\n\nLast time, we saw how to draw themed and unthemed radio buttons<\/A>,\nand I mentioned that menu glyphs are trickier.\nThey’re trickier because they are provided as raw monochrome bitmaps\ninstead of fully-formed color-coordinated bitmaps.\nFirst, let’s do it wrong in order to see what we get.\nThen we’ll try to fix it.\nStart with a clean\n\nnew scratch program<\/A>\n<\/P>\n void RootWindow::PaintContent(PAINTSTRUCT *pps)\n{\n int cxCheck = GetSystemMetrics(SM_CXMENUCHECK);\n int cyCheck = GetSystemMetrics(SM_CYMENUCHECK);\n RECT rc = { 0, 0, cxCheck, cyCheck };\n DrawFrameControl(pps->hdc, &rc, DFC_MENU, DFCS_MENUCHECK);\n}<\/FONT>\n<\/PRE>\n \nThis naïvely uses\n\nthe \nThe reason for this is called out in the documentation for\n \nAll we get from \nThe key steps here are\n(1) drawing into a temporary monochrome bitmap to generate the mask,\n(2) setting the text and background colors of the destination DC,\n(3) using \nObserve that the checkmark’s colors now match the system menu colors\nbecause we set them as the text and background colors for the\nmono-to-color blit.\n<\/P>\n\nclass RootWindow : public Window\n{\n …\nprotected:\n void PaintContent(PAINTSTRUCT *pps);\n BOOL WinRegisterClass(WNDCLASS *pwc)\n {\n pwc->hbrBackground = (HBRUSH)(COLOR_MENU + 1);\n return __super::WinRegisterClass(pwc);\n }<\/FONT>\n …\n};<\/p>\nDrawFrameControl<\/CODE> function<\/A>\nto draw the menu check mark directly into the paint DC.\nIf you are running with the default Windows XP theme you\nprobably won’t notice anything amiss, but switch to the Windows Classic\ntheme and you’ll see that the check mark is drawn in black and white\neven though the Classic menu background color is gray.\n<\/P>\nDrawFrameControl<\/CODE>:\n<\/P>\n\nIf uType is either DFC_MENU or DFC_BUTTON and uState is not DFCS_BUTTONPUSH,\nthe frame control is a black-on-white mask\n(that is, a black frame control on a white background).\n<\/BLOCKQUOTE>\n
DrawFrameControl<\/CODE> is a monochrome mask.\nIt is our responsibility to colorize it as necessary.\nTo do this, we draw the mask into a monochrome bitmap, and then\nuse\n\nthe BitBlt<\/CODE> function<\/A>\nto colorize it.\nRecall that when blitting from a monochrome bitmap to a color bitmap,\nthe color black in the source bitmap\nbecomes the destination DC’s text color,\nand the color white in the source bitmap\nbecomes the destination DC’s background color.\n<\/P>\n\nvoid RootWindow::PaintContent(PAINTSTRUCT *pps)\n{\n HDC hdcMem = CreateCompatibleDC(pps->hdc);\n if (hdcMem) {<\/FONT>\n int cxCheck = GetSystemMetrics(SM_CXMENUCHECK);\n int cyCheck = GetSystemMetrics(SM_CYMENUCHECK);\n HBITMAP hbmMono = CreateBitmap(cxCheck, cyCheck, 1, 1, NULL);\n if (hbmMono) {\n HBITMAP hbmPrev = SelectBitmap(hdcMem, hbmMono);\n if (hbmPrev) {<\/FONT>\n RECT rc = { 0, 0, cxCheck, cyCheck };\n DrawFrameControl(hdcMem<\/FONT>, &rc, DFC_MENU, DFCS_MENUCHECK);\n COLORREF clrTextPrev = SetTextColor(pps->hdc,\n GetSysColor(COLOR_MENUTEXT));\n COLORREF clrBkPrev = SetBkColor(pps->hdc,\n GetSysColor(COLOR_MENU));\n BitBlt(pps->hdc, 0, 0, cxCheck, cyCheck,\n hdcMem, 0, 0, SRCCOPY);\n SetBkColor(pps->hdc, clrBkPrev);\n SetTextColor(pps->hdc, clrTextPrev);\n SelectBitmap(hdcMem, hbmPrev);\n }\n DeleteObject(hbmMono);\n }\n DeleteDC(hdcMem);\n }<\/FONT>\n}\n<\/PRE>\nBitBlt<\/CODE> to do the color mapping.\nThe rest of the function is just boring bookkeeping.\n<\/P>\n