1
2/*
3 * Copyright 2012 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9#include "SkPictureStateTree.h"
10#include "SkCanvas.h"
11
12SkPictureStateTree::SkPictureStateTree()
13    : fAlloc(2048)
14    , fLastRestoredNode(NULL)
15    , fStateStack(sizeof(Draw), 16) {
16    fRootMatrix.reset();
17    fRoot.fParent = NULL;
18    fRoot.fMatrix = &fRootMatrix;
19    fRoot.fFlags = Node::kSave_Flag;
20    fRoot.fOffset = 0;
21    fRoot.fLevel = 0;
22    fCurrentState.fNode = &fRoot;
23    fCurrentState.fMatrix = &fRootMatrix;
24    *static_cast<Draw*>(fStateStack.push_back()) = fCurrentState;
25}
26
27SkPictureStateTree::~SkPictureStateTree() {
28}
29
30SkPictureStateTree::Draw* SkPictureStateTree::appendDraw(uint32_t offset) {
31    Draw* draw = static_cast<Draw*>(fAlloc.allocThrow(sizeof(Draw)));
32    *draw = fCurrentState;
33    draw->fOffset = offset;
34    return draw;
35}
36
37void SkPictureStateTree::appendSave() {
38    *static_cast<Draw*>(fStateStack.push_back()) = fCurrentState;
39    fCurrentState.fNode->fFlags |= Node::kSave_Flag;
40}
41
42void SkPictureStateTree::appendSaveLayer(uint32_t offset) {
43    *static_cast<Draw*>(fStateStack.push_back()) = fCurrentState;
44    this->appendNode(offset);
45    fCurrentState.fNode->fFlags |= Node::kSaveLayer_Flag;
46}
47
48void SkPictureStateTree::saveCollapsed() {
49    SkASSERT(NULL != fLastRestoredNode);
50    SkASSERT(SkToBool(fLastRestoredNode->fFlags & \
51        (Node::kSaveLayer_Flag | Node::kSave_Flag)));
52    SkASSERT(fLastRestoredNode->fParent == fCurrentState.fNode);
53    // The structure of the tree is not modified here. We just turn off
54    // the save or saveLayer flag to prevent the iterator from making state
55    // changing calls on the playback canvas when traversing a save or
56    // saveLayerNode node.
57    fLastRestoredNode->fFlags = 0;
58}
59
60void SkPictureStateTree::appendRestore() {
61    fLastRestoredNode = fCurrentState.fNode;
62    fCurrentState = *static_cast<Draw*>(fStateStack.back());
63    fStateStack.pop_back();
64}
65
66void SkPictureStateTree::appendTransform(const SkMatrix& trans) {
67    SkMatrix* m = static_cast<SkMatrix*>(fAlloc.allocThrow(sizeof(SkMatrix)));
68    *m = trans;
69    fCurrentState.fMatrix = m;
70}
71
72void SkPictureStateTree::appendClip(uint32_t offset) {
73    this->appendNode(offset);
74}
75
76SkPictureStateTree::Iterator SkPictureStateTree::getIterator(const SkTDArray<void*>& draws,
77                                                             SkCanvas* canvas) {
78    return Iterator(draws, canvas, &fRoot);
79}
80
81void SkPictureStateTree::appendNode(uint32_t offset) {
82    Node* n = static_cast<Node*>(fAlloc.allocThrow(sizeof(Node)));
83    n->fOffset = offset;
84    n->fFlags = 0;
85    n->fParent = fCurrentState.fNode;
86    n->fLevel = fCurrentState.fNode->fLevel + 1;
87    n->fMatrix = fCurrentState.fMatrix;
88    fCurrentState.fNode = n;
89}
90
91SkPictureStateTree::Iterator::Iterator(const SkTDArray<void*>& draws, SkCanvas* canvas, Node* root)
92    : fDraws(&draws)
93    , fCanvas(canvas)
94    , fCurrentNode(root)
95    , fPlaybackMatrix(canvas->getTotalMatrix())
96    , fCurrentMatrix(NULL)
97    , fPlaybackIndex(0)
98    , fSave(false)
99    , fValid(true) {
100}
101
102uint32_t SkPictureStateTree::Iterator::draw() {
103    SkASSERT(this->isValid());
104    if (fPlaybackIndex >= fDraws->count()) {
105        // restore back to where we started
106        if (fCurrentNode->fFlags & Node::kSaveLayer_Flag) { fCanvas->restore(); }
107        fCurrentNode = fCurrentNode->fParent;
108        while (NULL != fCurrentNode) {
109            if (fCurrentNode->fFlags & Node::kSave_Flag) { fCanvas->restore(); }
110            if (fCurrentNode->fFlags & Node::kSaveLayer_Flag) { fCanvas->restore(); }
111            fCurrentNode = fCurrentNode->fParent;
112        }
113        fCanvas->setMatrix(fPlaybackMatrix);
114        return kDrawComplete;
115    }
116
117    Draw* draw = static_cast<Draw*>((*fDraws)[fPlaybackIndex]);
118    Node* targetNode = draw->fNode;
119
120    if (fSave) {
121        fCanvas->save(SkCanvas::kClip_SaveFlag);
122        fSave = false;
123    }
124
125    if (fCurrentNode != targetNode) {
126        // If we're not at the target and we don't have a list of nodes to get there, we need to
127        // figure out the path from our current node, to the target
128        if (fNodes.count() == 0) {
129            // Trace back up to a common ancestor, restoring to get our current state to match that
130            // of the ancestor, and saving a list of nodes whose state we need to apply to get to
131            // the target (we can restore up to the ancestor immediately, but we'll need to return
132            // an offset for each node on the way down to the target, to apply the desired clips and
133            // saveLayers, so it may take several draw() calls before the next draw actually occurs)
134            Node* tmp = fCurrentNode;
135            Node* ancestor = targetNode;
136            while (tmp != ancestor) {
137                uint16_t currentLevel = tmp->fLevel;
138                uint16_t targetLevel = ancestor->fLevel;
139                if (currentLevel >= targetLevel) {
140                    if (tmp != fCurrentNode && tmp->fFlags & Node::kSave_Flag) { fCanvas->restore(); }
141                    if (tmp->fFlags & Node::kSaveLayer_Flag) { fCanvas->restore(); }
142                    tmp = tmp->fParent;
143                }
144                if (currentLevel <= targetLevel) {
145                    fNodes.push(ancestor);
146                    ancestor = ancestor->fParent;
147                }
148            }
149
150            if (ancestor->fFlags & Node::kSave_Flag) {
151                if (fCurrentNode != ancestor) { fCanvas->restore(); }
152                if (targetNode != ancestor) { fCanvas->save(SkCanvas::kClip_SaveFlag); }
153            }
154            fCurrentNode = ancestor;
155        }
156
157        // If we're not at the target node yet, we'll need to return an offset to make the caller
158        // apply the next clip or saveLayer.
159        if (fCurrentNode != targetNode) {
160            if (fCurrentMatrix != fNodes.top()->fMatrix) {
161                fCurrentMatrix = fNodes.top()->fMatrix;
162                SkMatrix tmp = *fNodes.top()->fMatrix;
163                tmp.postConcat(fPlaybackMatrix);
164                fCanvas->setMatrix(tmp);
165            }
166            uint32_t offset = fNodes.top()->fOffset;
167            fCurrentNode = fNodes.top();
168            fSave = fCurrentNode != targetNode && fCurrentNode->fFlags & Node::kSave_Flag;
169            fNodes.pop();
170            return offset;
171        }
172    }
173
174    // If we got this far, the clip/saveLayer state is all set, so we can proceed to set the matrix
175    // for the draw, and return its offset.
176
177    if (fCurrentMatrix != draw->fMatrix) {
178        SkMatrix tmp = *draw->fMatrix;
179        tmp.postConcat(fPlaybackMatrix);
180        fCanvas->setMatrix(tmp);
181        fCurrentMatrix = draw->fMatrix;
182    }
183
184    ++fPlaybackIndex;
185    return draw->fOffset;
186}
187