关于MFC：如何显示具有透明背景的菜单位图

How to show menu bitmaps with transparent background

我正在使用此代码：

1 2	m_bmpSwap.LoadBitmap(IDB_BITMAP2); pMnuPopup->SetMenuItemBitmaps(0, MF_BYPOSITION, &m_bmpSwap, &m_bmpSwap);

它看起来像：

这只是一个测试图像：

Bitmap

我如何准确地使图像看起来像具有透明背景？

这是24位图像。

我已经看到了，但是我无法解决。

我调整为以192/192/192为背景的8位图像，并像这样加载：

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HBITMAP hBmp;

hBmp = (HBITMAP)::LoadImage(AfxGetResourceHandle(),
MAKEINTRESOURCE(IDB_BITMAP2),
IMAGE_BITMAP,
0, 0, // cx,cy
LR_CREATEDIBSECTION | LR_LOADMAP3DCOLORS);
m_bmpSwap.Attach(hBmp);

pMnuPopup->SetMenuItemBitmaps(0, MF_BYPOSITION, &m_bmpSwap, &m_bmpSwap);

如果我没有运行WindowsBlinds，那似乎更好：

但是当我重新打开WindowsBlinds并再次显示它时：

我本人是色盲，但是我可以说背景实际上与对话框背景匹配，而不与菜单颜色背景匹配。

这是我能做的最好的吗？

请问如何将24位或32位图像作为菜单位图？

相关讨论

添加LR_LOADTRANSPARENT标志以及LR_LOADMAP3DCOLORS

这将适用于8位或4位图像(未经Windows百叶窗测试)

或者您可以手动更改背景颜色

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void swap_color(HBITMAP hbmp)
{
if(!hbmp)
return;
HDC hdc = ::GetDC(HWND_DESKTOP);
BITMAP bm;
GetObject(hbmp, sizeof(bm), &bm);
BITMAPINFO bi = { 0 };
bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bi.bmiHeader.biWidth = bm.bmWidth;
bi.bmiHeader.biHeight = bm.bmHeight;
bi.bmiHeader.biPlanes = 1;
bi.bmiHeader.biBitCount = 32;

std::vector<uint32_t> pixels(bm.bmWidth * bm.bmHeight);
GetDIBits(hdc, hbmp, 0, bm.bmHeight, &pixels[0], &bi, DIB_RGB_COLORS);

//assume that the color at (0,0) is the background color
uint32_t color_old = pixels[0];

//this is the new background color
uint32_t bk = GetSysColor(COLOR_MENU);

//swap RGB with BGR
uint32_t color_new = RGB(GetBValue(bk), GetGValue(bk), GetRValue(bk));

for (auto &pixel : pixels)
if(pixel == color_old)
pixel = color_new;

SetDIBits(hdc, hbmp, 0, bm.bmHeight, &pixels[0], &bi, DIB_RGB_COLORS);
::ReleaseDC(HWND_DESKTOP, hdc);
}

用法：

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CBitmap bmp;
bmp.LoadBitmap(IDB_BITMAP1);
swap_color(bmp);
menu.SetMenuItemBitmaps(0, MF_BYPOSITION, &bmp, &bmp);

相关讨论

我找到了这篇文章。我在这里复制生成的代码：

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#define COLORREF2RGB(Color) (Color & 0xff00) | ((Color >> 16) & 0xff) \\
| ((Color << 16) & 0xff0000)

//-------------------------------------------------------------------------------
// ReplaceColor
//
// Author : Dimitri Rochette [email protected]
// Specials Thanks to Joe Woodbury for his comments and code corrections
//
// Includes : Only <windows.h>

//
// hBmp : Source Bitmap
// cOldColor : Color to replace in hBmp
// cNewColor : Color used for replacement
// hBmpDC : DC of hBmp ( default NULL ) could be NULL if hBmp is not selected
//
// Retcode : HBITMAP of the modified bitmap or NULL for errors
//
//-------------------------------------------------------------------------------
HBITMAP ReplaceColor(HBITMAP hBmp,COLORREF cOldColor,COLORREF cNewColor,HDC hBmpDC)
{
HBITMAP RetBmp=NULL;
if (hBmp)
{
HDC BufferDC=CreateCompatibleDC(NULL); // DC for Source Bitmap
if (BufferDC)
{
HBITMAP hTmpBitmap = (HBITMAP) NULL;
if (hBmpDC)
if (hBmp == (HBITMAP)GetCurrentObject(hBmpDC, OBJ_BITMAP))
{
hTmpBitmap = CreateBitmap(1, 1, 1, 1, NULL);
SelectObject(hBmpDC, hTmpBitmap);
}

HGDIOBJ PreviousBufferObject=SelectObject(BufferDC,hBmp);
// here BufferDC contains the bitmap

HDC DirectDC=CreateCompatibleDC(NULL); // DC for working
if (DirectDC)
{
// Get bitmap size
BITMAP bm;
GetObject(hBmp, sizeof(bm), &bm);

// create a BITMAPINFO with minimal initilisation
// for the CreateDIBSection
BITMAPINFO RGB32BitsBITMAPINFO;
ZeroMemory(&RGB32BitsBITMAPINFO,sizeof(BITMAPINFO));
RGB32BitsBITMAPINFO.bmiHeader.biSize=sizeof(BITMAPINFOHEADER);
RGB32BitsBITMAPINFO.bmiHeader.biWidth=bm.bmWidth;
RGB32BitsBITMAPINFO.bmiHeader.biHeight=bm.bmHeight;
RGB32BitsBITMAPINFO.bmiHeader.biPlanes=1;
RGB32BitsBITMAPINFO.bmiHeader.biBitCount=32;

// pointer used for direct Bitmap pixels access
UINT * ptPixels;

HBITMAP DirectBitmap = CreateDIBSection(DirectDC,
(BITMAPINFO *)&RGB32BitsBITMAPINFO,
DIB_RGB_COLORS,
(void **)&ptPixels,
NULL, 0);
if (DirectBitmap)
{
// here DirectBitmap!=NULL so ptPixels!=NULL no need to test
HGDIOBJ PreviousObject=SelectObject(DirectDC, DirectBitmap);
BitBlt(DirectDC,0,0,
bm.bmWidth,bm.bmHeight,
BufferDC,0,0,SRCCOPY);

// here the DirectDC contains the bitmap

// Convert COLORREF to RGB (Invert RED and BLUE)
cOldColor=COLORREF2RGB(cOldColor);
cNewColor=COLORREF2RGB(cNewColor);

// After all the inits we can do the job : Replace Color
for (int i=((bm.bmWidth*bm.bmHeight)-1);i>=0;i--)
{
if (ptPixels[i]==cOldColor) ptPixels[i]=cNewColor;
}
// little clean up
// Don't delete the result of SelectObject because it's
// our modified bitmap (DirectBitmap)
SelectObject(DirectDC,PreviousObject);

// finish
RetBmp=DirectBitmap;
}
// clean up
DeleteDC(DirectDC);
}
if (hTmpBitmap)
{
SelectObject(hBmpDC, hBmp);
DeleteObject(hTmpBitmap);
}
SelectObject(BufferDC,PreviousBufferObject);
// BufferDC is now useless
DeleteDC(BufferDC);
}
}
return RetBmp;
}

现在，如果我将24位位图添加到我的项目中，并将背景设置为71/71/71并像这样加载它：

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HBITMAP hBmp = (HBITMAP)::LoadImage(AfxGetResourceHandle(),
MAKEINTRESOURCE(IDB_BITMAP1),
IMAGE_BITMAP,
0, 0, // cx,cy
LR_LOADTRANSPARENT | LR_LOADMAP3DCOLORS);
HBITMAP hBmp2 = ReplaceColor(hBmp, RGB(71, 71, 71), GetSysColor(COLOR_MENU), NULL);
DeleteObject(hBmp);

m_bmpSwap.Attach(hBmp2);
pMnuPopup->SetMenuItemBitmaps(0, MF_BYPOSITION, &m_bmpSwap, &m_bmpSwap);

结果：