGBColorSpace | 1 | When GL_ARB_framebuffer_sRGB or GL_EXT_framebuffer_sRGB is supported by the platform and this value is set, the window will be created with an sRGB-capable default framebuffer. Note that some platforms may return windows with a sRGB-capable default framebuffer even when not requested explicitly. |
enum QSurfaceFormat::FormatOption
flags QSurfaceFormat::FormatOptions
This enum contains format options for use with QSurfaceFormat.
| Constant | Value | Description |
|---|---|---|
QSurfaceFormat::StereoBuffers | 0x0001 | Used to request stereo buffers in the surface format. |
QSurfaceFormat::DebugContext | 0x0002 | Used to request a debug context with extra debugging information. |
QSurfaceFormat::DeprecatedFunctions | 0x0004 | Used to request that deprecated functions be included in the OpenGL context profile. If not specified, you should get a forward compatible context without support functionality marked as deprecated. This requires OpenGL version 3.0 or higher. |
QSurfaceFormat::ResetNotification | 0x0008 | Enables notifications about resets of the OpenGL context. The status is then queryable via the context's isValid() function. Note that not setting this flag does not guarantee that context state loss never occurs. Additionally, some implementations may choose to report context loss regardless of this flag. Platforms that support dynamically enabling the monitoring of the loss of context, such as, Windows with WGL, or Linux/X11 (xcb) with GLX, will monitor the status in every call to makeCurrent(). See isValid() for more information on this. |
The FormatOptions type is a typedef for QFlags<FormatOption>. It stores an OR combination of FormatOption values.
enum QSurfaceFormat::OpenGLContextProfile
This enum is used to specify the OpenGL context profile, in conjunction with QSurfaceFormat::setMajorVersion() and QSurfaceFormat::setMinorVersion().
Profiles are exposed in OpenGL 3.2 and above, and are used to choose between a restricted core profile, and a compatibility profile which might contain deprecated support functionality.
Note that the core profile might still contain functionality that is deprecated and scheduled for removal in a higher version. To get access to the deprecated functionality for the core profile in the set OpenGL version you can use the QSurfaceFormat format option QSurfaceFormat::DeprecatedFunctions.
| Constant | Value | Description |
|---|---|---|
QSurfaceFormat::NoProfile | 0 | OpenGL version is lower than 3.2. For 3.2 and newer this is same as CoreProfile. |
QSurfaceFormat::CoreProfile | 1 | Functionality deprecated in OpenGL version 3.0 is not available. |
QSurfaceFormat::CompatibilityProfile | 2 | Functionality from earlier OpenGL versions is available. |
enum QSurfaceFormat::RenderableType
This enum specifies the rendering backend for the surface.
| Constant | Value | Description |
|---|---|---|
QSurfaceFormat::DefaultRenderableType | 0x0 | The default, unspecified rendering method |
QSurfaceFormat::OpenGL | 0x1 | Desktop OpenGL rendering |
QSurfaceFormat::OpenGLES | 0x2 | OpenGL ES 2.0 rendering |
QSurfaceFormat::OpenVG | 0x4 | Open Vector Graphics rendering |
enum QSurfaceFormat::SwapBehavior
This enum is used by QSurfaceFormat to specify the swap behaviour of a surface. The swap behaviour is mostly transparent to the application, but it affects factors such as rendering latency and throughput.
| Constant | Value | Description |
|---|---|---|
QSurfaceFormat::DefaultSwapBehavior | 0 | The default, unspecified swap behaviour of the platform. |
QSurfaceFormat::SingleBuffer | 1 | Used to request single buffering, which might result in flickering when OpenGL rendering is done directly to screen without an intermediate offscreen buffer. |
QSurfaceFormat::DoubleBuffer | 2 | This is typically the default swap behaviour on desktop platforms, consisting of one back buffer and one front buffer. Rendering is done to the back buffer, and then the back buffer and front buffer are swapped, or the contents of the back buffer are copied to the front buffer, depending on the implementation. |
QSurfaceFormat::TripleBuffer | 3 | This swap behaviour is sometimes used in order to decrease the risk of skipping a frame when the rendering rate is just barely keeping up with the screen refresh rate. Depending on the platform it might also lead to slightly more efficient use of the GPU due to improved pipelining behaviour. Triple buffering comes at the cost of an extra frame of memory usage and latency, and might not be supported depending on the underlying platform. |
Member Function Documentation
QSurfaceFormat::QSurfaceFormat(const QSurfaceFormat &other)
Constructs a copy of other.
QSurfaceFormat::QSurfaceFormat(FormatOptions options)
Constructs a QSurfaceFormat with the given format options.
QSurfaceFormat::QSurfaceFormat()
Constructs a default initialized QSurfaceFormat.
Note: By default OpenGL 2.0 is requested since this provides the highest grade of portability between platforms and OpenGL implementations.
QSurfaceFormat &QSurfaceFormat::operator=(const QSurfaceFormat &other)
Assigns other to this object.
QSurfaceFormat::~QSurfaceFormat()
Destroys the QSurfaceFormat.
int QSurfaceFormat::alphaBufferSize() const
Get the size in bits of the alpha channel of the color buffer.
See also setAlphaBufferSize().
int QSurfaceFormat::blueBufferSize() const
Get the size in bits of the blue channel of the color buffer.
See also setBlueBufferSize().
ColorSpace QSurfaceFormat::colorSpace() const
Returns the color space.
This function was introduced in Qt 5.10.
See also setColorSpace().
[static] QSurfaceFormat QSurfaceFormat::defaultFormat()
Returns the global default surface format.
When setDefaultFormat() is not called, this is a default-constructed QSurfaceFormat.
This function was introduced in Qt 5.4.
See also setDefaultFormat().
int QSurfaceFormat::depthBufferSize() const
Returns the depth buffer size.
See also setDepthBufferSize().
int QSurfaceFormat::greenBufferSize() const
Get the size in bits of the green channel of the color buffer.
See also setGreenBufferSize().
bool QSurfaceFormat::hasAlpha() const
Returns true if the alpha buffer size is greater than zero.
This means that the surface might be used with per pixel translucency effects.
int QSurfaceFormat::majorVersion() const
Returns the major OpenGL version.
The default version is 2.0.
See also setMajorVersion().
int QSurfaceFormat::minorVersion() const
Returns the minor OpenGL version.
See also setMinorVersion().
QSurfaceFormat::FormatOptions QSurfaceFormat::options() const
Returns the currently set format options.
This function was introduced in Qt 5.3.
See also setOption(), setOptions(), and testOption().
OpenGLContextProfile QSurfaceFormat::profile() const
Get the configured OpenGL context profile.
This setting is ignored if the requested OpenGL version is less than 3.2.
See also setProfile().
int QSurfaceFormat::redBufferSize() const
Get the size in bits of the red channel of the color buffer.
See also setRedBufferSize().
RenderableType QSurfaceFormat::renderableType() const
Gets the renderable type.
Chooses between desktop OpenGL, OpenGL ES, and OpenVG.
See also setRenderableType().
int QSurfaceFormat::samples() const
Returns the number of samples per pixel when multisampling is enabled, or -1 when multisampling is disabled. The default return value is -1.
See also setSamples().
void QSurfaceFormat::setAlphaBufferSize(int size)
Set the desired size in bits of the alpha channel of the color buffer.
See also alphaBufferSize().
void QSurfaceFormat::setBlueBufferSize(int size)
Set the desired size in bits of the blue channel of the color buffer.
See also blueBufferSize().
void QSurfaceFormat::setColorSpace(ColorSpace colorSpace)
Sets the preferred colorSpace.
For example, this allows requesting windows with default framebuffers that are sRGB-capable on platforms that support it.
Note: When the requested color space is not supported by the platform, the request is ignored. Query the QSurfaceFormat after window creation to verify if the color space request could be honored or not.
Note: This setting controls if the default framebuffer of the window is capable of updates and blending in a given color space. It does not change applications' output by itself. The applications' rendering code will still have to opt in via the appropriate OpenGL calls to enable updates and blending to be performed in the given color space instead of using the standard linear operations.
This function was introduced in Qt 5.10.
See also colorSpace().
[static] void QSurfaceFormat::setDefaultFormat(const QSurfaceFormat &format)
Sets the global default surface format.
This format is used by default in QOpenGLContext, QWindow, QOpenGLWidget and similar classes.
It can always be overridden on a per-instance basis by using the class in question's own setFormat() function. However, it is often more convenient to set the format for all windows once at the start of the application. It also guarantees proper behavior in cases where shared contexts are required, because settings the format via this function guarantees that all contexts and surfaces, even the ones created internally by Qt, will use the same format.
Note: When setting Qt::AA_ShareOpenGLContexts, it is strongly recommended to place the call to this function before the construction of the QGuiApplication or QApplication. Otherwise format will not be applied to the global share context and therefore issues may arise with context sharing afterwards.
This function was introduced in Qt 5.4.
See also defaultFormat().
void QSurfaceFormat::setDepthBufferSize(int size)
Set the minimum depth buffer size to size.
See also depthBufferSize().
void QSurfaceFormat::setGreenBufferSize(int size)
Set the desired size in bits of the green channel of the color buffer.
See also greenBufferSize().
void QSurfaceFormat::setMajorVersion(int major)
Sets the desired major OpenGL version.
See also majorVersion().
void QSurfaceFormat::setMinorVersion(int minor)
Sets the desired minor OpenGL version.
The default version is 2.0.
See also minorVersion().
void QSurfaceFormat::setOption(FormatOption option, bool on = true)
Sets the format option option if on is true; otherwise, clears the option.
This function was introduced in Qt 5.3.
See also setOptions(), options(), and testOption().
void QSurfaceFormat::setOptions(QSurfaceFormat::FormatOptions options)
Sets the format options to options.
This function was introduced in Qt 5.3.
See also options() and testOption().
void QSurfaceFormat::setProfile(OpenGLContextProfile profile)
Sets the desired OpenGL context profile.
This setting is ignored if the requested OpenGL version is less than 3.2.
See also profile().
void QSurfaceFormat::setRedBufferSize(int size)
Set the desired size in bits of the red channel of the color buffer.
See also redBufferSize().
void QSurfaceFormat::setRenderableType(RenderableType type)
Sets the desired renderable type.
Chooses between desktop OpenGL, OpenGL ES, and OpenVG.
See also renderableType().
void QSurfaceFormat::setSamples(int numSamples)
Set the preferred number of samples per pixel when multisampling is enabled to numSamples. By default, multisampling is disabled.
See also samples().
void QSurfaceFormat::setStencilBufferSize(int size)
Set the preferred stencil buffer size to size bits.
See also stencilBufferSize().
void QSurfaceFormat::setStereo(bool enable)
If enable is true enables stereo buffering; otherwise disables stereo buffering.
Stereo buffering is disabled by default.
Stereo buffering provides extra color buffers to generate left-eye and right-eye images.
See also stereo().
void QSurfaceFormat::setSwapBehavior(SwapBehavior behavior)
Set the swap behavior of the surface.
The swap behavior specifies whether single, double, or triple buffering is desired. The default, DefaultSwapBehavior, gives the default swap behavior of the platform.
See also swapBehavior().
void QSurfaceFormat::setSwapInterval(int interval)
Sets the preferred swap interval. The swap interval specifies the minimum number of video frames that are displayed before a buffer swap occurs. This can be used to sync the GL drawing into a window to the vertical refresh of the screen.
Setting an interval value of 0 will turn the vertical refresh syncing off, any value higher than 0 will turn the vertical syncing on. Setting interval to a higher value, for example 10, results in having 10 vertical retraces between every buffer swap.
The default interval is 1.
Changing the swap interval may not be supported by the underlying platform. In this case, the request will be silently ignored.
This function was introduced in Qt 5.3.
See also swapInterval().
void QSurfaceFormat::setVersion(int major, int minor)
Sets the desired major and minor OpenGL versions.
The default version is 2.0.
See also version().
int QSurfaceFormat::stencilBufferSize() const
Returns the stencil buffer size in bits.
See also setStencilBufferSize().
bool QSurfaceFormat::stereo() const
Returns true if stereo buffering is enabled; otherwise returns false. Stereo buffering is disabled by default.
See also setStereo().
SwapBehavior QSurfaceFormat::swapBehavior() const
Returns the configured swap behaviour.
See also setSwapBehavior().
int QSurfaceFormat::swapInterval() const
Returns the swap interval.
This function was introduced in Qt 5.3.
See also setSwapInterval().
bool QSurfaceFormat::testOption(FormatOption option) const
Returns true if the format option option is set; otherwise returns false.
This function was introduced in Qt 5.3.
See also options().
QPair<int, int> QSurfaceFormat::version() const
Returns a QPair<int, int> representing the OpenGL version.
Useful for version checks, for example format.version() >= qMakePair(3, 2)
See also setVersion().
Related Non-Members
bool operator!=(const QSurfaceFormat &a, const QSurfaceFormat &b)
Returns false if all the options of the two QSurfaceFormat objects a and b are equal; otherwise returns true.
bool operator==(const QSurfaceFormat &a, const QSurfaceFormat &b)
Returns true if all the options of the two QSurfaceFormat objects a and b are equal.