RenderNodeDrawable.h revision 2f06e8ad1a1c4d0866bb66854d2759e275898635 
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
32/**
33 * This drawable wraps a RenderNode and enables it to be recorded into a list
34 * of Skia drawing commands.
35 */
36class RenderNodeDrawable : public SkDrawable {
37public:
38    /**
39     * This struct contains a pointer to a node that is to be
40     * projected into the drawing order of its closest ancestor
41     * (excluding its parent) that is marked as a projection
42     * receiver. The matrix is used to ensure that the node is
43     * drawn with same matrix as it would have prior to projection.
44     */
45    struct ProjectedChild {
46        const RenderNodeDrawable* node;
47        const SkMatrix matrix;
48    };
49
50    /**
51     * Creates a new RenderNodeDrawable backed by a render node.
52     *
53     * @param node that has to be drawn
54     * @param canvas is a recording canvas used to extract its matrix
55     * @param composeLayer if the node's layer type is RenderLayer this flag determines whether
56     *      we should draw into the contents of the layer or compose the existing contents of the
57     *      layer into the canvas.
58     */
59    explicit RenderNodeDrawable(RenderNode* node, SkCanvas* canvas, bool composeLayer = true,
60            bool inReorderingSection = false)
61            : mRenderNode(node)
62            , mRecordedTransform(canvas->getTotalMatrix())
63            , mComposeLayer(composeLayer)
64            , mInReorderingSection(inReorderingSection) {}
65
66    /**
67     * Draws into the canvas this render node and its children. If the node is marked as a
68     * projection receiver then all projected children (excluding direct children) will be drawn
69     * last. Any projected node not matching those requirements will not be drawn by this function.
70     */
71    void forceDraw(SkCanvas* canvas);
72
73    /**
74     * Returns readonly render properties for this render node.
75     */
76    const RenderProperties& getNodeProperties() const;
77
78    /**
79     * The renderNode (and its properties) that is to be drawn
80     */
81    RenderNode* getRenderNode() const { return mRenderNode.get(); }
82
83    /**
84     * Returns the transform on the canvas at time of recording and is used for
85     * computing total transform without rerunning DL contents.
86     */
87    const SkMatrix& getRecordedMatrix() const { return mRecordedTransform; }
88
89protected:
90    /*
91     * Return the (conservative) bounds of what the drawable will draw.
92     */
93    virtual SkRect onGetBounds() override {
94        // We don't want to enable a record time quick reject because the properties
95        // of the RenderNode may be updated on subsequent frames.
96        return SkRect::MakeLargest();
97    }
98    /**
99     * This function draws into a canvas as forceDraw, but does nothing if the render node has a
100     * non-zero elevation.
101     */
102    virtual void onDraw(SkCanvas* canvas) override;
103
104private:
105    /*
106     * Render node that is wrapped by this class.
107     */
108    sp<RenderNode> mRenderNode;
109
110    /**
111     * Applies the rendering properties of a view onto a SkCanvas.
112     */
113    static void setViewProperties(const RenderProperties& properties, SkCanvas* canvas,
114            float* alphaMultiplier);
115
116    /**
117     * Stores transform on the canvas at time of recording and is used for
118     * computing total transform without rerunning DL contents.
119     */
120    const SkMatrix mRecordedTransform;
121
122    /**
123     * If mRenderNode's layer type is RenderLayer this flag determines whether we
124     * should draw into the contents of the layer or compose the existing contents
125     * of the layer into the canvas.
126     */
127    const bool mComposeLayer;
128
129    /**
130     * List to which we will add any projected children we encounter while walking our descendents.
131     * This pointer is valid only while the node (including its children) is actively being drawn.
132     */
133    std::vector<ProjectedChild>* mProjectedChildrenTarget = nullptr;
134
135    /**
136     * The value to which we should set our children's mProjectedChildrenTarget. We use two pointers
137     * (mProjectedChildrenTarget and mNextProjectedChildrenTarget) because we need to skip over our
138     * parent when looking for a projection receiver.
139     */
140    std::vector<ProjectedChild>* mNextProjectedChildrenTarget = nullptr;
141
142    /*
143     * True if the render node is in a reordering section
144     */
145    bool mInReorderingSection;
146
147    /*
148     *  Draw the content into a canvas, depending on the render node layer type and mComposeLayer.
149     */
150    void drawContent(SkCanvas* canvas) const;
151};
152
153}; // namespace skiapipeline
154}; // namespace uirenderer
155}; // namespace android
156