工单 修复 微信复制图片上传不展示的bug

OrderSupportTicket/ViewModels/PendingAttachmentViewModel.cs

@@ -207,7 +207,7 @@ public sealed class PendingAttachmentViewModel : BindableBaseEx, IDisposable
 				Path.GetTempPath(),
 				"WxOrder-Clipboard-" + Guid.NewGuid().ToString("N") + ".png");
 			var encoder = new PngBitmapEncoder();
-			encoder.Frames.Add(BitmapFrame.Create(bitmap));
+			encoder.Frames.Add(BitmapFrame.Create(NormalizeClipboardBitmap(bitmap)));
 			using (var stream = File.Create(filePath))
 				encoder.Save(stream);
 
@@ -236,6 +236,29 @@ public sealed class PendingAttachmentViewModel : BindableBaseEx, IDisposable
 		}
 	}
 
+	private static BitmapSource NormalizeClipboardBitmap(BitmapSource bitmap)
+	{
+		if (bitmap.Format != PixelFormats.Bgra32 && bitmap.Format != PixelFormats.Pbgra32)
+			return bitmap;
+
+		var stride = checked(bitmap.PixelWidth * 4);
+		var pixels = new byte[checked(stride * bitmap.PixelHeight)];
+		bitmap.CopyPixels(pixels, stride, 0);
+		for (var i = 3; i < pixels.Length; i += 4)
+		{
+			if (pixels[i] != 0)
+				return bitmap;
+		}
+
+		// 微信等截图工具可能将 DIB 的保留字节全部置零，WPF 将其解释为 Alpha。
+		// 直接按 Bgr32 使用原始颜色，避免预乘 Alpha 转换时丢失 RGB；正常透明图保持原样。
+		var normalized = BitmapSource.Create(
+			bitmap.PixelWidth, bitmap.PixelHeight, bitmap.DpiX, bitmap.DpiY,
+			PixelFormats.Bgr32, null, pixels, stride);
+		normalized.Freeze();
+		return normalized;
+	}
+
 	public void Dispose()
 	{
 		if (_disposed)