skia2/include/core/SkDrawable.h
Derek Sollenberger 2fbf1bc8c9 Add SK_API to APIs used by the android framework.
This CL enables us to set the default visibility of the symbols
on Android to hidden.  It is the intent that all of he SK_APIs
that have been added to /src directies should be removed as soon
as we can remove their callers within Android.

Bug: b/31971097
Change-Id: Ic787f94df0fb0c2b8d941aa7095a12b317c4b5de
Reviewed-on: https://skia-review.googlesource.com/49501
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Derek Sollenberger <djsollen@google.com>
2017-09-21 18:14:36 +00:00

83 lines
2.7 KiB
C++

/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkDrawable_DEFINED
#define SkDrawable_DEFINED
#include "SkFlattenable.h"
#include "SkScalar.h"
class SkCanvas;
class SkMatrix;
class SkPicture;
struct SkRect;
/**
* Base-class for objects that draw into SkCanvas.
*
* The object has a generation ID, which is guaranteed to be unique across all drawables. To
* allow for clients of the drawable that may want to cache the results, the drawable must
* change its generation ID whenever its internal state changes such that it will draw differently.
*/
class SK_API SkDrawable : public SkFlattenable {
public:
SkDrawable();
/**
* Draws into the specified content. The drawing sequence will be balanced upon return
* (i.e. the saveLevel() on the canvas will match what it was when draw() was called,
* and the current matrix and clip settings will not be changed.
*/
void draw(SkCanvas*, const SkMatrix* = nullptr);
void draw(SkCanvas*, SkScalar x, SkScalar y);
SkPicture* newPictureSnapshot();
/**
* Return a unique value for this instance. If two calls to this return the same value,
* it is presumed that calling the draw() method will render the same thing as well.
*
* Subclasses that change their state should call notifyDrawingChanged() to ensure that
* a new value will be returned the next time it is called.
*/
uint32_t getGenerationID();
/**
* Return the (conservative) bounds of what the drawable will draw. If the drawable can
* change what it draws (e.g. animation or in response to some external change), then this
* must return a bounds that is always valid for all possible states.
*/
SkRect getBounds();
/**
* Calling this invalidates the previous generation ID, and causes a new one to be computed
* the next time getGenerationID() is called. Typically this is called by the object itself,
* in response to its internal state changing.
*/
void notifyDrawingChanged();
SK_DEFINE_FLATTENABLE_TYPE(SkDrawable)
Factory getFactory() const override { return nullptr; }
protected:
virtual SkRect onGetBounds() = 0;
virtual void onDraw(SkCanvas*) = 0;
/**
* Default implementation calls onDraw() with a canvas that records into a picture. Subclasses
* may override if they have a more efficient way to return a picture for the current state
* of their drawable. Note: this picture must draw the same as what would be drawn from
* onDraw().
*/
virtual SkPicture* onNewPictureSnapshot();
private:
int32_t fGenerationID;
};
#endif