用C++实现半透明按钮控件(PNG,GDI+)

使用MFC实现上面的按钮半透明效果能看到父窗口中的内容，上面是效果图(一个是带背景图片的、另一个是不带的)。控件继承自CWnd类(彩色的部分是窗口的背景图片、按钮是PNG图片，第二个图标是鼠标指向时的效果)。图标的绘制使用GDI+绘制PNG图片，在此不多说了(处理WM_PAINT消息):void PNGButton::OnPaint() { CPaintDC dc(this); Graphics g(dc.m_hDC); if(DrawBorder){ 　　　　g.DrawImage(hoverBg,0,0);//画鼠标指向时的亮色背景 } g.DrawImage(this->bg,0,0);//画按钮图标 g.ReleaseHDC(dc.m_hDC); }

透明的关键：注意后面调用此方法的代码

关键在于InvalidateRect函数:通知父窗口重新绘制特定区域,执行此函数后按钮所在区域就被父窗口绘制的内容覆盖.在父窗口绘制完成后,
按钮也会收到WM_PAINT消息,执行上面的一段OnPaint代码.void PNGButton::PaintParent() { CRect rect; GetWindowRect(&rect); GetParent()-> ScreenToClient(&rect); GetParent()-> InvalidateRect(&rect); } 捕获鼠标指向或移出事件(处理WM_MOUSEMOVE,WM_MOUSEOVER,WM_MOUSELEAVE消息)：void PNGButton::OnMouseHover(UINT nFlags, CPoint point) { DrawBorder=true; PaintParent();//通知父窗口重绘特定区域，会引发控件自身的重绘 } void PNGButton::OnMouseLeave() { m_is_mouse_over = false; m_is_tracked = false; DrawBorder=false; PaintParent(); //通知父窗口重绘特定区域，会引发控件自身的重绘 CWnd::OnMouseLeave(); } void PNGButton::OnMouseMove(UINT nFlags, CPoint point) { m_is_mouse_over = true; if(!m_is_tracked) { TRACKMOUSEEVENT tme; tme.cbSize = sizeof(TRACKMOUSEEVENT); tme.dwFlags = TME_LEAVE|TME_HOVER; tme.hwndTrack = GetSafeHwnd(); tme.dwHoverTime = 80; _TrackMouseEvent(&tme); m_is_tracked = true; } CWnd::OnMouseMove(nFlags, point); }
附：从资源加载PNG图片附：从资源加载PNG图片

View Code #pragma once #include "stdafx.h" using namespace Gdiplus; static bool ImageFromIDResource(UINT nID, LPCTSTR sTR,Image * &pImg) { HINSTANCE hInst = AfxGetResourceHandle(); HRSRC hRsrc = ::FindResource (hInst,MAKEINTRESOURCE(nID),sTR); // type if (!hRsrc) return FALSE; // load resource into memory DWORD len = SizeofResource(hInst, hRsrc); BYTE* lpRsrc = (BYTE*)LoadResource(hInst, hRsrc); if (!lpRsrc) return FALSE; // Allocate global memory on which to create stream HGLOBAL m_hMem = GlobalAlloc(GMEM_FIXED, len); BYTE* pmem = (BYTE*)GlobalLock(m_hMem); memcpy(pmem,lpRsrc,len); IStream* pstm; CreateStreamOnHGlobal(m_hMem,FALSE,&pstm); // load from stream pImg=Gdiplus::Image::FromStream(pstm); // free/release stuff GlobalUnlock(m_hMem); pstm->Release(); FreeResource(lpRsrc); return TRUE; }

平铺图片的代码

CPaintDC dc(this); CRect rect; GetClientRect(rect); CBrush bs(RGB(240,240,240));//窗口背景色 dc.FillRect(&rect,&bs); //窗口着色 //填充背景图片：平铺 Graphics g(dc.m_hDC); if(has_bg) g.DrawImage(this->bg,0,0); Gdiplus::TextureBrush bbs(this->img); g.FillRectangle(&bbs,0,0,rect.Width(),this->img->GetHeight()); g.ReleaseHDC(dc.m_hDC); //TRACE(L"CMainFrame::OnPaint\r\n");