react-native - 如何仅使用 React Native 中的一个功能通过 onLayout 获得多个视图的尺寸？
问题描述
我有一个包含 4*4 视图框的网格场景。我想获得每个人的尺寸，看看用户是否将他/她的手指移到他们身上。我成功地完成了这个过程，为我的 16 个盒子编写了 16 个单独的“onLayout”函数，然后尝试计算用户触摸动作。此外，我为此编写了 16 个视图 UI 而不是一个干净的 for 循环。
所以我最终得到了一些无法动态使用且无法实现的凌乱的脏代码。谁能帮我用函数和循环清理这段代码？
这就是我所拥有的：
render() {
return (
<View style={{justifyContent: 'center', alignItems: 'center', flex: 1}}>
<View style={{flex : 1}}><Text>{this.state.wordObj['A']}</Text></View>
<View onLayout={this.getExactPos} style={{flex : 4, backgroundColor: 'red', marginLeft:20,marginRight:20}} {...this._panResponder.panHandlers} >
<View style={{flexDirection: 'row', flex: 1 , backgroundColor: 'red', width: '100%'}}>
<View onLayout={this.getExactPosA} style={{flex : 1, backgroundColor: 'yellow', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box1}</Text></View>
<View onLayout={this.getExactPosB} style={{flex : 1, backgroundColor: 'orange', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box2}</Text></View>
<View onLayout={this.getExactPosC} style={{flex : 1, backgroundColor: 'gray', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box3}</Text></View>
</View>
<View onLayout={this.getExactPosRow2} style={{flexDirection: 'row', flex: 1 , backgroundColor: 'blue' , width: '100%'}}>
<View onLayout={this.getExactPosD} style={{flex : 1, backgroundColor: 'green', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box4}</Text></View>
<View onLayout={this.getExactPosE} style={{flex : 1, backgroundColor: 'red', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box5}</Text></View>
<View onLayout={this.getExactPosF} style={{flex : 1, backgroundColor: 'blue', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box6}</Text></View>
</View>
<View onLayout={this.getExactPosRow3} style={{flexDirection: 'row', flex: 1 , backgroundColor: 'green', width: '100%'}}>
<View onLayout={this.getExactPosG} style={{flex : 1, backgroundColor: 'purple', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box7}</Text></View>
<View onLayout={this.getExactPosH} style={{flex : 1, backgroundColor: 'skyblue', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box8}</Text></View>
<View onLayout={this.getExactPosI} style={{flex : 1, backgroundColor: '#124567', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box9}</Text></View>
</View>
</View>
<View style={{flex : 1}}><Text>3</Text></View>
<Text>Hello world! - Home</Text>
<TouchableOpacity style={{backgroundColor : 'red'}} onPress={this._signOutAsync}>
<Text>Log Out</Text>
</TouchableOpacity>
</View>
); }
这部分是视图的 onLayout 功能：
getExactPos = e => {
const { width, height, x, y } = e.nativeEvent.layout;
this.setState({
gridXstart : x,
gridXend : x + width,
gridYstart : y,
gridYend : y + height,
})
// alert(x);
};
getExactPosRow2 = e => {
const { width, height, x, y } = e.nativeEvent.layout;
this.setState({
row2Y : y,
})
};
getExactPosRow3 = e => {
const { width, height, x, y } = e.nativeEvent.layout;
this.setState({
row3Y : y,
})
};
getExactPosA = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray = this.state.a;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({a: newArray});
};
getExactPosB = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray =this.state.b;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({b: newArray});
};
getExactPosC = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray = this.state.c;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({c: newArray});
};
getExactPosD = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray = this.state.d;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({d: newArray});
};
getExactPosE = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray = this.state.e;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({e: newArray});
};
getExactPosF = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray = this.state.f;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({f: newArray});
};
getExactPosG = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray = this.state.g;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({g: newArray});
};
getExactPosH = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray = this.state.h;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({h: newArray});
};
getExactPosI = e => {
const { width, height, x, y } = e.nativeEvent.layout;
let newArray = this.state.i;
newArray.gridXstart = x;
newArray.gridXend = x + width;
newArray.gridYstart = y;
newArray.gridYend = y + height;
this.setState({i: newArray});
//alert('asdasdas')
};
我想使用这种循环来动态创建我的网格，并使用一个 onLayout 函数来处理所有内容。：
let rows = [];
let k = 0;
for(let i = 0; i<4 ; i++){
let row= [];
for(let j = 0; j<4; j++){
k++;
row.push(
<View onLayout={this.getExactPos2} style={{flex : 1, backgroundColor: 'yellow', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box1}</Text></View>
)
}
rows.push(
<View style={{flexDirection: 'row', flex: 1 , backgroundColor: 'red', width: '100%'}}>{row}</View>
)
}
为了检测盒子（如钢琴）上的用户触摸移动，我试图在屏幕上获取用户的手指位置并与每个盒子的位置进行比较。那是因为我找不到任何解决方案，每个盒子本身总是监听触摸运动。
这是我的手势处理代码：我将 panResponder 用于父视图。
<View onLayout={this.getExactPos} style={{flex : 4, backgroundColor: 'red', marginLeft:20,marginRight:20}} {...this._panResponder.panHandlers} >
<View style={{flexDirection: 'row', flex: 1 , backgroundColor: 'red', width: '100%'}}>
<View onLayout={this.getExactPosA} style={{flex : 1, backgroundColor: 'yellow', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box1}</Text></View>
<View onLayout={this.getExactPosB} style={{flex : 1, backgroundColor: 'orange', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box2}</Text></View>
<View onLayout={this.getExactPosC} style={{flex : 1, backgroundColor: 'gray', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box3}</Text></View>
</View>
<View onLayout={this.getExactPosRow2} style={{flexDirection: 'row', flex: 1 , backgroundColor: 'blue' , width: '100%'}}>
<View onLayout={this.getExactPosD} style={{flex : 1, backgroundColor: 'green', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box4}</Text></View>
<View onLayout={this.getExactPosE} style={{flex : 1, backgroundColor: 'red', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box5}</Text></View>
<View onLayout={this.getExactPosF} style={{flex : 1, backgroundColor: 'blue', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box6}</Text></View>
</View>
<View onLayout={this.getExactPosRow3} style={{flexDirection: 'row', flex: 1 , backgroundColor: 'green', width: '100%'}}>
<View onLayout={this.getExactPosG} style={{flex : 1, backgroundColor: 'purple', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box7}</Text></View>
<View onLayout={this.getExactPosH} style={{flex : 1, backgroundColor: 'skyblue', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box8}</Text></View>
<View onLayout={this.getExactPosI} style={{flex : 1, backgroundColor: '#124567', justifyContent: 'center', alignItems: 'center'}}><Text>{this.state.Box9}</Text></View>
</View>
</View>
这是我的 panResponder 函数：
componentWillMount() {
this._panResponder = PanResponder.create({
onMoveShouldSetPanResponder: (evt, gestureState) => true,
onPanResponderGrant: (evt) => {
this.setState({
zone: '',
});
},
onPanResponderMove: (evt, gestureState) => {
const drag = this.getDirectionAndColor(gestureState);
this.setState({
zone: drag ,
});
},
onPanResponderTerminationRequest: (evt, gestureState) => true,
onPanResponderRelease: (evt, gestureState) => {
this.setState({
zone: 'Finished',
});
},
});
}
这是我的计算函数：
getDirectionAndColor = ({ moveX, moveY, dx, dy, x0, y0, stateID }) => {
if(
(this.state.a.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.a.gridXend + this.state.gridXstart)
&&
(this.state.a.gridYstart+this.state.gridYstart < moveY)
&&
(moveY < this.state.a.gridYend + this.state.gridYstart)
){
return this.state.Box1;
}else if(
(this.state.b.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.b.gridXend + this.state.gridXstart)
&&
(this.state.b.gridYstart+this.state.gridYstart < moveY)
&&
(moveY < this.state.b.gridYend + this.state.gridYstart)
){
return this.state.Box2;
}else if(
(this.state.c.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.c.gridXend + this.state.gridXstart)
&&
(this.state.c.gridYstart+this.state.gridYstart < moveY)
&&
(moveY < this.state.c.gridYend + this.state.gridYstart)
){
return this.state.Box3;
}else if(
(this.state.d.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.d.gridXend + this.state.gridXstart)
&&
(this.state.d.gridYstart+this.state.gridYstart+this.state.row2Y < moveY)
&&
(moveY < this.state.d.gridYend + this.state.gridYstart + this.state.row2Y)
){
return this.state.Box4;
}else if(
(this.state.e.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.e.gridXend + this.state.gridXstart)
&&
(this.state.e.gridYstart+this.state.gridYstart+this.state.row2Y < moveY)
&&
(moveY < this.state.e.gridYend + this.state.gridYstart + this.state.row2Y)
){
return this.state.Box5;
}else if(
(this.state.f.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.f.gridXend + this.state.gridXstart)
&&
(this.state.f.gridYstart+this.state.gridYstart+this.state.row2Y < moveY)
&&
(moveY < this.state.f.gridYend + this.state.gridYstart + this.state.row2Y)
){
return this.state.Box6;
}else if(
(this.state.g.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.g.gridXend + this.state.gridXstart)
&&
(this.state.g.gridYstart+this.state.gridYstart+this.state.row2Y+ this.state.row2Y < moveY)
&&
(moveY < this.state.g.gridYend + this.state.gridYstart + this.state.row2Y+ this.state.row2Y)
){
return this.state.Box7;
}else if(
(this.state.h.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.h.gridXend + this.state.gridXstart)
&&
(this.state.h.gridYstart+this.state.gridYstart+this.state.row2Y+ this.state.row2Y < moveY)
&&
(moveY < this.state.h.gridYend + this.state.gridYstart + this.state.row2Y+ this.state.row2Y)
){
return this.state.Box8;
}else if(
(this.state.i.gridXstart+this.state.gridXstart < moveX)
&&
(moveX < this.state.i.gridXend + this.state.gridXstart)
&&
(this.state.i.gridYstart+this.state.gridYstart+this.state.row2Y+ this.state.row2Y < moveY)
&&
(moveY < this.state.i.gridYend + this.state.gridYstart + this.state.row2Y+ this.state.row2Y)
){
return this.state.Box9;
}else{
return 'No'
}
};
这是我的状态：
state = {
zone: "Still Touchable",
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
row2Y: 0,
row3Y: 0,
Box1: 'A',Box2: 'B', Box3: 'C', Box4: 'D', Box5: 'E',Box6: 'F',Box7: 'G', Box8: 'H', Box9: 'I',
wordObj : {},
a : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
b : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
c : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
d : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
e : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
f : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
g : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
h : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
i : {
gridXstart : 0,
gridXend : 0,
gridYstart : 0,
gridYend : 0,
},
};
请帮我一些建议。谢谢。
解决方案
onLayout由于您在当前设置中使用了两个不同的功能，因此您无法使用一个功能来做到这一点。所以可以用两个来做。您只需要进一步抽象代码，然后就可以使其工作。
如果我们认为您正在这样构建网格，如果我们遵循直接的命名约定XY，我们可以很容易地找到网格中的每个单元格，其中X行Y是列。
+----+----+----+
| 11 | 12 | 13 |
+----+----+----+
| 21 | 22 | 23 |
+----+----+----+
| 31 | 32 | 33 |
+----+----+----+
使用这个想法，我们可以将您的两个onLayout函数修改为如下所示：
getExactPos = (e, key) => { // pass a key as well now
const { width, height, x, y } = e.nativeEvent.layout;
let position = {};
position.gridXstart = x;
position.gridXend = x + width;
position.gridYstart = y;
position.gridYend = y + height;
this.setState({ [key]: position }); // notice that we use the key to store it in state
}
getExactPosRow = (e, key) => { // pass a key as well now
const { y } = e.nativeEvent.layout;
this.setState({ [key]: y }); // notice that we use the key to store it in state
};
我们将在下面的函数中设置这些函数中使用的键constructViews。现在有了这些，我们可以构造一个函数来构造网格：
constructViews = () => {
let rows = [];
for (let i = 1; i < 4; i++) {
let row = [];
for (let j = 1; j < 4; j++) {
let stateKey = `${i}${j}`;
let styleKey = `box${stateKey}`;
row.push(
<View onLayout={ (e) => this.getExactPos(e, stateKey)} style={styles[styleKey]} key={stateKey}><Text>{this.state[styleKey]}</Text></View>
);
}
rows.push(
<View onLayout={e => this.getExactPosRow(e, `${i}`)} style={styles[`row${i}`]} key={i}>{row}</View>
);
}
return rows;
}
在这个函数中，我们有一个嵌套for-loop的构造网格。请注意，我们构造并将键传递给onLayout我们创建的两个函数。我们可以通过动态获取正确的样式和正确的文本来进一步扩展使用键的想法。
这是一个有效的 POC。这应该给你足够的实现你想要的。我还没有实现任何手势响应器，这取决于你。
import React from 'react';
import { Text, View, StyleSheet, Button } from 'react-native';
export default class App extends React.Component {
state = {
box11: 'Box 11',
box12: 'Box 12',
box13: 'Box 13',
box21: 'Box 21',
box22: 'Box 22',
box23: 'Box 23',
box31: 'Box 31',
box32: 'Box 32',
box33: 'Box 33'
}
getExactPos = (e, key) => {
const { width, height, x, y } = e.nativeEvent.layout;
let position = {};
position.gridXstart = x;
position.gridXend = x + width;
position.gridYstart = y;
position.gridYend = y + height;
this.setState({ [key]: position });
}
getExactPosRow = (e, key) => {
const { y } = e.nativeEvent.layout;
this.setState({
[key]: y
});
};
constructViews = () => {
let rows = [];
for (let i = 1; i < 4; i++) {
let row = [];
for (let j = 1; j < 4; j++) {
let stateKey = `${i}${j}`;
let styleKey = `box${stateKey}`;
row.push(
<View onLayout={ (e) => this.getExactPos(e, stateKey)} style={styles[styleKey]} key={stateKey}><Text>{this.state[styleKey]}</Text></View>
);
}
rows.push(
<View onLayout={e => this.getExactPosRow(e, `${i}`)} style={styles[`row${i}`]} key={i}>{row}</View>
);
}
return rows;
}
render () {
return (
<View style={{ justifyContent: 'center', alignItems: 'center', flex: 1 }}>
<View style={{ flex: 1 }}></View>
<Button onPress={() => console.log(this.state)} title={'console log state'} />
<View style={{ flex: 4, backgroundColor: 'red', marginLeft: 20, marginRight: 20 }} >
{this.constructViews()}
</View>
<View style={{ flex: 1 }}></View>
</View>
);
}
}
const styles = StyleSheet.create({
row1: { flexDirection: 'row', flex: 1, backgroundColor: 'red', width: '100%' },
row2: { flexDirection: 'row', flex: 1, backgroundColor: 'blue', width: '100%' },
row3: { flexDirection: 'row', flex: 1, backgroundColor: 'green', width: '100%' },
box11: { flex: 1, backgroundColor: 'yellow', justifyContent: 'center', alignItems: 'center' },
box12: { flex: 1, backgroundColor: 'orange', justifyContent: 'center', alignItems: 'center' },
box13: { flex: 1, backgroundColor: 'gray', justifyContent: 'center', alignItems: 'center' },
box21: { flex: 1, backgroundColor: 'green', justifyContent: 'center', alignItems: 'center' },
box22: { flex: 1, backgroundColor: 'red', justifyContent: 'center', alignItems: 'center' },
box23: { flex: 1, backgroundColor: 'blue', justifyContent: 'center', alignItems: 'center' },
box31: { flex: 1, backgroundColor: 'purple', justifyContent: 'center', alignItems: 'center' },
box32: { flex: 1, backgroundColor: 'skyblue', justifyContent: 'center', alignItems: 'center' },
box33: { flex: 1, backgroundColor: '#124567', justifyContent: 'center', alignItems: 'center' }
});
在这里你可以看到它在这个小吃中工作https://snack.expo.io/@andypandy/dynamic-grid-using-onlayout
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