1. Printing Graphics
- Posted by rswiston at hotmail.com
Jul 16, 2002
Does anyone have a reliable method of printing bmps or gif from Euphoria
through Win32Lib?
I have scanned all of the related material and tried everything I can find,
but have come up short everytime. I can print text, lines, rectangles, etc,
but when it comes to printing a bitmap... I get black boxes, jumbled boxes,
or nothing at all (usually with an error).
Anyone have any susggestions?
2. Re: Printing Graphics
rswiston wrote:
>Does anyone have a reliable method of printing bmps or gif from Euphoria
>through Win32Lib?
First of all, I'm assuming that you don't need to break the image up into
multiple strips (bands) because of memory constraints. Some versions of
Windows support this automatically; others don't.
Secondly, I'm assuming you are using BitBlt to print the image. I'm also
assuming that you are using StretchBlt (or some equivalent) to resize the
image onto the printer. For example, a 200x200 pixel on a 300 dpi laser
printer only comes out to 2/3 of a square inch.
Another easy test is to try printing the image pixel by pixel, something
like:
for y = 1 to length( image ) do
scanline = image[i]
for x = 1 to length( scanline ) do
-- get a pixel from the image
color = scanline[x]
rgb = palette[color]
-- draw it on the printer
DrawPixel( Printer, ... )
end for
end for
It's likely to take forever this way, but it's one way to test what's going
on.
Most likely, the problem is that you need to convert the image into a
dithered image. That is, if the printer only prints black and you send it a
color or grey image, you only get a black and white image out of it. If it
doesn't have any pure white spots, that means that all colors get mapped to
black. Ick.
You can easily test this by trying to print a black and white image.
If that's the case, it's not too hard to write a program that converts a
color image into a black and white dithered image.
-- David Cuny
