具有透明背景的 win32 菜单项位图
win32 menu item bitmap with transparent background
我尝试完成的事情非常简单:将图像添加到菜单项。我正在使用 win32 API 在 C 中编程。显示图像/位图,但背景为白色。我想要的是把白色的背景变成透明的。
我一直在阅读我能找到的所有信息,包括 Whosebug,但这些信息似乎不一致。有人说位图不能有任何形式的透明度,而其他人则说可以。参见例如这个问题:
Simple way to show a bitmap next to a menu item in a CMenu with correct transparency
SetMenuItemBitmaps()
和 SetMenuItemInfo()
都是白色背景。以上 link 表示如果位图为 32bpp 且带有预乘 alpha,则它应该正确显示。因此,要么这种方式根本不可能,要么我使用的 bmp 格式错误。谁能给这个问题一个明确的答案。如果事实证明无法使用 SetMenuItemInfo()
完成,那么解决此问题的最简单方法是什么?我尽量避免所有者绘制解决方案,因为我觉得它有点矫枉过正。此外,据我所知,所有者绘制的解决方案很难遵守 Windows 主题。
menubitmap.rc:
#include "menubitmap.h"
ID_ICON ICON DISCARDABLE "menu1.ico"
ID_BITMAP_EXIT BITMAP DISCARDABLE "Exit-icn.bmp"
ID_MENU MENU DISCARDABLE
BEGIN
POPUP "&File"
BEGIN
MENUITEM "E&xit", ID_FILE_EXIT
END
END
menubitmap.c:
#include <windows.h>
#include "menubitmap.h"
const char g_szClassName[] = "myWindowClass";
LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)
{
switch(Message)
{
case WM_CREATE:
{
HBITMAP btmp;
MENUITEMINFOA miinfo;
HMENU menu;
btmp=LoadBitmap((HINSTANCE) GetModuleHandle (NULL), MAKEINTRESOURCE(ID_BITMAP_EXIT));
menu=GetMenu(hwnd);
miinfo.cbSize=sizeof(MENUITEMINFO);
if(!GetMenuItemInfo(menu,ID_FILE_EXIT,FALSE,&miinfo)){
printf("getmenuiteminfo failed\r\n");
}else{
miinfo.fMask |= MIIM_BITMAP;
miinfo.hbmpItem=btmp;
if(SetMenuItemInfo(menu,ID_FILE_EXIT,FALSE,&miinfo)){
printf("setmenuiteminfo");
}
}
}
case WM_COMMAND:
switch(LOWORD(wParam))
{
case ID_FILE_EXIT:
PostMessage(hwnd, WM_CLOSE, 0, 0);
break;
}
break;
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, Message, wParam, lParam);
}
return 0;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG Msg;
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = 0;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(GetModuleHandle(NULL), MAKEINTRESOURCE(ID_ICON));
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wc.lpszMenuName = MAKEINTRESOURCE(ID_MENU);
wc.lpszClassName = g_szClassName;
wc.hIconSm = (HICON)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(ID_ICON), IMAGE_ICON, 16, 16, 0);
if(!RegisterClassEx(&wc))
{
MessageBox(NULL, "Window Registration Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
hwnd = CreateWindowEx(
WS_EX_CLIENTEDGE,
g_szClassName,
"A Menu",
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 240, 120,
NULL, NULL, hInstance, NULL);
if(hwnd == NULL)
{
MessageBox(NULL, "Window Creation Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
while(GetMessage(&Msg, NULL, 0, 0) > 0)
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}
在这里你可以找到 bitmap
这里是bas64格式的位图: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您可以手动更改位图的背景颜色以实现透明。
代码如下:
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);
}
最少的代码示例:
HMENU m_hMenu;
HBITMAP g_BitMap;
...
case WM_CONTEXTMENU:
{
m_hMenu = CreatePopupMenu();
g_BitMap = (HBITMAP)LoadImage(NULL, L"UNTITLED.bmp", IMAGE_BITMAP, 16, 16, LR_LOADFROMFILE);
swap_color(g_BitMap);
InsertMenu(m_hMenu, 1, MF_BYPOSITION | MF_POPUP, NULL, L"Windows");
MENUITEMINFO mii = { sizeof(MENUITEMINFO) };
mii.fMask = MIIM_BITMAP;
mii.hbmpItem = g_BitMap;
SetMenuItemInfo(m_hMenu, 0, true, &mii);
TrackPopupMenu(m_hMenu, TPM_TOPALIGN | TPM_LEFTALIGN | TPM_HORPOSANIMATION, GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam), 0, hWnd, NULL);
}
break;
调试:
img from the link you mentioned, and I converted it to a 32-bit BMP picture.
参考:
Windows' GDI 中的 Alpha 透明度是一个雷区。它添加的很晚,只有少数 API 调用真正能够处理专用的 alpha 通道。 LoadBitmap 不是支持(或至少不破坏)alpha 透明度的那些之一。当您从应用程序的资源加载图像时,Alpha 通道会丢失。
要解决这个问题,您必须使用 LoadImage,传递正确的标志。 LR_CREATEDIBSECTION
是重要的,因为它保留了源位图中的 alpha 通道。
修复就像更换一样简单
LoadBitmap((HINSTANCE) GetModuleHandle (NULL), MAKEINTRESOURCE(ID_BITMAP_EXIT))
和
(HBITMAP)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(ID_BITMAP_EXIT),
IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION)
设置好后,您将看到显示的菜单图标具有每像素 alpha 透明度:
我尝试完成的事情非常简单:将图像添加到菜单项。我正在使用 win32 API 在 C 中编程。显示图像/位图,但背景为白色。我想要的是把白色的背景变成透明的。
我一直在阅读我能找到的所有信息,包括 Whosebug,但这些信息似乎不一致。有人说位图不能有任何形式的透明度,而其他人则说可以。参见例如这个问题:
Simple way to show a bitmap next to a menu item in a CMenu with correct transparency
SetMenuItemBitmaps()
和 SetMenuItemInfo()
都是白色背景。以上 link 表示如果位图为 32bpp 且带有预乘 alpha,则它应该正确显示。因此,要么这种方式根本不可能,要么我使用的 bmp 格式错误。谁能给这个问题一个明确的答案。如果事实证明无法使用 SetMenuItemInfo()
完成,那么解决此问题的最简单方法是什么?我尽量避免所有者绘制解决方案,因为我觉得它有点矫枉过正。此外,据我所知,所有者绘制的解决方案很难遵守 Windows 主题。
menubitmap.rc:
#include "menubitmap.h"
ID_ICON ICON DISCARDABLE "menu1.ico"
ID_BITMAP_EXIT BITMAP DISCARDABLE "Exit-icn.bmp"
ID_MENU MENU DISCARDABLE
BEGIN
POPUP "&File"
BEGIN
MENUITEM "E&xit", ID_FILE_EXIT
END
END
menubitmap.c:
#include <windows.h>
#include "menubitmap.h"
const char g_szClassName[] = "myWindowClass";
LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)
{
switch(Message)
{
case WM_CREATE:
{
HBITMAP btmp;
MENUITEMINFOA miinfo;
HMENU menu;
btmp=LoadBitmap((HINSTANCE) GetModuleHandle (NULL), MAKEINTRESOURCE(ID_BITMAP_EXIT));
menu=GetMenu(hwnd);
miinfo.cbSize=sizeof(MENUITEMINFO);
if(!GetMenuItemInfo(menu,ID_FILE_EXIT,FALSE,&miinfo)){
printf("getmenuiteminfo failed\r\n");
}else{
miinfo.fMask |= MIIM_BITMAP;
miinfo.hbmpItem=btmp;
if(SetMenuItemInfo(menu,ID_FILE_EXIT,FALSE,&miinfo)){
printf("setmenuiteminfo");
}
}
}
case WM_COMMAND:
switch(LOWORD(wParam))
{
case ID_FILE_EXIT:
PostMessage(hwnd, WM_CLOSE, 0, 0);
break;
}
break;
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, Message, wParam, lParam);
}
return 0;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG Msg;
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = 0;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(GetModuleHandle(NULL), MAKEINTRESOURCE(ID_ICON));
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wc.lpszMenuName = MAKEINTRESOURCE(ID_MENU);
wc.lpszClassName = g_szClassName;
wc.hIconSm = (HICON)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(ID_ICON), IMAGE_ICON, 16, 16, 0);
if(!RegisterClassEx(&wc))
{
MessageBox(NULL, "Window Registration Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
hwnd = CreateWindowEx(
WS_EX_CLIENTEDGE,
g_szClassName,
"A Menu",
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 240, 120,
NULL, NULL, hInstance, NULL);
if(hwnd == NULL)
{
MessageBox(NULL, "Window Creation Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
while(GetMessage(&Msg, NULL, 0, 0) > 0)
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}
在这里你可以找到 bitmap
这里是bas64格式的位图: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您可以手动更改位图的背景颜色以实现透明。
代码如下:
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);
}
最少的代码示例:
HMENU m_hMenu;
HBITMAP g_BitMap;
...
case WM_CONTEXTMENU:
{
m_hMenu = CreatePopupMenu();
g_BitMap = (HBITMAP)LoadImage(NULL, L"UNTITLED.bmp", IMAGE_BITMAP, 16, 16, LR_LOADFROMFILE);
swap_color(g_BitMap);
InsertMenu(m_hMenu, 1, MF_BYPOSITION | MF_POPUP, NULL, L"Windows");
MENUITEMINFO mii = { sizeof(MENUITEMINFO) };
mii.fMask = MIIM_BITMAP;
mii.hbmpItem = g_BitMap;
SetMenuItemInfo(m_hMenu, 0, true, &mii);
TrackPopupMenu(m_hMenu, TPM_TOPALIGN | TPM_LEFTALIGN | TPM_HORPOSANIMATION, GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam), 0, hWnd, NULL);
}
break;
调试:
img from the link you mentioned, and I converted it to a 32-bit BMP picture.
参考:
Windows' GDI 中的 Alpha 透明度是一个雷区。它添加的很晚,只有少数 API 调用真正能够处理专用的 alpha 通道。 LoadBitmap 不是支持(或至少不破坏)alpha 透明度的那些之一。当您从应用程序的资源加载图像时,Alpha 通道会丢失。
要解决这个问题,您必须使用 LoadImage,传递正确的标志。 LR_CREATEDIBSECTION
是重要的,因为它保留了源位图中的 alpha 通道。
修复就像更换一样简单
LoadBitmap((HINSTANCE) GetModuleHandle (NULL), MAKEINTRESOURCE(ID_BITMAP_EXIT))
和
(HBITMAP)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(ID_BITMAP_EXIT),
IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION)
设置好后,您将看到显示的菜单图标具有每像素 alpha 透明度: