cairoDrawFromGl
void cairoDrawFromGl(cairo.context.Context cr, gdk.window.Window window, int source, int sourceType, int bufferScale, int x, int y, int width, int height)This is the main way to draw GL content in GTK+. It takes a render buffer ID (source_type == #GL_RENDERBUFFER) or a texture id (source_type == #GL_TEXTURE) and draws it onto cr with an OVER operation, respecting the current clip. The top left corner of the rectangle specified by x, y, width and height will be drawn at the current (0,0) position of the cairo_t.
This will work for all cairo_t, as long as window is realized, but the fallback implementation that reads back the pixels from the buffer may be used in the general case. In the case of direct drawing to a window with no special effects applied to cr it will however use a more efficient approach.
For #GL_RENDERBUFFER the code will always fall back to software for buffers with alpha components, so make sure you use #GL_TEXTURE if using alpha.
Calling this may change the current GL context.
Parameters
cr | a cairo context |
window | The window we're rendering for (not necessarily into) |
source | The GL ID of the source buffer |
sourceType | The type of the source |
bufferScale | The scale-factor that the source buffer is allocated for |
x | The source x position in source to start copying from in GL coordinates |
y | The source y position in source to start copying from in GL coordinates |
width | The width of the region to draw |
height | The height of the region to draw |