0cfd547b46
Change-Id: I1d99d9bb83d8a612d1c1fd298c1f7ed706a2277b Reviewed-on: https://skia-review.googlesource.com/118990 Reviewed-by: Mike Reed <reed@google.com> Commit-Queue: Brian Osman <brianosman@google.com>
117 lines
4.1 KiB
C++
117 lines
4.1 KiB
C++
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/*
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* Copyright 2011 The Android Open Source Project
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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 SkDrawLooper_DEFINED
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#define SkDrawLooper_DEFINED
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#include "SkBlurTypes.h"
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#include "SkFlattenable.h"
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#include "SkPoint.h"
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#include "SkColor.h"
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class SkArenaAlloc;
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class SkCanvas;
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class SkColorSpaceXformer;
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class SkPaint;
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struct SkRect;
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class SkString;
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/** \class SkDrawLooper
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Subclasses of SkDrawLooper can be attached to a SkPaint. Where they are,
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and something is drawn to a canvas with that paint, the looper subclass will
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be called, allowing it to modify the canvas and/or paint for that draw call.
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More than that, via the next() method, the looper can modify the draw to be
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invoked multiple times (hence the name loop-er), allow it to perform effects
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like shadows or frame/fills, that require more than one pass.
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*/
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class SK_API SkDrawLooper : public SkFlattenable {
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public:
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/**
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* Holds state during a draw. Users call next() until it returns false.
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*
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* Subclasses of SkDrawLooper should create a subclass of this object to
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* hold state specific to their subclass.
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*/
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class SK_API Context : ::SkNoncopyable {
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public:
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Context() {}
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virtual ~Context() {}
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/**
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* Called in a loop on objects returned by SkDrawLooper::createContext().
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* Each time true is returned, the object is drawn (possibly with a modified
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* canvas and/or paint). When false is finally returned, drawing for the object
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* stops.
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*
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* On each call, the paint will be in its original state, but the
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* canvas will be as it was following the previous call to next() or
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* createContext().
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*
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* The implementation must ensure that, when next() finally returns
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* false, the canvas has been restored to the state it was
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* initially, before createContext() was first called.
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*/
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virtual bool next(SkCanvas* canvas, SkPaint* paint) = 0;
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};
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/**
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* Called right before something is being drawn. Returns a Context
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* whose next() method should be called until it returns false.
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*/
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virtual Context* makeContext(SkCanvas*, SkArenaAlloc*) const = 0;
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/**
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* The fast bounds functions are used to enable the paint to be culled early
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* in the drawing pipeline. If a subclass can support this feature it must
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* return true for the canComputeFastBounds() function. If that function
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* returns false then computeFastBounds behavior is undefined otherwise it
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* is expected to have the following behavior. Given the parent paint and
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* the parent's bounding rect the subclass must fill in and return the
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* storage rect, where the storage rect is with the union of the src rect
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* and the looper's bounding rect.
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*/
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bool canComputeFastBounds(const SkPaint& paint) const;
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void computeFastBounds(const SkPaint& paint, const SkRect& src, SkRect* dst) const;
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struct BlurShadowRec {
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SkScalar fSigma;
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SkVector fOffset;
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SkColor fColor;
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SkBlurStyle fStyle;
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};
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/**
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* If this looper can be interpreted as having two layers, such that
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* 1. The first layer (bottom most) just has a blur and translate
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* 2. The second layer has no modifications to either paint or canvas
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* 3. No other layers.
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* then return true, and if not null, fill out the BlurShadowRec).
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*
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* If any of the above are not met, return false and ignore the BlurShadowRec parameter.
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*/
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virtual bool asABlurShadow(BlurShadowRec*) const;
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virtual void toString(SkString* str) const = 0;
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SK_DEFINE_FLATTENABLE_TYPE(SkDrawLooper)
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protected:
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sk_sp<SkDrawLooper> makeColorSpace(SkColorSpaceXformer* xformer) const {
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return this->onMakeColorSpace(xformer);
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}
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virtual sk_sp<SkDrawLooper> onMakeColorSpace(SkColorSpaceXformer*) const = 0;
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SkDrawLooper() {}
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private:
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friend class SkColorSpaceXformer;
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typedef SkFlattenable INHERITED;
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};
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#endif
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