Vertices constructor Null safety
Creates a set of vertex data for use with Canvas.drawVertices.
The mode
and positions
parameters must not be null.
The positions
parameter is a list of triangular mesh vertices(xy).
If the textureCoordinates
or colors
parameters are provided, they must
be the same length as positions
.
The textureCoordinates
parameter is used to cutout
the image set in the image shader.
The cut part is applied to the triangular mesh.
Note that the textureCoordinates
are the coordinates on the image.
If the indices
parameter is provided, all values in the list must be
valid index values for positions
.
e.g. The indices
parameter for a simple triangle is 0,1,2
.
Implementation
Vertices(
VertexMode mode,
List<Offset> positions, {
List<Offset>? textureCoordinates,
List<Color>? colors,
List<int>? indices,
}) : assert(mode != null),
assert(positions != null) {
if (textureCoordinates != null && textureCoordinates.length != positions.length) {
throw ArgumentError('"positions" and "textureCoordinates" lengths must match.');
}
if (colors != null && colors.length != positions.length) {
throw ArgumentError('"positions" and "colors" lengths must match.');
}
if (indices != null && indices.any((int i) => i < 0 || i >= positions.length)) {
throw ArgumentError('"indices" values must be valid indices in the positions list.');
}
final Float32List encodedPositions = _encodePointList(positions);
final Float32List? encodedTextureCoordinates = (textureCoordinates != null)
? _encodePointList(textureCoordinates)
: null;
final Int32List? encodedColors = colors != null
? _encodeColorList(colors)
: null;
final Uint16List? encodedIndices = indices != null
? Uint16List.fromList(indices)
: null;
if (!_init(this, mode.index, encodedPositions, encodedTextureCoordinates, encodedColors, encodedIndices)) {
throw ArgumentError('Invalid configuration for vertices.');
}
}