/// <summary>
/// 返回实际占用的Rect 和 scale
/// </summary>
public static DrawBitmapResult DrawBitmap(this SKCanvas canvas, SKBitmap bitmap, SKRect dest,
SKStretchMode stretch,
SKAlignment horizontal = SKAlignment.Center,
SKAlignment vertical = SKAlignment.Center,
SKPaint?paint = null)
{
if (stretch == SKStretchMode.Fill)
{
canvas.DrawBitmap(bitmap, dest, paint);
return(new DrawBitmapResult(dest, dest.Width / bitmap.Width, dest.Height / bitmap.Height));
}
float scale = 1;
switch (stretch)
{
case SKStretchMode.None:
break;
case SKStretchMode.AspectFit:
scale = Math.Min(dest.Width / bitmap.Width, dest.Height / bitmap.Height);
break;
case SKStretchMode.AspectFill:
scale = Math.Max(dest.Width / bitmap.Width, dest.Height / bitmap.Height);
break;
}
SKRect display = CalculateDisplayRect(dest, scale * bitmap.Width, scale * bitmap.Height, horizontal, vertical);
canvas.DrawBitmap(bitmap, display, paint);
return(new DrawBitmapResult(display, scale, scale));
}
public static void DrawBitmap(this SKCanvas canvas, SKBitmap bitmap, SKRect dest,
SKStretch stretch,
SKAlignment horizontal = SKAlignment.Center,
SKAlignment vertical = SKAlignment.Center,
SKPaint paint = null)
{
if (stretch == SKStretch.Fill)
{
canvas.DrawBitmap(bitmap, dest, paint);
}
else
{
float scale = 1;
switch (stretch)
{
case SKStretch.None:
break;
case SKStretch.Uniform:
scale = Math.Min(dest.Width / bitmap.Width, dest.Height / bitmap.Height);
break;
case SKStretch.UniformToFill:
scale = Math.Max(dest.Width / bitmap.Width, dest.Height / bitmap.Height);
break;
}
SKRect display = CalculateDisplayRect(dest, scale * bitmap.Width, scale * bitmap.Height, horizontal, vertical);
canvas.DrawBitmap(bitmap, display, paint);
}
}
static SKRect CalculateDisplayRect(SKRect dest, float bmpWidth, float bmpHeight,
SKAlignment horizontal, SKAlignment vertical)
{
float x = 0;
float y = 0;
switch (horizontal)
{
case SKAlignment.Center:
x = (dest.Width - bmpWidth) / 2;
break;
case SKAlignment.Start:
break;
case SKAlignment.End:
x = dest.Width - bmpWidth;
break;
}
switch (vertical)
{
case SKAlignment.Center:
y = (dest.Height - bmpHeight) / 2;
break;
case SKAlignment.Start:
break;
case SKAlignment.End:
y = dest.Height - bmpHeight;
break;
}
x += dest.Left;
y += dest.Top;
return(new SKRect(x, y, x + bmpWidth, y + bmpHeight));
}
