Oliver Broad / Adafruit-GFX-Library-master

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.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfxfont.h	Sat May 07 12:50:37 2016 +0000
@@ -0,0 +1,24 @@
+// Font structures for newer Adafruit_GFX (1.1 and later).
+// Example fonts are included in 'Fonts' directory.
+// To use a font in your Arduino sketch, #include the corresponding .h
+// file and pass address of GFXfont struct to setFont().  Pass NULL to
+// revert to 'classic' fixed-space bitmap font.
+
+#ifndef _GFXFONT_H_
+#define _GFXFONT_H_
+
+typedef struct { // Data stored PER GLYPH
+	uint16_t bitmapOffset;     // Pointer into GFXfont->bitmap
+	uint8_t  width, height;    // Bitmap dimensions in pixels
+	uint8_t  xAdvance;         // Distance to advance cursor (x axis)
+	int8_t   xOffset, yOffset; // Dist from cursor pos to UL corner
+} GFXglyph;
+
+typedef struct { // Data stored for FONT AS A WHOLE:
+	uint8_t  *bitmap;      // Glyph bitmaps, concatenated
+	GFXglyph *glyph;       // Glyph array
+	uint8_t   first, last; // ASCII extents
+	uint8_t   yAdvance;    // Newline distance (y axis)
+} GFXfont;
+
+#endif // _GFXFONT_H_