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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/gpu/ShaderErrorHandler.h"
17 #include "include/private/GrTypesPriv.h"
18 
19 #include <vector>
20 
21 class SkExecutor;
22 
23 #if SK_SUPPORT_GPU
24 struct SK_API GrContextOptions {
25     enum class Enable {
26         /** Forces an option to be disabled. */
27         kNo,
28         /** Forces an option to be enabled. */
29         kYes,
30         /**
31          * Uses Skia's default behavior, which may use runtime properties (e.g. driver version).
32          */
33         kDefault
34     };
35 
36     enum class ShaderCacheStrategy {
37         kSkSL,
38         kBackendSource,
39         kBackendBinary,
40     };
41 
42     /**
43      * Abstract class which stores Skia data in a cache that persists between sessions. Currently,
44      * Skia stores compiled shader binaries (only when glProgramBinary / glGetProgramBinary are
45      * supported) when provided a persistent cache, but this may extend to other data in the future.
46      */
47     class SK_API PersistentCache {
48     public:
49         virtual ~PersistentCache() = default;
50 
51         /**
52          * Returns the data for the key if it exists in the cache, otherwise returns null.
53          */
54         virtual sk_sp<SkData> load(const SkData& key) = 0;
55 
56         // Placeholder until all clients override the 3-parameter store(), then remove this, and
57         // make that version pure virtual.
storeGrContextOptions58         virtual void store(const SkData& /*key*/, const SkData& /*data*/) { SkASSERT(false); }
59 
60         /**
61          * Stores data in the cache, indexed by key. description provides a human-readable
62          * version of the key.
63          */
storeGrContextOptions64         virtual void store(const SkData& key, const SkData& data, const SkString& /*description*/) {
65             this->store(key, data);
66         }
67 
68     protected:
69         PersistentCache() = default;
70         PersistentCache(const PersistentCache&) = delete;
71         PersistentCache& operator=(const PersistentCache&) = delete;
72     };
73 
74     using ShaderErrorHandler = skgpu::ShaderErrorHandler;
75 
GrContextOptionsGrContextOptions76     GrContextOptions() {}
77 
78     // Suppress prints for the GrContext.
79     bool fSuppressPrints = false;
80 
81     /**
82      * Controls whether we check for GL errors after functions that allocate resources (e.g.
83      * glTexImage2D), for shader compilation success, and program link success. Ignored on
84      * backends other than GL.
85      */
86     Enable fSkipGLErrorChecks = Enable::kDefault;
87 
88     /** Overrides: These options override feature detection using backend API queries. These
89         overrides can only reduce the feature set or limits, never increase them beyond the
90         detected values. */
91 
92     int  fMaxTextureSizeOverride = SK_MaxS32;
93 
94     /** the threshold in bytes above which we will use a buffer mapping API to map vertex and index
95         buffers to CPU memory in order to update them.  A value of -1 means the GrContext should
96         deduce the optimal value for this platform. */
97     int  fBufferMapThreshold = -1;
98 
99     /**
100      * Executor to handle threaded work within Ganesh. If this is nullptr, then all work will be
101      * done serially on the main thread. To have worker threads assist with various tasks, set this
102      * to a valid SkExecutor instance. Currently, used for software path rendering, but may be used
103      * for other tasks.
104      */
105     SkExecutor* fExecutor = nullptr;
106 
107     /** Construct mipmaps manually, via repeated downsampling draw-calls. This is used when
108         the driver's implementation (glGenerateMipmap) contains bugs. This requires mipmap
109         level control (ie desktop or ES3). */
110     bool fDoManualMipmapping = false;
111 
112     /**
113      * Disables the use of coverage counting shortcuts to render paths. Coverage counting can cause
114      * artifacts along shared edges if care isn't taken to ensure both contours wind in the same
115      * direction.
116      */
117     // FIXME: Once this is removed from Chrome and Android, rename to fEnable"".
118     bool fDisableCoverageCountingPaths = true;
119 
120     /**
121      * Disables distance field rendering for paths. Distance field computation can be expensive,
122      * and yields no benefit if a path is not rendered multiple times with different transforms.
123      */
124     bool fDisableDistanceFieldPaths = false;
125 
126     /**
127      * If true this allows path mask textures to be cached. This is only really useful if paths
128      * are commonly rendered at the same scale and fractional translation.
129      */
130     bool fAllowPathMaskCaching = true;
131 
132     /**
133      * If true, the GPU will not be used to perform YUV -> RGB conversion when generating
134      * textures from codec-backed images.
135      */
136     bool fDisableGpuYUVConversion = false;
137 
138     /**
139      * The maximum size of cache textures used for Skia's Glyph cache.
140      */
141     size_t fGlyphCacheTextureMaximumBytes = 2048 * 1024 * 4;
142 
143     /**
144      * Below this threshold size in device space distance field fonts won't be used. Distance field
145      * fonts don't support hinting which is more important at smaller sizes.
146      */
147     float fMinDistanceFieldFontSize = 18;
148 
149     /**
150      * Above this threshold size in device space glyphs are drawn as individual paths.
151      */
152 #if defined(SK_BUILD_FOR_ANDROID)
153     float fGlyphsAsPathsFontSize = 384;
154 #elif defined(SK_BUILD_FOR_MAC)
155     float fGlyphsAsPathsFontSize = 256;
156 #else
157     float fGlyphsAsPathsFontSize = 324;
158 #endif
159 
160     /**
161      * Can the glyph atlas use multiple textures. If allowed, the each texture's size is bound by
162      * fGlypheCacheTextureMaximumBytes.
163      */
164     Enable fAllowMultipleGlyphCacheTextures = Enable::kDefault;
165 
166     /**
167      * Bugs on certain drivers cause stencil buffers to leak. This flag causes Skia to avoid
168      * allocating stencil buffers and use alternate rasterization paths, avoiding the leak.
169      */
170     bool fAvoidStencilBuffers = false;
171 
172     /**
173      * If true, texture fetches from mip-mapped textures will be biased to read larger MIP levels.
174      * This has the effect of sharpening those textures, at the cost of some aliasing, and possible
175      * performance impact.
176      */
177     bool fSharpenMipmappedTextures = false;
178 
179     /**
180      * Enables driver workaround to use draws instead of HW clears, e.g. glClear on the GL backend.
181      */
182     Enable fUseDrawInsteadOfClear = Enable::kDefault;
183 
184     /**
185      * Allow Ganesh to more aggressively reorder operations to reduce the number of render passes.
186      * Offscreen draws will be done upfront instead of interrupting the main render pass when
187      * possible. May increase VRAM usage, but still observes the resource cache limit.
188      * Enabled by default.
189      */
190     Enable fReduceOpsTaskSplitting = Enable::kDefault;
191 
192     /**
193      * Some ES3 contexts report the ES2 external image extension, but not the ES3 version.
194      * If support for external images is critical, enabling this option will cause Ganesh to limit
195      * shaders to the ES2 shading language in that situation.
196      */
197     bool fPreferExternalImagesOverES3 = false;
198 
199     /**
200      * Disables correctness workarounds that are enabled for particular GPUs, OSes, or drivers.
201      * This does not affect code path choices that are made for perfomance reasons nor does it
202      * override other GrContextOption settings.
203      */
204     bool fDisableDriverCorrectnessWorkarounds = false;
205 
206     /**
207      * Maximum number of GPU programs or pipelines to keep active in the runtime cache.
208      */
209     int fRuntimeProgramCacheSize = 256;
210 
211     /**
212      * Cache in which to store compiled shader binaries between runs.
213      */
214     PersistentCache* fPersistentCache = nullptr;
215 
216     /**
217      * This affects the usage of the PersistentCache. We can cache SkSL, backend source (GLSL), or
218      * backend binaries (GL program binaries). By default we cache binaries, but if the driver's
219      * binary loading/storing is believed to have bugs, this can be limited to caching GLSL.
220      * Caching GLSL strings still saves CPU work when a GL program is created.
221      */
222     ShaderCacheStrategy fShaderCacheStrategy = ShaderCacheStrategy::kBackendBinary;
223 
224     /**
225      * If present, use this object to report shader compilation failures. If not, report failures
226      * via SkDebugf and assert.
227      */
228     ShaderErrorHandler* fShaderErrorHandler = nullptr;
229 
230     /**
231      * Specifies the number of samples Ganesh should use when performing internal draws with MSAA
232      * (hardware capabilities permitting).
233      *
234      * If 0, Ganesh will disable internal code paths that use multisampling.
235      */
236     int  fInternalMultisampleCount = 4;
237 
238     /**
239      * In Skia's vulkan backend a single GrContext submit equates to the submission of a single
240      * primary command buffer to the VkQueue. This value specifies how many vulkan secondary command
241      * buffers we will cache for reuse on a given primary command buffer. A single submit may use
242      * more than this many secondary command buffers, but after the primary command buffer is
243      * finished on the GPU it will only hold on to this many secondary command buffers for reuse.
244      *
245      * A value of -1 means we will pick a limit value internally.
246      */
247     int fMaxCachedVulkanSecondaryCommandBuffers = -1;
248 
249     /**
250      * If true, the caps will never support mipmaps.
251      */
252     bool fSuppressMipmapSupport = false;
253 
254     /**
255      * If true, and if supported, enables hardware tessellation in the caps.
256      */
257     bool fEnableExperimentalHardwareTessellation = false;
258 
259     /**
260      * If true, then add 1 pixel padding to all glyph masks in the atlas to support bi-lerp
261      * rendering of all glyphs. This must be set to true to use GrSlug.
262      */
263     #if defined(SK_EXPERIMENTAL_SIMULATE_DRAWGLYPHRUNLIST_WITH_SLUG)
264     bool fSupportBilerpFromGlyphAtlas = true;
265     #else
266     bool fSupportBilerpFromGlyphAtlas = false;
267     #endif
268 
269     /**
270      * Uses a reduced variety of shaders. May perform less optimally in steady state but can reduce
271      * jank due to shader compilations.
272      */
273     bool fReducedShaderVariations = false;
274 
275     /**
276      * If true, then allow to enable MSAA on new Intel GPUs.
277      */
278     bool fAllowMSAAOnNewIntel = false;
279 
280 #if GR_TEST_UTILS
281     /**
282      * Private options that are only meant for testing within Skia's tools.
283      */
284 
285     /**
286      * Prevents use of dual source blending, to test that all xfer modes work correctly without it.
287      */
288     bool fSuppressDualSourceBlending = false;
289 
290     /**
291      * Prevents the use of non-coefficient-based blend equations, for testing dst reads, barriers,
292      * and in-shader blending.
293      */
294     bool fSuppressAdvancedBlendEquations = false;
295 
296     /**
297      * Prevents the use of framebuffer fetches, for testing dst reads and texture barriers.
298      */
299     bool fSuppressFramebufferFetch = false;
300 
301     /**
302      * If greater than zero and less than the actual hardware limit, overrides the maximum number of
303      * tessellation segments supported by the caps.
304      */
305     int  fMaxTessellationSegmentsOverride = 0;
306 
307     /**
308      * If true, then all paths are processed as if "setIsVolatile" had been called.
309      */
310     bool fAllPathsVolatile = false;
311 
312     /**
313      * Render everything in wireframe
314      */
315     bool fWireframeMode = false;
316 
317     /**
318      * Enforces clearing of all textures when they're created.
319      */
320     bool fClearAllTextures = false;
321 
322     /**
323      * Randomly generate a (false) GL_OUT_OF_MEMORY error
324      */
325     bool fRandomGLOOM = false;
326 
327     /**
328      * Force off support for write/transfer pixels row bytes in caps.
329      */
330     bool fDisallowWriteAndTransferPixelRowBytes = false;
331 
332     /**
333      * Include or exclude specific GPU path renderers.
334      */
335     GpuPathRenderers fGpuPathRenderers = GpuPathRenderers::kDefault;
336 
337     /**
338      * Specify the GPU resource cache limit. Equivalent to calling `setResourceCacheLimit` on the
339      * context at construction time.
340      *
341      * A value of -1 means use the default limit value.
342      */
343     int fResourceCacheLimitOverride = -1;
344 
345     /**
346      * If true, then always try to use hardware tessellation, regardless of how small a path may be.
347      */
348     bool fAlwaysPreferHardwareTessellation = false;
349 
350     /**
351      * Maximum width and height of internal texture atlases.
352      */
353     int  fMaxTextureAtlasSize = 2048;
354 #endif
355 
356     GrDriverBugWorkarounds fDriverBugWorkarounds;
357 };
358 #else
359 struct GrContextOptions {
360     struct PersistentCache {};
361 };
362 #endif
363 
364 #endif
365