Firefox上的Canvas Draw Image问题，在chrome中效果很好

Question

我将假定这是某种兼容性问题。一切都可以在chrome中完美运行，但是在Firefox中，它<canvas>根本无法画任何东西。

function drawStage(stageNum) {
    var cap = canvasArray.length; //keeps the canvasElements
    var i;
    var stageImages = images["stage" + stageNum];
    var stageDimensions = imageDimensions["stage" + stageNum];
    //console.log("Cap is: " + cap);


    for (i = 0; i < cap; i++) {
        var canvas = document.getElementById(canvasArray[i]);
        var canvasContext = canvas.getContext("2d");
        var image = document.getElementById(stageImages[i]);

        canvasContext.clearRect(0, 0, 1280, 1280);
        canvasContext.drawImage(image, stageDimensions[i][0], stageDimensions[i][1], stageDimensions[i][2], stageDimensions[i][3]);
        //document.getElementById(zIndexes[i][0]).style["z-index"] = zIndexes[i][stageNum];
        //console.log(document.getElementById(zIndexes[i][0]).id);
    }
}

编辑： 这是我制作的“测试”代码示例的保管箱链接，它更简单，1张图像，1个画布，1个div，相似（实际上是相同的）脚本，但仍无法在Firefox中使用，但可以在chrome中使用。如果您可以在那里解决问题，那么这也将得到解决。

更新：数组在下面，根据请求，它们是不同元素/坐标的简单输入。不过，我向您保证，数组本身没有问题，在chrome中一切正常。该函数中有关DrawImage（）方法的某些问题引起了我要说的问题。（数组下方的进一步说明）

images是<img>元素的（全局）id数组。

    var images = {
    stage1: ["character1Base", "character2Base", "character3Base", "character4Base", "character5Base", "character6Base", "character3BotImg"],
    stage2: ["character1Sit", "character2Base", "character3Base", "character4Base", "character5Base", "character6Base", "character3BotImg"],
    stage3: ["character1Sit", "character2Drink", "character3Base", "character4Base", "character5Base", "character6Base", "character3BotImg"],
    stage4: ["character1Sit", "character2Drink", "character3Base", "character4Base", "character5Base", "character6Doll", "character3BotImg"],
    stage5: ["character1Sit", "character2Drink", "character3Eat", "character4Base", "character5Base", "character6Doll", "character3EatBot"],
    stage6: ["character1Sit", "character2Stand", "character3Eat", "character4Base", "character5Base", "character6Doll", "character3EatBot"],
    stage7: ["character1Sit", "character2Stand", "character3Eat", "character4Sit", "character5Base", "character6Doll", "character3EatBot"],
    stage8: ["character1Sit", "character2Stand", "character3Eat", "character4Sit", "character5Sit", "character6Doll", "character3EatBot"],
    stage9: ["character1Sit", "character2Eat", "character3Eat", "character4Sit", "character5Sit", "character6Doll", "character3EatBot"],
    stage10: ["character1Drink", "character2Eat", "character3Eat", "character4Sit", "character5Sit", "character6Doll", "character3EatBot"]
};

imageDimensions是井，尺寸，posX，posY，sizeX和sizeY的（全局）数组。

    var imageDimensions = {
    stage1: [[0, 0, 233, 485], [0, 0, 153, 407], [20, 0, 220, 200], [0, 150, 505, 210], [0, 0, 315, 391], [0, 0, 480, 435], [1, 0, 220, 180]],
    stage2: [[105, 35, 180, 440], [0, 0, 153, 407], [20, 0, 220, 200], [0, 150, 505, 210], [0, 0, 315, 391], [0, 0, 480, 435], [1, 0, 220, 180]],
    stage3: [[105, 35, 180, 440], [0, 0, 153, 407], [20, 0, 220, 200], [0, 150, 505, 210], [0, 0, 315, 391], [0, 0, 480, 435], [1, 0, 220, 180]],
    stage4: [[105, 35, 180, 440], [0, 0, 153, 407], [20, 0, 220, 200], [0, 150, 505, 210], [0, 0, 315, 391], [0, 0, 480, 435], [1, 0, 220, 180]],
    stage5: [[105, 35, 180, 440], [0, 0, 153, 407], [3, 7, 226, 180], [0, 150, 505, 210], [0, 0, 315, 391], [0, 0, 480, 435], [1, 9, 220, 180]],
    stage6: [[105, 35, 180, 440], [0, 0, 172, 490], [3, 7, 226, 180], [0, 150, 505, 210], [0, 0, 315, 391], [0, 0, 480, 435], [1, 9, 220, 180]],
    stage7: [[105, 35, 180, 440], [0, 0, 172, 490], [3, 7, 226, 180], [70, 0, 341, 380], [0, 0, 315, 391], [0, 0, 480, 435], [1, 9, 220, 180]],
    stage8: [[105, 35, 180, 440], [0, 0, 172, 490], [3, 7, 226, 180], [70, 0, 341, 380], [18, 72, 305, 422], [0, 0, 480, 435], [1, 9, 220, 180]],
    stage9: [[105, 35, 180, 440], [0, 0, 173, 473], [3, 7, 226, 180], [70, 0, 341, 380], [18, 72, 305, 422], [0, 0, 480, 435], [1, 9, 220, 180]],
    stage10: [[105, 32, 162, 440], [0, 0, 173, 473], [3, 7, 226, 180], [70, 0, 341, 380], [18, 72, 305, 422], [0, 0, 480, 435], [1, 9, 220, 180]]
};

说明： 该功能旨在在屏幕上绘制不同的元素，这些元素属于这些元素。它们是在画布中绘制的（稍后还将在画布中进行动画处理）。该stageNum参数是函数采用的唯一参数，它决定要绘制的内容。

有人知道是什么问题吗？（我读过一些类似的文章，但所有问题都是鼠标位置的layerX，layerY，但是我根本不在这里使用mouseover / mousein / mouseout，仍然没有绘制元素。

Answer 1

您的问题是您要绘制的图像是svg图像，并且这些svg文档具有相对width和height属性。

浏览器无法为其要绘制的图像设置高度或宽度，因此无法将其呈现到画布上。（它可以在文档中进行估算，因为它可以相对于某物，但不能相对于画布）。

因此，解决方案是在svg文件中设置绝对值width和height属性，

或者，更复杂的是，首先将其绘制为<iframe>或<object>，然后绘制一个序列化版本，在该版本中将设置这些属性。

function initialize() {
    var canvas = document.getElementById("char1Canvas");
    var canvasContext = canvas.getContext("2d");
    var image = document.getElementById("char1Img");
    resizeSVG(image, function(e){
        canvasContext.clearRect(0, 0, 1280, 1280);
        canvasContext.drawImage(this, 0, 0);
    });
};

var resizeSVG = function(svgImg, callback){
    // create an iframe
    var iframe = document.createElement('iframe');
    // so we don't see it
    iframe.height = 0;
    iframe.width = 0;
    iframe.onload = function(){
        var doc = iframe.contentDocument;
        var svg = doc.querySelector('svg');
        // get the computed width and height of your img element
        // should probably be tweaked
        var bbox = svgImg.getBoundingClientRect();
        // if it's a relative width
        if (svg.width.baseVal.unitType !== 1) {
            svg.setAttribute('width', bbox.width);
        }
        // or a relative height
        if (svg.height.baseVal.unitType !== 1) {
            svg.setAttribute('height', bbox.height);
        }
        // serialize our updated svg
        var svgData = (new XMLSerializer()).serializeToString(svg);
        var svgURL = 'data:image/svg+xml; charset=utf8, ' + encodeURIComponent(svgData);
        // create a new Image Object that ill be draw on the canvas
        var img = new Image();
        img.onload = callback;
        img.src = svgURL;
        // remove the iframe
        document.body.removeChild(iframe);
    };
    iframe.src = svgImg.src;
    document.body.appendChild(iframe);
}