Add skia to the repository.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@16 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 65 insertions, 0 deletions

diff --git a/skia/ports/SkFontHost_gamma.cpp b/skia/ports/SkFontHost_gamma.cpp
new file mode 100644
index 0000000..28c7051
--- /dev/null
+++ b/skia/ports/SkFontHost_gamma.cpp
@@ -0,0 +1,65 @@
+
+#include "SkFontHost.h"
+#include <math.h>
+
+static void build_power_table(uint8_t table[], float ee)
+{
+//    printf("------ build_power_table %g\n", ee);
+    for (int i = 0; i < 256; i++)
+    {
+        float x = i / 255.f;
+     //   printf(" %d %g", i, x);
+        x = powf(x, ee);
+     //   printf(" %g", x);
+        int xx = SkScalarRound(SkFloatToScalar(x * 255));
+     //   printf(" %d\n", xx);
+        table[i] = SkToU8(xx);
+    }
+}
+
+static bool gGammaIsBuilt;
+static uint8_t gBlackGamma[256], gWhiteGamma[256];
+
+#define ANDROID_BLACK_GAMMA     (1.4f)
+#define ANDROID_WHITE_GAMMA     (1/1.4f)
+
+void SkFontHost::GetGammaTables(const uint8_t* tables[2])
+{
+    // would be cleaner if these tables were precomputed and just linked in
+    if (!gGammaIsBuilt)
+    {
+        build_power_table(gBlackGamma, ANDROID_BLACK_GAMMA);
+        build_power_table(gWhiteGamma, ANDROID_WHITE_GAMMA);
+        gGammaIsBuilt = true;
+    }
+    tables[0] = gBlackGamma;
+    tables[1] = gWhiteGamma;
+}
+
+#define BLACK_GAMMA_THRESHOLD   0x40
+#define WHITE_GAMMA_THRESHOLD   0xC0
+
+int SkFontHost::ComputeGammaFlag(const SkPaint& paint)
+{
+    if (paint.getShader() == NULL)
+    {
+        SkColor c = paint.getColor();
+        int r = SkColorGetR(c);
+        int g = SkColorGetG(c);
+        int b = SkColorGetB(c);
+        int luminance = (r * 2 + g * 5 + b) >> 3;
+        
+        if (luminance <= BLACK_GAMMA_THRESHOLD)
+        {
+        //    printf("------ black gamma for [%d %d %d]\n", r, g, b);
+            return SkScalerContext::kGammaForBlack_Flag;
+        }
+        if (luminance >= WHITE_GAMMA_THRESHOLD)
+        {
+        //    printf("------ white gamma for [%d %d %d]\n", r, g, b);
+            return SkScalerContext::kGammaForWhite_Flag;
+        }
+    }
+    return 0;
+}
+