html5 canvas重绘大小调整 [英] html5 canvas redraw on resize

问题描述

我有两个canvas元素，需要在按钮上调整大小。

I have two canvas elements and need them to be resized on buttons click.

<div class="sDetails"><div>
                        <div id="canvasDiv" style="width: 310px;"><canvas id="canvasGraph"></canvas></div></div>
<div class="kDetails"><div><div>
<div id="canvasDiv" style="width: 310px; height: 240px;"><canvas id="canvasGraph"></canvas></div></div>

和脚本：

   var sketch;var sketch_sl;var onPaint;var canvas=null;var ctx=null;var tmp_ctx=null;
    function drawCanvas(div) {
        canvas = document.querySelector(div + " #canvasGraph");
        ctx = canvas.getContext('2d');
        sketch = document.querySelector(div + " #canvasDiv");
        sketch_sl = getComputedStyle(sketch);
        canvas.width = parseInt(sketch_style.getPropertyValue('width'));
        canvas.height = parseInt(sketch_style.getPropertyValue('height'));
        tmp_canvas = document.createElement('canvas');
        tmp_ctx = tmp_canvas.getContext('2d');
        tmp_canvas.id = 'tmp_canvas';
        tmp_canvas.width = canvas.width;
        tmp_canvas.height = canvas.height;
        sketch.appendChild(tmp_canvas);

重画功能：

// here I must redraw my lines resized 2 times ( *cScale ) where cScale=2 or =1
function drawScales(ctx, canvas) 
        ctx.strokeStyle = 'green';
        ctx.fillStyle = 'green';
        ctx.beginPath();
        ctx.moveTo(5, 0);
        ctx.lineTo(0, canvas.height);
        scaleStep = 24*cScale;

由于某种原因它工作真的很糟糕，旧职位留下。
有没有办法完全删除整个画布并添加或完全重绘？

for some reason it works really bad, old positions stay. Is there a way to completely delete the whole canvas and append it or redraw it completely?

我试过 canvas.width = canvas .width ，试过 ctx.clearRect（0，0，canvas.width，canvas.height）; tmp_ctx.clearRect（0，0，canvas.width，canvas.height） ; ，尝试 $（。sDetails #canvasGraph）[0] .reset（）;

逻辑上， drawCanvas（。sDetails）; drawLines（ctx，canvas）; 应该从头重新绘制，但不会。

logically, drawCanvas(".sDetails");drawLines(ctx, canvas); should redraw it from scratch but it will not.

推荐答案

我决定使用一个scale变量来调整我的scale。我调整画布 canvas.width * = 2; ，然后我重新绘制我的尺度。

I decided to use a scale variable to resize my scales. I resize the canvas canvas.width *= 2; and then I redraw my scales.

var scaleStep;

代码： ctx.lineTo（12 * 24 * cScale + 12，canvas.height-24）; 其中需要进行缩放。
scaleStep在最大化画布时为2，在返回原始大小时为1。

and use add it into the code: ctx.lineTo(12*24*cScale+12, canvas.height-24); where the scaling needs to be done. The scaleStep is 2 when maximizing the canvas and 1 when returning to the original size.

这篇关于html5 canvas重绘大小调整的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！