调整HTML5画布大小以适合窗口-Java 学习之路

354

如何自动缩放HTML5 <canvas> 元素以适合页面？

例如，我可以通过将 height 和 width 属性设置为100％来缩放 <div> ，但 <canvas> 不会缩放，是吗？

14 回答

以下解决方案最适合我 . 由于我对编码比较陌生，我喜欢用视觉确认某些东西按照我期望的方式工作 . 我在以下网站找到了它：http://htmlcheats.com/html/resize-the-html5-canvas-dyamically/

这是代码：

<!DOCTYPE html>

<head>
    <meta charset="utf-8">
    <title>Resize HTML5 canvas dynamically | www.htmlcheats.com</title>
    <style>
    html, body {
      width: 100%;
      height: 100%;
      margin: 0px;
      border: 0;
      overflow: hidden; /*  Disable scrollbars */
      display: block;  /* No floating content on sides */
    }
    </style>
</head>

<body>
    <canvas id='c' style='position:absolute; left:0px; top:0px;'>
    </canvas>

    <script>
    (function() {
        var
        // Obtain a reference to the canvas element using its id.
        htmlCanvas = document.getElementById('c'),
        // Obtain a graphics context on the canvas element for drawing.
        context = htmlCanvas.getContext('2d');

       // Start listening to resize events and draw canvas.
       initialize();

       function initialize() {
           // Register an event listener to call the resizeCanvas() function 
           // each time the window is resized.
           window.addEventListener('resize', resizeCanvas, false);
           // Draw canvas border for the first time.
           resizeCanvas();
        }

        // Display custom canvas. In this case it's a blue, 5 pixel 
        // border that resizes along with the browser window.
        function redraw() {
           context.strokeStyle = 'blue';
           context.lineWidth = '5';
           context.strokeRect(0, 0, window.innerWidth, window.innerHeight);
        }

        // Runs each time the DOM window resize event fires.
        // Resets the canvas dimensions to match window,
        // then draws the new borders accordingly.
        function resizeCanvas() {
            htmlCanvas.width = window.innerWidth;
            htmlCanvas.height = window.innerHeight;
            redraw();
        }
    })();

    </script>
</body> 
</html>

蓝色边框显示调整大小画布的边缘，并且始终沿着窗口的边缘，在所有4个边上都可见，而上述其他一些答案则不然 . 希望能帮助到你 .

回复于 2024-04-20T05:15:18+08:00

一个 pure CSS 方法添加到@jerseyboy的解决方案上面 .
适用于Firefox（在v29中测试），Chrome（在v34中测试）和Internet Explorer（在v11中测试） .

<!DOCTYPE html>
<html>
    <head>
    <style>
        html,
        body {
            width: 100%;
            height: 100%;
            margin: 0;
        }
        canvas {
            background-color: #ccc;
            display: block;
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            width: 100%;
            height: 100%;
        }
    </style>
</head>
<body>
    <canvas id="canvas" width="500" height="500"></canvas>
    <script>
        var canvas = document.getElementById('canvas');
        if (canvas.getContext) {
            var ctx = canvas.getContext('2d');
            ctx.fillRect(25,25,100,100);
            ctx.clearRect(45,45,60,60);
            ctx.strokeRect(50,50,50,50);
        }
    </script>
</body>
</html>

链接到示例：http://temporaer.net/open/so/140502_canvas-fit-to-window.html

但请小心，正如@jerseyboy在评论中所述：

用CSS重新调整画布很麻烦 . 至少在Chrome和Safari上，鼠标/触摸事件位置不会与画布像素位置1：1对应，您必须转换坐标系 .

回复于 2024-04-20T05:15:18+08:00

我认为这应该是我们应该做的：http://www.html5rocks.com/en/tutorials/casestudies/gopherwoord-studios-resizing-html5-games/

function resizeGame() {
    var gameArea = document.getElementById('gameArea');
    var widthToHeight = 4 / 3;
    var newWidth = window.innerWidth;
    var newHeight = window.innerHeight;
    var newWidthToHeight = newWidth / newHeight;

    if (newWidthToHeight > widthToHeight) {
        newWidth = newHeight * widthToHeight;
        gameArea.style.height = newHeight + 'px';
        gameArea.style.width = newWidth + 'px';
    } else {
        newHeight = newWidth / widthToHeight;
        gameArea.style.width = newWidth + 'px';
        gameArea.style.height = newHeight + 'px';
    }

    gameArea.style.marginTop = (-newHeight / 2) + 'px';
    gameArea.style.marginLeft = (-newWidth / 2) + 'px';

    var gameCanvas = document.getElementById('gameCanvas');
    gameCanvas.width = newWidth;
    gameCanvas.height = newHeight;
}

window.addEventListener('resize', resizeGame, false);
window.addEventListener('orientationchange', resizeGame, false);

回复于 2024-04-20T05:15:18+08:00

基本上你要做的是将onresize事件绑定到你的身体，一旦你捕获事件你只需要使用window.innerWidth和window.innerHeight来调整画布的大小 .

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Canvas Resize</title>

    <script type="text/javascript">
        function resize_canvas(){
            canvas = document.getElementById("canvas");
            if (canvas.width  < window.innerWidth)
            {
                canvas.width  = window.innerWidth;
            }

            if (canvas.height < window.innerHeight)
            {
                canvas.height = window.innerHeight;
            }
        }
    </script>
</head>

<body onresize="resize_canvas()">
        <canvas id="canvas">Your browser doesn't support canvas</canvas>
</body>
</html>

回复于 2024-04-20T05:15:18+08:00

-2

我相信我找到了一个优雅的解决方案：

JavaScript

/* important! for alignment, you should make things
 * relative to the canvas' current width/height.
 */
function draw() {
  var ctx = (a canvas context);
  ctx.canvas.width  = window.innerWidth;
  ctx.canvas.height = window.innerHeight;
  //...drawing code...
}

CSS

html, body {
  width:  100%;
  height: 100%;
  margin: 0px;
}

到目前为止，对我没有任何大的负面影响 .

回复于 2024-04-20T05:15:18+08:00

2

如果您的div完全填满了网页，那么您可以填满该div，因此有一个填充div的画布 .

您可能会觉得这很有趣，因为您可能需要使用css来使用百分比，但是，这取决于您使用的浏览器，以及与规范一致的程度：http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#the-canvas-element

canvas元素的固有尺寸等于坐标空间的大小，数字以CSS像素解释 . 但是，元素可以通过样式表任意调整大小 . 在渲染过程中，缩放图像以适合此布局大小 .

您可能需要获取div的offsetWidth和height，或获取窗口高度/宽度并将其设置为像素值 .

回复于 2024-04-20T05:15:18+08:00

(function() {

    // get viewport size
    getViewportSize = function() {
        return {
            height: window.innerHeight,
            width:  window.innerWidth
        };
    };

    // update canvas size
    updateSizes = function() {
        var viewportSize = getViewportSize();
        $('#myCanvas').width(viewportSize.width).height(viewportSize.height);
        $('#myCanvas').attr('width', viewportSize.width).attr('height', viewportSize.height);
    };

    // run on load
    updateSizes();

    // handle window resizing
    $(window).on('resize', function() {
        updateSizes();
    });

}());

回复于 2024-04-20T05:15:18+08:00

使用jQuery，您可以跟踪窗口调整大小并使用jQuery更改画布的宽度 .

这样的事情

$( window ).resize(function() {
 		$("#myCanvas").width($( window ).width())
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<canvas id="myCanvas" width="200" height="100" style="border:1px solid #000000;">

回复于 2024-04-20T05:15:18+08:00

335
根据浏览器客户端的尺寸设置画布坐标空间的宽度和高度，需要在调整浏览器大小时调整大小和重绘 .

一个不太复杂的解决方案是在Javascript变量中维护可绘制的维度，但是根据screen.width，screen.height维度设置画布尺寸 . 使用CSS来适应：
```
#containingDiv { 
  overflow: hidden;
}
#myCanvas {
  position: absolute; 
  top: 0px;
  left: 0px;
}
```
浏览器窗口通常不会大于屏幕本身（除非屏幕分辨率被误报，因为它可能与非匹配的双显示器一样），因此背景将不会显示，像素比例也不会变化 . 除非您使用CSS来缩放画布，否则画布像素将与屏幕分辨率成正比 .
回复于 2024-04-20T05:15:18+08:00
18

除非您希望画布自动升级您的图像数据（'s what James Black'的答案谈到，但它看起来不太漂亮），您必须自己调整大小并重新绘制图像 . Centering a canvas

回复于 2024-04-20T05:15:18+08:00

CSS

body { margin: 0; } 
canvas { display: block; }

JavaScript

window.addEventListener("load", function()
{
    var canvas = document.createElement('canvas'); document.body.appendChild(canvas);
    var context = canvas.getContext('2d');

    function draw()
    {
        context.clearRect(0, 0, canvas.width, canvas.height);
        context.beginPath();
        context.moveTo(0, 0); context.lineTo(canvas.width, canvas.height); 
        context.moveTo(canvas.width, 0); context.lineTo(0, canvas.height); 
        context.stroke();
    }
    function resize()
    {
        canvas.width = window.innerWidth;
        canvas.height = window.innerHeight;
        draw();
    }
    window.addEventListener("resize", resize);
    resize();
});

回复于 2024-04-20T05:15:18+08:00

function resize() {

    var canvas = document.getElementById('game');
    var canvasRatio = canvas.height / canvas.width;
    var windowRatio = window.innerHeight / window.innerWidth;
    var width;
    var height;

    if (windowRatio < canvasRatio) {
        height = window.innerHeight;
        width = height / canvasRatio;
    } else {
        width = window.innerWidth;
        height = width * canvasRatio;
    }

    canvas.style.width = width + 'px';
    canvas.style.height = height + 'px';
};

window.addEventListener('resize', resize, false);

回复于 2024-04-20T05:15:18+08:00

如果您对保留纵横比感兴趣并且在纯CSS中这样做（给定纵横比），您可以执行以下操作 . 关键是 ::content 元素上的 padding-bottom ，它调整了 container 元素的大小 . 它的大小相对于其父级的宽度，默认为 100% . 此处指定的比率必须与 canvas 元素上的大小比例相匹配 .

// Javascript

var canvas = document.querySelector('canvas'),
    context = canvas.getContext('2d');

context.fillStyle = '#ff0000';
context.fillRect(500, 200, 200, 200);

context.fillStyle = '#000000';
context.font = '30px serif';
context.fillText('This is some text that should not be distorted, just scaled', 10, 40);

/*CSS*/

.container {
  position: relative; 
  background-color: green;
}

.container::after {
  content: ' ';
  display: block;
  padding: 0 0 50%;
}

.wrapper {
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  bottom: 0;
}

canvas {
  width: 100%;
  height: 100%;
}

<!-- HTML -->

<div class=container>
  <div class=wrapper>
    <canvas width=1200 height=600></canvas>  
  </div>
</div>

回复于 2024-04-20T05:15:18+08:00

0

我正在使用sketch.js所以在我为画布运行init命令后，我用jquery更改了宽度和高度 . 它基于父元素的维度 .

$（'＃DrawCanvas'） . sketch（） . attr（'height'，$（'＃DrawCanvas'） . parent（） . height（）） . attr（'width'，$（'＃DrawCanvas'） . . 父（）宽度（））;

回复于 2024-04-20T05:15:18+08:00

调整HTML5画布大小以适合窗口

14 回答

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