gfx/skia/trunk/src/core/SkAntiRun.h@129ffea94266
gfx/skia/trunk/src/core/SkAntiRun.h
Sat, 03 Jan 2015 20:18:00 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Sat, 03 Jan 2015 20:18:00 +0100
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
- permissions
- -rw-r--r--
Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.
2 /*
3 * Copyright 2006 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 */
10 #ifndef SkAntiRun_DEFINED
11 #define SkAntiRun_DEFINED
13 #include "SkBlitter.h"
15 /** Sparse array of run-length-encoded alpha (supersampling coverage) values.
16 Sparseness allows us to independently compose several paths into the
17 same SkAlphaRuns buffer.
18 */
20 class SkAlphaRuns {
21 public:
22 int16_t* fRuns;
23 uint8_t* fAlpha;
25 /// Returns true if the scanline contains only a single run,
26 /// of alpha value 0.
27 bool empty() const {
28 SkASSERT(fRuns[0] > 0);
29 return fAlpha[0] == 0 && fRuns[fRuns[0]] == 0;
30 }
32 /// Reinitialize for a new scanline.
33 void reset(int width);
35 /**
36 * Insert into the buffer a run starting at (x-offsetX):
37 * if startAlpha > 0
38 * one pixel with value += startAlpha,
39 * max 255
40 * if middleCount > 0
41 * middleCount pixels with value += maxValue
42 * if stopAlpha > 0
43 * one pixel with value += stopAlpha
44 * Returns the offsetX value that should be passed on the next call,
45 * assuming we're on the same scanline. If the caller is switching
46 * scanlines, then offsetX should be 0 when this is called.
47 */
48 SK_ALWAYS_INLINE int add(int x, U8CPU startAlpha, int middleCount, U8CPU stopAlpha,
49 U8CPU maxValue, int offsetX) {
50 SkASSERT(middleCount >= 0);
51 SkASSERT(x >= 0 && x + (startAlpha != 0) + middleCount + (stopAlpha != 0) <= fWidth);
53 SkASSERT(fRuns[offsetX] >= 0);
55 int16_t* runs = fRuns + offsetX;
56 uint8_t* alpha = fAlpha + offsetX;
57 uint8_t* lastAlpha = alpha;
58 x -= offsetX;
60 if (startAlpha) {
61 SkAlphaRuns::Break(runs, alpha, x, 1);
62 /* I should be able to just add alpha[x] + startAlpha.
63 However, if the trailing edge of the previous span and the leading
64 edge of the current span round to the same super-sampled x value,
65 I might overflow to 256 with this add, hence the funny subtract (crud).
66 */
67 unsigned tmp = alpha[x] + startAlpha;
68 SkASSERT(tmp <= 256);
69 alpha[x] = SkToU8(tmp - (tmp >> 8)); // was (tmp >> 7), but that seems wrong if we're trying to catch 256
71 runs += x + 1;
72 alpha += x + 1;
73 x = 0;
74 lastAlpha += x; // we don't want the +1
75 SkDEBUGCODE(this->validate();)
76 }
78 if (middleCount) {
79 SkAlphaRuns::Break(runs, alpha, x, middleCount);
80 alpha += x;
81 runs += x;
82 x = 0;
83 do {
84 alpha[0] = SkToU8(alpha[0] + maxValue);
85 int n = runs[0];
86 SkASSERT(n <= middleCount);
87 alpha += n;
88 runs += n;
89 middleCount -= n;
90 } while (middleCount > 0);
91 SkDEBUGCODE(this->validate();)
92 lastAlpha = alpha;
93 }
95 if (stopAlpha) {
96 SkAlphaRuns::Break(runs, alpha, x, 1);
97 alpha += x;
98 alpha[0] = SkToU8(alpha[0] + stopAlpha);
99 SkDEBUGCODE(this->validate();)
100 lastAlpha = alpha;
101 }
103 return SkToS32(lastAlpha - fAlpha); // new offsetX
104 }
106 SkDEBUGCODE(void assertValid(int y, int maxStep) const;)
107 SkDEBUGCODE(void dump() const;)
109 /**
110 * Break the runs in the buffer at offsets x and x+count, properly
111 * updating the runs to the right and left.
112 * i.e. from the state AAAABBBB, run-length encoded as A4B4,
113 * Break(..., 2, 5) would produce AAAABBBB rle as A2A2B3B1.
114 * Allows add() to sum another run to some of the new sub-runs.
115 * i.e. adding ..CCCCC. would produce AADDEEEB, rle as A2D2E3B1.
116 */
117 static void Break(int16_t runs[], uint8_t alpha[], int x, int count) {
118 SkASSERT(count > 0 && x >= 0);
120 // SkAlphaRuns::BreakAt(runs, alpha, x);
121 // SkAlphaRuns::BreakAt(&runs[x], &alpha[x], count);
123 int16_t* next_runs = runs + x;
124 uint8_t* next_alpha = alpha + x;
126 while (x > 0) {
127 int n = runs[0];
128 SkASSERT(n > 0);
130 if (x < n) {
131 alpha[x] = alpha[0];
132 runs[0] = SkToS16(x);
133 runs[x] = SkToS16(n - x);
134 break;
135 }
136 runs += n;
137 alpha += n;
138 x -= n;
139 }
141 runs = next_runs;
142 alpha = next_alpha;
143 x = count;
145 for (;;) {
146 int n = runs[0];
147 SkASSERT(n > 0);
149 if (x < n) {
150 alpha[x] = alpha[0];
151 runs[0] = SkToS16(x);
152 runs[x] = SkToS16(n - x);
153 break;
154 }
155 x -= n;
156 if (x <= 0) {
157 break;
158 }
159 runs += n;
160 alpha += n;
161 }
162 }
164 /**
165 * Cut (at offset x in the buffer) a run into two shorter runs with
166 * matching alpha values.
167 * Used by the RectClipBlitter to trim a RLE encoding to match the
168 * clipping rectangle.
169 */
170 static void BreakAt(int16_t runs[], uint8_t alpha[], int x) {
171 while (x > 0) {
172 int n = runs[0];
173 SkASSERT(n > 0);
175 if (x < n) {
176 alpha[x] = alpha[0];
177 runs[0] = SkToS16(x);
178 runs[x] = SkToS16(n - x);
179 break;
180 }
181 runs += n;
182 alpha += n;
183 x -= n;
184 }
185 }
187 private:
188 SkDEBUGCODE(int fWidth;)
189 SkDEBUGCODE(void validate() const;)
190 };
192 #endif
