class QSurfaceFormat

The QSurfaceFormat class represents the format of a QSurface . More…

Synopsis

Methods

Static functions

Note

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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.

class FormatOption

(inherits enum.Flag) This enum contains format options for use with QSurfaceFormat .

Constant

Description

QSurfaceFormat.StereoBuffers

Used to request stereo buffers in the surface format.

QSurfaceFormat.DebugContext

Used to request a debug context with extra debugging information.

QSurfaceFormat.DeprecatedFunctions

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

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.

QSurfaceFormat.ProtectedContent

Enables access to protected content. This allows the GPU to operate on protected resources (surfaces, buffers, textures), for example DRM-protected video content. Currently only implemented for EGL.
class 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

Description

QSurfaceFormat.DefaultSwapBehavior

The default, unspecified swap behaviour of the platform.

QSurfaceFormat.SingleBuffer

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

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

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.
class RenderableType

This enum specifies the rendering backend for the surface.

Constant

Description

QSurfaceFormat.DefaultRenderableType

The default, unspecified rendering method

QSurfaceFormat.OpenGL

Desktop OpenGL rendering

QSurfaceFormat.OpenGLES

OpenGL ES 2.0 rendering

QSurfaceFormat.OpenVG

Open Vector Graphics rendering
class OpenGLContextProfile

This enum is used to specify the OpenGL context profile, in conjunction with setMajorVersion() and 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 DeprecatedFunctions .

Constant

Description

QSurfaceFormat.NoProfile

OpenGL version is lower than 3.2. For 3.2 and newer this is same as CoreProfile.

QSurfaceFormat.CoreProfile

Functionality deprecated in OpenGL version 3.0 is not available.

QSurfaceFormat.CompatibilityProfile

Functionality from earlier OpenGL versions is available.
class 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

Description

QSurfaceFormat.DefaultColorSpace

The default, unspecified color space.

QSurfaceFormat.sRGBColorSpace

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.
__init__()

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.

__init__(options)
Parameters:

options – Combination of FormatOption

Constructs a QSurfaceFormat with the given format options.

__init__(other)
Parameters:

other – QSurfaceFormat

Constructs a copy of other.

alphaBufferSize()
Return type:

int

Get the size in bits of the alpha channel of the color buffer.

blueBufferSize()
Return type:

int

Get the size in bits of the blue channel of the color buffer.

colorSpace()
Return type:

QColorSpace

Returns the color space.

See also

setColorSpace()

static defaultFormat()
Return type:

QSurfaceFormat

Returns the global default surface format.

When setDefaultFormat() is not called, this is a default-constructed QSurfaceFormat .

depthBufferSize()
Return type:

int

Returns the depth buffer size.

greenBufferSize()
Return type:

int

Get the size in bits of the green channel of the color buffer.

hasAlpha()
Return type:

bool

Returns true if the alpha buffer size is greater than zero.

This means that the surface might be used with per pixel translucency effects.

majorVersion()
Return type:

int

Returns the major OpenGL version.

The default version is 2.0.

minorVersion()
Return type:

int

Returns the minor OpenGL version.

__ne__(rhs)
Parameters:

rhs – QSurfaceFormat

Return type:

bool

Returns false if all the options of the two QSurfaceFormat objects lhs and rhs are equal; otherwise returns true.

__eq__(rhs)
Parameters:

rhs – QSurfaceFormat

Return type:

bool

Returns true if all the options of the two QSurfaceFormat objects lhs and rhs are equal.

options()
Return type:

Combination of FormatOption

Returns the currently set format options.

profile()
Return type:

OpenGLContextProfile

Get the configured OpenGL context profile.

This setting is ignored if the requested OpenGL version is less than 3.2.

See also

setProfile()

redBufferSize()
Return type:

int

Get the size in bits of the red channel of the color buffer.

renderableType()
Return type:

RenderableType

Gets the renderable type.

Chooses between desktop OpenGL, OpenGL ES, and OpenVG .

samples()
Return type:

int

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()

setAlphaBufferSize(size)
Parameters:

size – int

Set the desired size in bits of the alpha channel of the color buffer.

setBlueBufferSize(size)
Parameters:

size – int

Set the desired size in bits of the blue channel of the color buffer.

See also

blueBufferSize()

setColorSpace(colorSpace)
Parameters:

colorSpace – ColorSpace

Note

This function is deprecated.

This is an overloaded function.

Use setColorSpace ( QColorSpace ) instead.

Sets the colorspace to one of the predefined values.

See also

colorSpace()

setColorSpace(colorSpace)
Parameters:

colorSpace – QColorSpace

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.

See also

colorSpace()

static setDefaultFormat(format)
Parameters:

format – QSurfaceFormat

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 setting 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.

See also

defaultFormat()

setDepthBufferSize(size)
Parameters:

size – int

Set the minimum depth buffer size to size.

setGreenBufferSize(size)
Parameters:

size – int

Set the desired size in bits of the green channel of the color buffer.

setMajorVersion(majorVersion)
Parameters:

majorVersion – int

Sets the desired major OpenGL version.

See also

majorVersion()

setMinorVersion(minorVersion)
Parameters:

minorVersion – int

Sets the desired minor OpenGL version.

The default version is 2.0.

See also

minorVersion()

setOption(option[, on=true])
Parameters:

Sets the format option option if on is true; otherwise, clears the option.

To verify that an option was respected, compare the actual format to the requested format after surface/context creation.

setOptions(options)
Parameters:

options – Combination of FormatOption

Sets the format options to options.

To verify that an option was respected, compare the actual format to the requested format after surface/context creation.

setProfile(profile)
Parameters:

profile – OpenGLContextProfile

Sets the desired OpenGL context profile.

This setting is ignored if the requested OpenGL version is less than 3.2.

See also

profile()

setRedBufferSize(size)
Parameters:

size – int

Set the desired size in bits of the red channel of the color buffer.

See also

redBufferSize()

setRenderableType(type)
Parameters:

type – RenderableType

Sets the desired renderable type.

Chooses between desktop OpenGL, OpenGL ES, and OpenVG .

See also

renderableType()

setSamples(numSamples)
Parameters:

numSamples – int

Set the preferred number of samples per pixel when multisampling is enabled to numSamples. By default, multisampling is disabled.

See also

samples()

setStencilBufferSize(size)
Parameters:

size – int

Set the preferred stencil buffer size to size bits.

setStereo(enable)
Parameters:

enable – bool

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()

setSwapBehavior(behavior)
Parameters:

behavior – SwapBehavior

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()

setSwapInterval(interval)
Parameters:

interval – int

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.

See also

swapInterval()

setVersion(major, minor)
Parameters:

  • major – int

  • minor – int

Sets the desired major and minor OpenGL versions.

The default version is 2.0.

See also

version()

stencilBufferSize()
Return type:

int

Returns the stencil buffer size in bits.

stereo()
Return type:

bool

Returns true if stereo buffering is enabled; otherwise returns false. Stereo buffering is disabled by default.

See also

setStereo()

swapBehavior()
Return type:

SwapBehavior

Returns the configured swap behaviour.

swapInterval()
Return type:

int

Returns the swap interval.

testOption(option)
Parameters:

option – FormatOption

Return type:

bool

Returns true if the format option option is set; otherwise returns false.

See also

options()

version()
Return type:

.std.pairint,int

Returns a QPair<int, int> representing the OpenGL version.

Useful for version checks, for example format.version() >= qMakePair(3, 2)

See also

setVersion()