Buffers topic

2-dimensional views of pixel data are provided by the Buffer type, which provides a read-only view, with similar functionality to an Iterable: it can be extended or mixed-in as a base class provided the necessary methods are implemented.

final class MyBuffer extends Buffer<int> {
  @override
  PixelFormat<int, void> get format => myFormat;

  @override
  int get width => 640;

  @override
  int get height => 480;

  /* ... rest of the class implementation ... */
}

In most cases, a concrete Pixels instance will be used to represent pixel data, which is a buffer that can be read from and written to and guarantees fast access to linearly stored pixel data. For example, the IntPixels class stores pixel data as a list of integers, and Float32x4Pixels stores pixel data as a 32x4 matrix of floating-point values.

// Creating a 320x240 pixel buffer with the default `abgr8888` format.
final pixels = new IntPixels(320, 240);

// Setting the pixel at (10, 20) to red.
pixels.set(Pos(10, 20), abgr8888.red);

Writing data

The set method is not the only way to write data to a buffer:

• clear: Clears a region to the zero value.
• fill: Fills a region with a pixel value.
• copyFrom: Copies pixel data from another buffer.

For example, to fill the entire buffer with red:

pixels.fill(abgr8888.red);

Pixels also support alpha blending; see blending for more information.

Reading data

Reading data from a buffer is done using the get method:

final pixel = pixels.get(Pos(10, 20));

The get method is not the only way to read data from a buffer:

• getRange: Reads a range of pixels lazily.
• getRect: Reads a rectangular region of pixels lazily.

Converting data

Many operations in Pxl can automatically convert between different pixel formats as needed.

To lazily convert buffers, use the mapConvert method:

final abgr8888Pixels = IntPixels(320, 240);
final rgba8888Buffer = abgr8888Pixels.mapConvert(rgba8888);

To copy the actual data, use IntPixels.from or Float32x4Pixels.from:

final rgba8888Pixels = IntPixels.from(abgr8888Pixels);