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      1 
      2 /*
      3  * Copyright 2009 The Android Open Source Project
      4  *
      5  * Use of this source code is governed by a BSD-style license that can be
      6  * found in the LICENSE file.
      7  */
      8 
      9 
     10 #include "SkColorPriv.h"
     11 
     12 /*
     13     Filter_32_opaque
     14 
     15     There is no hard-n-fast rule that the filtering must produce
     16     exact results for the color components, but if the 4 incoming colors are
     17     all opaque, then the output color must also be opaque. Subsequent parts of
     18     the drawing pipeline may rely on this (e.g. which blitrow proc to use).
     19  */
     20 
     21 static inline void Filter_32_opaque(unsigned x, unsigned y,
     22                                     SkPMColor a00, SkPMColor a01,
     23                                     SkPMColor a10, SkPMColor a11,
     24                                     SkPMColor* dstColor) {
     25     SkASSERT((unsigned)x <= 0xF);
     26     SkASSERT((unsigned)y <= 0xF);
     27 
     28     int xy = x * y;
     29     const uint32_t mask = 0xFF00FF;
     30 
     31     int scale = 256 - 16*y - 16*x + xy;
     32     uint32_t lo = (a00 & mask) * scale;
     33     uint32_t hi = ((a00 >> 8) & mask) * scale;
     34 
     35     scale = 16*x - xy;
     36     lo += (a01 & mask) * scale;
     37     hi += ((a01 >> 8) & mask) * scale;
     38 
     39     scale = 16*y - xy;
     40     lo += (a10 & mask) * scale;
     41     hi += ((a10 >> 8) & mask) * scale;
     42 
     43     lo += (a11 & mask) * xy;
     44     hi += ((a11 >> 8) & mask) * xy;
     45 
     46     *dstColor = ((lo >> 8) & mask) | (hi & ~mask);
     47 }
     48 
     49 static inline void Filter_32_alpha(unsigned x, unsigned y,
     50                                    SkPMColor a00, SkPMColor a01,
     51                                    SkPMColor a10, SkPMColor a11,
     52                                    SkPMColor* dstColor,
     53                                    unsigned alphaScale) {
     54     SkASSERT((unsigned)x <= 0xF);
     55     SkASSERT((unsigned)y <= 0xF);
     56     SkASSERT(alphaScale <= 256);
     57 
     58     int xy = x * y;
     59     const uint32_t mask = 0xFF00FF;
     60 
     61     int scale = 256 - 16*y - 16*x + xy;
     62     uint32_t lo = (a00 & mask) * scale;
     63     uint32_t hi = ((a00 >> 8) & mask) * scale;
     64 
     65     scale = 16*x - xy;
     66     lo += (a01 & mask) * scale;
     67     hi += ((a01 >> 8) & mask) * scale;
     68 
     69     scale = 16*y - xy;
     70     lo += (a10 & mask) * scale;
     71     hi += ((a10 >> 8) & mask) * scale;
     72 
     73     lo += (a11 & mask) * xy;
     74     hi += ((a11 >> 8) & mask) * xy;
     75 
     76     lo = ((lo >> 8) & mask) * alphaScale;
     77     hi = ((hi >> 8) & mask) * alphaScale;
     78 
     79     *dstColor = ((lo >> 8) & mask) | (hi & ~mask);
     80 }
     81 
     82 // Two color version, where we filter only along 1 axis
     83 static inline void Filter_32_opaque(unsigned t,
     84                                     SkPMColor color0,
     85                                     SkPMColor color1,
     86                                     SkPMColor* dstColor) {
     87     SkASSERT((unsigned)t <= 0xF);
     88 
     89     const uint32_t mask = 0xFF00FF;
     90 
     91     int scale = 256 - 16*t;
     92     uint32_t lo = (color0 & mask) * scale;
     93     uint32_t hi = ((color0 >> 8) & mask) * scale;
     94 
     95     scale = 16*t;
     96     lo += (color1 & mask) * scale;
     97     hi += ((color1 >> 8) & mask) * scale;
     98 
     99     *dstColor = ((lo >> 8) & mask) | (hi & ~mask);
    100 }
    101 
    102 // Two color version, where we filter only along 1 axis
    103 static inline void Filter_32_alpha(unsigned t,
    104                                    SkPMColor color0,
    105                                    SkPMColor color1,
    106                                    SkPMColor* dstColor,
    107                                    unsigned alphaScale) {
    108     SkASSERT((unsigned)t <= 0xF);
    109     SkASSERT(alphaScale <= 256);
    110 
    111     const uint32_t mask = 0xFF00FF;
    112 
    113     int scale = 256 - 16*t;
    114     uint32_t lo = (color0 & mask) * scale;
    115     uint32_t hi = ((color0 >> 8) & mask) * scale;
    116 
    117     scale = 16*t;
    118     lo += (color1 & mask) * scale;
    119     hi += ((color1 >> 8) & mask) * scale;
    120 
    121     lo = ((lo >> 8) & mask) * alphaScale;
    122     hi = ((hi >> 8) & mask) * alphaScale;
    123 
    124     *dstColor = ((lo >> 8) & mask) | (hi & ~mask);
    125 }
    126