This makes it a bit easier to follow what is going on, and
allow future subdrivers to hook into a few of these functions.
Reworked the code slighly while at it, to return early where
possible.
When we clip the region that is only been redrawn, something
weird happens on Windows. When pushing 60 frames per second on a
60Hz monitor, it appears that the clipped region is often shown
of another frame, instead of the current.
Examples of this are:
- pause the game, move your mouse to the left, and at the right
speed it totally disappears.
- fast aircrafts seem to be in several places at once, weirdly
lagging behind.
- in title screen, moving your mouse gives you the idea it is
jumping places, instead of smooth movements.
In the end, if you do nothing, everything is correct, so it is
eventually consistent. Just when we are firing many BitBlt in
a clipped region, the in-between is not.
What goes wrong exactly, I honestly do not know. On every frame
that we push to the DC is a mouse painted, but visually it
sometimes appears like it is not. Recording with external software
shows it really is there.
It is also not our eyes playing tricks on us, as the first example
makes it really clear the mouse pointer really is not painted.
And to be clear, with the mouse this is easiest reproduceable,
as high-speed objects are influences by this most. But this happens
for all movement that redraws small regions.
Either way, not using clipped regions resolves the issue completely,
and there appears to be little to no penalty (I failed to measure
any impact of drawing the full screen). So better have a good game
than fast code, I guess?
When drawing an 8bpp screen buffer, palette resolving was done for each
dirty rectangle. In areas with high activity, this would mean a pixel might
have been resolved multiple times. Also, if too many individual updates
were queued, the whole screen would be refreshed, even if unnecessary.
All other drivers only keep one overall dirty rect, so do it here as well.
These were special settings only for the win32-drivers, and
introduced in the very first version we track.
Time kinda had caught up with those variables, so it is time to
say farewell.
force_full_redraw was most likely a debug functionality "in case
our dirty-rect fails". This should no longer be needed.
display_hz was cute, as it had a max of 120. That is kinda
out-dated information, but I also doubt anyone was really using
this.
WM_PAINT hits when-ever Windows feels like, but always after we
marked the screen as dirty. In result, it was lagging behind,
giving a sub-60fps experience.
With the new draw-tick there is no longer a need to be driven by
WM_PAINT, so it is better anyway to drive the drawing ourself. As
an added bonus this makes the win32 driver more like the others.
Patric Stout