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如何使用 javascript/jquery 调整画布的大小?

使用 css 函数调整大小并将其应用于画布元素只会拉伸内容,就像拉伸图像一样。

如果没有拉伸,我将如何做呢?

http://jsfiddle.net/re8KU/4/

4

3 回答 3

26

制作一个绘制函数,然后在需要它的更改时重新绘制(如页面大小调整等)。试试看

确保设置 context.canvas.width/height,而不是 CSS 宽度/高度。另请注意,设置大小会清除画布。

我会怎么写:

(function(){
    var c = $("#canvas"), 
        ctx = c[0].getContext('2d');

    var draw = function(){
        ctx.fillStyle = "#000";
        ctx.fillRect(10,10,50,50);   
    };

    $(function(){
        // set width and height
         ctx.canvas.height = 600;
         ctx.canvas.width = 600;
        // draw
        draw();

        // wait 2 seconds, repeate same process
        setTimeout(function(){
            ctx.canvas.height = 400;
            ctx.canvas.width = 400;
            draw();
        }, 2000)
    });
})();

​</p>

于 2012-07-06T19:39:01.600 回答
10
 (function($) {  
        $.fn.extend({  
            //Let the user resize the canvas to the size he/she wants  
            resizeCanvas:  function(w, h) {  
                var c = $(this)[0]  
                c.width = w;  
                c.height = h  
            }  
        })  
    })(jQuery)

使用我创建的这个小功能来随时随地调整大小。以这种方式使用它——

$("the canvas element id/class").resizeCanvas(desired width, desired height)
于 2012-10-11T16:14:51.243 回答
1

每当调整浏览器的大小时,以下解决方案都会根据窗口的尺寸通过创建初始比例来调整画布的尺寸。

jsfiddle:http: //jsfiddle.net/h6c3rxxf/9/

注意:画布在调整大小时需要重新绘制。

HTML:

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

CSS:

canvas {
    border: 1px dotted black;
    background: blue;
}

JavaScript:

(function() {
    // get the precentage of height and width  of the cavas based on the height and width of the window
    getPercentageOfWindow = function() {
        var viewportSize = getViewportSize();
        var canvasSize = getCanvastSize();
        return {
            x: canvasSize.width / (viewportSize.width - 10),
            y: canvasSize.height / (viewportSize.height - 10)
        };
    };
    //get the context of the canvas 
    getCanvasContext = function() {
        return $("#myCanvas")[0].getContext('2d');
    };
    // get viewport size
    getViewportSize = function() {
        return {
            height: window.innerHeight,
            width: window.innerWidth
        };
    };
    // get canvas size
    getCanvastSize = function() {
        var ctx = getCanvasContext();
        return {
            height: ctx.canvas.height,
            width: ctx.canvas.width
        };
    };
    // update canvas size
    updateSizes = function() {
        var viewportSize = getViewportSize();
        var ctx = getCanvasContext();
        ctx.canvas.height = viewportSize.height * percentage.y;
        ctx.canvas.width = viewportSize.width * percentage.x;
    };
    var percentage = getPercentageOfWindow();
    $(window).on('resize', function() {
        updateSizes();
    });
}());
于 2015-06-25T01:46:46.200 回答