include/gpu/GrContextOptions.h - platform/external/skia - Gitiles

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #ifndef GrContextOptions_DEFINED
 #define GrContextOptions_DEFINED

 #include "SkData.h"
 #include "SkTypes.h"
 #include "GrTypes.h"
 #include "../private/GrTypesPriv.h"
 #include "GrDriverBugWorkarounds.h"

 #include <vector>

 class SkExecutor;

 #if SK_SUPPORT_GPU
 struct GrContextOptions {
     enum class Enable {
         /** Forces an option to be disabled. */
         kNo,
         /** Forces an option to be enabled. */
         kYes,
         /**
          * Uses Skia's default behavior, which may use runtime properties (e.g. driver version).
          */
         kDefault
     };

     /**
      * Abstract class which stores Skia data in a cache that persists between sessions. Currently,
      * Skia stores compiled shader binaries (only when glProgramBinary / glGetProgramBinary are
      * supported) when provided a persistent cache, but this may extend to other data in the future.
      */
     class PersistentCache {
     public:
         virtual ~PersistentCache() {}

         /**
          * Returns the data for the key if it exists in the cache, otherwise returns null.
          */
         virtual sk_sp<SkData> load(const SkData& key) = 0;

         virtual void store(const SkData& key, const SkData& data) = 0;
     };

     GrContextOptions() {}

     // Suppress prints for the GrContext.
     bool fSuppressPrints = false;

     /** Overrides: These options override feature detection using backend API queries. These
         overrides can only reduce the feature set or limits, never increase them beyond the
         detected values. */

     int  fMaxTextureSizeOverride = SK_MaxS32;

     /** the threshold in bytes above which we will use a buffer mapping API to map vertex and index
         buffers to CPU memory in order to update them.  A value of -1 means the GrContext should
         deduce the optimal value for this platform. */
     int  fBufferMapThreshold = -1;

     /**
      * Executor to handle threaded work within Ganesh. If this is nullptr, then all work will be
      * done serially on the main thread. To have worker threads assist with various tasks, set this
      * to a valid SkExecutor instance. Currently, used for software path rendering, but may be used
      * for other tasks.
      */
     SkExecutor* fExecutor = nullptr;

     /** Construct mipmaps manually, via repeated downsampling draw-calls. This is used when
         the driver's implementation (glGenerateMipmap) contains bugs. This requires mipmap
         level and LOD control (ie desktop or ES3). */
     bool fDoManualMipmapping = false;

     /**
      * Disables the coverage counting path renderer. Coverage counting can sometimes cause new
      * rendering artifacts along shared edges if care isn't taken to ensure both contours wind in
      * the same direction.
      */
     bool fDisableCoverageCountingPaths = false;

     /**
      * Disables distance field rendering for paths. Distance field computation can be expensive,
      * and yields no benefit if a path is not rendered multiple times with different transforms.
      */
     bool fDisableDistanceFieldPaths = false;

     /**
      * If true this allows path mask textures to be cached. This is only really useful if paths
      * are commonly rendered at the same scale and fractional translation.
      */
     bool fAllowPathMaskCaching = true;

     /**
      * If true, the GPU will not be used to perform YUV -> RGB conversion when generating
      * textures from codec-backed images.
      */
     bool fDisableGpuYUVConversion = false;

     /**
      * The maximum size of cache textures used for Skia's Glyph cache.
      */
     size_t fGlyphCacheTextureMaximumBytes = 2048 * 1024 * 4;

     /**
      * Below this threshold size in device space distance field fonts won't be used. Distance field
      * fonts don't support hinting which is more important at smaller sizes. A negative value means
      * use the default threshold.
      */
     float fMinDistanceFieldFontSize = -1.f;

     /**
      * Above this threshold size in device space glyphs are drawn as individual paths. A negative
      * value means use the default threshold.
      */
     float fGlyphsAsPathsFontSize = -1.f;

     /**
      * Can the glyph atlas use multiple textures. If allowed, the each texture's size is bound by
      * fGlypheCacheTextureMaximumBytes.
      */
     Enable fAllowMultipleGlyphCacheTextures = Enable::kDefault;

     /**
      * Bugs on certain drivers cause stencil buffers to leak. This flag causes Skia to avoid
      * allocating stencil buffers and use alternate rasterization paths, avoiding the leak.
      */
     bool fAvoidStencilBuffers = false;

     /**
      * When specifing new data for a vertex/index buffer that replaces old data Ganesh can give
      * a hint to the driver that the previous data will not be used in future draws like this:
      *  glBufferData(GL_..._BUFFER, size, NULL, usage);       //<--hint, NULL means
      *  glBufferSubData(GL_..._BUFFER, 0, lessThanSize, data) //   old data can't be
      *                                                        //   used again.
      * However, this can be an unoptimization on some platforms, esp. Chrome.
      * Chrome's cmd buffer will create a new allocation and memset the whole thing
      * to zero (for security reasons).
      * Defaults to the value of GR_GL_USE_BUFFER_DATA_NULL_HINT #define (which is, by default, 1).
      */
     Enable fUseGLBufferDataNullHint = Enable::kDefault;

     /**
      * If true, texture fetches from mip-mapped textures will be biased to read larger MIP levels.
      * This has the effect of sharpening those textures, at the cost of some aliasing, and possible
      * performance impact.
      */
     bool fSharpenMipmappedTextures = false;

     /**
      * Enables driver workaround to use draws instead of glClear. This only applies to
      * kOpenGL_GrBackend.
      */
     Enable fUseDrawInsteadOfGLClear = Enable::kDefault;

     /**
      * Allow Ganesh to explicitly allocate resources at flush time rather than incrementally while
      * drawing. This will eventually just be the way it is but, for now, it is optional.
      */
     Enable fExplicitlyAllocateGPUResources = Enable::kDefault;

     /**
      * Allow Ganesh to sort the opLists prior to allocating resources. This is an optional
      * behavior that is only relevant when 'fExplicitlyAllocateGPUResources' is enabled.
      * Eventually this will just be what is done and will not be optional.
      */
     Enable fSortRenderTargets = Enable::kDefault;

     /**
      * Some ES3 contexts report the ES2 external image extension, but not the ES3 version.
      * If support for external images is critical, enabling this option will cause Ganesh to limit
      * shaders to the ES2 shading language in that situation.
      */
     bool fPreferExternalImagesOverES3 = false;

     /**
      * Disables correctness workarounds that are enabled for particular GPUs, OSes, or drivers.
      * This does not affect code path choices that are made for perfomance reasons nor does it
      * override other GrContextOption settings.
      */
     bool fDisableDriverCorrectnessWorkarounds = false;

     /**
      * Cache in which to store compiled shader binaries between runs.
      */
     PersistentCache* fPersistentCache = nullptr;

 #if GR_TEST_UTILS
     /**
      * Private options that are only meant for testing within Skia's tools.
      */

     /**
      * If non-zero, overrides the maximum size of a tile for sw-backed images and bitmaps rendered
      * by SkGpuDevice.
      */
     int  fMaxTileSizeOverride = 0;

     /**
      * Prevents use of dual source blending, to test that all xfer modes work correctly without it.
      */
     bool fSuppressDualSourceBlending = false;

     /**
      * If true, the caps will never report driver support for path rendering.
      */
     bool fSuppressPathRendering = false;

     /**
      * If true, the caps will never support geometry shaders.
      */
     bool fSuppressGeometryShaders = false;

     /**
      * Render everything in wireframe
      */
     bool fWireframeMode = false;

     /**
      * Include or exclude specific GPU path renderers.
      */
     GpuPathRenderers fGpuPathRenderers = GpuPathRenderers::kAll;

     /**
      * Disables using multiple texture units to batch multiple images into a single draw on
      * supported GPUs.
      */
     bool fDisableImageMultitexturing = false;
 #endif

 #if SK_SUPPORT_ATLAS_TEXT
     /**
      * Controls whether distance field glyph vertices always have 3 components even when the view
      * matrix does not have perspective.
      */
     Enable fDistanceFieldGlyphVerticesAlwaysHaveW = Enable::kDefault;
 #endif

     GrDriverBugWorkarounds fDriverBugWorkarounds;
 };
 #else
 struct GrContextOptions {
     struct PersistentCache {};
 };
 #endif

 #endif
	/*
	* Copyright 2015 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#ifndef GrContextOptions_DEFINED
	#define GrContextOptions_DEFINED

	#include "SkData.h"
	#include "SkTypes.h"
	#include "GrTypes.h"
	#include "../private/GrTypesPriv.h"
	#include "GrDriverBugWorkarounds.h"

	#include <vector>

	class SkExecutor;

	#if SK_SUPPORT_GPU
	struct GrContextOptions {
	enum class Enable {
	/** Forces an option to be disabled. */
	kNo,
	/** Forces an option to be enabled. */
	kYes,
	/**
	* Uses Skia's default behavior, which may use runtime properties (e.g. driver version).
	*/
	kDefault
	};

	/**
	* Abstract class which stores Skia data in a cache that persists between sessions. Currently,
	* Skia stores compiled shader binaries (only when glProgramBinary / glGetProgramBinary are
	* supported) when provided a persistent cache, but this may extend to other data in the future.
	*/
	class PersistentCache {
	public:
	virtual ~PersistentCache() {}

	/**
	* Returns the data for the key if it exists in the cache, otherwise returns null.
	*/
	virtual sk_sp<SkData> load(const SkData& key) = 0;

	virtual void store(const SkData& key, const SkData& data) = 0;
	};

	GrContextOptions() {}

	// Suppress prints for the GrContext.
	bool fSuppressPrints = false;

	/** Overrides: These options override feature detection using backend API queries. These
	overrides can only reduce the feature set or limits, never increase them beyond the
	detected values. */

	int fMaxTextureSizeOverride = SK_MaxS32;

	/** the threshold in bytes above which we will use a buffer mapping API to map vertex and index
	buffers to CPU memory in order to update them. A value of -1 means the GrContext should
	deduce the optimal value for this platform. */
	int fBufferMapThreshold = -1;

	/**
	* Executor to handle threaded work within Ganesh. If this is nullptr, then all work will be
	* done serially on the main thread. To have worker threads assist with various tasks, set this
	* to a valid SkExecutor instance. Currently, used for software path rendering, but may be used
	* for other tasks.
	*/
	SkExecutor* fExecutor = nullptr;

	/** Construct mipmaps manually, via repeated downsampling draw-calls. This is used when
	the driver's implementation (glGenerateMipmap) contains bugs. This requires mipmap
	level and LOD control (ie desktop or ES3). */
	bool fDoManualMipmapping = false;

	/**
	* Disables the coverage counting path renderer. Coverage counting can sometimes cause new
	* rendering artifacts along shared edges if care isn't taken to ensure both contours wind in
	* the same direction.
	*/
	bool fDisableCoverageCountingPaths = false;

	/**
	* Disables distance field rendering for paths. Distance field computation can be expensive,
	* and yields no benefit if a path is not rendered multiple times with different transforms.
	*/
	bool fDisableDistanceFieldPaths = false;

	/**
	* If true this allows path mask textures to be cached. This is only really useful if paths
	* are commonly rendered at the same scale and fractional translation.
	*/
	bool fAllowPathMaskCaching = true;

	/**
	* If true, the GPU will not be used to perform YUV -> RGB conversion when generating
	* textures from codec-backed images.
	*/
	bool fDisableGpuYUVConversion = false;

	/**
	* The maximum size of cache textures used for Skia's Glyph cache.
	*/
	size_t fGlyphCacheTextureMaximumBytes = 2048 * 1024 * 4;

	/**
	* Below this threshold size in device space distance field fonts won't be used. Distance field
	* fonts don't support hinting which is more important at smaller sizes. A negative value means
	* use the default threshold.
	*/
	float fMinDistanceFieldFontSize = -1.f;

	/**
	* Above this threshold size in device space glyphs are drawn as individual paths. A negative
	* value means use the default threshold.
	*/
	float fGlyphsAsPathsFontSize = -1.f;

	/**
	* Can the glyph atlas use multiple textures. If allowed, the each texture's size is bound by
	* fGlypheCacheTextureMaximumBytes.
	*/
	Enable fAllowMultipleGlyphCacheTextures = Enable::kDefault;

	/**
	* Bugs on certain drivers cause stencil buffers to leak. This flag causes Skia to avoid
	* allocating stencil buffers and use alternate rasterization paths, avoiding the leak.
	*/
	bool fAvoidStencilBuffers = false;

	/**
	* When specifing new data for a vertex/index buffer that replaces old data Ganesh can give
	* a hint to the driver that the previous data will not be used in future draws like this:
	* glBufferData(GL_..._BUFFER, size, NULL, usage); //<--hint, NULL means
	* glBufferSubData(GL_..._BUFFER, 0, lessThanSize, data) // old data can't be
	* // used again.
	* However, this can be an unoptimization on some platforms, esp. Chrome.
	* Chrome's cmd buffer will create a new allocation and memset the whole thing
	* to zero (for security reasons).
	* Defaults to the value of GR_GL_USE_BUFFER_DATA_NULL_HINT #define (which is, by default, 1).
	*/
	Enable fUseGLBufferDataNullHint = Enable::kDefault;

	/**
	* If true, texture fetches from mip-mapped textures will be biased to read larger MIP levels.
	* This has the effect of sharpening those textures, at the cost of some aliasing, and possible
	* performance impact.
	*/
	bool fSharpenMipmappedTextures = false;

	/**
	* Enables driver workaround to use draws instead of glClear. This only applies to
	* kOpenGL_GrBackend.
	*/
	Enable fUseDrawInsteadOfGLClear = Enable::kDefault;

	/**
	* Allow Ganesh to explicitly allocate resources at flush time rather than incrementally while
	* drawing. This will eventually just be the way it is but, for now, it is optional.
	*/
	Enable fExplicitlyAllocateGPUResources = Enable::kDefault;

	/**
	* Allow Ganesh to sort the opLists prior to allocating resources. This is an optional
	* behavior that is only relevant when 'fExplicitlyAllocateGPUResources' is enabled.
	* Eventually this will just be what is done and will not be optional.
	*/
	Enable fSortRenderTargets = Enable::kDefault;

	/**
	* Some ES3 contexts report the ES2 external image extension, but not the ES3 version.
	* If support for external images is critical, enabling this option will cause Ganesh to limit
	* shaders to the ES2 shading language in that situation.
	*/
	bool fPreferExternalImagesOverES3 = false;

	/**
	* Disables correctness workarounds that are enabled for particular GPUs, OSes, or drivers.
	* This does not affect code path choices that are made for perfomance reasons nor does it
	* override other GrContextOption settings.
	*/
	bool fDisableDriverCorrectnessWorkarounds = false;

	/**
	* Cache in which to store compiled shader binaries between runs.
	*/
	PersistentCache* fPersistentCache = nullptr;

	#if GR_TEST_UTILS
	/**
	* Private options that are only meant for testing within Skia's tools.
	*/

	/**
	* If non-zero, overrides the maximum size of a tile for sw-backed images and bitmaps rendered
	* by SkGpuDevice.
	*/
	int fMaxTileSizeOverride = 0;

	/**
	* Prevents use of dual source blending, to test that all xfer modes work correctly without it.
	*/
	bool fSuppressDualSourceBlending = false;

	/**
	* If true, the caps will never report driver support for path rendering.
	*/
	bool fSuppressPathRendering = false;

	/**
	* If true, the caps will never support geometry shaders.
	*/
	bool fSuppressGeometryShaders = false;

	/**
	* Render everything in wireframe
	*/
	bool fWireframeMode = false;

	/**
	* Include or exclude specific GPU path renderers.
	*/
	GpuPathRenderers fGpuPathRenderers = GpuPathRenderers::kAll;

	/**
	* Disables using multiple texture units to batch multiple images into a single draw on
	* supported GPUs.
	*/
	bool fDisableImageMultitexturing = false;
	#endif

	#if SK_SUPPORT_ATLAS_TEXT
	/**
	* Controls whether distance field glyph vertices always have 3 components even when the view
	* matrix does not have perspective.
	*/
	Enable fDistanceFieldGlyphVerticesAlwaysHaveW = Enable::kDefault;
	#endif

	GrDriverBugWorkarounds fDriverBugWorkarounds;
	};
	#else
	struct GrContextOptions {
	struct PersistentCache {};
	};
	#endif

	#endif