rework Color to have R,G,B,A public variables

Color is a wrapper around a sal_uInt32 variable. With a union,
separate channels R, G, B, A sal_uInt8 variables can be added
that occupy the same memory. This makes it much easier to access
each color component separately, which is used quite a lot by
various algorithms. This also adds the variables to public so
everyone can enjoy the benefits.

Tests have been extended to make sure this doesn't break the
existing algroithms.

Change-Id: I2e78e12df68e8c7f0f49420eef5e659b335ee397
Reviewed-on: https://gerrit.libreoffice.org/71002
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

1 files changed, 47 insertions, 38 deletions

diff --git a/include/tools/color.hxx b/include/tools/color.hxx
index 26d587b7e1f5..25032c5d29b9 100644
--- a/include/tools/color.hxx
+++ b/include/tools/color.hxx
@@ -26,29 +26,44 @@
 
 class SvStream;
 
-constexpr sal_uInt8  COLORDATA_RED( sal_uInt32 n )          { return static_cast<sal_uInt8>(n>>16); }
-constexpr sal_uInt8  COLORDATA_GREEN( sal_uInt32 n )        { return static_cast<sal_uInt8>(static_cast<sal_uInt16>(n) >> 8); }
-constexpr sal_uInt8  COLORDATA_BLUE( sal_uInt32 n )         { return static_cast<sal_uInt8>(n); }
-constexpr sal_uInt8  COLORDATA_TRANSPARENCY( sal_uInt32 n ) { return static_cast<sal_uInt8>(n>>24); }
 constexpr sal_uInt32 COLORDATA_RGB( sal_uInt32 n )          { return static_cast<sal_uInt32>(n & 0x00FFFFFF); }
 
 // Color
 
 class SAL_WARN_UNUSED TOOLS_DLLPUBLIC Color final
 {
-    sal_uInt32 mnColor;
-
 public:
+    union
+    {
+        sal_uInt32 mValue;
+        struct
+        {
+    #ifdef OSL_BIGENDIAN
+                sal_uInt8 A;
+                sal_uInt8 R;
+                sal_uInt8 G;
+                sal_uInt8 B;
+    #else
+                sal_uInt8 B;
+                sal_uInt8 G;
+                sal_uInt8 R;
+                sal_uInt8 A;
+    #endif
+        };
+    };
+
     constexpr Color()
-        : mnColor(0) // black
+        : mValue(0) // black
     {}
+
     constexpr Color(sal_uInt32 nColor)
-        : mnColor(nColor)
+        : mValue(nColor)
     {}
+
     constexpr Color(sal_uInt8 nTransparency, sal_uInt8 nRed, sal_uInt8 nGreen, sal_uInt8 nBlue)
-        : mnColor( sal_uInt32(nBlue) | (sal_uInt32(nGreen) << 8) | (sal_uInt32(nRed) << 16)
-                   | (sal_uInt32(nTransparency) << 24) )
+        : mValue(sal_uInt32(nBlue) | (sal_uInt32(nGreen) << 8) | (sal_uInt32(nRed) << 16) | (sal_uInt32(nTransparency) << 24))
     {}
+
     constexpr Color(sal_uInt8 nRed, sal_uInt8 nGreen, sal_uInt8 nBlue)
         : Color(0, nRed, nGreen, nBlue)
     {}
@@ -56,51 +71,51 @@ public:
     // constructor to create a tools-Color from ::basegfx::BColor
     explicit Color(const basegfx::BColor& rBColor)
         : Color(0,
-                sal_uInt8((rBColor.getRed() * 255.0) + 0.5),
-                sal_uInt8((rBColor.getGreen() * 255.0) + 0.5),
-                sal_uInt8((rBColor.getBlue() * 255.0) + 0.5))
+                sal_uInt8(std::lround(rBColor.getRed() * 255.0)),
+                sal_uInt8(std::lround(rBColor.getGreen() * 255.0)),
+                sal_uInt8(std::lround(rBColor.getBlue() * 255.0)))
     {}
 
     /** Primarily used when passing Color objects to UNO API */
     constexpr explicit operator sal_uInt32() const
     {
-        return mnColor;
+        return mValue;
     }
 
     constexpr explicit operator sal_Int32() const
     {
-        return sal_Int32(mnColor);
+        return sal_Int32(mValue);
     }
 
-    bool operator<(const Color& b) const
+    bool operator<(const Color& aCompareColor) const
     {
-        return mnColor < b.mnColor;
+        return mValue < aCompareColor.mValue;
     }
 
     void SetRed(sal_uInt8 nRed);
     sal_uInt8 GetRed() const
     {
-        return COLORDATA_RED(mnColor);
+        return R;
     }
     void SetGreen(sal_uInt8 nGreen);
     sal_uInt8 GetGreen() const
     {
-        return COLORDATA_GREEN(mnColor);
+        return G;
     }
     void SetBlue(sal_uInt8 nBlue);
     sal_uInt8 GetBlue() const
     {
-        return COLORDATA_BLUE(mnColor);
+        return B;
     }
     void SetTransparency(sal_uInt8 nTransparency);
     sal_uInt8 GetTransparency() const
     {
-        return COLORDATA_TRANSPARENCY(mnColor);
+        return A;
     }
 
     Color GetRGBColor() const
     {
-        return COLORDATA_RGB(mnColor);
+        return COLORDATA_RGB(mValue);
     }
 
     sal_uInt8 GetColorError(const Color& rCompareColor) const;
@@ -141,7 +156,7 @@ public:
 
     bool operator==(const Color& rColor) const
     {
-        return mnColor == rColor.mnColor;
+        return mValue == rColor.mValue;
     }
     bool operator!=(const Color& rColor) const
     {
@@ -167,38 +182,32 @@ public:
 
 inline void Color::SetRed( sal_uInt8 nRed )
 {
-    mnColor &= 0xFF00FFFF;
-    mnColor |= static_cast<sal_uInt32>(nRed)<<16;
+    R = nRed;
 }
 
 inline void Color::SetGreen( sal_uInt8 nGreen )
 {
-    mnColor &= 0xFFFF00FF;
-    mnColor |= static_cast<sal_uInt16>(nGreen)<<8;
+    G = nGreen;
 }
 
 inline void Color::SetBlue( sal_uInt8 nBlue )
 {
-    mnColor &= 0xFFFFFF00;
-    mnColor |= nBlue;
+    B = nBlue;
 }
 
 inline void Color::SetTransparency( sal_uInt8 nTransparency )
 {
-    mnColor &= 0x00FFFFFF;
-    mnColor |= static_cast<sal_uInt32>(nTransparency)<<24;
+    A = nTransparency;
 }
 
 inline bool Color::IsRGBEqual( const Color& rColor ) const
 {
-    return COLORDATA_RGB( mnColor ) == COLORDATA_RGB(rColor.mnColor);
+    return COLORDATA_RGB(mValue) == COLORDATA_RGB(rColor.mValue);
 }
 
 inline sal_uInt8 Color::GetLuminance() const
 {
-    return static_cast<sal_uInt8>((COLORDATA_BLUE(mnColor) * 29UL +
-                                   COLORDATA_GREEN(mnColor) * 151UL +
-                                   COLORDATA_RED(mnColor) * 76UL) >> 8);
+    return sal_uInt8((B * 29UL + G * 151UL + R * 76UL) >> 8);
 }
 
 constexpr sal_uInt8 ColorChannelMerge(sal_uInt8 nDst, sal_uInt8 nSrc, sal_uInt8 nSrcTrans)
@@ -208,9 +217,9 @@ constexpr sal_uInt8 ColorChannelMerge(sal_uInt8 nDst, sal_uInt8 nSrc, sal_uInt8
 
 inline void Color::Merge( const Color& rMergeColor, sal_uInt8 cTransparency )
 {
-    SetRed(ColorChannelMerge(COLORDATA_RED(mnColor), COLORDATA_RED(rMergeColor.mnColor), cTransparency));
-    SetGreen(ColorChannelMerge(COLORDATA_GREEN(mnColor), COLORDATA_GREEN(rMergeColor.mnColor), cTransparency));
-    SetBlue(ColorChannelMerge(COLORDATA_BLUE(mnColor), COLORDATA_BLUE(rMergeColor.mnColor), cTransparency));
+    R = ColorChannelMerge(R, rMergeColor.R, cTransparency);
+    G = ColorChannelMerge(G, rMergeColor.G, cTransparency);
+    B = ColorChannelMerge(B, rMergeColor.B, cTransparency);
 }
 
 // to reduce the noise when moving these into and out of Any