Line data Source code
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 SkShader_DEFINED
9 : #define SkShader_DEFINED
10 :
11 : #include "SkBitmap.h"
12 : #include "SkFilterQuality.h"
13 : #include "SkFlattenable.h"
14 : #include "SkImageInfo.h"
15 : #include "SkMask.h"
16 : #include "SkMatrix.h"
17 : #include "SkPaint.h"
18 : #include "../gpu/GrColor.h"
19 :
20 : class SkArenaAlloc;
21 : class SkColorFilter;
22 : class SkColorSpace;
23 : class SkImage;
24 : class SkPath;
25 : class SkPicture;
26 : class SkRasterPipeline;
27 : class GrContext;
28 : class GrFragmentProcessor;
29 :
30 : /** \class SkShader
31 : *
32 : * Shaders specify the source color(s) for what is being drawn. If a paint
33 : * has no shader, then the paint's color is used. If the paint has a
34 : * shader, then the shader's color(s) are use instead, but they are
35 : * modulated by the paint's alpha. This makes it easy to create a shader
36 : * once (e.g. bitmap tiling or gradient) and then change its transparency
37 : * w/o having to modify the original shader... only the paint's alpha needs
38 : * to be modified.
39 : */
40 : class SK_API SkShader : public SkFlattenable {
41 : public:
42 : SkShader(const SkMatrix* localMatrix = NULL);
43 : ~SkShader() override;
44 :
45 : /**
46 : * Returns the local matrix.
47 : *
48 : * FIXME: This can be incorrect for a Shader with its own local matrix
49 : * that is also wrapped via CreateLocalMatrixShader.
50 : */
51 2 : const SkMatrix& getLocalMatrix() const { return fLocalMatrix; }
52 :
53 : enum TileMode {
54 : /** replicate the edge color if the shader draws outside of its
55 : * original bounds
56 : */
57 : kClamp_TileMode,
58 :
59 : /** repeat the shader's image horizontally and vertically */
60 : kRepeat_TileMode,
61 :
62 : /** repeat the shader's image horizontally and vertically, alternating
63 : * mirror images so that adjacent images always seam
64 : */
65 : kMirror_TileMode,
66 :
67 : #if 0
68 : /** only draw within the original domain, return 0 everywhere else */
69 : kDecal_TileMode,
70 : #endif
71 : };
72 :
73 : enum {
74 : kTileModeCount = kMirror_TileMode + 1
75 : };
76 :
77 : // override these in your subclass
78 :
79 : enum Flags {
80 : //!< set if all of the colors will be opaque
81 : kOpaqueAlpha_Flag = 1 << 0,
82 :
83 : /** set if the spans only vary in X (const in Y).
84 : e.g. an Nx1 bitmap that is being tiled in Y, or a linear-gradient
85 : that varies from left-to-right. This flag specifies this for
86 : shadeSpan().
87 : */
88 : kConstInY32_Flag = 1 << 1,
89 :
90 : /** hint for the blitter that 4f is the preferred shading mode.
91 : */
92 : kPrefers4f_Flag = 1 << 2,
93 : };
94 :
95 : /**
96 : * Returns true if the shader is guaranteed to produce only opaque
97 : * colors, subject to the SkPaint using the shader to apply an opaque
98 : * alpha value. Subclasses should override this to allow some
99 : * optimizations.
100 : */
101 0 : virtual bool isOpaque() const { return false; }
102 :
103 : /**
104 : * Returns true if the shader is guaranteed to produce only a single color.
105 : * Subclasses can override this to allow loop-hoisting optimization.
106 : */
107 0 : virtual bool isConstant() const { return false; }
108 :
109 : /**
110 : * ContextRec acts as a parameter bundle for creating Contexts.
111 : */
112 : struct ContextRec {
113 : enum DstType {
114 : kPMColor_DstType, // clients prefer shading into PMColor dest
115 : kPM4f_DstType, // clients prefer shading into PM4f dest
116 : };
117 :
118 166 : ContextRec(const SkPaint& paint, const SkMatrix& matrix, const SkMatrix* localM,
119 : DstType dstType, SkColorSpace* dstColorSpace)
120 166 : : fPaint(&paint)
121 : , fMatrix(&matrix)
122 : , fLocalMatrix(localM)
123 : , fPreferredDstType(dstType)
124 166 : , fDstColorSpace(dstColorSpace) {}
125 :
126 : const SkPaint* fPaint; // the current paint associated with the draw
127 : const SkMatrix* fMatrix; // the current matrix in the canvas
128 : const SkMatrix* fLocalMatrix; // optional local matrix
129 : const DstType fPreferredDstType; // the "natural" client dest type
130 : SkColorSpace* fDstColorSpace; // the color space of the dest surface (if any)
131 : };
132 :
133 : class Context : public ::SkNoncopyable {
134 : public:
135 : Context(const SkShader& shader, const ContextRec&);
136 :
137 : virtual ~Context();
138 :
139 : /**
140 : * Called sometimes before drawing with this shader. Return the type of
141 : * alpha your shader will return. The default implementation returns 0.
142 : * Your subclass should override if it can (even sometimes) report a
143 : * non-zero value, since that will enable various blitters to perform
144 : * faster.
145 : */
146 25 : virtual uint32_t getFlags() const { return 0; }
147 :
148 : /**
149 : * Called for each span of the object being drawn. Your subclass should
150 : * set the appropriate colors (with premultiplied alpha) that correspond
151 : * to the specified device coordinates.
152 : */
153 : virtual void shadeSpan(int x, int y, SkPMColor[], int count) = 0;
154 :
155 : virtual void shadeSpan4f(int x, int y, SkPM4f[], int count);
156 :
157 : struct BlitState;
158 : typedef void (*BlitBW)(BlitState*,
159 : int x, int y, const SkPixmap&, int count);
160 : typedef void (*BlitAA)(BlitState*,
161 : int x, int y, const SkPixmap&, int count, const SkAlpha[]);
162 :
163 : struct BlitState {
164 : // inputs
165 : Context* fCtx;
166 : SkBlendMode fMode;
167 :
168 : // outputs
169 : enum { N = 2 };
170 : void* fStorage[N];
171 : BlitBW fBlitBW;
172 : BlitAA fBlitAA;
173 : };
174 :
175 : // Returns true if one or more of the blitprocs are set in the BlitState
176 0 : bool chooseBlitProcs(const SkImageInfo& info, BlitState* state) {
177 0 : state->fBlitBW = nullptr;
178 0 : state->fBlitAA = nullptr;
179 0 : if (this->onChooseBlitProcs(info, state)) {
180 0 : SkASSERT(state->fBlitBW || state->fBlitAA);
181 0 : return true;
182 : }
183 0 : return false;
184 : }
185 :
186 : /**
187 : * The const void* ctx is only const because all the implementations are const.
188 : * This can be changed to non-const if a new shade proc needs to change the ctx.
189 : */
190 : typedef void (*ShadeProc)(const void* ctx, int x, int y, SkPMColor[], int count);
191 : virtual ShadeProc asAShadeProc(void** ctx);
192 :
193 : /**
194 : * Similar to shadeSpan, but only returns the alpha-channel for a span.
195 : * The default implementation calls shadeSpan() and then extracts the alpha
196 : * values from the returned colors.
197 : */
198 : virtual void shadeSpanAlpha(int x, int y, uint8_t alpha[], int count);
199 :
200 : // Notification from blitter::blitMask in case we need to see the non-alpha channels
201 0 : virtual void set3DMask(const SkMask*) {}
202 :
203 : protected:
204 : // Reference to shader, so we don't have to dupe information.
205 : const SkShader& fShader;
206 :
207 : enum MatrixClass {
208 : kLinear_MatrixClass, // no perspective
209 : kFixedStepInX_MatrixClass, // fast perspective, need to call fixedStepInX() each
210 : // scanline
211 : kPerspective_MatrixClass // slow perspective, need to mappoints each pixel
212 : };
213 : static MatrixClass ComputeMatrixClass(const SkMatrix&);
214 :
215 79 : uint8_t getPaintAlpha() const { return fPaintAlpha; }
216 42 : const SkMatrix& getTotalInverse() const { return fTotalInverse; }
217 : MatrixClass getInverseClass() const { return (MatrixClass)fTotalInverseClass; }
218 0 : const SkMatrix& getCTM() const { return fCTM; }
219 :
220 0 : virtual bool onChooseBlitProcs(const SkImageInfo&, BlitState*) { return false; }
221 :
222 : private:
223 : SkMatrix fCTM;
224 : SkMatrix fTotalInverse;
225 : uint8_t fPaintAlpha;
226 : uint8_t fTotalInverseClass;
227 :
228 : typedef SkNoncopyable INHERITED;
229 : };
230 :
231 : /**
232 : * Make a context using the memory provided by the arena.
233 : *
234 : * @return pointer to context or nullptr if can't be created
235 : */
236 : Context* makeContext(const ContextRec&, SkArenaAlloc*) const;
237 :
238 : #ifdef SK_SUPPORT_LEGACY_SHADER_ISABITMAP
239 : /**
240 : * Returns true if this shader is just a bitmap, and if not null, returns the bitmap,
241 : * localMatrix, and tilemodes. If this is not a bitmap, returns false and ignores the
242 : * out-parameters.
243 : */
244 : bool isABitmap(SkBitmap* outTexture, SkMatrix* outMatrix, TileMode xy[2]) const {
245 : return this->onIsABitmap(outTexture, outMatrix, xy);
246 : }
247 :
248 : bool isABitmap() const {
249 : return this->isABitmap(nullptr, nullptr, nullptr);
250 : }
251 : #endif
252 :
253 : /**
254 : * Iff this shader is backed by a single SkImage, return its ptr (the caller must ref this
255 : * if they want to keep it longer than the lifetime of the shader). If not, return nullptr.
256 : */
257 0 : SkImage* isAImage(SkMatrix* localMatrix, TileMode xy[2]) const {
258 0 : return this->onIsAImage(localMatrix, xy);
259 : }
260 :
261 0 : bool isAImage() const {
262 0 : return this->isAImage(nullptr, nullptr) != nullptr;
263 : }
264 :
265 : /**
266 : * If the shader subclass can be represented as a gradient, asAGradient
267 : * returns the matching GradientType enum (or kNone_GradientType if it
268 : * cannot). Also, if info is not null, asAGradient populates info with
269 : * the relevant (see below) parameters for the gradient. fColorCount
270 : * is both an input and output parameter. On input, it indicates how
271 : * many entries in fColors and fColorOffsets can be used, if they are
272 : * non-NULL. After asAGradient has run, fColorCount indicates how
273 : * many color-offset pairs there are in the gradient. If there is
274 : * insufficient space to store all of the color-offset pairs, fColors
275 : * and fColorOffsets will not be altered. fColorOffsets specifies
276 : * where on the range of 0 to 1 to transition to the given color.
277 : * The meaning of fPoint and fRadius is dependant on the type of gradient.
278 : *
279 : * None:
280 : * info is ignored.
281 : * Color:
282 : * fColorOffsets[0] is meaningless.
283 : * Linear:
284 : * fPoint[0] and fPoint[1] are the end-points of the gradient
285 : * Radial:
286 : * fPoint[0] and fRadius[0] are the center and radius
287 : * Conical:
288 : * fPoint[0] and fRadius[0] are the center and radius of the 1st circle
289 : * fPoint[1] and fRadius[1] are the center and radius of the 2nd circle
290 : * Sweep:
291 : * fPoint[0] is the center of the sweep.
292 : */
293 :
294 : enum GradientType {
295 : kNone_GradientType,
296 : kColor_GradientType,
297 : kLinear_GradientType,
298 : kRadial_GradientType,
299 : kSweep_GradientType,
300 : kConical_GradientType,
301 : kLast_GradientType = kConical_GradientType
302 : };
303 :
304 : struct GradientInfo {
305 : int fColorCount; //!< In-out parameter, specifies passed size
306 : // of fColors/fColorOffsets on input, and
307 : // actual number of colors/offsets on
308 : // output.
309 : SkColor* fColors; //!< The colors in the gradient.
310 : SkScalar* fColorOffsets; //!< The unit offset for color transitions.
311 : SkPoint fPoint[2]; //!< Type specific, see above.
312 : SkScalar fRadius[2]; //!< Type specific, see above.
313 : TileMode fTileMode; //!< The tile mode used.
314 : uint32_t fGradientFlags; //!< see SkGradientShader::Flags
315 : };
316 :
317 : virtual GradientType asAGradient(GradientInfo* info) const;
318 :
319 : /**
320 : * If the shader subclass is composed of two shaders, return true, and if rec is not NULL,
321 : * fill it out with info about the shader.
322 : *
323 : * These are bare pointers; the ownership and reference count are unchanged.
324 : */
325 :
326 : struct ComposeRec {
327 : const SkShader* fShaderA;
328 : const SkShader* fShaderB;
329 : SkBlendMode fBlendMode;
330 : };
331 :
332 0 : virtual bool asACompose(ComposeRec*) const { return false; }
333 :
334 : #if SK_SUPPORT_GPU
335 : struct AsFPArgs {
336 0 : AsFPArgs() {}
337 0 : AsFPArgs(GrContext* context,
338 : const SkMatrix* viewMatrix,
339 : const SkMatrix* localMatrix,
340 : SkFilterQuality filterQuality,
341 : SkColorSpace* dstColorSpace)
342 0 : : fContext(context)
343 : , fViewMatrix(viewMatrix)
344 : , fLocalMatrix(localMatrix)
345 : , fFilterQuality(filterQuality)
346 0 : , fDstColorSpace(dstColorSpace) {}
347 :
348 : GrContext* fContext;
349 : const SkMatrix* fViewMatrix;
350 : const SkMatrix* fLocalMatrix;
351 : SkFilterQuality fFilterQuality;
352 : SkColorSpace* fDstColorSpace;
353 : };
354 :
355 : /**
356 : * Returns a GrFragmentProcessor that implements the shader for the GPU backend. NULL is
357 : * returned if there is no GPU implementation.
358 : *
359 : * The GPU device does not call SkShader::createContext(), instead we pass the view matrix,
360 : * local matrix, and filter quality directly.
361 : *
362 : * The GrContext may be used by the to create textures that are required by the returned
363 : * processor.
364 : *
365 : * The returned GrFragmentProcessor should expect an unpremultiplied input color and
366 : * produce a premultiplied output.
367 : */
368 : virtual sk_sp<GrFragmentProcessor> asFragmentProcessor(const AsFPArgs&) const;
369 : #endif
370 :
371 : /**
372 : * If the shader can represent its "average" luminance in a single color, return true and
373 : * if color is not NULL, return that color. If it cannot, return false and ignore the color
374 : * parameter.
375 : *
376 : * Note: if this returns true, the returned color will always be opaque, as only the RGB
377 : * components are used to compute luminance.
378 : */
379 : bool asLuminanceColor(SkColor*) const;
380 :
381 : //////////////////////////////////////////////////////////////////////////
382 : // Methods to create combinations or variants of shaders
383 :
384 : /**
385 : * Return a shader that will apply the specified localMatrix to this shader.
386 : * The specified matrix will be applied before any matrix associated with this shader.
387 : */
388 : sk_sp<SkShader> makeWithLocalMatrix(const SkMatrix&) const;
389 :
390 : /**
391 : * Create a new shader that produces the same colors as invoking this shader and then applying
392 : * the colorfilter.
393 : */
394 : sk_sp<SkShader> makeWithColorFilter(sk_sp<SkColorFilter>) const;
395 :
396 : //////////////////////////////////////////////////////////////////////////
397 : // Factory methods for stock shaders
398 :
399 : /**
400 : * Call this to create a new "empty" shader, that will not draw anything.
401 : */
402 : static sk_sp<SkShader> MakeEmptyShader();
403 :
404 : /**
405 : * Call this to create a new shader that just draws the specified color. This should always
406 : * draw the same as a paint with this color (and no shader).
407 : */
408 : static sk_sp<SkShader> MakeColorShader(SkColor);
409 :
410 : /**
411 : * Create a shader that draws the specified color (in the specified colorspace).
412 : *
413 : * This works around the limitation that SkPaint::setColor() only takes byte values, and does
414 : * not support specific colorspaces.
415 : */
416 : static sk_sp<SkShader> MakeColorShader(const SkColor4f&, sk_sp<SkColorSpace>);
417 :
418 : static sk_sp<SkShader> MakeComposeShader(sk_sp<SkShader> dst, sk_sp<SkShader> src, SkBlendMode);
419 :
420 : /** Call this to create a new shader that will draw with the specified bitmap.
421 : *
422 : * If the bitmap cannot be used (e.g. has no pixels, or its dimensions
423 : * exceed implementation limits (currently at 64K - 1)) then SkEmptyShader
424 : * may be returned.
425 : *
426 : * If the src is kA8_Config then that mask will be colorized using the color on
427 : * the paint.
428 : *
429 : * @param src The bitmap to use inside the shader
430 : * @param tmx The tiling mode to use when sampling the bitmap in the x-direction.
431 : * @param tmy The tiling mode to use when sampling the bitmap in the y-direction.
432 : * @return Returns a new shader object. Note: this function never returns null.
433 : */
434 : static sk_sp<SkShader> MakeBitmapShader(const SkBitmap& src, TileMode tmx, TileMode tmy,
435 : const SkMatrix* localMatrix = nullptr);
436 :
437 : // NOTE: You can create an SkImage Shader with SkImage::newShader().
438 :
439 : /** Call this to create a new shader that will draw with the specified picture.
440 : *
441 : * @param src The picture to use inside the shader (if not NULL, its ref count
442 : * is incremented). The SkPicture must not be changed after
443 : * successfully creating a picture shader.
444 : * @param tmx The tiling mode to use when sampling the bitmap in the x-direction.
445 : * @param tmy The tiling mode to use when sampling the bitmap in the y-direction.
446 : * @param tile The tile rectangle in picture coordinates: this represents the subset
447 : * (or superset) of the picture used when building a tile. It is not
448 : * affected by localMatrix and does not imply scaling (only translation
449 : * and cropping). If null, the tile rect is considered equal to the picture
450 : * bounds.
451 : * @return Returns a new shader object. Note: this function never returns null.
452 : */
453 : static sk_sp<SkShader> MakePictureShader(sk_sp<SkPicture> src, TileMode tmx, TileMode tmy,
454 : const SkMatrix* localMatrix, const SkRect* tile);
455 :
456 : /**
457 : * If this shader can be represented by another shader + a localMatrix, return that shader and
458 : * the localMatrix. If not, return nullptr and ignore the localMatrix parameter.
459 : */
460 : virtual sk_sp<SkShader> makeAsALocalMatrixShader(SkMatrix* localMatrix) const;
461 :
462 : SK_TO_STRING_VIRT()
463 0 : SK_DEFINE_FLATTENABLE_TYPE(SkShader)
464 : SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
465 :
466 : bool appendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*,
467 : const SkMatrix& ctm, const SkPaint&) const;
468 :
469 : protected:
470 : void flatten(SkWriteBuffer&) const override;
471 :
472 : bool computeTotalInverse(const ContextRec&, SkMatrix* totalInverse) const;
473 :
474 : /**
475 : * Specialize creating a SkShader context using the supplied allocator.
476 : * @return pointer to context owned by the arena allocator.
477 : */
478 0 : virtual Context* onMakeContext(const ContextRec&, SkArenaAlloc*) const {
479 0 : return nullptr;
480 : }
481 :
482 0 : virtual bool onAsLuminanceColor(SkColor*) const {
483 0 : return false;
484 : }
485 :
486 : #ifdef SK_SUPPORT_LEGACY_SHADER_ISABITMAP
487 : virtual bool onIsABitmap(SkBitmap*, SkMatrix*, TileMode[2]) const {
488 : return false;
489 : }
490 : #endif
491 :
492 0 : virtual SkImage* onIsAImage(SkMatrix*, TileMode[2]) const {
493 0 : return nullptr;
494 : }
495 :
496 : virtual bool onAppendStages(SkRasterPipeline*, SkColorSpace*, SkArenaAlloc*,
497 : const SkMatrix&, const SkPaint&,
498 : const SkMatrix* /*local matrix*/) const;
499 :
500 : private:
501 : // This is essentially const, but not officially so it can be modified in
502 : // constructors.
503 : SkMatrix fLocalMatrix;
504 :
505 : // So the SkLocalMatrixShader can whack fLocalMatrix in its SkReadBuffer constructor.
506 : friend class SkLocalMatrixShader;
507 : friend class SkBitmapProcLegacyShader; // for computeTotalInverse()
508 :
509 : typedef SkFlattenable INHERITED;
510 : };
511 :
512 : #endif
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