原文链接：https://www.oschina.net/code/snippet_222150_16279
1. [代码][C/C++]代码
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// Resize CImage
void
CreateStretchImage(CImage *pImage,CImage *ResultImage,
int
StretchHeight,
int
StretchWidth){
if
(pImage->IsDIBSection()){
// 取得 pImage 的 DC
CDC* pImageDC1 = CDC::FromHandle(pImage->GetDC());
// Image 因為有自己的 DC, 所以必須使用 FromHandle 取得對應的 DC
CBitmap *bitmap1=pImageDC1->GetCurrentBitmap();
BITMAP bmpInfo;
bitmap1->GetBitmap(&bmpInfo);
// 建立新的 CImage
ResultImage->Create(StretchWidth,StretchHeight,bmpInfo.bmBitsPixel);
CDC* ResultImageDC = CDC::FromHandle(ResultImage->GetDC());
// 當 Destination 比較小的時候, 會根據 Destination DC 上的 Stretch Blt mode 決定是否要保留被刪除點的資訊
ResultImageDC->SetStretchBltMode(HALFTONE);
// 使用最高品質的方式
::SetBrushOrgEx(ResultImageDC->m_hDC,0,0,NULL);
// 調整 Brush 的起點
// 把 pImage 畫到 ResultImage 上面
StretchBlt(*ResultImageDC,0,0,StretchWidth,StretchHeight,*pImageDC1,0,0,pImage->GetWidth(),pImage->GetHeight(),SRCCOPY);
// pImage->Draw(*ResultImageDC,0,0,StretchWidth,StretchHeight,0,0,pImage->GetWidth(),pImage->GetHeight());
pImage->ReleaseDC();
ResultImage->ReleaseDC();
}
}
// 建立指定大小的圖形
// 輸入: 原始圖檔=pBitmap, 指定大小=StretchHeight StretchWidth, 結果圖檔=pResultBmp
// Usage:
void
reateStretchBmp(CBitmap* pBitmap ,
int
StretchHeight ,
int
StretchWidth, CBitmap *pResultBmp){
// 建立顯示螢幕的 DC
CDC dcScreen;
dcScreen.Attach(::GetDC(NULL));
// 取得原始圖檔的 dc
CDC dcMemory;
dcMemory.CreateCompatibleDC(&dcScreen);
CBitmap *pOldOrgBitmap= dcMemory.SelectObject(pBitmap);
// 建立新的結果圖形 (指定大小)
pResultBmp->CreateCompatibleBitmap(&dcScreen,StretchWidth,StretchHeight);
// 取得結果圖形的 dc
CDC dcFixMemory;
dcFixMemory.CreateCompatibleDC(&dcScreen);
CBitmap *pOldReslutBitmap=dcFixMemory.SelectObject(pResultBmp);
// 讓 dcFixMemory 選擇到 "結果bmp", 任何對 dcFixMemory 的動作都會反映到 pResultBmp
// 把原始圖形縮放畫到 Memory DC上面
BITMAP bmpInfo;
pBitmap->GetBitmap(&bmpInfo);
// 取得 原始圖檔的寬度與高度
StretchBlt(dcFixMemory,0,0,StretchWidth,StretchHeight,dcMemory,0,0,bmpInfo.bmWidth,bmpInfo.bmHeight,SRCCOPY);
// Set Back
dcMemory.SelectObject(pOldOrgBitmap);
dcFixMemory.SelectObject(pOldReslutBitmap);
}
2. [代码]对整个图片做缩放
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unsigned
char
* HCNImage::do_Stretch_Linear(
int
w_Dest,
int
h_Dest,
int
bit_depth,unsigned
char
*src,
int
w_Src,
int
h_Src)
{
int
sw = w_Src-1, sh = h_Src-1, dw = w_Dest-1, dh = h_Dest-1;
int
B, N, x, y;
int
nPixelSize = bit_depth/8;
unsigned
char
*pLinePrev,*pLineNext;
unsigned
char
*pDest =
new
unsigned
char
[w_Dest*h_Dest*bit_depth/8];
unsigned
char
*tmp;
unsigned
char
*pA,*pB,*pC,*pD;
for
(
int
i=0;i<=dh;++i)
{
tmp =pDest + i*w_Dest*nPixelSize;
y = i*sh/dh;
N = dh - i*sh%dh;
pLinePrev = src + (y++)*w_Src*nPixelSize;
pLineNext = (N==dh) ? pLinePrev : src+y*w_Src*nPixelSize;
for
(
int
j=0;j<=dw;++j)
{
x = j*sw/dw*nPixelSize;
B = dw-j*sw%dw;
pA = pLinePrev+x;
pB = pA+nPixelSize;
pC = pLineNext + x;
pD = pC + nPixelSize;
if
(B == dw)
{
pB=pA;
pD=pC;
}
for
(
int
k=0;k<nPixelSize;++k)
{
*tmp++ = ( unsigned
char
)(
int
)(
( B * N * ( *pA++ - *pB - *pC + *pD ) + dw * N * *pB++
+ dh * B * *pC++ + ( dw * dh - dh * B - dw * N ) * *pD++
+ dw * dh / 2 ) / ( dw * dh ) );
}
}
}
return
pDest;
}
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