84PCSE:BCALLs:54A0
Synopsis
Unofficial Name: UnHighlightRect
BCALL Address: 54A0h
Un-highlight a rectangular area of the LCD by changing non-black pixels to white.
Inputs
- HL = X coordinate of left edge
- DE = X coordinate of right edge (must be greater than or equal to HL and at most 319)
- B = Y coordinate of top edge (from top of screen)
- C = Y coordinate of bottom edge (must be greater than or equal to B and at most 239)
Outputs
None
Destroys
- AF
Comments
The rectangle is drawn only to the LCD, never to the graph buffer.
This is designed to reverse the effect of HighlightRect. For each pixel in the rectangle, if its most significant byte is zero (i.e., the color is either black, blue, or blue plus a very small amount of green), the pixel will be set to black. Otherwise it will be set to white. (The fact that blue pixels are treated as black may be a mistake on TI's part, but in any case, it is clear that this routine isn't intended to be used for anything other than black-and-white text.)
The dimensions of the highlighted area are (HL-DE+1) × (C-B+1). The routine doesn't check that the provided coordinates are valid.
The interrupt state (IFF) is preserved.
