如何在圆圈内绘制图像

How to draw an image inside a circle?

本文关键字：绘制 图像      更新时间：2023-10-16

我有一个MFC应用程序，我需要在圆圈内绘制图像(或在圆圈中裁剪图像(。

我使用免费映射来加载图像，因此使用免费映像或MFC功能的答案将起作用。

这就是我加载图像的方式：

void DrawImage(CDC *pDC, RECT *pRect, const BYTE *pBuffer, int nBufferLength)
{
    FIMEMORY *pfmem = FreeImage_OpenMemory((BYTE*)pBuffer, nBufferLength);
    FREE_IMAGE_FORMAT fif = FreeImage_GetFileTypeFromMemory(pfmem);
    FIBITMAP *pdib = FreeImage_LoadFromMemory(fif, pfmem);  
    sz.cx = FreeImage_GetWidth(pdib);
    sz.cy = FreeImage_GetHeight(pdib);
    CRect rc(pRect);
    BITMAPINFO *pbmpi = FreeImage_GetInfo(pdib);
    BYTE *pDibBits = FreeImage_GetBits(pdib);
    ::SetDIBitsToDevice(pDC->GetSafeHdc(), 
                            rc.left, 
                            rc.top, 
                            rc.Width(), 
                            rc.Height(), 
                            0, 
                            0, 
                            0, 
                            rc.Height(), 
                            pDibBits, 
                            pbmpi, 
                            DIB_RGB_COLORS);
    FreeImage_Unload(pdib);
    FreeImage_CloseMemory(pfmem);
}

发布我的答案，以防有人在同一问题中运行，实际上很容易做到了@karthik Krish写的：

//  Get the rect of a circle in the center o the image.
CRect rectMask(pRect);
int cx = rectMask.Width();
int cy = rectMask.Heigth();
if (cx > cy)
{
    rectMask.left += (cx - cy) / 2;
    rectMask.right = rectMask.left + cy;
}
else
{
    rectMask.top += (cy - cx) / 2;
    rectMask.bottom = rectMask.top + cx;
}
HRGN hRegiaoClip = NULL;
//  Create a region for the circle
hRegiaoClip = ::CreateEllipticRgnIndirect(&rectMask);
//  Select circle in the Device context.
::SelectClipRgn(pDC->GetSafeHdc(), hRegiaoClip);
//  Call function to draw the image (the one in the question).
DrawImage(pDC, pRect, pImgBytes, pSerial->GetImageBufferSize(), TRUE);
//  Clean up
::SelectClipRgn(pDC->GetSafeHdc(), NULL);
::DeleteObject(hRegiaoClip);
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