1 /* 2 * Copyright 2013 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 SkMipmap_DEFINED 9 #define SkMipmap_DEFINED 10 11 #include "include/core/SkPixmap.h" 12 #include "include/core/SkScalar.h" 13 #include "include/core/SkSize.h" 14 #include "include/private/SkImageInfoPriv.h" 15 #include "src/core/SkCachedData.h" 16 #include "src/shaders/SkShaderBase.h" 17 18 class SkBitmap; 19 class SkData; 20 class SkDiscardableMemory; 21 class SkMipmapBuilder; 22 23 typedef SkDiscardableMemory* (*SkDiscardableFactoryProc)(size_t bytes); 24 25 /* 26 * SkMipmap will generate mipmap levels when given a base mipmap level image. 27 * 28 * Any function which deals with mipmap levels indices will start with index 0 29 * being the first mipmap level which was generated. Said another way, it does 30 * not include the base level in its range. 31 */ 32 class SkMipmap : public SkCachedData { 33 public: 34 // Allocate and fill-in a mipmap. If computeContents is false, we just allocated 35 // and compute the sizes/rowbytes, but leave the pixel-data uninitialized. 36 static SkMipmap* Build(const SkPixmap& src, SkDiscardableFactoryProc, 37 bool computeContents = true); 38 39 static SkMipmap* Build(const SkBitmap& src, SkDiscardableFactoryProc); 40 41 // Determines how many levels a SkMipmap will have without creating that mipmap. 42 // This does not include the base mipmap level that the user provided when 43 // creating the SkMipmap. 44 static int ComputeLevelCount(int baseWidth, int baseHeight); ComputeLevelCount(SkISize s)45 static int ComputeLevelCount(SkISize s) { return ComputeLevelCount(s.width(), s.height()); } 46 47 // Determines the size of a given mipmap level. 48 // |level| is an index into the generated mipmap levels. It does not include 49 // the base level. So index 0 represents mipmap level 1. 50 static SkISize ComputeLevelSize(int baseWidth, int baseHeight, int level); 51 52 // Computes the fractional level based on the scaling in X and Y. 53 static float ComputeLevel(SkSize scaleSize); 54 55 // We use a block of (possibly discardable) memory to hold an array of Level structs, followed 56 // by the pixel data for each level. On 32-bit platforms, Level would naturally be 4 byte 57 // aligned, so the pixel data could end up with 4 byte alignment. If the pixel data is F16, 58 // it must be 8 byte aligned. To ensure this, keep the Level struct 8 byte aligned as well. 59 struct alignas(8) Level { 60 SkPixmap fPixmap; 61 SkSize fScale; // < 1.0 62 }; 63 64 bool extractLevel(SkSize scale, Level*) const; 65 66 // countLevels returns the number of mipmap levels generated (which does not 67 // include the base mipmap level). 68 int countLevels() const; 69 70 // |index| is an index into the generated mipmap levels. It does not include 71 // the base level. So index 0 represents mipmap level 1. 72 bool getLevel(int index, Level*) const; 73 74 bool validForRootLevel(const SkImageInfo&) const; 75 76 sk_sp<SkData> serialize() const; 77 static bool Deserialize(SkMipmapBuilder*, const void* data, size_t size); 78 79 protected: onDataChange(void * oldData,void * newData)80 void onDataChange(void* oldData, void* newData) override { 81 fLevels = (Level*)newData; // could be nullptr 82 } 83 84 private: 85 sk_sp<SkColorSpace> fCS; 86 Level* fLevels; // managed by the baseclass, may be null due to onDataChanged. 87 int fCount; 88 SkMipmap(void * malloc,size_t size)89 SkMipmap(void* malloc, size_t size) : INHERITED(malloc, size) {} SkMipmap(size_t size,SkDiscardableMemory * dm)90 SkMipmap(size_t size, SkDiscardableMemory* dm) : INHERITED(size, dm) {} 91 92 static size_t AllocLevelsSize(int levelCount, size_t pixelSize); 93 94 using INHERITED = SkCachedData; 95 }; 96 97 #endif 98