/*
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* Copyright 2013 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkMipMap_DEFINED
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#define SkMipMap_DEFINED
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#include "SkCachedData.h"
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#include "SkImageInfoPriv.h"
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#include "SkPixmap.h"
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#include "SkScalar.h"
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#include "SkSize.h"
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#include "SkShaderBase.h"
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class SkBitmap;
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class SkDiscardableMemory;
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typedef SkDiscardableMemory* (*SkDiscardableFactoryProc)(size_t bytes);
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/*
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* SkMipMap will generate mipmap levels when given a base mipmap level image.
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*
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* Any function which deals with mipmap levels indices will start with index 0
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* being the first mipmap level which was generated. Said another way, it does
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* not include the base level in its range.
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*/
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class SkMipMap : public SkCachedData {
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public:
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static SkMipMap* Build(const SkPixmap& src, SkDiscardableFactoryProc);
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static SkMipMap* Build(const SkBitmap& src, SkDiscardableFactoryProc);
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// Determines how many levels a SkMipMap will have without creating that mipmap.
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// This does not include the base mipmap level that the user provided when
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// creating the SkMipMap.
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static int ComputeLevelCount(int baseWidth, int baseHeight);
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// Determines the size of a given mipmap level.
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// |level| is an index into the generated mipmap levels. It does not include
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// the base level. So index 0 represents mipmap level 1.
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static SkISize ComputeLevelSize(int baseWidth, int baseHeight, int level);
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// We use a block of (possibly discardable) memory to hold an array of Level structs, followed
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// by the pixel data for each level. On 32-bit platforms, Level would naturally be 4 byte
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// aligned, so the pixel data could end up with 4 byte alignment. If the pixel data is F16,
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// it must be 8 byte aligned. To ensure this, keep the Level struct 8 byte aligned as well.
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struct alignas(8) Level {
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SkPixmap fPixmap;
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SkSize fScale; // < 1.0
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};
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bool extractLevel(const SkSize& scale, Level*) const;
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// countLevels returns the number of mipmap levels generated (which does not
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// include the base mipmap level).
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int countLevels() const;
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// |index| is an index into the generated mipmap levels. It does not include
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// the base level. So index 0 represents mipmap level 1.
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bool getLevel(int index, Level*) const;
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protected:
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void onDataChange(void* oldData, void* newData) override {
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fLevels = (Level*)newData; // could be nullptr
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}
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private:
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sk_sp<SkColorSpace> fCS;
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Level* fLevels; // managed by the baseclass, may be null due to onDataChanged.
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int fCount;
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SkMipMap(void* malloc, size_t size) : INHERITED(malloc, size) {}
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SkMipMap(size_t size, SkDiscardableMemory* dm) : INHERITED(size, dm) {}
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static size_t AllocLevelsSize(int levelCount, size_t pixelSize);
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typedef SkCachedData INHERITED;
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};
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#endif
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