1 /*
2 * Copyright (c) 2022-2024 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16 #include "core/components_ng/syntax/if_else_node.h"
17
18 #include <list>
19 #include <type_traits>
20
21 #include "base/log/ace_trace.h"
22 #include "core/components_ng/base/frame_node.h"
23 #include "core/components_ng/layout/layout_property.h"
24 #include "core/components_ng/property/property.h"
25 #include "core/pipeline/base/element_register.h"
26
27 namespace OHOS::Ace::NG {
28
GetOrCreateIfElseNode(int32_t nodeId)29 RefPtr<IfElseNode> IfElseNode::GetOrCreateIfElseNode(int32_t nodeId)
30 {
31 auto node = ElementRegister::GetInstance()->GetSpecificItemById<IfElseNode>(nodeId);
32 if (node) {
33 return node;
34 }
35 node = MakeRefPtr<IfElseNode>(nodeId);
36 ElementRegister::GetInstance()->AddUINode(node);
37 return node;
38 }
39
40 /*
41 * how if else works:
42 *
43 * the transpiler generated JS code is like this(simplified, but main points shown):
44 *
45 * this.observeComponentCreation(..., () => {
46 * If.create();
47 * if (condition1) {
48 * this.ifElseBranchUpdateFunction(compilerGeneratedUniqueConstBranchId, () =>
49 * code for children first render
50 * })
51 * } else if (condition2) {
52 * this.ifElseBranchUpdateFunction(compilerGeneratedUniqueConstBranchId, () =>
53 * code for children first render
54 * })
55 * } else {
56 * // else added by the transpiler
57 * If.setBranchId(compilerGeneratedUniqueConstBranchId)
58 * }
59 * If.pop()
60 *
61 * - if re-renders whenever one of the variables used in 'condition' during last render has changed.
62 * - the dependent variables can change from one render of if to the next, depending if 'condition1' and
63 * 'condition2' bind to different variables.
64 * - If can re-render, but the branch does not change, e.g. if 'condition1' is (this.i > 20)
65 * then If will re-render whenever i changes.
66 *
67 * - eDSL to JS traspiler generates a unique id for each branch of the code inside.
68 * Thereby the framework can detect that the branch has actually changed.
69 * In this case ViewPU.ifElseBranchUpdateFunction will call IfElseNode::SetBranchId to upate
70 * and it will execute the 2nd parameter lambda function to re-generate the children.
71 *
72 * - In case of if without else, or if ... else if ... , eDSL to JS traspiler generates
73 * an extra else clause in which to set the branchId (calls IfElseNode::SetBranchId)
74 *
75 * - IfElseNode::FlushUpdateAndMarkDirty is called upon If.Pop() FIXME
76 */
77
SetBranchId(int32_t value,std::list<int32_t> & removedElmtId)78 void IfElseNode::SetBranchId(int32_t value, std::list<int32_t>& removedElmtId)
79 {
80 branchIdChanged_ = (branchId_ != value);
81 if (branchIdChanged_) {
82 // collect elmtIds of all children and their children up to CustomNode object
83 // these will be removed, but possibly with a delay if their is an animation
84 // list of elmtIds is sent back to calling TS ViewPU.ifElseBranchUpdateFunction()
85 CollectRemovedChildren(GetChildren(), removedElmtId);
86 Clean(false, true);
87 branchId_ = value;
88 }
89 }
90
CollectRemovedChildren(const std::list<RefPtr<UINode>> & children,std::list<int32_t> & removedElmtId)91 void IfElseNode::CollectRemovedChildren(const std::list<RefPtr<UINode>>& children, std::list<int32_t>& removedElmtId)
92 {
93 for (auto const& child : children) {
94 CollectRemovedChild(child, removedElmtId);
95 }
96 }
97
CollectRemovedChild(const RefPtr<UINode> & child,std::list<int32_t> & removedElmtId)98 void IfElseNode::CollectRemovedChild(const RefPtr<UINode>& child, std::list<int32_t>& removedElmtId)
99 {
100 removedElmtId.emplace_back(child->GetId());
101 if (child->GetTag() != V2::JS_VIEW_ETS_TAG) {
102 // add CustomNode but do not recurse into its children
103 CollectRemovedChildren(child->GetChildren(), removedElmtId);
104 }
105 }
106
FlushUpdateAndMarkDirty()107 void IfElseNode::FlushUpdateAndMarkDirty()
108 {
109 if (branchIdChanged_) {
110 auto parent = GetParent();
111 while (parent) {
112 auto frameNode = AceType::DynamicCast<FrameNode>(parent);
113 if (frameNode) {
114 frameNode->ChildrenUpdatedFrom(0);
115 break;
116 }
117 parent = parent->GetParent();
118 }
119 // mark parent dirty to flush measure.
120 MarkNeedFrameFlushDirty(PROPERTY_UPDATE_BY_CHILD_REQUEST);
121 }
122 branchIdChanged_ = false;
123 }
124
TryRetake(const std::string & id)125 bool IfElseNode::TryRetake(const std::string& id)
126 {
127 auto node = GetDisappearingChildById(id);
128 if (node) {
129 AddChild(node);
130 // for geometryTransition, let all reused children call UpdateGeometryTransition.
131 LayoutProperty::UpdateAllGeometryTransition(node);
132 return true;
133 }
134 return false;
135 }
136
137 } // namespace OHOS::Ace::NG