core.git: vcl/source

[Christopher Sherlock (via logerrit)]

 vcl/source/outdev/bitmap.cxx |   36 +++++++++++++++---------------------
 1 file changed, 15 insertions(+), 21 deletions(-)

New commits:
commit e68ae6bbdaa9b39949c7e1215e48ef31f0e32efd
Author:     Christopher Sherlock <chris.sherloc...@gmail.com>
AuthorDate: Sat Aug 2 16:18:40 2025 +1000
Commit:     Noel Grandin <noel.gran...@collabora.co.uk>
CommitDate: Fri Aug 8 09:24:03 2025 +0200

    vcl: lcl_AlphaBlend() simplify to mix a color with another with an alpha 
value
    
    Change-Id: I72725af813935bf2788618ef9f34eeef2ad1bbf2
    Reviewed-on: https://gerrit.libreoffice.org/c/core/+/188800
    Reviewed-by: Noel Grandin <noel.gran...@collabora.co.uk>
    Tested-by: Jenkins

diff --git a/vcl/source/outdev/bitmap.cxx b/vcl/source/outdev/bitmap.cxx
index 3c91094fa025..bd49345c8acd 100644
--- a/vcl/source/outdev/bitmap.cxx
+++ b/vcl/source/outdev/bitmap.cxx
@@ -421,31 +421,24 @@ sal_uInt8 lcl_CalcColor( const sal_uInt8 nSourceColor, 
const sal_uInt8 nSourceAl
     return sal_uInt8( c );
 }
 
-BitmapColor lcl_AlphaBlend(int nX, int nY,
-                               const tools::Long            nMapX,
-                               const tools::Long            nMapY,
-                               BitmapReadAccess const* pSrcBmp,
-                               BitmapReadAccess const* pSrcAlphaBmp,
-                               BitmapReadAccess const* pDstBmp)
-{
-    const BitmapColor aSrcCol = pSrcBmp->GetColor(nMapY, nMapX);
-    BitmapColor aDstCol = pDstBmp->GetColor(nY, nX);
+// blend one color with another color with an alpha value
 
-    const sal_uInt8 nSrcAlpha = pSrcAlphaBmp->GetPixelIndex(nMapY, nMapX);
-    const sal_uInt8 nDstAlpha = aDstCol.GetAlpha();
+BitmapColor lcl_AlphaBlend(const BitmapColor& rCol1, const BitmapColor& rCol2, 
const sal_uInt8 nAlpha)
+{
+    BitmapColor aCol(rCol2);
 
     // Perform porter-duff compositing 'over' operation
 
     // Co = Cs + Cd*(1-As)
     // Ad = As + Ad*(1-As)
-    sal_uInt8 nResAlpha = static_cast<int>(nSrcAlpha) + 
static_cast<int>(nDstAlpha)
-              - static_cast<int>(nDstAlpha) * nSrcAlpha / 255;
-    aDstCol.SetAlpha(nResAlpha);
-    aDstCol.SetRed(lcl_CalcColor(aSrcCol.GetRed(), nSrcAlpha, nDstAlpha, 
nResAlpha, aDstCol.GetRed()));
-    aDstCol.SetBlue(lcl_CalcColor(aSrcCol.GetBlue(), nSrcAlpha, nDstAlpha, 
nResAlpha, aDstCol.GetBlue()));
-    aDstCol.SetGreen(lcl_CalcColor(aSrcCol.GetGreen(), nSrcAlpha, nDstAlpha, 
nResAlpha, aDstCol.GetGreen()));
-
-    return aDstCol;
+    sal_uInt8 nResAlpha = static_cast<int>(nAlpha) + 
static_cast<int>(rCol2.GetAlpha())
+              - static_cast<int>(rCol2.GetAlpha()) * nAlpha / 255;
+    aCol.SetAlpha(nResAlpha);
+    aCol.SetRed(lcl_CalcColor(rCol1.GetRed(), nAlpha, rCol2.GetAlpha(), 
nResAlpha, aCol.GetRed()));
+    aCol.SetBlue(lcl_CalcColor(rCol1.GetBlue(), nAlpha, rCol2.GetAlpha(), 
nResAlpha, aCol.GetBlue()));
+    aCol.SetGreen(lcl_CalcColor(rCol1.GetGreen(), nAlpha, rCol2.GetAlpha(), 
nResAlpha, aCol.GetGreen()));
+
+    return aCol;
 }
 
 Bitmap lcl_BlendBitmapWithAlpha(
@@ -471,8 +464,9 @@ Bitmap lcl_BlendBitmapWithAlpha(
 
                 for( int nX = 0; nX < nDstWidth; nX++ )
                 {
-                    const tools::Long nMapX = pMapX[ nX ];
-                    BitmapColor aDstCol = lcl_AlphaBlend(nX, nY, nMapX, nMapY, 
pSrcBmp, pSrcAlphaBmp, pDstBmp.get());
+                    BitmapColor aDstCol = 
lcl_AlphaBlend(pSrcBmp->GetColor(nMapY, pMapX[nX]),
+                                                         pDstBmp->GetColor(nY, 
nX),
+                                                         
pSrcAlphaBmp->GetPixelIndex(nMapY, pMapX[nX]));
 
                     pDstBmp->SetPixelOnData(pScanlineB, nX, aDstCol);
                 }