Commit f9d18d96 authored by Rami Ali's avatar Rami Ali Committed by Damien George
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docs/library: Add framebuf documentation.

parent c98d7461
:mod:`framebuf` --- Frame buffer manipulation
=============================================
.. module:: framebuf
:synopsis: Frame buffer manipulation
This module provides a general frame buffer which can be used to create
bitmap images, which can then be sent to a display.
class FrameBuffer
-----------------
The FrameBuffer class provides a pixel buffer which can be drawn upon with
pixels, lines, rectangles, text and even other FrameBuffer's. It is useful
when generating output for displays.
For example::
import framebuf
# FrameBuffer needs 2 bytes for every RGB565 pixel
fbuf = FrameBuffer(bytearray(10 * 100 * 2), 10, 100, framebuf.RGB565)
fbuf.fill(0)
fbuf.text('MicroPython!', 0, 0, 0xffff)
fbuf.hline(0, 10, 96, 0xffff)
Constructors
------------
.. class:: FrameBuffer(buffer, width, height, format, stride=width)
Construct a FrameBuffer object. The parameters are:
- `buffer` is an object with a buffer protocol which must be large
enough to contain every pixel defined by the width, height and
format of the FrameBuffer.
- `width` is the width of the FrameBuffer in pixels
- `height` is the height of the FrameBuffer in pixels
- `format` specifies the type of pixel used in the FrameBuffer;
valid values are ``framebuf.MVLSB``, ``framebuf.RGB565``
and ``framebuf.GS4_HMSB``. MVLSB is monochrome 8-bit color,
RGB565 is RGB 16-bit color, and GS4_HMSB is grayscale 4-bit color.
Where a color value c is passed to a method, c is a small integer
with an encoding that is dependent on the format of the FrameBuffer.
- `stride` is the number of pixels between each horizontal line
of pixels in the FrameBuffer. This defaults to `width` but may
need adjustments when implementing a FrameBuffer within another
larger FrameBuffer or screen. The `buffer` size must accommodate
an increased step size.
One must specify valid `buffer`, `width`, `height`, `format` and
optionally `stride`. Invalid `buffer` size or dimensions may lead to
unexpected errors.
Drawing primitive shapes
------------------------
The following methods draw shapes onto the FrameBuffer.
.. method:: FrameBuffer.fill(c)
Fill the entire FrameBuffer with the specified color.
.. method:: FrameBuffer.pixel(x, y[, c])
If `c` is not given, get the color value of the specified pixel.
If `c` is given, set the specified pixel to the given color.
.. method:: FrameBuffer.hline(x, y, w, c)
.. method:: FrameBuffer.vline(x, y, h, c)
.. method:: FrameBuffer.line(x1, y1, x2, y2, c)
Draw a line from a set of coordinates using the given color and
a thickness of 1 pixel. The `line` method draws the line up to
a second set of coordinates whereas the `hline` and `vline`
methods draw horizontal and vertical lines respectively up to
a given length.
.. method:: FrameBuffer.rect(x, y, w, h, c)
.. method:: FrameBuffer.fill_rect(x, y, w, h, c)
Draw a rectangle at the given location, size and color. The `rect`
method draws only a 1 pixel outline whereas the `fill_rect` method
draws both the outline and interior.
Drawing text
------------
.. method:: FrameBuffer.text(s, x, y[, c])
Write text to the FrameBuffer using the the coordinates as the upper-left
corner of the text. The color of the text can be defined by the optional
argument but is otherwise a default value of 1. All characters have
dimensions of 8x8 pixels and there is currently no way to change the font.
Other methods
-------------
.. method:: FrameBuffer.scroll(xstep, ystep)
Shift the contents of the FrameBuffer by the given vector. This may
leave a footprint of the previous colors in the FrameBuffer.
.. method:: FrameBuffer.blit(fbuf, x, y[, key])
Draw another FrameBuffer on top of the current one at the given coordinates.
If `key` is specified then it should be a color integer and the
corresponding color will be considered transparent: all pixels with that
color value will not be drawn.
This method works between FrameBuffer's utilising different formats, but the
resulting colors may be unexpected due to the mismatch in color formats.
Constants
---------
.. data:: framebuf.MVLSB
Monochrome (1-bit) color format
.. data:: framebuf.RGB565
Red Green Blue (16-bit, 5+6+5) color format
.. data:: framebuf.GS4_HMSB
Grayscale (4-bit) color format
......@@ -153,6 +153,7 @@ the following libraries.
.. toctree::
:maxdepth: 1
framebuf.rst
machine.rst
micropython.rst
network.rst
......
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