make the Color constructors explicitly specify transparency

to reduce the churn, we leave the existing constructor in place,
and add a clang plugin to detect when the value passed to the
existing constructor may contain transparency/alpha data.

i.e. we leave expressions like Color(0xffffff) alone, but
warn about any non-constant expression, and any expression
like Color(0xff000000)

Change-Id: Id2ce58e08882d9b7bd0b9f88eca97359dcdbcc8c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/109362
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

3 files changed, 16 insertions, 16 deletions

diff --git a/drawinglayer/source/primitive2d/sceneprimitive2d.cxx b/drawinglayer/source/primitive2d/sceneprimitive2d.cxx
index b96cca222e7f..21bf591aecc0 100644
--- a/drawinglayer/source/primitive2d/sceneprimitive2d.cxx
+++ b/drawinglayer/source/primitive2d/sceneprimitive2d.cxx
@@ -82,14 +82,14 @@ namespace
 
                         if(nAlpha)
                         {
-                            aContent.SetPixel(y, x, Color(
-                                255 - static_cast<sal_uInt8>(nAlpha),
+                            aContent.SetPixel(y, x, Color(ColorAlpha,
+                                static_cast<sal_uInt8>(nAlpha),
                                 static_cast<sal_uInt8>(nRed / nDivisor),
                                 static_cast<sal_uInt8>(nGreen / nDivisor),
                                 static_cast<sal_uInt8>(nBlue / nDivisor) ));
                         }
                         else
-                            aContent.SetPixel(y, x, Color(255, 0, 0, 0));
+                            aContent.SetPixel(y, x, Color(ColorAlpha, 0, 0, 0, 0));
                     }
                 }
             }
@@ -105,10 +105,10 @@ namespace
 
                         if(rPixel.getAlpha())
                         {
-                            aContent.SetPixel(y, x, Color(255 - rPixel.getAlpha(), rPixel.getRed(), rPixel.getGreen(), rPixel.getBlue()));
+                            aContent.SetPixel(y, x, Color(ColorAlpha, rPixel.getAlpha(), rPixel.getRed(), rPixel.getGreen(), rPixel.getBlue()));
                         }
                         else
-                            aContent.SetPixel(y, x, Color(255, 0, 0, 0));
+                            aContent.SetPixel(y, x, Color(ColorAlpha, 0, 0, 0, 0));
                     }
                 }
             }
diff --git a/drawinglayer/source/tools/emfpbrush.cxx b/drawinglayer/source/tools/emfpbrush.cxx
index ca0c27b23ecf..24c3f281812b 100644
--- a/drawinglayer/source/tools/emfpbrush.cxx
+++ b/drawinglayer/source/tools/emfpbrush.cxx
@@ -77,7 +77,7 @@ namespace emfplushelper
                 sal_uInt32 color;
                 s.ReadUInt32(color);
 
-                solidColor = ::Color(0xff - (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
+                solidColor = ::Color(ColorAlpha, (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tSolid color: 0x" << std::hex << color << std::dec);
                 break;
             }
@@ -91,8 +91,8 @@ namespace emfplushelper
                 s.ReadUInt32(backgroundColor);
 
                 hatchStyle = static_cast<EmfPlusHatchStyle>(style);
-                solidColor = ::Color(0xff - (foregroundColor >> 24), (foregroundColor >> 16) & 0xff, (foregroundColor >> 8) & 0xff, foregroundColor & 0xff);
-                secondColor = ::Color(0xff - (backgroundColor >> 24), (backgroundColor >> 16) & 0xff, (backgroundColor >> 8) & 0xff, backgroundColor & 0xff);
+                solidColor = ::Color(ColorAlpha, (foregroundColor >> 24), (foregroundColor >> 16) & 0xff, (foregroundColor >> 8) & 0xff, foregroundColor & 0xff);
+                secondColor = ::Color(ColorAlpha, (backgroundColor >> 24), (backgroundColor >> 16) & 0xff, (backgroundColor >> 8) & 0xff, backgroundColor & 0xff);
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tHatch style: 0x" << std::hex << style);
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tForeground color: 0x" << solidColor.AsRGBHexString());
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tBackground color: 0x" << secondColor.AsRGBHexString());
@@ -109,7 +109,7 @@ namespace emfplushelper
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tAdditional flags: 0x" << std::hex << additionalFlags << std::dec);
                 sal_uInt32 color;
                 s.ReadUInt32(color);
-                solidColor = ::Color(0xff - (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
+                solidColor = ::Color(ColorAlpha, (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tCenter color: 0x" << std::hex << color << std::dec);
                 s.ReadFloat(firstPointX).ReadFloat(firstPointY);
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tCenter point: " << firstPointX << "," << firstPointY);
@@ -126,7 +126,7 @@ namespace emfplushelper
                 for (int i = 0; i < surroundColorsNumber; i++)
                 {
                     s.ReadUInt32(color);
-                    surroundColors[i] = ::Color(0xff - (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
+                    surroundColors[i] = ::Color(ColorAlpha, (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
                     if (i == 0)
                         secondColor = surroundColors[0];
                     SAL_INFO("drawinglayer", "EMF+\t\t\t\tSurround color[" << i << "]: 0x" << std::hex << color << std::dec);
@@ -236,7 +236,7 @@ namespace emfplushelper
                     for (int i = 0; i < colorblendPoints; i++)
                     {
                         s.ReadUInt32(color);
-                        colorblendColors[i] = ::Color(0xff - (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
+                        colorblendColors[i] = ::Color(ColorAlpha, (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
                         SAL_INFO("drawinglayer", "EMF+\t\t\t\tColor[" << i << "]: 0x" << std::hex << color << std::dec);
                     }
                 }
@@ -252,10 +252,10 @@ namespace emfplushelper
                                          << ", size " << aWidth << "x" << aHeight);
                 sal_uInt32 color;
                 s.ReadUInt32(color);
-                solidColor = ::Color(0xff - (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
+                solidColor = ::Color(ColorAlpha, (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tfirst color: 0x" << std::hex << color << std::dec);
                 s.ReadUInt32(color);
-                secondColor = ::Color(0xff - (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
+                secondColor = ::Color(ColorAlpha, (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
                 SAL_INFO("drawinglayer", "EMF+\t\t\t\tsecond color: 0x" << std::hex << color << std::dec);
 
                 // repeated colors, unknown meaning, see http://www.aces.uiuc.edu/~jhtodd/Metafile/MetafileRecords/ObjectBrush.html
@@ -318,7 +318,7 @@ namespace emfplushelper
                     for (int i = 0; i < colorblendPoints; i++)
                     {
                         s.ReadUInt32(color);
-                        colorblendColors[i] = ::Color(0xff - (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
+                        colorblendColors[i] = ::Color(ColorAlpha, (color >> 24), (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff);
                         SAL_INFO("drawinglayer", "EMF+\t\t\t\tColor[" << i << "]: 0x" << std::hex << color << std::dec);
                     }
                 }
diff --git a/drawinglayer/source/tools/emfphelperdata.cxx b/drawinglayer/source/tools/emfphelperdata.cxx
index fb34dac496e2..d55babc0e960 100644
--- a/drawinglayer/source/tools/emfphelperdata.cxx
+++ b/drawinglayer/source/tools/emfphelperdata.cxx
@@ -454,7 +454,7 @@ namespace emfplushelper
         Color color;
         if (flags & 0x8000) // we use a color
         {
-            color = Color(0xff - (brushIndexOrColor >> 24), (brushIndexOrColor >> 16) & 0xff,
+            color = Color(ColorAlpha, (brushIndexOrColor >> 24), (brushIndexOrColor >> 16) & 0xff,
                           (brushIndexOrColor >> 8) & 0xff, brushIndexOrColor & 0xff);
         }
         else // we use a pen
@@ -724,7 +724,7 @@ namespace emfplushelper
 
             // EMF Alpha (1 byte): An 8-bit unsigned integer that specifies the transparency of the background,
             // ranging from 0 for completely transparent to 0xFF for completely opaque.
-            const Color color(0xff - (brushIndexOrColor >> 24), (brushIndexOrColor >> 16) & 0xff, (brushIndexOrColor >> 8) & 0xff, brushIndexOrColor & 0xff);
+            const Color color(ColorAlpha, (brushIndexOrColor >> 24), (brushIndexOrColor >> 16) & 0xff, (brushIndexOrColor >> 8) & 0xff, brushIndexOrColor & 0xff);
             EMFPPlusFillPolygonSolidColor(polygon, color);
 
             mrPropertyHolders.Current().setFillColor(color.getBColor());