CSS Triangles in React Native

问题

I'm working on an app that uses triangles that overlay other containers/divs. Had that solved with CSS before:

.triangle:after {
  content: "";
  display: block;
  position: absolute;
  top: 15px;
  left: -15px;
  width: 0;
  border-width: 0px 0px 15px 15px;
  border-style: solid;
}

but that doesn't work in React any more. What's the best solution to go here?

回答1:

The best way to do this is to create an <Image> component and absolutely position it, similar to how you would a pure CSS triangle. If the triangle has a flat color, as opposed to a gradient or other pattern, you can set its color using the tintColor style property.

Example:

<Image
  source={require('image!triangle')}
  style={{tintColor: '#008080'}}
/>

回答2:

It is still possible to draw triangles in React Native using the CSS trick. I wrote a class to encapsulate this: https://github.com/Jpoliachik/react-native-triangle

If you'd like to write it yourself, I used this tool: http://apps.eky.hk/css-triangle-generator/ to generate the triangle I wanted and modify the styles to React Native syntax.

For example, an Isosceles triangle 90x90 pointing up in CSS reads:

width: 0;
height: 0;
border-style: solid;
border-width: 0 45px 90px 45px;
border-color: transparent transparent #007bff transparent;

But in React Native the styles would be:

triangle: {
     width: 0,
     height: 0,
     backgroundColor: 'transparent',
     borderStyle: 'solid',
     borderTopWidth: 0,
     borderRightWidth: 45,
     borderBottomWidth: 90,
     borderLeftWidth: 45,
     borderTopColor: 'transparent',
     borderRightColor: 'transparent',
     borderBottomColor: 'red',
     borderLeftColor: 'transparent',
   },

回答3:

render() {
    return (
        <View style={[styles.triangle,styles.arrowUp]}/>
    );
}

And styles

const styles = {
    triangle: {
        width: 0,
        height: 0,
        backgroundColor: 'transparent',
        borderStyle: 'solid',
    },
    arrowUp: {
        borderTopWidth: 0,
        borderRightWidth: 30,
        borderBottomWidth: 30,
        borderLeftWidth: 30,
        borderTopColor: 'transparent',
        borderRightColor: 'transparent',
        borderBottomColor: "tomato",
        borderLeftColor: 'transparent',
    },
    arrowRight: {
        borderTopWidth: 30,
        borderRightWidth: 0,
        borderBottomWidth: 30,
        borderLeftWidth: "tomato",
        borderTopColor: 'transparent',
        borderRightColor: 'transparent',
        borderBottomColor: 'transparent',
        borderLeftColor: "tomato",
    },
    arrowDown: {
        borderTopWidth: 30,
        borderRightWidth: 30,
        borderBottomWidth: 0,
        borderLeftWidth: 30,
        borderTopColor: "tomato",
        borderRightColor: 'transparent',
        borderBottomColor: 'transparent',
        borderLeftColor: 'transparent',
    },
    arrowLeft: {
        borderTopWidth: 30,
        borderRightWidth: "tomato",
        borderBottomWidth: 30,
        borderLeftWidth: 0,
        borderTopColor: 'transparent',
        borderRightColor: "tomato",
        borderBottomColor: 'transparent',
        borderLeftColor: 'transparent',
    },
    arrowUpLeft: {
        borderTopWidth: 30,
        borderRightWidth: "tomato",
        borderBottomWidth: 0,
        borderLeftWidth: 0,
        borderTopColor: "tomato",
        borderRightColor: 'transparent',
        borderBottomColor: 'transparent',
        borderLeftColor: 'transparent',
    },
    arrowUpRight: {
        borderTopWidth: 0,
        borderRightWidth: "tomato",
        borderBottomWidth: 30,
        borderLeftWidth: 0,
        borderTopColor: 'transparent',
        borderRightColor: "tomato",
        borderBottomColor: 'transparent',
        borderLeftColor: 'transparent',
    },
    arrowDownLeft: {
        borderTopWidth: 30,
        borderRightWidth: 0,
        borderBottomWidth: 0,
        borderLeftWidth: "tomato",
        borderTopColor: 'transparent',
        borderRightColor: 'transparent',
        borderBottomColor: 'transparent',
        borderLeftColor: "tomato",
    },
    arrowDownRight: {
        borderTopWidth: 0,
        borderRightWidth: 0,
        borderBottomWidth: 30,
        borderLeftWidth: "tomato",
        borderTopColor: 'transparent',
        borderRightColor: 'transparent',
        borderBottomColor: "tomato",
        borderLeftColor: 'transparent',
    },
}

Source : https://github.com/Jpoliachik/react-native-triangle

回答4:

Why not use a dedicated library? https://github.com/react-native-community/react-native-svg

来源：https://stackoverflow.com/questions/30216929/css-triangles-in-react-native

标签

reactjs

stylesheet

react-native