A grid of lit cells - a bitmap - as a shape.
Each lit cell covers a square of side size, so a cell at {column, row}
covers everything from origin + {column, row} * size up to, but not
including, the next cell along. Covering an area rather than marking a position
is the whole point: it means a bitmap drawn at twice its size comes out as
blocks of four pixels rather than as the same pixels twice as far apart, and it
means sampling a frame more than once per pixel still finds a cell wherever it
looks inside one.
Cells are half-open deliberately. A pixel of a frame is covered by the sample
taken at its own coordinates, so a cell running from 2 up to 3 lights pixel
2 and leaves pixel 3 to the next cell along, whatever size it is drawn at.
Example
A cross, drawn at one pixel per cell and then at three.
iex> use Vivid
...> cross = Bitmap.init([{1, 0}, {0, 1}, {1, 1}, {2, 1}, {1, 2}])
...> Frame.init(3, 3, RGBA.white())
...> |> Frame.push(cross, RGBA.black())
...> |> to_string()
"@ @\n" <>
" \n" <>
"@ @\n"
iex> use Vivid
...> cross = Bitmap.init([{1, 0}, {0, 1}, {1, 1}, {2, 1}, {1, 2}], Point.init(0, 0), 3)
...> Frame.init(9, 9, RGBA.white())
...> |> Frame.push(cross, RGBA.black())
...> |> to_string()
"@@@ @@@\n" <>
"@@@ @@@\n" <>
"@@@ @@@\n" <>
" \n" <>
" \n" <>
" \n" <>
"@@@ @@@\n" <>
"@@@ @@@\n" <>
"@@@ @@@\n"Summary
Functions
Returns the range of frame coordinates covered by cell index index along one
axis, given the origin and size of the bitmap.
Initialize a bitmap of lit cells, one unit square each, from the origin.
Initialize a bitmap of lit cells of side size, starting at origin.
Returns the point bitmap's cells are measured from.
Returns the lit cells of bitmap.
Returns the length of a side of one of bitmap's cells.
Types
@type t() :: %Vivid.Bitmap{ origin: Vivid.Point.t(), pixels: [{integer(), integer()}], size: number() }
Functions
Returns the range of frame coordinates covered by cell index index along one
axis, given the origin and size of the bitmap.
Example
The third cell of a bitmap with cells three wide covers nine, ten and eleven.
iex> Vivid.Bitmap.cell_span(0, 3, 3)
9..11Initialize a bitmap of lit cells, one unit square each, from the origin.
Example
iex> Vivid.Bitmap.init([{0, 0}, {1, 1}])
...> |> Vivid.Bitmap.size()
1@spec init([{integer(), integer()}], Vivid.Point.t(), number()) :: t()
Initialize a bitmap of lit cells of side size, starting at origin.
Example
iex> Vivid.Bitmap.init([{0, 0}], Vivid.Point.init(4, 4), 2)
...> |> Vivid.Bitmap.origin()
Vivid.Point.init(4, 4)@spec origin(t()) :: Vivid.Point.t()
Returns the point bitmap's cells are measured from.
Example
iex> Vivid.Bitmap.init([{0, 0}])
...> |> Vivid.Bitmap.origin()
Vivid.Point.init(0, 0)Returns the lit cells of bitmap.
Example
iex> Vivid.Bitmap.init([{0, 0}, {1, 1}])
...> |> Vivid.Bitmap.pixels()
[{0, 0}, {1, 1}]Returns the length of a side of one of bitmap's cells.
Example
iex> Vivid.Bitmap.init([{0, 0}], Vivid.Point.init(0, 0), 2.5)
...> |> Vivid.Bitmap.size()
2.5