grab from latest android

git-svn-id: http://skia.googlecode.com/svn/trunk@27 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 205 insertions, 0 deletions

diff --git a/include/core/SkDither.h b/include/core/SkDither.h
new file mode 100644
index 0000000000..5b2552d1c1
--- /dev/null
+++ b/include/core/SkDither.h
@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SkDither_DEFINED
+#define SkDither_DEFINED
+
+#include "SkColorPriv.h"
+
+#define SK_DitherValueMax4444   15
+#define SK_DitherValueMax565    7
+
+/*  need to use macros for bit-counts for each component, and then
+    move these into SkColorPriv.h
+*/
+
+#define SkDITHER_R32_FOR_565_MACRO(r, d)    (r + d - (r >> 5))
+#define SkDITHER_G32_FOR_565_MACRO(g, d)    (g + (d >> 1) - (g >> 6))
+#define SkDITHER_B32_FOR_565_MACRO(b, d)    (b + d - (b >> 5))
+
+#define SkDITHER_A32_FOR_4444_MACRO(a, d)    (a + 15 - (a >> 4))
+#define SkDITHER_R32_FOR_4444_MACRO(r, d)    (r + d - (r >> 4))
+#define SkDITHER_G32_FOR_4444_MACRO(g, d)    (g + d - (g >> 4))
+#define SkDITHER_B32_FOR_4444_MACRO(b, d)    (b + d - (b >> 4))
+
+#ifdef SK_DEBUG
+    inline unsigned SkDITHER_R32_FOR_565(unsigned r, unsigned d)
+    {
+        SkASSERT(d <= SK_DitherValueMax565);
+        SkA32Assert(r);
+        r = SkDITHER_R32_FOR_565_MACRO(r, d);
+        SkA32Assert(r);
+        return r;
+    }
+    inline unsigned SkDITHER_G32_FOR_565(unsigned g, unsigned d)
+    {
+        SkASSERT(d <= SK_DitherValueMax565);
+        SkG32Assert(g);
+        g = SkDITHER_G32_FOR_565_MACRO(g, d);
+        SkG32Assert(g);
+        return g;
+    }
+    inline unsigned SkDITHER_B32_FOR_565(unsigned b, unsigned d)
+    {
+        SkASSERT(d <= SK_DitherValueMax565);
+        SkB32Assert(b);
+        b = SkDITHER_B32_FOR_565_MACRO(b, d);
+        SkB32Assert(b);
+        return b;
+    }
+#else
+    #define SkDITHER_R32_FOR_565(r, d)  SkDITHER_R32_FOR_565_MACRO(r, d)
+    #define SkDITHER_G32_FOR_565(g, d)  SkDITHER_G32_FOR_565_MACRO(g, d)
+    #define SkDITHER_B32_FOR_565(b, d)  SkDITHER_B32_FOR_565_MACRO(b, d)
+#endif
+
+#define SkDITHER_R32To565(r, d)  SkR32ToR16(SkDITHER_R32_FOR_565(r, d))
+#define SkDITHER_G32To565(g, d)  SkG32ToG16(SkDITHER_G32_FOR_565(g, d))
+#define SkDITHER_B32To565(b, d)  SkB32ToB16(SkDITHER_B32_FOR_565(b, d))
+
+#define SkDITHER_A32To4444(a, d)  SkA32To4444(SkDITHER_A32_FOR_4444_MACRO(a, d))
+#define SkDITHER_R32To4444(r, d)  SkR32To4444(SkDITHER_R32_FOR_4444_MACRO(r, d))
+#define SkDITHER_G32To4444(g, d)  SkG32To4444(SkDITHER_G32_FOR_4444_MACRO(g, d))
+#define SkDITHER_B32To4444(b, d)  SkB32To4444(SkDITHER_B32_FOR_4444_MACRO(b, d))
+
+static inline SkPMColor SkDitherARGB32For565(SkPMColor c, unsigned dither)
+{
+    SkASSERT(dither <= SK_DitherValueMax565);
+    
+    unsigned sa = SkGetPackedA32(c);
+    dither = SkAlphaMul(dither, SkAlpha255To256(sa));
+
+    unsigned sr = SkGetPackedR32(c);
+    unsigned sg = SkGetPackedG32(c);
+    unsigned sb = SkGetPackedB32(c);
+    sr = SkDITHER_R32_FOR_565(sr, dither);
+    sg = SkDITHER_G32_FOR_565(sg, dither);
+    sb = SkDITHER_B32_FOR_565(sb, dither);
+    
+    return SkPackARGB32(sa, sr, sg, sb);
+}
+
+static inline SkPMColor SkDitherRGB32For565(SkPMColor c, unsigned dither)
+{
+    SkASSERT(dither <= SK_DitherValueMax565);
+    
+    unsigned sr = SkGetPackedR32(c);
+    unsigned sg = SkGetPackedG32(c);
+    unsigned sb = SkGetPackedB32(c);
+    sr = SkDITHER_R32_FOR_565(sr, dither);
+    sg = SkDITHER_G32_FOR_565(sg, dither);
+    sb = SkDITHER_B32_FOR_565(sb, dither);
+    
+    return SkPackARGB32(0xFF, sr, sg, sb);
+}
+
+static inline uint16_t SkDitherRGBTo565(U8CPU r, U8CPU g, U8CPU b,
+                                              unsigned dither)
+{
+    SkASSERT(dither <= SK_DitherValueMax565);
+    r = SkDITHER_R32To565(r, dither);
+    g = SkDITHER_G32To565(g, dither);
+    b = SkDITHER_B32To565(b, dither);
+    return SkPackRGB16(r, g, b);
+}
+
+static inline uint16_t SkDitherRGB32To565(SkPMColor c, unsigned dither)
+{
+    SkASSERT(dither <= SK_DitherValueMax565);
+    
+    unsigned sr = SkGetPackedR32(c);
+    unsigned sg = SkGetPackedG32(c);
+    unsigned sb = SkGetPackedB32(c);
+    sr = SkDITHER_R32To565(sr, dither);
+    sg = SkDITHER_G32To565(sg, dither);
+    sb = SkDITHER_B32To565(sb, dither);
+    
+    return SkPackRGB16(sr, sg, sb);
+}
+
+static inline uint16_t SkDitherARGB32To565(U8CPU sa, SkPMColor c, unsigned dither)
+{
+    SkASSERT(dither <= SK_DitherValueMax565);    
+    dither = SkAlphaMul(dither, SkAlpha255To256(sa));
+    
+    unsigned sr = SkGetPackedR32(c);
+    unsigned sg = SkGetPackedG32(c);
+    unsigned sb = SkGetPackedB32(c);
+    sr = SkDITHER_R32To565(sr, dither);
+    sg = SkDITHER_G32To565(sg, dither);
+    sb = SkDITHER_B32To565(sb, dither);
+    
+    return SkPackRGB16(sr, sg, sb);
+}
+
+///////////////////////// 4444
+
+static inline SkPMColor16 SkDitherARGB32To4444(U8CPU a, U8CPU r, U8CPU g,
+                                               U8CPU b, unsigned dither)
+{
+    dither = SkAlphaMul(dither, SkAlpha255To256(a));
+
+    a = SkDITHER_A32To4444(a, dither);
+    r = SkDITHER_R32To4444(r, dither);
+    g = SkDITHER_G32To4444(g, dither);
+    b = SkDITHER_B32To4444(b, dither);
+    
+    return SkPackARGB4444(a, r, g, b);
+}
+
+static inline SkPMColor16 SkDitherARGB32To4444(SkPMColor c, unsigned dither)
+{
+    unsigned a = SkGetPackedA32(c);
+    unsigned r = SkGetPackedR32(c);
+    unsigned g = SkGetPackedG32(c);
+    unsigned b = SkGetPackedB32(c);
+
+    dither = SkAlphaMul(dither, SkAlpha255To256(a));
+
+    a = SkDITHER_A32To4444(a, dither);
+    r = SkDITHER_R32To4444(r, dither);
+    g = SkDITHER_G32To4444(g, dither);
+    b = SkDITHER_B32To4444(b, dither);
+    
+    return SkPackARGB4444(a, r, g, b);
+}
+
+// TODO: need dither routines for 565 -> 4444
+
+// this toggles between a 4x4 and a 1x4 array
+//#define ENABLE_DITHER_MATRIX_4X4
+
+#ifdef ENABLE_DITHER_MATRIX_4X4
+    extern const uint8_t gDitherMatrix_4Bit_4X4[4][4];
+    extern const uint8_t gDitherMatrix_3Bit_4X4[4][4];
+
+    #define DITHER_4444_SCAN(y) const uint8_t* dither_scan = gDitherMatrix_4Bit_4X4[(y) & 3]
+    #define DITHER_565_SCAN(y)  const uint8_t* dither_scan = gDitherMatrix_3Bit_4X4[(y) & 3]
+
+    #define DITHER_VALUE(x) dither_scan[(x) & 3]
+#else
+    extern const uint16_t gDitherMatrix_4Bit_16[4];
+    extern const uint16_t gDitherMatrix_3Bit_16[4];
+
+    #define DITHER_4444_SCAN(y) const uint16_t dither_scan = gDitherMatrix_4Bit_16[(y) & 3]
+    #define DITHER_565_SCAN(y)  const uint16_t dither_scan = gDitherMatrix_3Bit_16[(y) & 3]
+
+    #define DITHER_VALUE(x) ((dither_scan >> (((x) & 3) << 2)) & 0xF)
+#endif
+
+#define DITHER_INC_X(x) ++(x)
+
+#endif