[英]Unable to render canvas or run script in react-native android webview
[英]React Native canvas in WebView
我正在嘗試使用 React Native 0.17 編寫一個“繪畫”Android 應用程序。
我有一個Canvas
組件(強烈受到react-native-canvas 的啟發):
import React from 'react-native';
import Paint from '../utils/paint'
var {
View,
WebView
} = React;
const Canvas = React.createClass({
render() {
return (
<WebView
html={Paint}
style={this.props.style}
javaScriptEnabledAndroid={true}
/>
);
},
});
export default Canvas;
以及我在上面Canvas
組件中WebView
的html
道具中使用的Paint
組件。
這個組件只不過是一個很長的字符串,包含來自這個教程的 HTML 和 JS: creating-a-paint-application-with-html5-canvas
export default `<html>
<head></head>
<body>
<h1 id='toto'>TATA</h1>
<br />
<div id="sketch">
<canvas id="paint" style='border: 1px solid black'></canvas>
</div>
<script>
(function() {
var canvas = document.querySelector('#paint');
var ctx = canvas.getContext('2d');
var sketch = document.querySelector('#sketch');
var sketch_style = getComputedStyle(sketch);
canvas.width = parseInt(sketch_style.getPropertyValue('width'));
canvas.height = parseInt(sketch_style.getPropertyValue('height'));
var mouse = {x: 0, y: 0};
var start_events = ["mousedown", "touchstart"];
var move_events = ["mousemove", "touchmove"];
var end_events = ["mouseup", "touchend"];
/* Mouse Capturing Work */
move_events.forEach(function(event) {
canvas.addEventListener(event, function(e) {
mouse.x = e.pageX - this.offsetLeft;
mouse.y = e.pageY - this.offsetTop;
}, false);
});
/* Drawing on Paint App */
ctx.lineWidth = 5;
ctx.lineJoin = 'round';
ctx.lineCap = 'round';
ctx.strokeStyle = 'back';
start_events.forEach(function(event) {
canvas.addEventListener(event, function(e) {
ctx.beginPath();
ctx.moveTo(mouse.x, mouse.y);
move_events.forEach(function(me){ canvas.addEventListener(me, onPaint, false); });
}, false);
});
end_events.forEach(function(event) {
canvas.addEventListener(event, function(e) {
move_events.forEach(function(me){ canvas.removeEventListener(me, onPaint, false); });
}, false);
});
var onPaint = function() {
ctx.lineTo(mouse.x, mouse.y);
ctx.stroke();
};
}());
</script>
</body>
</html>`;
我的 HTML/JS 在瀏覽器 (Chrome) 中運行良好,但不幸的是我無法在我的 React Native 應用程序中繪制任何內容。
有人能幫我嗎? 我應該在 React Native 中監聽哪些事件?
當您在<script>
標記中注釋某些 JS 行時,ES6 模板字符串似乎會中斷。
嘗試刪除它們:
export default `<html>
<head></head>
<body>
<h1 id='toto'>TATA</h1>
<br />
<div id="sketch">
<canvas id="paint" style='border: 1px solid black'></canvas>
</div>
<script>
(function() {
var canvas = document.querySelector('#paint');
var ctx = canvas.getContext('2d');
var sketch = document.querySelector('#sketch');
var sketch_style = getComputedStyle(sketch);
canvas.width = parseInt(sketch_style.getPropertyValue('width'));
canvas.height = parseInt(sketch_style.getPropertyValue('height'));
var mouse = {x: 0, y: 0};
var start_events = ["mousedown", "touchstart"];
var move_events = ["mousemove", "touchmove"];
var end_events = ["mouseup", "touchend"];
move_events.forEach(function(event) {
canvas.addEventListener(event, function(e) {
mouse.x = e.pageX - this.offsetLeft;
mouse.y = e.pageY - this.offsetTop;
}, false);
});
ctx.lineWidth = 5;
ctx.lineJoin = 'round';
ctx.lineCap = 'round';
ctx.strokeStyle = 'back';
start_events.forEach(function(event) {
canvas.addEventListener(event, function(e) {
ctx.beginPath();
ctx.moveTo(mouse.x, mouse.y);
move_events.forEach(function(me){ canvas.addEventListener(me, onPaint, false); });
}, false);
});
end_events.forEach(function(event) {
canvas.addEventListener(event, function(e) {
move_events.forEach(function(me){ canvas.removeEventListener(me, onPaint, false); });
}, false);
});
var onPaint = function() {
ctx.lineTo(mouse.x, mouse.y);
ctx.stroke();
};
}());
</script>
</body>
</html>`;
react-native-canvas
目前的維護者,對於來這里尋找 React Native canvas 解決方案的人們:我想讓你知道今天的react-native-canvas
是一個穩定的解決方案,它與它過去的代碼注入 hack 有很大的不同是。
@flyskywhy/react-native-gcanvas是一個基於 gpu opengl glsl shader 的 C++ 原生畫布組件,在 Android 和 iOS 上運行良好。 您可以看到Performance Test Result ,以及一個易於移植的<canvas/>
示例react-native-particles-bg在 Android、iOS 和 Web 上運行。
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