🚀 go-pugleaf

In article <1993Jan7.211926.11912@physics.ucla.edu> mmccarri@physics.ucla.edu (Mike McCarrick) writes:
>I could rotate a bitmap pixel by pixel, but it seems like a
>lot of work given the various color formats.  Is there an
>easier (and faster) way?
	No, you can not draw rotated bitmaps in Windows 3.1.
	Apparently you will be able to in Windows NT.

>Speaking of bitmaps, I am drawing a large, multi-color bitmap
>(a frequeny-time spectrogram) using the Rectangle() function
>to fill in each df dt block.  This also seems like too much 
>work since I have to create a pen and a brush with the desired
>color, select these objects, draw the rectangle, and then delete
>both objects.  This is repeated 100,000 times or so and is very
>slow.  I experimented with the SetPixel() function instead, but
>it is even slower!  Also, SetPixel() will not dither the color
>if I am running on a paletteless display.  Any suggestions?

	You missed my recent post on this subject.  I
	was doing the same thing you are doing and experimented
	with ways of making it faster.  Scan backwards on
	your newsreader to see if the summary is still on
	your machine.  I also provided the test program I
	used.  mail me if you can't find the post

	What you want to do is fill your rectangles with
	PatBlt, not Rectangle or FillRect.  Also, despite
	the warnings about not wasting resources, you can
	create quite a few brushes (just don't leave them
	hanging around for very long).  I'm using 256
	colours to draw a grid file.  First I create a table
	of 256 hbrush values.  Then I loop through the
	grid, selecting each brush and doing a PatBlt.
	At the end of the whole ordeal, I just delete
	the table of 256 brushes.

	SetPixel will choose the closest solid colour that
	your device is capable of displaying.  If you have
	a standard 16-colour VGA display, the best you
	will get is 16 colours with SetPixel.  Besides,
	how can it produce a dithered pattern with a
	single pixel?
-- 
John A. Grant						jagrant@emr1.emr.ca
Airborne Geophysics
Geological Survey of Canada, Ottawa