micropython: add micropython component

components/language/micropython/docs/library/framebuf.rst

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+: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 = framebuf.FrameBuffer(bytearray(100 * 10 * 2), 100, 10, framebuf.RGB565)
+
+    fbuf.fill(0)
+    fbuf.text('MicroPython!', 0, 0, 0xffff)
+    fbuf.hline(0, 9, 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;
+          permissible values are listed under Constants below. These set the
+          number of bits used to encode a color value and the layout of these
+          bits in *buffer*.
+          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=-1, palette=None)
+
+    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.
+
+    The *palette* argument enables blitting between FrameBuffers with differing
+    formats. Typical usage is to render a monochrome or grayscale glyph/icon to
+    a color display. The *palette* is a FrameBuffer instance whose format is
+    that of the current FrameBuffer. The *palette* height is one pixel and its
+    pixel width is the number of colors in the source FrameBuffer. The *palette*
+    for an N-bit source needs 2**N pixels; the *palette* for a monochrome source
+    would have 2 pixels representing background and foreground colors. The
+    application assigns a color to each pixel in the *palette*. The color of the
+    current pixel will be that of that *palette* pixel whose x position is the
+    color of the corresponding source pixel.
+
+Constants
+---------
+
+.. data:: framebuf.MONO_VLSB
+
+    Monochrome (1-bit) color format
+    This defines a mapping where the bits in a byte are vertically mapped with
+    bit 0 being nearest the top of the screen. Consequently each byte occupies
+    8 vertical pixels. Subsequent bytes appear at successive horizontal
+    locations until the rightmost edge is reached. Further bytes are rendered
+    at locations starting at the leftmost edge, 8 pixels lower.
+
+.. data:: framebuf.MONO_HLSB
+
+    Monochrome (1-bit) color format
+    This defines a mapping where the bits in a byte are horizontally mapped.
+    Each byte occupies 8 horizontal pixels with bit 7 being the leftmost.
+    Subsequent bytes appear at successive horizontal locations until the
+    rightmost edge is reached. Further bytes are rendered on the next row, one
+    pixel lower.
+
+.. data:: framebuf.MONO_HMSB
+
+    Monochrome (1-bit) color format
+    This defines a mapping where the bits in a byte are horizontally mapped.
+    Each byte occupies 8 horizontal pixels with bit 0 being the leftmost.
+    Subsequent bytes appear at successive horizontal locations until the
+    rightmost edge is reached. Further bytes are rendered on the next row, one
+    pixel lower.
+
+.. data:: framebuf.RGB565
+
+    Red Green Blue (16-bit, 5+6+5) color format
+
+.. data:: framebuf.GS2_HMSB
+
+    Grayscale (2-bit) color format
+
+.. data:: framebuf.GS4_HMSB
+
+    Grayscale (4-bit) color format
+
+.. data:: framebuf.GS8
+
+    Grayscale (8-bit) color format