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
18class SkBitmap;
19class SkDiscardableMemory;
20
21typedef SkDiscardableMemory* (*SkDiscardableFactoryProc)(size_t bytes);
22
23/*
24 * SkMipMap will generate mipmap levels when given a base mipmap level image.
25 *
26 * Any function which deals with mipmap levels indices will start with index 0
27 * being the first mipmap level which was generated. Said another way, it does
28 * not include the base level in its range.
29 */
30class SkMipMap : public SkCachedData {
31public:
32 static SkMipMap* Build(const SkPixmap& src, SkDiscardableFactoryProc);
33 static SkMipMap* Build(const SkBitmap& src, SkDiscardableFactoryProc);
34
35 // Determines how many levels a SkMipMap will have without creating that mipmap.
36 // This does not include the base mipmap level that the user provided when
37 // creating the SkMipMap.
38 static int ComputeLevelCount(int baseWidth, int baseHeight);
39
40 // Determines the size of a given mipmap level.
41 // |level| is an index into the generated mipmap levels. It does not include
42 // the base level. So index 0 represents mipmap level 1.
43 static SkISize ComputeLevelSize(int baseWidth, int baseHeight, int level);
44
45 // We use a block of (possibly discardable) memory to hold an array of Level structs, followed
46 // by the pixel data for each level. On 32-bit platforms, Level would naturally be 4 byte
47 // aligned, so the pixel data could end up with 4 byte alignment. If the pixel data is F16,
48 // it must be 8 byte aligned. To ensure this, keep the Level struct 8 byte aligned as well.
49 struct alignas(8) Level {
50 SkPixmap fPixmap;
51 SkSize fScale; // < 1.0
52 };
53
54 bool extractLevel(const SkSize& scale, Level*) const;
55
56 // countLevels returns the number of mipmap levels generated (which does not
57 // include the base mipmap level).
58 int countLevels() const;
59
60 // |index| is an index into the generated mipmap levels. It does not include
61 // the base level. So index 0 represents mipmap level 1.
62 bool getLevel(int index, Level*) const;
63
64protected:
65 void onDataChange(void* oldData, void* newData) override {
66 fLevels = (Level*)newData; // could be nullptr
67 }
68
69private:
70 sk_sp<SkColorSpace> fCS;
71 Level* fLevels; // managed by the baseclass, may be null due to onDataChanged.
72 int fCount;
73
74 SkMipMap(void* malloc, size_t size) : INHERITED(malloc, size) {}
75 SkMipMap(size_t size, SkDiscardableMemory* dm) : INHERITED(size, dm) {}
76
77 static size_t AllocLevelsSize(int levelCount, size_t pixelSize);
78
79 typedef SkCachedData INHERITED;
80};
81
82#endif
83