by Robert Lockwoo » Tue, 17 Oct 2000 04:00:00
Thanks
by Feng Yua » Wed, 18 Oct 2000 04:00:00
Use ChangeDisplaySettings to change.
Feng Yuan ( for the GDI to read, check www.fengyuan.com )
by Robert Lockwoo » Wed, 18 Oct 2000 04:00:00
Bob
Quote:> Use EnumDisplaySettings to enumerate supported settings. Some display card
> does not support 24-bpp display mode, but supports 32-bpp display modes.
> Use ChangeDisplaySettings to change.
> Feng Yuan ( for the GDI to read, check www.fengyuan.com )
by Robert Lockwoo » Wed, 18 Oct 2000 04:00:00
I ran a test loop incrementing iModNum until EnumDisplaySettings returned
false. iModeNum was 98 at that point. I have a laptop with 8Mb of memory.
The display is 1024x768 and supports 32 bit color.
What's happening in my ap is that it runs on some machines that are set to
8bit color by another program. My program does not display correctly in
this mode so I want to save the current mode, in this case, and increase the
display to high color. At the very least I want to alert the user so the
display can be changed. When the program is quit I want to restore the
display if it has been changed. I know that I need a reference book so
thanks for the tip.
Bob
Quote:> Use EnumDisplaySettings to enumerate supported settings. Some display card
> does not support 24-bpp display mode, but supports 32-bpp display modes.
> Use ChangeDisplaySettings to change.
> Feng Yuan ( for the GDI to read, check www.fengyuan.com )
by dbulme » Fri, 20 Oct 2000 04:00:00
www.bcbfaq.com has a FAQ on detecting screen res.
Might be useful for you.
Dave B.
by Robert Lockwoo » Fri, 20 Oct 2000 04:00:00
> www.bcbfaq.com has a FAQ on detecting screen res.
> Might be useful for you.
> Dave B.
by dbulme » Sat, 21 Oct 2000 04:00:00
1. Bitmap: True/High-color to 256 color
Alex:
I'll try.
Is the main goal here to reduce the size of the bitmap? If so, you
might want to investigate JPEGs with a fairly high quality factor --
say 75 or more. With screen shots it's likely you need a fairly
high "quality" to avoid artifacts along lines. JPEGs do a good
job in maintaining colors (especially for > 256 colors) and give
quite a bit of compression.
For 256 colors you may want to investigate GIFs and try Anders
Melanders TGIFImage at www.melander.dk/delphi/gifimage .
GIFs may do better if you have lines (like in a screen shot) and
more limited colors. GIFs will give you 256 colors and file
compression.
If you really want a pf8bit bitmap from a pf24bit bitmap, that's
a bit complicated. The process involves coming up with an
appropriate palette, which may be difficult since some images
can have thousands of colors and you want the best 236 to
display your image. (In 256 color mode you must limit your
selection to 236 colors sinces Windows reserves 20 for
display of icons, buttons, panels, etc. In high color or
true color display modes, you can use all 256 colors for
display, but the results are a bit unpredictable in 256 color
mode.)
My ShowDemoOne Lab Reports shows how to get the
needed palette for a pf24bit bitmap that's good enough
to just display a pf24bit bitmap in 256 color mode.
However, if you want to create a pf8bit bitmap, I've never
finished the final step of taking each pf24bit RGB pixell
and find the right index in the palette table for the pf8bit
scanline.
There is C++ code for converting a pf24bit bitmap to a
pf8bit bitmap on my (non-Delphi) color page.
Look for "Octree Color Quantization" and the link to the
article by I. Ashdown in the C/C++ User's Journal. There's
complete code there but in C++. Find the link in Section B of
http://www.efg2.com/Lab/Library/Color.htm
Best wishes to Brazil,
--
efg
Overland Park, KS USA
efg's Computer Lab: http://www.efg2.com/Lab
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