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 /* how if else works
41 * the transpiler generated JS code is like this(simplified, but main points shown)
42 * this.observeComponentCreation(..., () => {
43 * If.create();
44 * if (condition1) {
45 * this.ifElseBranchUpdateFunction(compilerGeneratedUniqueConstBranchId, () =>
46 * code for children first render
47 * })
48 * } else if (condition2) {
49 * this.ifElseBranchUpdateFunction(compilerGeneratedUniqueConstBranchId, () =>
50 * code for children first render
51 * })
52 * } else {
53 * // else added by the transpiler
54 * If.setBranchId(compilerGeneratedUniqueConstBranchId)
55 * }
56 * If.pop()
57 * - if re-renders whenever one of the variables used in 'condition' during last render has changed.
58 * - the dependent variables can change from one render of if to the next, depending if 'condition1' and
59 * 'condition2' bind to different variables.
60 * - If can re-render, but the branch does not change, e.g. if 'condition1' is (this.i > 20)
61 * then If will re-render whenever i changes.
62 * - eDSL to JS traspiler generates a unique id for each branch of the code inside.
63 * Thereby the framework can detect that the branch has actually changed.
64 * In this case ViewPU.ifElseBranchUpdateFunction will call IfElseNode::SetBranchId to upate
65 * and it will execute the 2nd parameter lambda function to re-generate the children.
66 * - In case of if without else, or if ... else if ... , eDSL to JS traspiler generates
67 * an extra else clause in which to set the branchId (calls IfElseNode::SetBranchId)
68 * - IfElseNode::FlushUpdateAndMarkDirty is called upon If.Pop()
69 */
SetBranchId(int32_t value,std::list<int32_t> & removedElmtId)70 void IfElseNode::SetBranchId(int32_t value, std::list<int32_t>& removedElmtId)
71 {
72 branchIdChanged_ = (branchId_ != value);
73 TAG_LOGD(AceLogTag::ACE_IF, "id: %{public}d, branchIdChanged_: %{public}d", GetId(), branchIdChanged_);
74 if (branchIdChanged_) {
75 // collect elmtIds of all children and their children up to CustomNode object
76 // these will be removed, but possibly with a delay if their is an animation
77 // list of elmtIds is sent back to calling TS ViewPU.ifElseBranchUpdateFunction()
78 Clean(false, true, branchId_);
79 CollectRemovedChildren(GetChildren(), removedElmtId, true);
80 branchId_ = value;
81 }
82 }
83
FlushUpdateAndMarkDirty()84 void IfElseNode::FlushUpdateAndMarkDirty()
85 {
86 if (branchIdChanged_) {
87 auto parent = GetParent();
88 while (parent) {
89 auto frameNode = AceType::DynamicCast<FrameNode>(parent);
90 if (frameNode) {
91 frameNode->ChildrenUpdatedFrom(0);
92 break;
93 }
94 parent = parent->GetParent();
95 }
96 // mark parent dirty to flush measure.
97 MarkNeedFrameFlushDirty(PROPERTY_UPDATE_BY_CHILD_REQUEST);
98 }
99 branchIdChanged_ = false;
100 }
101
TryRetake(const std::string & id)102 bool IfElseNode::TryRetake(const std::string& id)
103 {
104 auto node = GetDisappearingChildById(id, branchId_);
105 if (node) {
106 ACE_SCOPED_TRACE("IfElse TryRetake validate.");
107 AddChild(node);
108 // for geometryTransition, let all reused children call UpdateGeometryTransition.
109 LayoutProperty::UpdateAllGeometryTransition(node);
110 return true;
111 }
112 return false;
113 }
114
115 } // namespace OHOS::Ace::NG
116