Source code of Windows XP (NT5)
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/*******************************************************************************
*
* (C) COPYRIGHT MICROSOFT CORPORATION, 1998
*
* TITLE: RESCALE.CPP
*
* VERSION: 1.0
*
* AUTHOR: ShaunIv
*
* DATE: 10/15/1998
*
* DESCRIPTION: Scale HBITMAPs using StretchBlt
*
*******************************************************************************/
#include "precomp.h"
#pragma hdrstop
/*
* ScaleImage: Scale hBmpSrc and store the scaled dib in hBmpTgt
*/
HRESULT ScaleImage( HDC hDC, HBITMAP hBmpSrc, HBITMAP &hBmpTgt, const SIZE &sizeTgt )
{
WIA_PUSH_FUNCTION((TEXT("ScaleImage( sizeTgt = [%d,%d] )"), sizeTgt.cx, sizeTgt.cy ));
BITMAPINFO bmi;
BITMAP bm;
HRESULT hr = E_FAIL;
HBITMAP hBmp = NULL;
hBmpTgt = NULL;
GetObject( hBmpSrc, sizeof(BITMAP), &bm );
ZeroMemory( &bmi, sizeof(BITMAPINFO) );
bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmi.bmiHeader.biWidth = sizeTgt.cx;
bmi.bmiHeader.biHeight = sizeTgt.cy;
bmi.bmiHeader.biPlanes = 1;
bmi.bmiHeader.biBitCount = 24;
bmi.bmiHeader.biCompression = BI_RGB;
HPALETTE hHalftonePalette = CreateHalftonePalette(hDC);
if (hHalftonePalette)
{
PBYTE pBitmapData = NULL;
hBmp = CreateDIBSection( hDC, &bmi, DIB_RGB_COLORS, (LPVOID*)&pBitmapData, NULL, 0 );
if (hBmp)
{
// Create the source dc
HDC hMemoryDC = CreateCompatibleDC( hDC );
if (hMemoryDC)
{
HPALETTE hOldMemDCPalette = SelectPalette( hMemoryDC, hHalftonePalette , 0 );
RealizePalette( hMemoryDC );
SetBrushOrgEx( hMemoryDC, 0,0, NULL );
HBITMAP hOldMemDCBitmap = (HBITMAP)SelectObject( hMemoryDC, hBmpSrc );
// Create the target dc
HDC hStretchDC = CreateCompatibleDC( hDC );
if (hStretchDC)
{
HPALETTE hOldStretchDCPalette = SelectPalette( hStretchDC, hHalftonePalette , 0 );
RealizePalette( hStretchDC );
SetBrushOrgEx( hStretchDC, 0,0, NULL );
HBITMAP hOldStretchDCBitmap = (HBITMAP)SelectObject( hStretchDC, hBmp );
INT nOldStretchMode = SetStretchBltMode( hStretchDC, STRETCH_HALFTONE );
SIZE sizeScaled;
// Width is constraining factor
if (sizeTgt.cy*bm.bmWidth > sizeTgt.cx*bm.bmHeight)
{
sizeScaled.cx = sizeTgt.cx;
sizeScaled.cy = WiaUiUtil::MulDivNoRound(bm.bmHeight,sizeTgt.cx,bm.bmWidth);
}
// Height is constraining factor
else
{
sizeScaled.cx = WiaUiUtil::MulDivNoRound(bm.bmWidth,sizeTgt.cy,bm.bmHeight);
sizeScaled.cy = sizeTgt.cy;
}
// Fill the background
RECT rc;
rc.left = rc.top = 0;
rc.right = sizeTgt.cx;
rc.bottom = sizeTgt.cy;
FillRect( hStretchDC, &rc, GetSysColorBrush(COLOR_WINDOW) );
// Paint the image
StretchBlt( hStretchDC, (sizeTgt.cx - sizeScaled.cx) / 2, (sizeTgt.cy - sizeScaled.cy) / 2, sizeScaled.cx, sizeScaled.cy, hMemoryDC, 0, 0, bm.bmWidth, bm.bmHeight, SRCCOPY );
// Everything is OK
hBmpTgt = hBmp;
hr = S_OK;
// Restore the dc's state and delete it
SetStretchBltMode( hStretchDC, nOldStretchMode );
SelectObject( hStretchDC, hOldStretchDCBitmap );
SelectPalette( hStretchDC, hOldStretchDCPalette , 0 );
DeleteDC( hStretchDC );
}
// Restore the dc's state
SelectObject( hMemoryDC, hOldMemDCBitmap );
SelectPalette( hMemoryDC, hOldMemDCPalette , 0 );
DeleteDC( hMemoryDC );
}
}
if (hHalftonePalette)
{
DeleteObject( hHalftonePalette );
}
}
// Clean up the new bitmap if there was an error
if (!SUCCEEDED(hr) && hBmp)
DeleteObject( hBmp );
WIA_TRACE((TEXT("hBmpTgt = %p")));
return (hr);
}