我正在尝试创建一个简单的应用程序，在 Canvas 标签内绘制矩形。我已将画布大小调整为全屏，但每当我调整视口大小时，画布都会清除。我试图阻止它被清除并只保留其中的内容。有任何想法吗？
http://mediajux.com/experiments/canvas/drawing/ http://mediajux.com/experiments/canvas/drawing/
/*
* This is the primary class used for the application
* @author Alvin Crespo
*/
var app = (function(){
var domBod = document.body;
var canvas = null;
var canvasWidth = null;
var canvasHeight = null;
return {
//Runs after the DOM has achieved an onreadystatechange of "complete"
initApplication: function()
{
//setup envrionment variables
canvas = document.getElementById('canvas') || null;
//we need to resize the canvas at the start of the app to be the full window
this.windowResized();
//only set the canvas height and width if it is not false/null
if(canvas)
{
canvasWidth = canvas.offsetWidth;
canvasHeight = canvas.offsetHeight;
}
//add window events
window.onresize = this.windowResized;
circles.canvas = canvas;
circles.canvasWidth = canvasWidth;
circles.canvasHeight = canvasHeight;
circles.generateCircles(10);
setInterval(function(){
circles.animateCircles();
}, 50);
},
/**
* Executes Resizing procedures on the canvas element
*/
windowResized: function()
{
(this.domBod === null) ? 'true' : 'false';
try{
console.log(canvas);
canvas.setAttribute('width', document.body.clientWidth);
canvas.setAttribute('height', document.body.clientHeight);
}catch(e) {
console.log(e.name + " :: " + e.message);
}
},
/**
* Returns the canvas element
* @returns canvas
*/
getCanvas: function()
{
return canvas;
}
};
})();
设置画布宽度属性将清除画布。
如果您调整样式宽度（例如canvas.style.visibility），它会扩展（通常不会以如此漂亮的方式）。
如果您想让画布更大但保持其中的元素不变，我建议将画布存储为图像 - 例如打电话给toDataURL方法获取图像，然后将其绘制到调整大小的画布上drawImage().
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