如何使用CImage类调整位图的大小 [英] How to use CImage class to resize a bitmap

问题描述

我想使用以下代码调整保存在文件中的位图的大小

I want to resize a bit picture saved in a file with the following code

CImage img;
CImage sm_img;

img.Load(FileName);

sm_img.Create(80,60,img.GetBPP(),
HDC sm_hdc = sm_img.GetDC();

img.StretchBlt(sm_hdc,0,0,80,60,SRCCOPY);
sm_img.Save(sjpgFileName);

img.Detach();

由于颜色丢失，结果很糟糕.我来宾，我们需要为变量 sm_img 设置som属性，但不知道如何.

The result is bad as colors are lost. I guest we need to set som attributes for the variable sm_img but don''t know how. Can you help me, please !

推荐答案

例如，请参见: [ ^ ].

See, for instance, here: "Scaling CImage"[^].

您无需创建DC(pMDC).只需使用sm_img(sm_img.GetDC())中的DC:

You don''t need to create a DC (pMDC). Just use the DC from sm_img (sm_img.GetDC()):

    CImage img;
CImage sm_img;
HRESULT res = img.Load(jpgFileName);

CDC *screenDC = GetDC();

int iNewWidth = 80;
int iNewHeight = 60;

sm_img.Create(iNewWidth, iNewHeight,32);

SetStretchBltMode(sm_img.GetDC(),COLORONCOLOR);
img.StretchBlt(sm_img.GetDC(),0, 0, iNewWidth, iNewHeight, SRCCOPY);
// The next two lines test the image on a picture control.
// The output has wrong color palette, like my initial version
HDC hdcpic = ::GetDC(m_ClipPreview.m_hWnd);

img.StretchBlt( hdcpic,0, 0, iNewWidth, iNewHeight, SRCCOPY);

sm_img.Save(jpgFileName);
ReleaseDC(screenDC);

希望对您有帮助

我加了一行

Hope it helps

I added one line

sm_img.ReleaseDC();

最后避免退出函数时出错

in the end to avoid error when exiting the function

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