full-screen background image

@allObjects updating 60% is of course not desirable.

@Gordon
The idea I was thinking of is a bit different.
What I would like to do is to use something like drawImage but instead of drawing the actual image I would like to select the pixels from another image, while using the transparency and position information of the actual image.

To phrase it differently.
I would like to erase the clock hand by redrawing those pixels from the background image that were written when the clock was drawn.

Or, if I simplify the drawing of the clock hand to:
for all clock hand pixels that are not transparent write the pixel to LCD
Then the restore could be
for all clock hand pixels that are not transparent write the pixel from the background image to LCD.

Only pixels that are overwritten by the hand need to be restored.
So basically instead of writing a clock hand pixel we write a background image pixel to restore the background.
And after restoring the background of course a new clockhand can be drawn.

Does this sound feasible?

edit: a possible call could be something like
g.restoreImage({image:fgimg,x:120,y:120,center:true,scale:0.7,rotate:1.1, pixelimg: bgimg})