OptionalangleThe direction of the gradient in degrees, like CSS' linear-gradient(): 0 goes up, 90 to the right, 180
down, 270 to the left. The first stop is at the start of the line through the center that touches the
corners. Default: 180
The colors along the gradient: their positions (0..1) and colors, like Colors.gradient takes them
({ 0: 0xff0000ff, 0.5: 0xffff00ff, 1: 0x00ff00ff }), or just the colors, evenly spaced
([0xff0000ff, 0x00ff00ff])
Options of Image.linearGradient