OpenEuphoria

Re: Stellar Project

• Posted by ghaberek (admin) Nov 19, 2012
• 1531 views

This is a very common mistake when you first start out with drawing directly onto a window. We often assume that since controls persist visually on the window, so do the raw graphics we place there. This is however, simply incorrect. Your graphics might persist, but Windows will almost certainly draw over them again the next time anything happens to your window (move, resize, etc.). Your issue is made especially worse because the w32HOpen event occurs before the window is ever visible.

And so, to persist the graphics, you must only draw to the window during the w32HPaint event, like this:

-- declare your bitmap outside your events 
atom hbitmap 
 
procedure starWindowOpen (integer self, integer event, sequence params)--params is () 
 
	-- create the bitmap during the w32HOpen event 
	hbitmap =  createDIB( {pal, starTable[3]} ) 
	 
end procedure 
setHandler( starWindow, w32HOpen, routine_id("starWindowOpen")) 
 
procedure starWindowPaint( integer self, integer event, sequence params ) 
 
	-- draw the bitmap to the window during the w32HPaint event 
	copyBlt(starWindow,0,0,hbitmap) 
 
	 
end procedure 
setHandler( starWindow, w32HPaint, routine_id("starWindowPaint")) 
	 
WinMain(starWindow, Normal) 

You could also create a Pixmap instead of using createDIB, but you don't need both.

-Greg