/// <summary>
/// Create matrix to transform image based on relative dimensions of bitmap and drawRect, Stretch mode, and RelativeTransform
/// </summary>
/// <param name="drawRect"></param>
/// <param name="bitmap"></param>
/// <returns></returns>
private Android.Graphics.Matrix GenerateMatrix(Windows.Foundation.Rect drawRect, Bitmap bitmap)
{
var matrix = new Android.Graphics.Matrix();
// Note that bitmap.Width and bitmap.Height (in physical pixels) are automatically scaled up when loaded from local resources, but aren't when acquired externally.
// This means that bitmaps acquired externally might not render the same way on devices with different densities when using Stretch.None.
var sourceRect = new Windows.Foundation.Rect(0, 0, bitmap.Width, bitmap.Height);
var destinationRect = GetArrangedImageRect(sourceRect.Size, drawRect);
matrix.SetRectToRect(sourceRect.ToRectF(), destinationRect.ToRectF(), Android.Graphics.Matrix.ScaleToFit.Fill);
RelativeTransform?.ToNativeMatrix(matrix, size: new Size(sourceRect.Width, sourceRect.Height));
return(matrix);
}
protected internal override Shader GetShader(Rect destinationRect)
{
var center = Center;
var radiusX = RadiusX;
var radiusY = RadiusY;
float radius;
if (MappingMode == BrushMappingMode.RelativeToBoundingBox)
{
var size = destinationRect.Size;
center = new Point(center.X * size.Width, Center.Y * size.Height);
radius = (float)(radiusX * size.Width + radiusY * size.Height) / 2.0f; // We take the avg
}
else
{
center = center.LogicalToPhysicalPixels();
radius = ViewHelper.LogicalToPhysicalPixels((radiusX + radiusY) / 2.0d); // We take the avg
}
// Android requires a radius and two or more stop points.
if (radius <= 0 || GradientStops.Count < 2)
{
return(null);
}
var colors = GradientStops.SelectToArray(s => ((Android.Graphics.Color)GetColorWithOpacity(s.Color)).ToArgb());
var locations = GradientStops.SelectToArray(s => (float)s.Offset);
var width = destinationRect.Width;
var height = destinationRect.Height;
var transform = RelativeTransform?.ToNativeMatrix(size: new Windows.Foundation.Size(width, height));
var shader = new RadialGradient(
(float)center.X,
(float)center.Y,
radius,
colors,
locations,
Shader.TileMode.Clamp);
return(shader);
}
