[英]Convert HBitmap to Bitmap preserving alpha channel
I have been searching in Google and Stack Overflow , and I cannot find a working example. 我一直在Google和Stack Overflow中进行搜索,但找不到有效的示例。
I need to convert a HBitmap to a Managed .NET bitmap, but the following code does not preserve the alpha channel . 我需要将HBitmap转换为Managed .NET位图,但是以下代码不保留alpha通道 。
private static Bitmap GetBitmapFromHBitmap(IntPtr nativeHBitmap)
{
Bitmap bmp = Bitmap.FromHbitmap(nativeHBitmap);
return bmp;
}
I found this answer in SO , but it does not work for me, the example preserves the transparency, however it flips my image 180º in Y axis and also rotate it 180º. 我在SO中找到了这个答案 ,但是它对我不起作用,该示例保留了透明度,但是它将图像在Y轴上翻转了180º,并将其旋转了180º。 I don't know why. 我不知道为什么
This other example seems to work, but it is C++ 这个其他示例似乎可行,但是它是C ++
Someone has this working in C#, and very important, without memory leaks? 有人使用C#进行这项工作,并且非常重要,没有内存泄漏吗?
Thanks in advance. 提前致谢。
EDIT : Regarding the comment from @Hans Passant, I use the following code to get the HBitmap (it's a shell call to get the thumbnail or icon from the OS (only Vista and Win7). 编辑 :关于@Hans Passant的评论,我使用以下代码获取HBitmap(这是从OS(仅Vista和Win7)获取缩略图或图标的shell调用。
private static IntPtr GetHBitmap(string fileName, int width, int height, ThumbnailOptions options)
{
IShellItem nativeShellItem;
Guid shellItem2Guid = new Guid(IShellItem2Guid);
int retCode = SHCreateItemFromParsingName(fileName, IntPtr.Zero, ref shellItem2Guid, out nativeShellItem);
NativeSize nativeSize = new NativeSize();
nativeSize.Width = width;
nativeSize.Height = height;
IntPtr hBitmap;
HResult hr = ((IShellItemImageFactory)nativeShellItem).GetImage(nativeSize, options, out hBitmap);
Marshal.ReleaseComObject(nativeShellItem);
if (hr == HResult.Ok) return hBitmap;
throw Marshal.GetExceptionForHR((int) hr);
}
Please take a look at Preserving the alpha channel when converting images . 转换图像时,请查看保留alpha通道 。 It seems that it is your case. 看来这是您的情况。
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