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1 /*
2  * Copyright 2015 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 #ifndef GrContextOptions_DEFINED
9 #define GrContextOptions_DEFINED
10 
11 #include "include/core/SkData.h"
12 #include "include/core/SkString.h"
13 #include "include/core/SkTypes.h"
14 #include "include/gpu/GrDriverBugWorkarounds.h"
15 #include "include/gpu/GrTypes.h"
16 #include "include/private/GrTypesPriv.h"
17 
18 #include <vector>
19 
20 class SkExecutor;
21 
22 #if SK_SUPPORT_GPU
23 struct SK_API GrContextOptions {
24     enum class Enable {
25         /** Forces an option to be disabled. */
26         kNo,
27         /** Forces an option to be enabled. */
28         kYes,
29         /**
30          * Uses Skia's default behavior, which may use runtime properties (e.g. driver version).
31          */
32         kDefault
33     };
34 
35     enum class ShaderCacheStrategy {
36         kSkSL,
37         kBackendSource,
38         kBackendBinary,
39     };
40 
41     /**
42      * Abstract class which stores Skia data in a cache that persists between sessions. Currently,
43      * Skia stores compiled shader binaries (only when glProgramBinary / glGetProgramBinary are
44      * supported) when provided a persistent cache, but this may extend to other data in the future.
45      */
46     class SK_API PersistentCache {
47     public:
48         virtual ~PersistentCache() = default;
49 
50         /**
51          * Returns the data for the key if it exists in the cache, otherwise returns null.
52          */
53         virtual sk_sp<SkData> load(const SkData& key) = 0;
54 
55         // Placeholder until all clients override the 3-parameter store(), then remove this, and
56         // make that version pure virtual.
storeGrContextOptions57         virtual void store(const SkData& /*key*/, const SkData& /*data*/) { SkASSERT(false); }
58 
59         /**
60          * Stores data in the cache, indexed by key. description provides a human-readable
61          * version of the key.
62          */
storeGrContextOptions63         virtual void store(const SkData& key, const SkData& data, const SkString& /*description*/) {
64             this->store(key, data);
65         }
66 
67     protected:
68         PersistentCache() = default;
69         PersistentCache(const PersistentCache&) = delete;
70         PersistentCache& operator=(const PersistentCache&) = delete;
71     };
72 
73     /**
74      * Abstract class to report errors when compiling shaders. If fShaderErrorHandler is present,
75      * it will be called to report any compilation failures. Otherwise, failures will be reported
76      * via SkDebugf and asserts.
77      */
78     class SK_API ShaderErrorHandler {
79     public:
80         virtual ~ShaderErrorHandler() = default;
81 
82         virtual void compileError(const char* shader, const char* errors) = 0;
83 
84     protected:
85         ShaderErrorHandler() = default;
86         ShaderErrorHandler(const ShaderErrorHandler&) = delete;
87         ShaderErrorHandler& operator=(const ShaderErrorHandler&) = delete;
88     };
89 
GrContextOptionsGrContextOptions90     GrContextOptions() {}
91 
92     // Suppress prints for the GrContext.
93     bool fSuppressPrints = false;
94 
95     /**
96      * Controls whether we check for GL errors after functions that allocate resources (e.g.
97      * glTexImage2D), for shader compilation success, and program link success. Ignored on
98      * backends other than GL.
99      */
100     Enable fSkipGLErrorChecks = Enable::kDefault;
101 
102     /** Overrides: These options override feature detection using backend API queries. These
103         overrides can only reduce the feature set or limits, never increase them beyond the
104         detected values. */
105 
106     int  fMaxTextureSizeOverride = SK_MaxS32;
107 
108     /** the threshold in bytes above which we will use a buffer mapping API to map vertex and index
109         buffers to CPU memory in order to update them.  A value of -1 means the GrContext should
110         deduce the optimal value for this platform. */
111     int  fBufferMapThreshold = -1;
112 
113     /**
114      * Executor to handle threaded work within Ganesh. If this is nullptr, then all work will be
115      * done serially on the main thread. To have worker threads assist with various tasks, set this
116      * to a valid SkExecutor instance. Currently, used for software path rendering, but may be used
117      * for other tasks.
118      */
119     SkExecutor* fExecutor = nullptr;
120 
121     /** Construct mipmaps manually, via repeated downsampling draw-calls. This is used when
122         the driver's implementation (glGenerateMipmap) contains bugs. This requires mipmap
123         level control (ie desktop or ES3). */
124     bool fDoManualMipmapping = false;
125 
126     /**
127      * Disables the use of coverage counting shortcuts to render paths. Coverage counting can cause
128      * artifacts along shared edges if care isn't taken to ensure both contours wind in the same
129      * direction.
130      */
131     // FIXME: Once this is removed from Chrome and Android, rename to fEnable"".
132     bool fDisableCoverageCountingPaths = true;
133 
134     /**
135      * Disables distance field rendering for paths. Distance field computation can be expensive,
136      * and yields no benefit if a path is not rendered multiple times with different transforms.
137      */
138     bool fDisableDistanceFieldPaths = false;
139 
140     /**
141      * If true this allows path mask textures to be cached. This is only really useful if paths
142      * are commonly rendered at the same scale and fractional translation.
143      */
144     bool fAllowPathMaskCaching = true;
145 
146     /**
147      * If true, the GPU will not be used to perform YUV -> RGB conversion when generating
148      * textures from codec-backed images.
149      */
150     bool fDisableGpuYUVConversion = false;
151 
152     /**
153      * The maximum size of cache textures used for Skia's Glyph cache.
154      */
155     size_t fGlyphCacheTextureMaximumBytes = 2048 * 1024 * 4;
156 
157     /**
158      * Below this threshold size in device space distance field fonts won't be used. Distance field
159      * fonts don't support hinting which is more important at smaller sizes.
160      */
161     float fMinDistanceFieldFontSize = 18;
162 
163     /**
164      * Above this threshold size in device space glyphs are drawn as individual paths.
165      */
166 #if defined(SK_BUILD_FOR_ANDROID)
167     float fGlyphsAsPathsFontSize = 384;
168 #elif defined(SK_BUILD_FOR_MAC)
169     float fGlyphsAsPathsFontSize = 256;
170 #else
171     float fGlyphsAsPathsFontSize = 324;
172 #endif
173 
174     /**
175      * Can the glyph atlas use multiple textures. If allowed, the each texture's size is bound by
176      * fGlypheCacheTextureMaximumBytes.
177      */
178     Enable fAllowMultipleGlyphCacheTextures = Enable::kDefault;
179 
180     /**
181      * Bugs on certain drivers cause stencil buffers to leak. This flag causes Skia to avoid
182      * allocating stencil buffers and use alternate rasterization paths, avoiding the leak.
183      */
184     bool fAvoidStencilBuffers = false;
185 
186     /**
187      * If true, texture fetches from mip-mapped textures will be biased to read larger MIP levels.
188      * This has the effect of sharpening those textures, at the cost of some aliasing, and possible
189      * performance impact.
190      */
191     bool fSharpenMipmappedTextures = false;
192 
193     /**
194      * Enables driver workaround to use draws instead of HW clears, e.g. glClear on the GL backend.
195      */
196     Enable fUseDrawInsteadOfClear = Enable::kDefault;
197 
198     /**
199      * Allow Ganesh to more aggressively reorder operations to reduce the number of render passes.
200      * Offscreen draws will be done upfront instead of interrupting the main render pass when
201      * possible. May increase VRAM usage, but still observes the resource cache limit.
202      * Enabled by default.
203      */
204     Enable fReduceOpsTaskSplitting = Enable::kDefault;
205 
206     /**
207      * Some ES3 contexts report the ES2 external image extension, but not the ES3 version.
208      * If support for external images is critical, enabling this option will cause Ganesh to limit
209      * shaders to the ES2 shading language in that situation.
210      */
211     bool fPreferExternalImagesOverES3 = false;
212 
213     /**
214      * Disables correctness workarounds that are enabled for particular GPUs, OSes, or drivers.
215      * This does not affect code path choices that are made for perfomance reasons nor does it
216      * override other GrContextOption settings.
217      */
218     bool fDisableDriverCorrectnessWorkarounds = false;
219 
220     /**
221      * Maximum number of GPU programs or pipelines to keep active in the runtime cache.
222      */
223     int fRuntimeProgramCacheSize = 256;
224 
225     /**
226      * Cache in which to store compiled shader binaries between runs.
227      */
228     PersistentCache* fPersistentCache = nullptr;
229 
230     /**
231      * This affects the usage of the PersistentCache. We can cache SkSL, backend source (GLSL), or
232      * backend binaries (GL program binaries). By default we cache binaries, but if the driver's
233      * binary loading/storing is believed to have bugs, this can be limited to caching GLSL.
234      * Caching GLSL strings still saves CPU work when a GL program is created.
235      */
236     ShaderCacheStrategy fShaderCacheStrategy = ShaderCacheStrategy::kBackendBinary;
237 
238     /**
239      * If present, use this object to report shader compilation failures. If not, report failures
240      * via SkDebugf and assert.
241      */
242     ShaderErrorHandler* fShaderErrorHandler = nullptr;
243 
244     /**
245      * Specifies the number of samples Ganesh should use when performing internal draws with MSAA
246      * (hardware capabilities permitting).
247      *
248      * If 0, Ganesh will disable internal code paths that use multisampling.
249      */
250     int  fInternalMultisampleCount = 4;
251 
252     /**
253      * In Skia's vulkan backend a single GrContext submit equates to the submission of a single
254      * primary command buffer to the VkQueue. This value specifies how many vulkan secondary command
255      * buffers we will cache for reuse on a given primary command buffer. A single submit may use
256      * more than this many secondary command buffers, but after the primary command buffer is
257      * finished on the GPU it will only hold on to this many secondary command buffers for reuse.
258      *
259      * A value of -1 means we will pick a limit value internally.
260      */
261     int fMaxCachedVulkanSecondaryCommandBuffers = -1;
262 
263     /**
264      * If true, the caps will never support mipmaps.
265      */
266     bool fSuppressMipmapSupport = false;
267 
268     /**
269      * If true, and if supported, enables hardware tessellation in the caps.
270      */
271     bool fEnableExperimentalHardwareTessellation = false;
272 
273     /**
274      * Uses a reduced variety of shaders. May perform less optimally in steady state but can reduce
275      * jank due to shader compilations.
276      */
277     bool fReducedShaderVariations = false;
278 
279     // Advanced Filter: Record process name, so that we can get it in other places easily.
280     std::string fProcessName;
281 
282 #if GR_TEST_UTILS
283     /**
284      * Private options that are only meant for testing within Skia's tools.
285      */
286 
287     /**
288      * Prevents use of dual source blending, to test that all xfer modes work correctly without it.
289      */
290     bool fSuppressDualSourceBlending = false;
291 
292     /**
293      * Prevents the use of non-coefficient-based blend equations, for testing dst reads, barriers,
294      * and in-shader blending.
295      */
296     bool fSuppressAdvancedBlendEquations = false;
297 
298     /**
299      * Prevents the use of framebuffer fetches, for testing dst reads and texture barriers.
300      */
301     bool fSuppressFramebufferFetch = false;
302 
303     /**
304      * If greater than zero and less than the actual hardware limit, overrides the maximum number of
305      * tessellation segments supported by the caps.
306      */
307     int  fMaxTessellationSegmentsOverride = 0;
308 
309     /**
310      * If true, then all paths are processed as if "setIsVolatile" had been called.
311      */
312     bool fAllPathsVolatile = false;
313 
314     /**
315      * Render everything in wireframe
316      */
317     bool fWireframeMode = false;
318 
319     /**
320      * Enforces clearing of all textures when they're created.
321      */
322     bool fClearAllTextures = false;
323 
324     /**
325      * Randomly generate a (false) GL_OUT_OF_MEMORY error
326      */
327     bool fRandomGLOOM = false;
328 
329     /**
330      * Force off support for write/transfer pixels row bytes in caps.
331      */
332     bool fDisallowWriteAndTransferPixelRowBytes = false;
333 
334     /**
335      * Include or exclude specific GPU path renderers.
336      */
337     GpuPathRenderers fGpuPathRenderers = GpuPathRenderers::kDefault;
338 
339     /**
340      * Specify the GPU resource cache limit. Equivalent to calling `setResourceCacheLimit` on the
341      * context at construction time.
342      *
343      * A value of -1 means use the default limit value.
344      */
345     int fResourceCacheLimitOverride = -1;
346 
347     /**
348      * If true, then always try to use hardware tessellation, regardless of how small a path may be.
349      */
350     bool fAlwaysPreferHardwareTessellation = false;
351 
352     /**
353      * Maximum width and height of internal texture atlases.
354      */
355     int  fMaxTextureAtlasSize = 2048;
356 #endif
357 
358     GrDriverBugWorkarounds fDriverBugWorkarounds;
359 };
360 #else
361 struct GrContextOptions {
362     struct PersistentCache {};
363 };
364 #endif
365 
366 #endif
367