黑色透明png使用其他颜色填充（PPC或windows）

最新推荐文章于 2024-05-24 22:26:42 发布

原创最新推荐文章于 2024-05-24 22:26:42 发布 · 1.1k 阅读

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#windows #float #null

本文详细介绍了如何使用黑色透明PNG图片，并通过特定的算法填充其他颜色，包括颜色对比度计算、Alpha通道调整及颜色融合过程。

黑色透明png使用其他颜色填充：

int SGDrawImageWithColor( HDC hdc, const RECT* pdstRect, SGImageInfo* pImageinfo, COLORREF crFillColor )

{
   IImage* pImage = pImageinfo->pImage;
   if( pImage ) {

       int hOffset = (*pdstRect).left;
       int vOffset = (*pdstRect).top;
       RECT rcArea = {0,0, (*pdstRect).right - (*pdstRect).left, (*pdstRect).bottom-(*pdstRect).top};
       HDC hMemDC = CreateCompatibleDC(hdc);
       if (hMemDC) {
           HBITMAP hBitmap = CreateCompatibleBitmap(hdc, rcArea.right-rcArea.left, rcArea.bottom-rcArea.top);
           HBITMAP hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);
           //COLORREF crbkg = RGB(180,180,180);
           //FillSolidRect( hMemDC, &rcArea, crbkg);
           BitBlt( hMemDC, 0, 0, rcArea.right-rcArea.left, rcArea.bottom-rcArea.top, hdc, hOffset, vOffset, SRCCOPY );
           pImage->Draw( hMemDC, &rcArea, NULL);

           //calculate alpha
           COLORREF color = 0;
           COLORREF crbkg = 0;
           for( int i = rcArea.left; i < rcArea.right ; ++i) {
               for ( int j = rcArea.top; j < rcArea.bottom; ++j )
               {
                   crbkg = GetPixel(hdc, i+hOffset, j+vOffset);
                   color = GetPixel(hMemDC, i, j);

                   float rc = (GetRValue(color)-0);
                   float rb = (GetRValue(crbkg)-0);
                   float alpha = 0.0;
                   if( rb <= 0 ) {
                       rc = (GetGValue(color)-0);
                       rb = (GetGValue(crbkg)-0);
                       if( rb <= 0 ) {
                           rc = (GetBValue(color)-0);
                           rb = (GetBValue(crbkg)-0);
                       }
                   }
                   if( rb > 0 ) {
                       alpha = rc/rb;
                   }
                   if( alpha < 1.0 ) {
                       //printf( " rgb(%d,%d) alpha = %f \n ", i,j, alpha );
                       //color = GetPixel(hdc, i+hOffset, j+vOffset);
                       int r = (1-alpha)*GetRValue(crFillColor)+alpha*GetRValue(crbkg);
                       int g = (1-alpha)*GetGValue(crFillColor)+alpha*GetGValue(crbkg);
                       int b = (1-alpha)*GetBValue(crFillColor)+alpha*GetBValue(crbkg);
                       //SetPixel( hdc, i+hOffset, j+vOffset, RGB(r,g,b) );
                       SetPixel( hMemDC, i, j, RGB(r,g,b) );
                   }
               }
           }

           BitBlt( hdc, hOffset, vOffset, rcArea.right-rcArea.left, rcArea.bottom-rcArea.top, hMemDC, 0, 0, SRCCOPY );

           SelectObject(hMemDC, hOldBitmap);
           DeleteObject( hBitmap );
           DeleteDC(hMemDC);
       }

       return 1;
   }

   return -1;
}