Roman Kennke wrote: > Hi Gary, > > >>>>The setComposite method of anything that extends java.awt. >>>>Graphics2D is supposed to do a permisson check if "...this >>>>Graphics2D context is drawing to a Component on the display >>>>screen and the Composite is a custom object rather than an >>>>instance of the AlphaComposite class." The latter is easy >>>>to check, but how do I tell whether the context is drawing >>>>to a Component on the display screen? >>> >>>Only one subclass of CairoGraphics2D draws on the screen, I >>>think this is ComponentGraphics. >> >>Ok. Do you know about its subclass, VolatileImageGraphics? > > > VolatileImage doesn't draw on the screen. It draws on a backbuffer (an > XImage really). I don't know if that counts as drawing on screen though. > Because the backbuffer should be synced with the screen sooner or later. > But maybe you try against the JDK (Component.createVolatileImage() gives > you a VolatileImage instance). > The check is for "readDisplayPixels", so something that is not visible would seem to be exempt. David Daney.
