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/license.txt	Sat May 07 12:50:37 2016 +0000
@@ -0,0 +1,24 @@
+Software License Agreement (BSD License)
+
+Copyright (c) 2012 Adafruit Industries.  All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+- Redistributions of source code must retain the above copyright notice,
+  this list of conditions and the following disclaimer.
+- Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.