1/*
2 * Copyright 2006 The Android Open Source Project
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#ifndef SkBlitter_DEFINED
9#define SkBlitter_DEFINED
10
11#include "include/core/SkColor.h"
12#include "include/core/SkRect.h"
13#include "include/core/SkRegion.h"
14#include "include/private/SkTo.h"
15#include "src/core/SkAutoMalloc.h"
16#include "src/core/SkImagePriv.h"
17#include "src/shaders/SkShaderBase.h"
18
19class SkArenaAlloc;
20class SkMatrix;
21class SkPaint;
22class SkPixmap;
23struct SkMask;
24
25/** SkBlitter and its subclasses are responsible for actually writing pixels
26 into memory. Besides efficiency, they handle clipping and antialiasing.
27 A SkBlitter subclass contains all the context needed to generate pixels
28 for the destination and how src/generated pixels map to the destination.
29 The coordinates passed to the blitX calls are in destination pixel space.
30*/
31class SkBlitter {
32public:
33 virtual ~SkBlitter();
34
35 /// Blit a horizontal run of one or more pixels.
36 virtual void blitH(int x, int y, int width) = 0;
37
38 /// Blit a horizontal run of antialiased pixels; runs[] is a *sparse*
39 /// zero-terminated run-length encoding of spans of constant alpha values.
40 /// The runs[] and antialias[] work together to represent long runs of pixels with the same
41 /// alphas. The runs[] contains the number of pixels with the same alpha, and antialias[]
42 /// contain the coverage value for that number of pixels. The runs[] (and antialias[]) are
43 /// encoded in a clever way. The runs array is zero terminated, and has enough entries for
44 /// each pixel plus one, in most cases some of the entries will not contain valid data. An entry
45 /// in the runs array contains the number of pixels (np) that have the same alpha value. The
46 /// next np value is found np entries away. For example, if runs[0] = 7, then the next valid
47 /// entry will by at runs[7]. The runs array and antialias[] are coupled by index. So, if the
48 /// np entry is at runs[45] = 12 then the alpha value can be found at antialias[45] = 0x88.
49 /// This would mean to use an alpha value of 0x88 for the next 12 pixels starting at pixel 45.
50 virtual void blitAntiH(int x, int y, const SkAlpha antialias[], const int16_t runs[]) = 0;
51
52 /// Blit a vertical run of pixels with a constant alpha value.
53 virtual void blitV(int x, int y, int height, SkAlpha alpha);
54
55 /// Blit a solid rectangle one or more pixels wide.
56 virtual void blitRect(int x, int y, int width, int height);
57
58 /** Blit a rectangle with one alpha-blended column on the left,
59 width (zero or more) opaque pixels, and one alpha-blended column
60 on the right.
61 The result will always be at least two pixels wide.
62 */
63 virtual void blitAntiRect(int x, int y, int width, int height,
64 SkAlpha leftAlpha, SkAlpha rightAlpha);
65
66 // Blit a rect in AA with size at least 3 x 3 (small rect has too many edge cases...)
67 void blitFatAntiRect(const SkRect& rect);
68
69 /// Blit a pattern of pixels defined by a rectangle-clipped mask;
70 /// typically used for text.
71 virtual void blitMask(const SkMask&, const SkIRect& clip);
72
73 /** If the blitter just sets a single value for each pixel, return the
74 bitmap it draws into, and assign value. If not, return nullptr and ignore
75 the value parameter.
76 */
77 virtual const SkPixmap* justAnOpaqueColor(uint32_t* value);
78
79 // (x, y), (x + 1, y)
80 virtual void blitAntiH2(int x, int y, U8CPU a0, U8CPU a1) {
81 int16_t runs[3];
82 uint8_t aa[2];
83
84 runs[0] = 1;
85 runs[1] = 1;
86 runs[2] = 0;
87 aa[0] = SkToU8(a0);
88 aa[1] = SkToU8(a1);
89 this->blitAntiH(x, y, aa, runs);
90 }
91
92 // (x, y), (x, y + 1)
93 virtual void blitAntiV2(int x, int y, U8CPU a0, U8CPU a1) {
94 int16_t runs[2];
95 uint8_t aa[1];
96
97 runs[0] = 1;
98 runs[1] = 0;
99 aa[0] = SkToU8(a0);
100 this->blitAntiH(x, y, aa, runs);
101 // reset in case the clipping blitter modified runs
102 runs[0] = 1;
103 runs[1] = 0;
104 aa[0] = SkToU8(a1);
105 this->blitAntiH(x, y + 1, aa, runs);
106 }
107
108 /**
109 * Special method just to identify the null blitter, which is returned
110 * from Choose() if the request cannot be fulfilled. Default impl
111 * returns false.
112 */
113 virtual bool isNullBlitter() const;
114
115 /**
116 * Special methods for blitters that can blit more than one row at a time.
117 * This function returns the number of rows that this blitter could optimally
118 * process at a time. It is still required to support blitting one scanline
119 * at a time.
120 */
121 virtual int requestRowsPreserved() const { return 1; }
122
123 /**
124 * This function allocates memory for the blitter that the blitter then owns.
125 * The memory can be used by the calling function at will, but it will be
126 * released when the blitter's destructor is called. This function returns
127 * nullptr if no persistent memory is needed by the blitter.
128 */
129 virtual void* allocBlitMemory(size_t sz) {
130 return fBlitMemory.reset(sz, SkAutoMalloc::kReuse_OnShrink);
131 }
132
133 ///@name non-virtual helpers
134 void blitMaskRegion(const SkMask& mask, const SkRegion& clip);
135 void blitRectRegion(const SkIRect& rect, const SkRegion& clip);
136 void blitRegion(const SkRegion& clip);
137 ///@}
138
139 /** @name Factories
140 Return the correct blitter to use given the specified context.
141 */
142 static SkBlitter* Choose(const SkPixmap& dst,
143 const SkMatrix& matrix,
144 const SkPaint& paint,
145 SkArenaAlloc*,
146 bool drawCoverage,
147 sk_sp<SkShader> clipShader);
148
149 static SkBlitter* ChooseSprite(const SkPixmap& dst,
150 const SkPaint&,
151 const SkPixmap& src,
152 int left, int top,
153 SkArenaAlloc*, sk_sp<SkShader> clipShader);
154 ///@}
155
156 static bool UseRasterPipelineBlitter(const SkPixmap&, const SkPaint&, const SkMatrix&);
157
158protected:
159 SkAutoMalloc fBlitMemory;
160};
161
162/** This blitter silently never draws anything.
163*/
164class SkNullBlitter : public SkBlitter {
165public:
166 void blitH(int x, int y, int width) override;
167 void blitAntiH(int x, int y, const SkAlpha[], const int16_t runs[]) override;
168 void blitV(int x, int y, int height, SkAlpha alpha) override;
169 void blitRect(int x, int y, int width, int height) override;
170 void blitMask(const SkMask&, const SkIRect& clip) override;
171 const SkPixmap* justAnOpaqueColor(uint32_t* value) override;
172 bool isNullBlitter() const override;
173};
174
175/** Wraps another (real) blitter, and ensures that the real blitter is only
176 called with coordinates that have been clipped by the specified clipRect.
177 This means the caller need not perform the clipping ahead of time.
178*/
179class SkRectClipBlitter : public SkBlitter {
180public:
181 void init(SkBlitter* blitter, const SkIRect& clipRect) {
182 SkASSERT(!clipRect.isEmpty());
183 fBlitter = blitter;
184 fClipRect = clipRect;
185 }
186
187 void blitH(int x, int y, int width) override;
188 void blitAntiH(int x, int y, const SkAlpha[], const int16_t runs[]) override;
189 void blitV(int x, int y, int height, SkAlpha alpha) override;
190 void blitRect(int x, int y, int width, int height) override;
191 virtual void blitAntiRect(int x, int y, int width, int height,
192 SkAlpha leftAlpha, SkAlpha rightAlpha) override;
193 void blitMask(const SkMask&, const SkIRect& clip) override;
194 const SkPixmap* justAnOpaqueColor(uint32_t* value) override;
195
196 int requestRowsPreserved() const override {
197 return fBlitter->requestRowsPreserved();
198 }
199
200 void* allocBlitMemory(size_t sz) override {
201 return fBlitter->allocBlitMemory(sz);
202 }
203
204private:
205 SkBlitter* fBlitter;
206 SkIRect fClipRect;
207};
208
209/** Wraps another (real) blitter, and ensures that the real blitter is only
210 called with coordinates that have been clipped by the specified clipRgn.
211 This means the caller need not perform the clipping ahead of time.
212*/
213class SkRgnClipBlitter : public SkBlitter {
214public:
215 void init(SkBlitter* blitter, const SkRegion* clipRgn) {
216 SkASSERT(clipRgn && !clipRgn->isEmpty());
217 fBlitter = blitter;
218 fRgn = clipRgn;
219 }
220
221 void blitH(int x, int y, int width) override;
222 void blitAntiH(int x, int y, const SkAlpha[], const int16_t runs[]) override;
223 void blitV(int x, int y, int height, SkAlpha alpha) override;
224 void blitRect(int x, int y, int width, int height) override;
225 void blitAntiRect(int x, int y, int width, int height,
226 SkAlpha leftAlpha, SkAlpha rightAlpha) override;
227 void blitMask(const SkMask&, const SkIRect& clip) override;
228 const SkPixmap* justAnOpaqueColor(uint32_t* value) override;
229
230 int requestRowsPreserved() const override {
231 return fBlitter->requestRowsPreserved();
232 }
233
234 void* allocBlitMemory(size_t sz) override {
235 return fBlitter->allocBlitMemory(sz);
236 }
237
238private:
239 SkBlitter* fBlitter;
240 const SkRegion* fRgn;
241};
242
243#ifdef SK_DEBUG
244class SkRectClipCheckBlitter : public SkBlitter {
245public:
246 void init(SkBlitter* blitter, const SkIRect& clipRect) {
247 SkASSERT(blitter);
248 SkASSERT(!clipRect.isEmpty());
249 fBlitter = blitter;
250 fClipRect = clipRect;
251 }
252
253 void blitH(int x, int y, int width) override;
254 void blitAntiH(int x, int y, const SkAlpha[], const int16_t runs[]) override;
255 void blitV(int x, int y, int height, SkAlpha alpha) override;
256 void blitRect(int x, int y, int width, int height) override;
257 void blitAntiRect(int x, int y, int width, int height,
258 SkAlpha leftAlpha, SkAlpha rightAlpha) override;
259 void blitMask(const SkMask&, const SkIRect& clip) override;
260 const SkPixmap* justAnOpaqueColor(uint32_t* value) override;
261 void blitAntiH2(int x, int y, U8CPU a0, U8CPU a1) override;
262 void blitAntiV2(int x, int y, U8CPU a0, U8CPU a1) override;
263
264 int requestRowsPreserved() const override {
265 return fBlitter->requestRowsPreserved();
266 }
267
268 void* allocBlitMemory(size_t sz) override {
269 return fBlitter->allocBlitMemory(sz);
270 }
271
272private:
273 SkBlitter* fBlitter;
274 SkIRect fClipRect;
275};
276#endif
277
278/** Factory to set up the appropriate most-efficient wrapper blitter
279 to apply a clip. Returns a pointer to a member, so lifetime must
280 be managed carefully.
281*/
282class SkBlitterClipper {
283public:
284 SkBlitter* apply(SkBlitter* blitter, const SkRegion* clip,
285 const SkIRect* bounds = nullptr);
286
287private:
288 SkNullBlitter fNullBlitter;
289 SkRectClipBlitter fRectBlitter;
290 SkRgnClipBlitter fRgnBlitter;
291};
292
293#define SHARD(code) fA->code; fB->code;
294
295class SkPairBlitter : public SkBlitter {
296 SkBlitter* fA = nullptr;
297 SkBlitter* fB = nullptr;
298public:
299 SkPairBlitter(SkBlitter* a, SkBlitter* b) : fA(a), fB(b) {}
300
301 void blitH(int x, int y, int width) override { SHARD(blitH(x, y, width)) }
302 void blitAntiH(int x, int y, const SkAlpha alphas[], const int16_t runs[]) override {
303 SHARD(blitAntiH(x, y, alphas, runs))
304 }
305 void blitV(int x, int y, int height, SkAlpha alpha) override {
306 SHARD(blitV(x, y, height, alpha))
307 }
308 void blitRect(int x, int y, int width, int height) override {
309 SHARD(blitRect(x, y, width, height))
310 }
311 void blitAntiRect(int x, int y, int width, int height,
312 SkAlpha leftAlpha, SkAlpha rightAlpha) override {
313 SHARD(blitAntiRect(x, y, width, height, leftAlpha, rightAlpha))
314 }
315 void blitMask(const SkMask& mask, const SkIRect& clip) override { SHARD(blitMask(mask, clip)) }
316 const SkPixmap* justAnOpaqueColor(uint32_t* value) override { return nullptr; }
317 void blitAntiH2(int x, int y, U8CPU a0, U8CPU a1) override { SHARD(blitAntiH2(x, y, a0, a1)) }
318 void blitAntiV2(int x, int y, U8CPU a0, U8CPU a1) override { SHARD(blitAntiV2(x, y, a0, a1)) }
319};
320#undef SHARD
321
322#endif
323