GLContext

gdk.glcontext.GLContext is an object representing a platform-specific OpenGL draw context.

gdk.glcontext.GLContexts are created for a surface using gdk.surface.Surface.createGlContext, and the context will match the characteristics of the surface.

A gdk.glcontext.GLContext is not tied to any particular normal framebuffer. For instance, it cannot draw to the surface back buffer. The GDK repaint system is in full control of the painting to that. Instead, you can create render buffers or textures and use func@cairo_draw_from_gl in the draw function of your widget to draw them. Then GDK will handle the integration of your rendering with that of other widgets.

Support for gdk.glcontext.GLContext is platform-specific and context creation can fail, returning null context.

A gdk.glcontext.GLContext has to be made "current" in order to start using it, otherwise any OpenGL call will be ignored.

Creating a new OpenGL context

In order to create a new gdk.glcontext.GLContext instance you need a gdk.surface.Surface, which you typically get during the realize call of a widget.

A gdk.glcontext.GLContext is not realized until either gdk.glcontext.GLContext.makeCurrent or gdk.glcontext.GLContext.realize is called. It is possible to specify details of the GL context like the OpenGL version to be used, or whether the GL context should have extra state validation enabled after calling gdk.surface.Surface.createGlContext by calling gdk.glcontext.GLContext.realize. If the realization fails you have the option to change the settings of the gdk.glcontext.GLContext and try again.

Using a GdkGLContext

You will need to make the gdk.glcontext.GLContext the current context before issuing OpenGL calls; the system sends OpenGL commands to whichever context is current. It is possible to have multiple contexts, so you always need to ensure that the one which you want to draw with is the current one before issuing commands:

gdk_gl_context_make_current (context);

You can now perform your drawing using OpenGL commands.

You can check which gdk.glcontext.GLContext is the current one by using gdk.glcontext.GLContext.getCurrent; you can also unset any gdk.glcontext.GLContext that is currently set by calling gdk.glcontext.GLContext.clearCurrent.

Members

Functions

getAllowedApis gdk.types.GLAPI getAllowedApis(): Gets the allowed APIs set via gdk.glcontext.GLContext.setAllowedApis.
getApi gdk.types.GLAPI getApi(): Gets the API currently in use.
getDebugEnabled bool getDebugEnabled(): Retrieves whether the context is doing extra validations and runtime checking.
getDisplay gdk.display.Display getDisplay(): Retrieves the display the context is created for
getForwardCompatible bool getForwardCompatible(): Retrieves whether the context is forward-compatible.
getRequiredVersion void getRequiredVersion(int major, int minor): Retrieves required OpenGL version set as a requirement for the context realization. It will not change even if a greater OpenGL version is supported and used after the context is realized. See gdk.glcontext.GLContext.getVersion for the real version in use.
getSharedContext gdk.glcontext.GLContext getSharedContext(): Used to retrieves the gdk.glcontext.GLContext that this context share data with.
getSurface gdk.surface.Surface getSurface(): Retrieves the surface used by the context.
getUseEs bool getUseEs(): Checks whether the context is using an OpenGL or OpenGL ES profile.
getVersion void getVersion(int major, int minor): Retrieves the OpenGL version of the context.
isLegacy bool isLegacy(): Whether the gdk.glcontext.GLContext is in legacy mode or not.
isShared bool isShared(gdk.glcontext.GLContext other): Checks if the two GL contexts can share resources.
makeCurrent void makeCurrent(): Makes the context the current one.
realize bool realize(): Realizes the given gdk.glcontext.GLContext.
setAllowedApis void setAllowedApis(gdk.types.GLAPI apis): Sets the allowed APIs. When gdk.glcontext.GLContext.realize is called, only the allowed APIs will be tried. If you set this to 0, realizing will always fail.
setDebugEnabled void setDebugEnabled(bool enabled): Sets whether the gdk.glcontext.GLContext should perform extra validations and runtime checking.
setForwardCompatible void setForwardCompatible(bool compatible): Sets whether the gdk.glcontext.GLContext should be forward-compatible.
setRequiredVersion void setRequiredVersion(int major, int minor): Sets the major and minor version of OpenGL to request.
setUseEs void setUseEs(int useEs): Requests that GDK create an OpenGL ES context instead of an OpenGL one.

Static functions

clearCurrent void clearCurrent(): Clears the current gdk.glcontext.GLContext.
getCurrent gdk.glcontext.GLContext getCurrent(): Retrieves the current gdk.glcontext.GLContext.

Inherited Members

From DrawContext

beginFrame void beginFrame(cairo.region.Region region): Indicates that you are beginning the process of redrawing region on the context's surface.
endFrame void endFrame(): Ends a drawing operation started with gdk.draw_context.DrawContext.beginFrame.
getDisplay gdk.display.Display getDisplay(): Retrieves the gdk.display.Display the context is created for
getFrameRegion cairo.region.Region getFrameRegion(): Retrieves the region that is currently being repainted.
getSurface gdk.surface.Surface getSurface(): Retrieves the surface that context is bound to.
isInFrame bool isInFrame(): Returns true if context is in the process of drawing to its surface.

gdk glcontext classes

GLContext