LCD graphics controller

Steve,

I'm not sure about (1), but (2) is commonly used in games for transferring (bit-blitting) images (sprites) with transparency to the video memory. Typically you designate one color (RGB triplet) to be transparent and when copying images to the video memory you only copy the pixels that differ from the transparent color thus preserving the background. This can also be used for text. For example, let's say you want to display the letter "A" but preserve the underlying background. The character "A" is stored as a rectangular image somewhere in memory. So in this image you mark all pixels that are not part of the character itself as transparent and the hardware will not modify the corresponding background pixels. Normally, if you do not have the conditional write in hardware you have to inspect every pixel or perform a two-stage image transfer by using an "and" mask and an "or" mask.

HTH,

-- Georgi

Wow. Steve, you will soon be either a graphics wiz or a basket case. Most guys that ;have never done grahiocs' start with a 2 line text lcd, then maybe got to a small monochrome graphics lcd, port some minimalist graphics functions like draw lines, draw text from some similare micro or similar lcd, THEN maybe try to push some of that functionality into a more complex lcd controller that will handle pages, text and graphics, and COLORS. That subject alone would be a thick book. There must be someone that understands how to draw rgb colors fast... thats how those hw graphics cards work... I think you should dl and try the Scitech MGL graphics library... it will do EVERY resolution and color combination, comes with MANY examples, and C SOURCE. Or just buy an expensive graphics library for your cpu and controller and study the graphics.h file to learn all the functions and their paramaters. Good luck!

Some operations are used 2 xor a "moving" object into the bitmap such as a cursor or depressed button, then reverse it with the same bitblit operation.