MBED Import of ADAFRUIT graphics library, BSD License

Dependents:   GP9002adafruit GP9002af_gray

Notes on this library

This was imported into MBED specifically to support the GP9002 VFD, as a result it has some "hacks" to optimize it for the GP9002.

Due to the GP9002 internal organization it draws vertical lines much faster than horizontal (assuming you orient it "landscape"). This is likely to be true of other displays that have bits in a byte arranged vertically, which seems a common theme in small GLCDs. Some types may have a more CGA-like memory organization and will draw faster horizontally.

On a vertical-organised display the graphics functions are often substantially faster if X and Y are exchanged, especially with the dot-write optimization. This is because vertical lines can be written byte-at-a-time with no need for read-modify-write, and even when individual bits are written a significant number will "land" in the byte previously written. In contrast a horizontal line would require changing one bit of each byte in turn, requiring a sequence of set-address,read,write operations for each dot in turn.

I've hacked this in the library. I forget exactly how but I believe I simply exchanged X with W in the code for drawing filled shapes.

I would like to come up with a more generic way to do this, such as having internal coordinates that are not defined as X and Y, then leaving it up to the display library to "wrap" them in the way that is best for that display.

I would like to apologize for abandoning this project, but the test harness still exists and I might return to it, though I'm more interested in TFT systems like the STM discovery now.

Committer:
oliverb
Date:
Sat May 07 12:50:37 2016 +0000
Revision:
0:3bf8ef959338
Converting to Library, this is a base class that needs extending for a specific device. Note that as it stands it favors devices with vertical bit-organisation

Who changed what in which revision?

UserRevisionLine numberNew contents of line
oliverb 0:3bf8ef959338 1 // Font structures for newer Adafruit_GFX (1.1 and later).
oliverb 0:3bf8ef959338 2 // Example fonts are included in 'Fonts' directory.
oliverb 0:3bf8ef959338 3 // To use a font in your Arduino sketch, #include the corresponding .h
oliverb 0:3bf8ef959338 4 // file and pass address of GFXfont struct to setFont(). Pass NULL to
oliverb 0:3bf8ef959338 5 // revert to 'classic' fixed-space bitmap font.
oliverb 0:3bf8ef959338 6
oliverb 0:3bf8ef959338 7 #ifndef _GFXFONT_H_
oliverb 0:3bf8ef959338 8 #define _GFXFONT_H_
oliverb 0:3bf8ef959338 9
oliverb 0:3bf8ef959338 10 typedef struct { // Data stored PER GLYPH
oliverb 0:3bf8ef959338 11 uint16_t bitmapOffset; // Pointer into GFXfont->bitmap
oliverb 0:3bf8ef959338 12 uint8_t width, height; // Bitmap dimensions in pixels
oliverb 0:3bf8ef959338 13 uint8_t xAdvance; // Distance to advance cursor (x axis)
oliverb 0:3bf8ef959338 14 int8_t xOffset, yOffset; // Dist from cursor pos to UL corner
oliverb 0:3bf8ef959338 15 } GFXglyph;
oliverb 0:3bf8ef959338 16
oliverb 0:3bf8ef959338 17 typedef struct { // Data stored for FONT AS A WHOLE:
oliverb 0:3bf8ef959338 18 uint8_t *bitmap; // Glyph bitmaps, concatenated
oliverb 0:3bf8ef959338 19 GFXglyph *glyph; // Glyph array
oliverb 0:3bf8ef959338 20 uint8_t first, last; // ASCII extents
oliverb 0:3bf8ef959338 21 uint8_t yAdvance; // Newline distance (y axis)
oliverb 0:3bf8ef959338 22 } GFXfont;
oliverb 0:3bf8ef959338 23
oliverb 0:3bf8ef959338 24 #endif // _GFXFONT_H_