1 /*
2 * Copyright 2013 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "SkBitmap.h"
9 #include "SkColorFilter.h"
10 #include "SkPaintPriv.h"
11 #include "SkImage.h"
12 #include "SkPaint.h"
13 #include "SkShaderBase.h"
14 #include "SkUtils.h"
15 #include "SkXfermodePriv.h"
16
changes_alpha(const SkPaint & paint)17 static bool changes_alpha(const SkPaint& paint) {
18 SkColorFilter* cf = paint.getColorFilter();
19 return cf && !(cf->getFlags() & SkColorFilter::kAlphaUnchanged_Flag);
20 }
21
Overwrites(const SkPaint * paint,ShaderOverrideOpacity overrideOpacity)22 bool SkPaintPriv::Overwrites(const SkPaint* paint, ShaderOverrideOpacity overrideOpacity) {
23 if (!paint) {
24 // No paint means we default to SRC_OVER, so we overwrite iff our shader-override
25 // is opaque, or we don't have one.
26 return overrideOpacity != kNotOpaque_ShaderOverrideOpacity;
27 }
28
29 SkXfermode::SrcColorOpacity opacityType = SkXfermode::kUnknown_SrcColorOpacity;
30
31 if (!changes_alpha(*paint)) {
32 const unsigned paintAlpha = paint->getAlpha();
33 if (0xff == paintAlpha && overrideOpacity != kNotOpaque_ShaderOverrideOpacity &&
34 (!paint->getShader() || paint->getShader()->isOpaque()))
35 {
36 opacityType = SkXfermode::kOpaque_SrcColorOpacity;
37 } else if (0 == paintAlpha) {
38 if (overrideOpacity == kNone_ShaderOverrideOpacity && !paint->getShader()) {
39 opacityType = SkXfermode::kTransparentBlack_SrcColorOpacity;
40 } else {
41 opacityType = SkXfermode::kTransparentAlpha_SrcColorOpacity;
42 }
43 }
44 }
45
46 return SkXfermode::IsOpaque(paint->getBlendMode(), opacityType);
47 }
48
Overwrites(const SkBitmap & bitmap,const SkPaint * paint)49 bool SkPaintPriv::Overwrites(const SkBitmap& bitmap, const SkPaint* paint) {
50 return Overwrites(paint, bitmap.isOpaque() ? kOpaque_ShaderOverrideOpacity
51 : kNotOpaque_ShaderOverrideOpacity);
52 }
53
Overwrites(const SkImage * image,const SkPaint * paint)54 bool SkPaintPriv::Overwrites(const SkImage* image, const SkPaint* paint) {
55 return Overwrites(paint, image->isOpaque() ? kOpaque_ShaderOverrideOpacity
56 : kNotOpaque_ShaderOverrideOpacity);
57 }
58
ScaleFontMetrics(SkPaint::FontMetrics * metrics,SkScalar scale)59 void SkPaintPriv::ScaleFontMetrics(SkPaint::FontMetrics* metrics, SkScalar scale) {
60 metrics->fTop *= scale;
61 metrics->fAscent *= scale;
62 metrics->fDescent *= scale;
63 metrics->fBottom *= scale;
64 metrics->fLeading *= scale;
65 metrics->fAvgCharWidth *= scale;
66 metrics->fMaxCharWidth *= scale;
67 metrics->fXMin *= scale;
68 metrics->fXMax *= scale;
69 metrics->fXHeight *= scale;
70 metrics->fCapHeight *= scale;
71 metrics->fUnderlineThickness *= scale;
72 metrics->fUnderlinePosition *= scale;
73 metrics->fStrikeoutThickness *= scale;
74 metrics->fStrikeoutPosition *= scale;
75 }
76
ShouldDither(const SkPaint & p,SkColorType dstCT)77 bool SkPaintPriv::ShouldDither(const SkPaint& p, SkColorType dstCT) {
78 // The paint dither flag can veto.
79 if (!p.isDither()) {
80 return false;
81 }
82
83 // We always dither 565 or 4444 when requested.
84 if (dstCT == kRGB_565_SkColorType || dstCT == kARGB_4444_SkColorType) {
85 return true;
86 }
87
88 // Otherwise, dither is only needed for non-const paints.
89 return p.getImageFilter() || p.getMaskFilter()
90 || !p.getShader() || !as_SB(p.getShader())->isConstant();
91 }
92
ValidCountText(const void * text,size_t length,SkPaint::TextEncoding encoding)93 int SkPaintPriv::ValidCountText(const void* text, size_t length, SkPaint::TextEncoding encoding) {
94 if (length == 0) {
95 return 0;
96 }
97 switch (encoding) {
98 case SkPaint::kUTF8_TextEncoding: return SkUTF8_CountUnichars(text, length);
99 case SkPaint::kUTF16_TextEncoding: return SkUTF16_CountUnichars(text, length);
100 case SkPaint::kUTF32_TextEncoding: return SkUTF32_CountUnichars(text, length);
101 case SkPaint::kGlyphID_TextEncoding:
102 if (SkIsAlign2(intptr_t(text)) && SkIsAlign2(length)) {
103 return length >> 1;
104 }
105 break;
106 }
107 return 0;
108 }
109
110