Hello, Quite easy. Abstract concept: - Take one framebuffer `ImageBuffer`, whose contents is the final image - Take another framebuffer `InteractionBuffer` whose contents is everything that's interactive - The InteractionBuffer shall be an overlay of the imagebuffer
So when you want to draw it interactively, you draw the ellipse in InteractionBuffer, and once the user confirms that `yes draw what I see right now`, you simply draw the ellipse in the ImageBuffer and clear the InteractionBuffer. If you want to update the interaction buffer with a new ellipse, you clear it and draw the new ellipse. As for the third party library: how could you expect for a third party library to give you such lazarus-specific functionality? Anyway, hope it helps. Once upon a time, on 01/23/2013 11:27 AM to be precise, duilio foschi said: > Hi! > > this code > > [snip] > > will draw 10 ellipses on Image1. > > However, I want to do it interactively, like it is done in Photo-Paint. > > The ellipse should be contained in a rectangle R whose upper-left > corner is given by the original position of the mouse on screen. > > And the bottom-right corner of R will be the final position of the mouse. > > During dragging, a temporary ellipse should be shown on screen and the > mouse will be cross-shaped. > > Any idea re how to do it ? > > An unexpensive well debugged 3th-party library would be the ideal > solution (as I don't plan to work in graphics in the future). > -- Ewald _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
