<CT> Re: BUG Found

  • From: Erwin Dokter <edokter@xxxxxxx>
  • To: calmira_tips@xxxxxxxxxxxxx
  • Date: Fri, 25 May 2001 23:47:23 +0200

Brian L. Johnson wrote:
> In Windows 3.1, the drawing of the
> titlebars is done by the video driver, and to change that, we'd not only
> have to hack the video driver, but we'd have to do it for each and every
> video driver out there (!)

It works a little differently (now it's my turn to show off :) )

It is true that 'accelerated' cards handle a lot of the drawing
'on-board', but not in such a way you describe. A video graphics chip
can handle drawing a lot faster then software manipulating the video
memory. It does so by performing common tasks itself. These tasks are
rather simple though; drawing lines, circles, filling regions and
copying bitmaps in memory. But not stuff like "drawing the title bar".

The drawing of windows is all done by GDI.EXE. GDI sends commands to the
video driver, like "draw this line, then this line, etc". The driver
then "translates" these commands for the video chip, which actually
preforms the drawing on the screen.

Every application calling drawing functions in GDI will benefit from
this acceleration technique. So patching the video driver is not
necesary at all.

Mask is far too bloated, but it would be possible to do the same and not
loose resources. The trick is to find GDI's internal drawing routines,
but more important, the poiners to those routines. But (naturally) they
are totally undocumented.

-- Erwin Dokter
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