2

私はJavascriptにかなり慣れていないので、少し助けてくれることを望んでいました. canvas と javascript を使用してグラフをアニメーション化して遊んでいます。ページが読み込まれると、事前に決められたパーセンテージまでグラフがいっぱいになるようにしています。

onclick のあるボタンもいくつかあります。目的は、これらのボタンをクリックしてアニメーション機能を再度実行することですが、割合は異なります。ただし、それらをクリックしても問題はありません。

これについてあなたが私に与えることができるどんな助けも素晴らしいでしょう.

コード：

    window.onload = function(){
    //canvas initialization
    var canvas = document.getElementById("canvas");
    var ctx = canvas.getContext("2d");
    //dimensions
    var W = canvas.width;
    var H = canvas.height;
    //Variables
    var degrees = 0;
    var new_degrees = 0;
    var difference = 0;
    var color = "#c70505"; //green looks better to me
    var bgcolor = "#222";
    var text;
    var animation_loop, redraw_loop;

    function init()
    {
        //Clear the canvas everytime a chart is drawn
        ctx.clearRect(0, 0, W, H);

        //Background 360 degree arc
        ctx.beginPath();
        ctx.strokeStyle = bgcolor;
        ctx.lineWidth = 30;
        ctx.arc(W/2, H/2, 100, 0, Math.PI*2, false); //you can see the arc now
        ctx.stroke();

        //gauge will be a simple arc
        //Angle in radians = angle in degrees * PI / 180
        var radians = degrees * Math.PI / 180;
        ctx.beginPath();
        ctx.strokeStyle = color;
        ctx.lineWidth = 30;
        //The arc starts from the rightmost end. If we deduct 90 degrees from the angles
        //the arc will start from the topmost end
        ctx.arc(W/2, H/2, 100, 0 - 90*Math.PI/180, radians - 90*Math.PI/180, false); 
        //you can see the arc now
        ctx.stroke();

        //Lets add the text
        ctx.fillStyle = color;
        ctx.font = "50px bebas";
        text = Math.floor(degrees/360*100) + "%";
        //Lets center the text
        //deducting half of text width from position x
        text_width = ctx.measureText(text).width;
        //adding manual value to position y since the height of the text cannot
        //be measured easily. There are hacks but we will keep it manual for now.
        ctx.fillText(text, W/2 - text_width/2, H/2 + 15);
    }

    function draw(percent)
    {
        //Cancel any movement animation if a new chart is requested
        if(typeof animation_loop != undefined) clearInterval(animation_loop);

        //random degree from 0 to 360
        new_degrees = percent
        difference = new_degrees - degrees;
        //This will animate the gauge to new positions
        //The animation will take 1 second
        //time for each frame is 1sec / difference in degrees
        animation_loop = setInterval(animate_to, 1000/difference);
    }

    //function to make the chart move to new degrees
    function animate_to()
    {
        //clear animation loop if degrees reaches to new_degrees
        if(degrees == new_degrees) 
            clearInterval(animation_loop);

        if(degrees < new_degrees)
            degrees++;
        else
            degrees--;

        init();
    }

        draw(100);

}

<canvas id="canvas" width="300" height="300"></canvas>


<button onclick="draw(360)">100%</button>
<button onclick="draw(270)">75%</button>
4

2 に答える 2

0

draw割り当てた無名関数のwindow.onload実行が終了するとすぐに、関数はスコープ外になります。代わりにグローバルスコープで関数を宣言すると、どこからでも呼び出すことができます。これが実用的なフィドルです。

于 2012-10-27T20:00:00.757 に答える
0

私のアップデートを試してください：

<script>
//canvas initialization
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
//dimensions
var W = canvas.width;
var H = canvas.height;
//Variables
var degrees = 0;
var new_degrees = 0;
var difference = 0;
var color = "#c70505"; //green looks better to me
var bgcolor = "#222";
var text;
var animation_loop, redraw_loop;

function init()
{
    //Clear the canvas everytime a chart is drawn
    ctx.clearRect(0, 0, W, H);

    //Background 360 degree arc
    ctx.beginPath();
    ctx.strokeStyle = bgcolor;
    ctx.lineWidth = 30;
    ctx.arc(W/2, H/2, 100, 0, Math.PI*2, false); //you can see the arc now
    ctx.stroke();

    //gauge will be a simple arc
    //Angle in radians = angle in degrees * PI / 180
    var radians = degrees * Math.PI / 180;
    ctx.beginPath();
    ctx.strokeStyle = color;
    ctx.lineWidth = 30;
    //The arc starts from the rightmost end. If we deduct 90 degrees from the angles
    //the arc will start from the topmost end
    ctx.arc(W/2, H/2, 100, 0 - 90*Math.PI/180, radians - 90*Math.PI/180, false); 
    //you can see the arc now
    ctx.stroke();

    //Lets add the text
    ctx.fillStyle = color;
    ctx.font = "50px bebas";
    text = Math.floor(degrees/360*100) + "%";
    //Lets center the text
    //deducting half of text width from position x
    text_width = ctx.measureText(text).width;
    //adding manual value to position y since the height of the text cannot
    //be measured easily. There are hacks but we will keep it manual for now.
    ctx.fillText(text, W/2 - text_width/2, H/2 + 15);
}

function draw(percent)
{
    //Cancel any movement animation if a new chart is requested
    if(typeof animation_loop != undefined) clearInterval(animation_loop);

    //random degree from 0 to 360
    new_degrees = percent
    difference = new_degrees - degrees;
    //This will animate the gauge to new positions
    //The animation will take 1 second
    //time for each frame is 1sec / difference in degrees
    animation_loop = setInterval(animate_to, 1000/difference);
}

//function to make the chart move to new degrees
function animate_to()
{
    //clear animation loop if degrees reaches to new_degrees
    if(degrees == new_degrees) 
        clearInterval(animation_loop);

    if(degrees < new_degrees)
        degrees++;
    else
        degrees--;

    init();
}
draw(100);
</script>

<canvas id="canvas" width="300" height="300"></canvas>
<button onclick="draw(360)">100%</button>
<button onclick="draw(270)">75%</button>
于 2012-10-27T20:03:05.917 に答える