/// <summary>
/// 工厂方法：用设定的颜色和位置创建一个 GlowBitmap 对象。
/// </summary>
/// <param name="drawingContext"></param>
/// <param name="bitmapPart"></param>
/// <param name="color"></param>
/// <returns></returns>
public static GlowEdgeBitmap Create(GlowEdgeDrawingContext dc, GlowEdgeBitmapParts part, Color color)
{
CachedBitmapInfo mast = GetOrCreateAlphaMast(part);
GlowEdgeBitmap glowEdgeBitmap = new GlowEdgeBitmap(dc.ScreenDC, mast.Width, mast.Height);
// 创建数据
for (int i = 0; i < mast.DIBits.Length; i += BytesPerPixelBgra32)
{
byte a = mast.DIBits[i + 3];
byte r = PremultiplyAlpha(color.R, a);
byte g = PremultiplyAlpha(color.G, a);
byte b = PremultiplyAlpha(color.B, a);
Marshal.WriteByte(glowEdgeBitmap.DIBits, i, b);
Marshal.WriteByte(glowEdgeBitmap.DIBits, i + 1, g);
Marshal.WriteByte(glowEdgeBitmap.DIBits, i + 2, r);
Marshal.WriteByte(glowEdgeBitmap.DIBits, i + 3, a);
}
return(glowEdgeBitmap);
}
/// <summary>
/// 读取图片的 Alpha 通道作为阴影的 Alpha 通道
/// </summary>
/// <param name="part"></param>
/// <returns></returns>
private static CachedBitmapInfo GetOrCreateAlphaMast(GlowEdgeBitmapParts part)
{
int index = (int)part;
if (_transparencyMasks[index] == null)
{
BitmapImage mastImage =
new BitmapImage(
new Uri($"pack://application:,,,/WindowCustomizeTest;Component/GlowWindowCore/Resource/{part}.png" /*, UriKind.Relative*/));
byte[] pixels = new byte[BytesPerPixelBgra32 * mastImage.PixelWidth * mastImage.PixelHeight];
int stride = BytesPerPixelBgra32 * mastImage.PixelWidth;
mastImage.CopyPixels(pixels, stride, 0);
mastImage.Freeze();
_transparencyMasks[index] =
new CachedBitmapInfo(pixels, mastImage.PixelWidth, mastImage.PixelHeight);
}
return(_transparencyMasks[index]);
}