TImage drawing in OpenGL-preferring canvas


I tried to draw JPEG picture using TImage in the canvas after calling gStyle->SetCanvasPreferGL(kTRUE) and found some strange behaviour: picture is not seen most of the time, yet sometimes it gets visible briefly during e.g. canvas window resizing operation. I ran image drawing sample from the ROOT tutorials (root\tutorials\image\rose_image.C) using OpenGL-preferring canvas and got the same behaviour. For the standard (non-GL) canvas there’s no problem. Moreover, GL-enabled canvas works nicely for drawing vector graphics objects (e.g. TBox, TArrow, etc), so it seems to be a problem of GL+TImage combination only.

Is it a known problem and, if so, is it going to be fixed someday? The usage of GL-enabled canvas for drawing pictures is especially crucial e.g. when the picture is overlaid with the dense motion vector field: in GL canvas the vectors are much more smooth and distinct unlike the case of non-GL canvas.

– Valery