使用 html5 canvas 的等待动画

发布于 2024-12-23 05:21:58 字数 1751 浏览 2 评论 0原文

我正在尝试实现在此问题中提到的那种等待动画，特别是看起来像这样的动画：

在此处输入图像描述

但我不想使用图形文件，并且我尝试纯粹在 html5 canvas 和 javascript 中实现它。另外，我想要一个圆形的黑色背景而不是方形的。作为第一步，我尝试绘制一个静态框架（没有任何移动/旋转）并执行以下操作：

<html>
<head><script>
window.onload = function(){
    var c=document.getElementById("waiting").getContext("2d");
    c.lineCap="round";
    c.fillStyle="#353535";
    c.translate(100,100);
    function slit(p){
        shade = 256*p;
        th = 2*Math.PI*p;
        cos = Math.cos(th);
        sin = Math.sin(th);
        c.strokeStyle = '#'+((shade<<16)+(shade<<8)+shade).toString(16);
        c.moveTo(55*cos, 55*sin);
        c.lineTo(84*cos, 84*sin);
        c.stroke();
        c.closePath();
    }
    c.lineWidth=0;
    c.arc(0,0,100,0,Math.PI*2);
    c.fill();
    c.lineWidth=7;
    for(var i = 0;i<1;i+=0.05){slit(i);}
}
</script></head>
<body><canvas id="waiting" width=200 height=200></canvas></body>
</html>

我得到的结果是：

“在此处输入图像描述”

问题在于，lineCap="round" 无法对所有“狭缝”正常工作，并且 lineWidth=0 属性不适用于圆的边缘。我做错了什么？我用Chrome 16.0.912.63和Firefox 10.0检查过，得到了类似的结果。

下一步，我将让上面创建的部分函数进行交互，

window.animationFrames = (function(callback){
    return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    window.oRequestAnimationFrame ||
    window.msRequestAnimationFrame ||
    function(callback){window.setTimeout(callback, 1000 / 60);};
 })();

但目前我需要先解决这个问题。

原文

I am trying to implement a wating animation of the kind mentioned in this question, particularly something that looks like this:

enter image description here

But I do not want to use graphic files, and am trying to implement it purely in html5 canvas and javascript. Also, I want a circular black background rather than a square one. As a first step, I tried to draw a static frame (without any movement/rotation) and did this:

<html>
<head><script>
window.onload = function(){
    var c=document.getElementById("waiting").getContext("2d");
    c.lineCap="round";
    c.fillStyle="#353535";
    c.translate(100,100);
    function slit(p){
        shade = 256*p;
        th = 2*Math.PI*p;
        cos = Math.cos(th);
        sin = Math.sin(th);
        c.strokeStyle = '#'+((shade<<16)+(shade<<8)+shade).toString(16);
        c.moveTo(55*cos, 55*sin);
        c.lineTo(84*cos, 84*sin);
        c.stroke();
        c.closePath();
    }
    c.lineWidth=0;
    c.arc(0,0,100,0,Math.PI*2);
    c.fill();
    c.lineWidth=7;
    for(var i = 0;i<1;i+=0.05){slit(i);}
}
</script></head>
<body><canvas id="waiting" width=200 height=200></canvas></body>
</html>

The result I get is:

enter image description here

The problem is that, the lineCap="round" is not working correctly for all of the "slits", and the lineWidth=0 attribute is not working for the edge of the circle. What am I doing wrong? I checked it with Chrome 16.0.912.63 and Firefox 10.0, and got similar results.

For the next step, I am going to let parts of the functions that I created above interact with

window.animationFrames = (function(callback){
    return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    window.oRequestAnimationFrame ||
    window.msRequestAnimationFrame ||
    function(callback){window.setTimeout(callback, 1000 / 60);};
 })();

but for the time being, I need to solve this problem first.

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娇柔作态 2024-12-30 05:21:58

这里有一点混乱。

零不是可接受的线宽值。规范规定，如果您说 lineWidth = 0 这将是一个空操作。

此外，您没有在那里使用 lineWidth ，因为您没有抚摸。 fill() 不考虑线宽。

至于另一个问题，你所要做的就是调用beginPath！请参阅此处：

http://jsfiddle.net/JfcDL/

只需添加 beginPath 调用，您将通过代码得到以下内容：

在此处输入图像描述

您所做的错误是绘制整个路径到目前为止每一个新的中风()。您需要调用 beginPath 打开一个新的路径，以便 lines 仅适用于最后一个零件，而不适用于迄今为止制作的所有零件。

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淤浪 2024-12-30 05:21:58

感谢这里几个人的帮助，我终于想出了这段代码，它完全可以与运动配合使用：

<html>
<head><script>
var r1 =  400;
var r2 =  340;
var r3 = 220;
var slitWidth = 40;
var speed = 0.0004;
var attenuation = 1.7;

function rgbToHex(r, g, b){
    return '#' + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
}

window.nextFrame = (function(callback){
    return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    window.oRequestAnimationFrame ||
    window.msRequestAnimationFrame ||
    function(callback){window.setTimeout(callback, 1000 / 60);};
})();

window.onload = function(){
    var waiting=document.getElementById('waiting').getContext('2d');
    function slit(d,p){
        shade = Math.round(Math.pow(1-(d+p)%1, attenuation)*255)
        th = Math.PI*2*(p);
        cos = Math.cos(th);
        sin = Math.sin(th);
        waiting.strokeStyle = rgbToHex(shade, shade, shade);
        waiting.beginPath();
        waiting.moveTo(r2*cos, r2*sin);
        waiting.lineTo(r3*cos, r3*sin);
        waiting.stroke();
        waiting.closePath();
    }
    function frame(){
        waiting.arc(0,0,r1,0,Math.PI*2);
        waiting.fill();
        var time = new Date().getTime()* speed;
        for(var p = 1;p>0;p-=0.05){slit(time,p);}
        nextFrame(function(){frame();});
    }
    waiting.lineCap='round';
    waiting.lineWidth=slitWidth;
    waiting.fillStyle='#353535';
    waiting.translate(r1, r1);
    frame();
}
</script></head>
<body><canvas id='waiting' width=800 height=800></canvas></body>
</html>

Thanks to the help by the several people here, I finally came up with this code, which works fully with the movement:

<html>
<head><script>
var r1 =  400;
var r2 =  340;
var r3 = 220;
var slitWidth = 40;
var speed = 0.0004;
var attenuation = 1.7;

function rgbToHex(r, g, b){
    return '#' + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
}

window.nextFrame = (function(callback){
    return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    window.oRequestAnimationFrame ||
    window.msRequestAnimationFrame ||
    function(callback){window.setTimeout(callback, 1000 / 60);};
})();

window.onload = function(){
    var waiting=document.getElementById('waiting').getContext('2d');
    function slit(d,p){
        shade = Math.round(Math.pow(1-(d+p)%1, attenuation)*255)
        th = Math.PI*2*(p);
        cos = Math.cos(th);
        sin = Math.sin(th);
        waiting.strokeStyle = rgbToHex(shade, shade, shade);
        waiting.beginPath();
        waiting.moveTo(r2*cos, r2*sin);
        waiting.lineTo(r3*cos, r3*sin);
        waiting.stroke();
        waiting.closePath();
    }
    function frame(){
        waiting.arc(0,0,r1,0,Math.PI*2);
        waiting.fill();
        var time = new Date().getTime()* speed;
        for(var p = 1;p>0;p-=0.05){slit(time,p);}
        nextFrame(function(){frame();});
    }
    waiting.lineCap='round';
    waiting.lineWidth=slitWidth;
    waiting.fillStyle='#353535';
    waiting.translate(r1, r1);
    frame();
}
</script></head>
<body><canvas id='waiting' width=800 height=800></canvas></body>
</html>

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