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 "SkData.h"
12#include "SkTypes.h"
13#include "GrTypes.h"
14#include "../private/GrTypesPriv.h"
15
16#include <vector>
17
18class SkExecutor;
19
20struct GrContextOptions {
21    enum class Enable {
22        /** Forces an option to be disabled. */
23        kNo,
24        /** Forces an option to be enabled. */
25        kYes,
26        /**
27         * Uses Skia's default behavior, which may use runtime properties (e.g. driver version).
28         */
29        kDefault
30    };
31
32    /**
33     * Abstract class which stores Skia data in a cache that persists between sessions. Currently,
34     * Skia stores compiled shader binaries (only when glProgramBinary / glGetProgramBinary are
35     * supported) when provided a persistent cache, but this may extend to other data in the future.
36     */
37    class PersistentCache {
38    public:
39        virtual ~PersistentCache() {}
40
41        /**
42         * Returns the data for the key if it exists in the cache, otherwise returns null.
43         */
44        virtual sk_sp<SkData> load(const SkData& key) = 0;
45
46        virtual void store(const SkData& key, const SkData& data) = 0;
47    };
48
49    GrContextOptions() {}
50
51    // Suppress prints for the GrContext.
52    bool fSuppressPrints = false;
53
54    /** Overrides: These options override feature detection using backend API queries. These
55        overrides can only reduce the feature set or limits, never increase them beyond the
56        detected values. */
57
58    int  fMaxTextureSizeOverride = SK_MaxS32;
59
60    /** the threshold in bytes above which we will use a buffer mapping API to map vertex and index
61        buffers to CPU memory in order to update them.  A value of -1 means the GrContext should
62        deduce the optimal value for this platform. */
63    int  fBufferMapThreshold = -1;
64
65    /**
66     * Executor to handle threaded work within Ganesh. If this is nullptr, then all work will be
67     * done serially on the main thread. To have worker threads assist with various tasks, set this
68     * to a valid SkExecutor instance. Currently, used for software path rendering, but may be used
69     * for other tasks.
70     */
71    SkExecutor* fExecutor = nullptr;
72
73    /** some gpus have problems with partial writes of the rendertarget */
74    bool fUseDrawInsteadOfPartialRenderTargetWrite = false;
75
76    /** Construct mipmaps manually, via repeated downsampling draw-calls. This is used when
77        the driver's implementation (glGenerateMipmap) contains bugs. This requires mipmap
78        level and LOD control (ie desktop or ES3). */
79    bool fDoManualMipmapping = false;
80
81    /**
82     * Disables distance field rendering for paths. Distance field computation can be expensive,
83     * and yields no benefit if a path is not rendered multiple times with different transforms.
84     */
85    bool fDisableDistanceFieldPaths = false;
86
87    /**
88     * If true this allows path mask textures to be cached. This is only really useful if paths
89     * are commonly rendered at the same scale and fractional translation.
90     */
91    bool fAllowPathMaskCaching = true;
92
93    /**
94     * If true, sRGB support will not be enabled unless sRGB decoding can be disabled (via an
95     * extension). If mixed use of "legacy" mode and sRGB/color-correct mode is not required, this
96     * can be set to false, which will significantly expand the number of devices that qualify for
97     * sRGB support.
98     */
99    bool fRequireDecodeDisableForSRGB = true;
100
101    /**
102     * If true, the GPU will not be used to perform YUV -> RGB conversion when generating
103     * textures from codec-backed images.
104     */
105    bool fDisableGpuYUVConversion = false;
106
107    /**
108     * The maximum size of cache textures used for Skia's Glyph cache.
109     */
110    float fGlyphCacheTextureMaximumBytes = 2048 * 1024 * 4;
111
112    /**
113     * Below this threshold size in device space distance field fonts won't be used. Distance field
114     * fonts don't support hinting which is more important at smaller sizes. A negative value means
115     * use the default threshold.
116     */
117    float fMinDistanceFieldFontSize = -1.f;
118
119    /**
120     * Above this threshold size in device space glyphs are drawn as individual paths. A negative
121     * value means use the default threshold.
122     */
123    float fGlyphsAsPathsFontSize = -1.f;
124
125    /**
126     * Can the glyph atlas use multiple textures. If allowed, the each texture's size is bound by
127     * fGlypheCacheTextureMaximumBytes.
128     */
129    Enable fAllowMultipleGlyphCacheTextures = Enable::kDefault;
130
131    /**
132     * Bugs on certain drivers cause stencil buffers to leak. This flag causes Skia to avoid
133     * allocating stencil buffers and use alternate rasterization paths, avoiding the leak.
134     */
135    bool fAvoidStencilBuffers = false;
136
137    /**
138     * Enables driver workaround to use draws instead of glClear. This only applies to
139     * kOpenGL_GrBackend.
140     */
141    Enable fUseDrawInsteadOfGLClear = Enable::kDefault;
142
143    /**
144     * Disables correctness workarounds that are enabled for particular GPUs, OSes, or drivers.
145     * This does not affect code path choices that are made for perfomance reasons nor does it
146     * override other GrContextOption settings.
147     */
148    bool fDisableDriverCorrectnessWorkarounds = false;
149
150    /**
151     * Cache in which to store compiled shader binaries between runs.
152     */
153    PersistentCache* fPersistentCache = nullptr;
154
155#if GR_TEST_UTILS
156    /**
157     * Private options that are only meant for testing within Skia's tools.
158     */
159
160    /**
161     * If non-zero, overrides the maximum size of a tile for sw-backed images and bitmaps rendered
162     * by SkGpuDevice.
163     */
164    int  fMaxTileSizeOverride = 0;
165
166    /**
167     * Prevents use of dual source blending, to test that all xfer modes work correctly without it.
168     */
169    bool fSuppressDualSourceBlending = false;
170
171    /**
172     * If true, the caps will never report driver support for path rendering.
173     */
174    bool fSuppressPathRendering = false;
175
176    /**
177     * If true, the caps will never support geometry shaders.
178     */
179    bool fSuppressGeometryShaders = false;
180
181    /**
182     * Render everything in wireframe
183     */
184    bool fWireframeMode = false;
185
186    /**
187     * Include or exclude specific GPU path renderers.
188     */
189    GpuPathRenderers fGpuPathRenderers = GpuPathRenderers::kDefault;
190
191    /**
192     * Disables using multiple texture units to batch multiple images into a single draw on
193     * supported GPUs.
194     */
195    bool fDisableImageMultitexturing = false;
196#endif
197
198#if SK_SUPPORT_ATLAS_TEXT
199    /**
200     * Controls whether distance field glyph vertices always have 3 components even when the view
201     * matrix does not have perspective.
202     */
203    Enable fDistanceFieldGlyphVerticesAlwaysHaveW = Enable::kDefault;
204#endif
205};
206
207#endif
208