use same [un]premultiply

Change-Id: Idd1ca1243b64a9ec606382a0895e11376a2ec186
Reviewed-on: https://gerrit.libreoffice.org/64406
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

include/vcl/BitmapTools.hxx

@@ -28,6 +28,11 @@ namespace com { namespace sun { namespace star { namespace geometry { struct Int
 namespace vcl {
 namespace bitmap {
 
+typedef sal_uInt8 (*lookup_table)[256];
+
+lookup_table VCL_DLLPUBLIC get_premultiply_table();
+lookup_table VCL_DLLPUBLIC get_unpremultiply_table();
+
 /**
  * Intended to be used to feed into CreateFromData to create a BitmapEx. RGB data format.
  */

vcl/headless/svpgdi.cxx

@@ -29,6 +29,7 @@
 
 #include <sal/log.hxx>
 #include <o3tl/safeint.hxx>
+#include <vcl/BitmapTools.hxx>
 #include <vcl/sysdata.hxx>
 #include <config_cairo_canvas.h>
 #include <basegfx/numeric/ftools.hxx>
@@ -1639,50 +1640,6 @@ void SvpSalGraphics::drawBitmap( const SalTwoRect& rTR,
     drawAlphaBitmap(rTR, rSourceBitmap, rTransparentBitmap);
 }
 
-static sal_uInt8 unpremultiply(sal_uInt8 c, sal_uInt8 a)
-{
-    return (a == 0) ? 0 : (c * 255 + a / 2) / a;
-}
-
-static sal_uInt8 premultiply(sal_uInt8 c, sal_uInt8 a)
-{
-    return (c * a + 127) / 255;
-}
-
-typedef sal_uInt8 (*lookup_table)[256];
-
-static lookup_table get_unpremultiply_table()
-{
-    static bool inited;
-    static sal_uInt8 unpremultiply_table[256][256];
-
-    if (!inited)
-    {
-        for (int a = 0; a < 256; ++a)
-            for (int c = 0; c < 256; ++c)
-                unpremultiply_table[a][c] = unpremultiply(c, a);
-        inited = true;
-    }
-
-    return unpremultiply_table;
-}
-
-static lookup_table get_premultiply_table()
-{
-    static bool inited;
-    static sal_uInt8 premultiply_table[256][256];
-
-    if (!inited)
-    {
-        for (int a = 0; a < 256; ++a)
-            for (int c = 0; c < 256; ++c)
-                premultiply_table[a][c] = premultiply(c, a);
-        inited = true;
-    }
-
-    return premultiply_table;
-}
-
 void SvpSalGraphics::drawMask( const SalTwoRect& rTR,
                                const SalBitmap& rSalBitmap,
                                Color nMaskColor )
@@ -1697,7 +1654,7 @@ void SvpSalGraphics::drawMask( const SalTwoRect& rTR,
     }
     sal_Int32 nStride;
     unsigned char *mask_data = aSurface.getBits(nStride);
-    lookup_table unpremultiply_table = get_unpremultiply_table();
+    vcl::bitmap::lookup_table unpremultiply_table = vcl::bitmap::get_unpremultiply_table();
     for (long y = rTR.mnSrcY ; y < rTR.mnSrcY + rTR.mnSrcHeight; ++y)
     {
         unsigned char *row = mask_data + (nStride*y);
@@ -1805,7 +1762,7 @@ Color SvpSalGraphics::getPixel( long nX, long nY )
     cairo_destroy(cr);
 
     cairo_surface_flush(target);
-    lookup_table unpremultiply_table = get_unpremultiply_table();
+    vcl::bitmap::lookup_table unpremultiply_table = vcl::bitmap::get_unpremultiply_table();
     unsigned char *data = cairo_image_surface_get_data(target);
     sal_uInt8 a = data[SVP_CAIRO_ALPHA];
     sal_uInt8 b = unpremultiply_table[a][data[SVP_CAIRO_BLUE]];
@@ -2139,8 +2096,8 @@ void SvpSalGraphics::releaseCairoContext(cairo_t* cr, bool bXorModeAllowed, cons
         sal_Int32 nUnscaledExtentsRight = nExtentsRight * m_fScale;
         sal_Int32 nUnscaledExtentsTop = nExtentsTop * m_fScale;
         sal_Int32 nUnscaledExtentsBottom = nExtentsBottom * m_fScale;
-        lookup_table unpremultiply_table = get_unpremultiply_table();
-        lookup_table premultiply_table = get_premultiply_table();
+        vcl::bitmap::lookup_table unpremultiply_table = vcl::bitmap::get_unpremultiply_table();
+        vcl::bitmap::lookup_table premultiply_table = vcl::bitmap::get_premultiply_table();
         for (sal_Int32 y = nUnscaledExtentsTop; y < nUnscaledExtentsBottom; ++y)
         {
             unsigned char *true_row = target_surface_data + (nStride*y);