canvasResize | Javascript Canvas Resize Plugin | Computer Vision library

You have a number of things going on in this sample that are all possibly contributing:

• The most immediate issue might simply be that the tab window is covering the canvas window and you are not actually painting anything in response to WM_PAINT. The tab control is going to paint over your canvas as soon as its invalidated as Windows usually lets child windows paint all over each other; so adding WS_CLIPSIBLINGS to the tab control might help.

• You are grabbing an HDC to the static control and holding on to it after associating it with the current wgl context. You should not really do this unless you are using a window class with CS_OWNDC and especially not with one that probably has CS_PARENTDC (because then, as soon as the parent - or a different child - window paints, the DC is re-associated with a window that never had SetPixelFormat associated with it).

• You are just making your opengl context current, and expecting it to be set later. This is fine - assuming you have a CS_OWNDC window with an HDC you can grab up front and keep around - and also assuming you never want to create a 2nd GL context for any reason.

So, when doing OpenGL in an application where you are not controlling the window class styles (or there might be more than one OpenGL context) you need to ensure that you always clear the current context and release the DC as soon as you are done with it.

For example, your CanvasWindowProc should look more like this: