162 lines
4.2 KiB
C++
162 lines
4.2 KiB
C++
// transbmp.cpp : implementation of the CTransBmp class
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//
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// support for transparent CBitmap objects. Used in the CUserList class.
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// Based on a class from MSDN 7/95
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#include "stdafx.h"
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#include "transbmp.h"
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#ifdef _DEBUG
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#undef THIS_FILE
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static char BASED_CODE THIS_FILE[] = __FILE__;
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#endif
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// Colors
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#define rgbWhite RGB(255,255,255)
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// Raster op codes
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#define DSa 0x008800C6L
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#define DSx 0x00660046L
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/////////////////////////////////////////////////////////////////////////////
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// CTransBmp construction/destruction
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CTransBmp::CTransBmp()
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{
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m_iWidth = 0;
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m_iHeight = 0;
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m_hbmMask = NULL;
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}
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CTransBmp::~CTransBmp()
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{
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if (m_hbmMask != NULL) delete m_hbmMask;
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}
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void CTransBmp::GetMetrics()
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{
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// Get the width and height
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BITMAP bm;
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GetObject(sizeof(bm), &bm);
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m_iWidth = bm.bmWidth;
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m_iHeight = bm.bmHeight;
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}
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int CTransBmp::GetWidth()
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{
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if ((m_iWidth == 0) || (m_iHeight == 0)){
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GetMetrics();
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}
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return m_iWidth;
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}
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int CTransBmp::GetHeight()
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{
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if ((m_iWidth == 0) || (m_iHeight == 0)){
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GetMetrics();
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}
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return m_iHeight;
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}
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void CTransBmp::CreateMask(CDC* pDC)
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{
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m_hbmMask = new CBitmap;
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// Nuke any existing mask
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if (m_hbmMask) m_hbmMask->DeleteObject();
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// Create memory DCs to work with
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CDC* hdcMask = new CDC;
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CDC* hdcImage = new CDC;
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hdcMask->CreateCompatibleDC(pDC);
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hdcImage->CreateCompatibleDC(pDC);
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// Create a monochrome bitmap for the mask
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m_hbmMask->CreateBitmap(GetWidth(),
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GetHeight(),
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1,
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1,
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NULL);
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// Select the mono bitmap into its DC
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CBitmap* hbmOldMask = hdcMask->SelectObject(m_hbmMask);
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// Select the image bitmap into its DC
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CBitmap* hbmOldImage = hdcImage->SelectObject(CBitmap::FromHandle((HBITMAP)m_hObject));
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// Set the transparency color to be the top-left pixel
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hdcImage->SetBkColor(hdcImage->GetPixel(0, 0));
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// Make the mask
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hdcMask->BitBlt(0, 0,
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GetWidth(), GetHeight(),
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hdcImage,
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0, 0,
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SRCCOPY);
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// clean up
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hdcMask->SelectObject(hbmOldMask);
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hdcImage->SelectObject(hbmOldImage);
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delete hdcMask;
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delete hdcImage;
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}
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// draw the transparent bitmap using the created mask
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void CTransBmp::DrawTrans(CDC* pDC, int x, int y)
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{
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if (m_hbmMask == NULL) CreateMask(pDC);
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int dx = GetWidth();
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int dy = GetHeight();
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// Create a memory DC to do the drawing to
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CDC* hdcOffScr = new CDC;
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hdcOffScr->CreateCompatibleDC(pDC);
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// Create a bitmap for the off-screen DC that is really
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// color compatible with the destination DC.
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CBitmap hbmOffScr;
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hbmOffScr.CreateBitmap(dx, dy,
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pDC->GetDeviceCaps(PLANES),
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pDC->GetDeviceCaps(BITSPIXEL),
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NULL);
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// Select the buffer bitmap into the off-screen DC
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HBITMAP hbmOldOffScr = (HBITMAP)hdcOffScr->SelectObject(hbmOffScr);
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// Copy the image of the destination rectangle to the
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// off-screen buffer DC so we can play with it
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hdcOffScr->BitBlt(0, 0, dx, dy, pDC, x, y, SRCCOPY);
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// Create a memory DC for the source image
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CDC* hdcImage = new CDC;
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hdcImage->CreateCompatibleDC(pDC);
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CBitmap* hbmOldImage = hdcImage->SelectObject(CBitmap::FromHandle((HBITMAP)m_hObject));
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// Create a memory DC for the mask
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CDC* hdcMask = new CDC;
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hdcMask->CreateCompatibleDC(pDC);
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CBitmap* hbmOldMask = hdcMask->SelectObject(m_hbmMask);
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// XOR the image with the destination
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hdcOffScr->SetBkColor(rgbWhite);
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hdcOffScr->BitBlt(0, 0, dx, dy ,hdcImage, 0, 0, DSx);
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// AND the destination with the mask
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hdcOffScr->BitBlt(0, 0, dx, dy, hdcMask, 0,0, DSa);
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// XOR the destination with the image again
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hdcOffScr->BitBlt(0, 0, dx, dy, hdcImage, 0, 0, DSx);
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// Copy the resultant image back to the screen DC
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pDC->BitBlt(x, y, dx, dy, hdcOffScr, 0, 0, SRCCOPY);
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// Tidy up
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hdcOffScr->SelectObject(hbmOldOffScr);
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hdcImage->SelectObject(hbmOldImage);
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hdcMask->SelectObject(hbmOldMask);
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delete hdcOffScr;
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delete hdcImage;
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delete hdcMask;
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}
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