On Fri, 16 Feb 2001, François Gouget wrote:
I just wanted to avoid copying the pixmap back into the DIB for the GetPixel case since obviously it has not been modified. That's what commit is here for of course. OTOH the subtleties of lossy are a bit lost on me. AFAICS it's always set to false so I'll just do the same.
The "lossy" is only meant for extreme optimization cases - "lossy" suppresses the copying entirely, and is only meant to be useful when some operation would completely overwrite/obliterate everything on the DIB surface anyway, for example, a SRCCOPY blit that'd cover the entire destination DIB. In such cases, it'd just be a waste to do a copy only to have all of the copied data overwritten, it would be more efficient to not copy anything then. But such optimization checks isn't being done yet.
I think the reason GetPixel/PutPixel hasn't done DIB updates yet is because it's wasteful to copy the entire DIB graphic back and forth for a single pixel, when it should really be easy to add code that could access the DIB data directly... just that nobody did that yet. We're going to need a proper DIB (aka FB) graphics engine someday...