/// <summary>
/// The GradientFill function fills rectangle and triangle structures
/// </summary>
/// <param name="hdc">Handle to the destination device contex</param>
/// <param name="pVertex">Array of TRIVERTEX structures that each define a triangle vertex</param>
/// <param name="nVertex">The number of vertices in pVertex</param>
/// <param name="pMesh">an array of GRADIENT_RECT structures in rectangle mode</param>
/// <param name="nMesh">The number of elements in pMesh</param>
/// <param name="ulMode">Specifies gradient fill mode</param>
/// <returns>If the function succeeds, the return value is true, false</returns>
public static bool GradientFill([In] IntPtr hdc, TriVertex[] pVertex, uint nVertex, GradientRect[] pMesh,
uint nMesh, GradientFillMode ulMode)
{
return Native.GradientFill(hdc, pVertex, nVertex, pMesh, nMesh, ulMode);
}
private void Create(IRenderLayer layer)
{
var zoom = Context.Zoom;
var colors = layer.Colors.Data;
int length = colors.Length;
int size = layer.Points.Size;
var data = layer.Points.Data;
if (length != data.Length / size)
{
throw new Exception();
}
this.points = new TriVertex[length];
TriVertex vertex;
Color color;
PointF p = new PointF((float)data[0], (float)data[1]);
zoom.WorldToScreen(ref p);
// Get correction distance
float dx = (p.X - (int)p.X) * 2.0f;
float dy = (p.Y - (int)p.Y) * 2.0f;
// Create vertices.
for (int i = 0; i < length; i++)
{
p.X = (float)data[size * i];
p.Y = (float)data[size * i + 1];
zoom.WorldToScreen(ref p);
color = colors[i];
vertex = new TriVertex();
vertex.x = (int)(p.X + dx);
vertex.y = (int)(p.Y + dy);
vertex.Red = (ushort)(color.R << 8);
vertex.Green = (ushort)(color.G << 8);
vertex.Blue = (ushort)(color.B << 8);
vertex.Alpha = (ushort)(color.A << 8);
this.points[i] = vertex;
}
var triangles = layer.Indices.Data;
length = triangles.Length / 3;
this.elements = new GradientTriangle[length];
GradientTriangle e;
// Create triangles.
for (int i = 0; i < length; i++)
{
e = new GradientTriangle();
e.Vertex1 = (uint)triangles[3 * i];
e.Vertex2 = (uint)triangles[3 * i + 1];
e.Vertex3 = (uint)triangles[3 * i + 2];
this.elements[i] = e;
}
}