RenderNodeDrawable.h revision db45a4bfaff1120a9b23073e46a0cc6d39f56023 
1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#pragma once
18
19#include <SkCanvas.h>
20#include <SkDrawable.h>
21#include <SkMatrix.h>
22#include <utils/RefBase.h>
23
24namespace android {
25namespace uirenderer {
26
27class RenderNode;
28class RenderProperties;
29
30namespace skiapipeline {
31
32class SkiaDisplayList;
33
34/**
35 * This drawable wraps a RenderNode and enables it to be recorded into a list
36 * of Skia drawing commands.
37 */
38class RenderNodeDrawable : public SkDrawable {
39public:
40    /**
41     * Creates a new RenderNodeDrawable backed by a render node.
42     *
43     * @param node that has to be drawn
44     * @param canvas is a recording canvas used to extract its matrix
45     * @param composeLayer if the node's layer type is RenderLayer this flag determines whether
46     *      we should draw into the contents of the layer or compose the existing contents of the
47     *      layer into the canvas.
48     */
49    explicit RenderNodeDrawable(RenderNode* node, SkCanvas* canvas, bool composeLayer = true,
50            bool inReorderingSection = false)
51            : mRenderNode(node)
52            , mRecordedTransform(canvas->getTotalMatrix())
53            , mComposeLayer(composeLayer)
54            , mInReorderingSection(inReorderingSection) {}
55
56    /**
57     * Draws into the canvas this render node and its children. If the node is marked as a
58     * projection receiver then all projected children (excluding direct children) will be drawn
59     * last. Any projected node not matching those requirements will not be drawn by this function.
60     */
61    void forceDraw(SkCanvas* canvas);
62
63    /**
64     * Returns readonly render properties for this render node.
65     */
66    const RenderProperties& getNodeProperties() const;
67
68    /**
69     * The renderNode (and its properties) that is to be drawn
70     */
71    RenderNode* getRenderNode() const { return mRenderNode.get(); }
72
73    /**
74     * Returns the transform on the canvas at time of recording and is used for
75     * computing total transform without rerunning DL contents.
76     */
77    const SkMatrix& getRecordedMatrix() const { return mRecordedTransform; }
78
79    /**
80     * Sets a pointer to a display list of the parent render node. The display list is used when
81     * drawing backward projected nodes, when this node is a projection receiver.
82     */
83    void setProjectedDisplayList(SkiaDisplayList* projectedDisplayList) {
84        mProjectedDisplayList = projectedDisplayList;
85    }
86
87protected:
88    /*
89     * Return the (conservative) bounds of what the drawable will draw.
90     */
91    virtual SkRect onGetBounds() override {
92        // We don't want to enable a record time quick reject because the properties
93        // of the RenderNode may be updated on subsequent frames.
94        return SkRect::MakeLargest();
95    }
96    /**
97     * This function draws into a canvas as forceDraw, but does nothing if the render node has a
98     * non-zero elevation.
99     */
100    virtual void onDraw(SkCanvas* canvas) override;
101
102private:
103    /*
104     * Render node that is wrapped by this class.
105     */
106    sp<RenderNode> mRenderNode;
107
108    /**
109     * Walks recursively the display list and draws the content of backward projected nodes.
110     *
111     * @param canvas used to draw the backward projected nodes
112     * @param displayList is a display list that contains a projection receiver
113     * @param nestLevel should be always 0. Used to track how far we are from the receiver.
114     */
115    void drawBackwardsProjectedNodes(SkCanvas* canvas, const SkiaDisplayList& displayList,
116            int nestLevel = 0);
117
118    /**
119     * Applies the rendering properties of a view onto a SkCanvas.
120     */
121    static void setViewProperties(const RenderProperties& properties, SkCanvas* canvas,
122            float* alphaMultiplier);
123
124    /**
125     * Stores transform on the canvas at time of recording and is used for
126     * computing total transform without rerunning DL contents.
127     */
128    const SkMatrix mRecordedTransform;
129
130    /**
131     * If mRenderNode's layer type is RenderLayer this flag determines whether we
132     * should draw into the contents of the layer or compose the existing contents
133     * of the layer into the canvas.
134     */
135    const bool mComposeLayer;
136
137    /*
138     * True if the render node is in a reordering section
139     */
140    bool mInReorderingSection;
141
142    /*
143     *  Draw the content into a canvas, depending on the render node layer type and mComposeLayer.
144     */
145    void drawContent(SkCanvas* canvas) const;
146
147    /*
148     * display list that is searched for any render nodes with getProjectBackwards==true
149     */
150    SkiaDisplayList* mProjectedDisplayList = nullptr;
151};
152
153}; // namespace skiapipeline
154}; // namespace uirenderer
155}; // namespace android
156