canvas拼图功能实现代码示例

/**     * canvas绘图数据     * @param {Object[]} option.photoData     * @param {string} option.photoData[].photo - 照片的链接地址     * @param {number} option.photoData[].width -  照片的宽度     * @param {number} option.photoData[].height -  照片的高度     * @param {Object[]} option.wordData     * @param {string} option.wordData[].color - 文字的颜色     * @param {number} option.wordData[].fontSize - 文字的大小     * @param {string} option.wordData[].fontWeight -  文字的粗细     * @param {number} option.wordData[].left - 文字的左边距     * @param {number} option.wordData[].top -  文字的上边距     * @param {string} option.wordData[].word -  文字的内容     * @param {Object[]} option.iconData     * @param {string} option.iconData[].photo - icon的链接地址     * @param {number} option.iconData[].left -  icon的左边距     * @param {number} option.iconData[].top -  icon的上边距     * @param {number} option.iconData[].width -  icon的宽度     * @param {number} option.iconData[].height -  icon的高度     *    */function canvasDraw(option){        var canvas = document.createElement('canvas'),            ctx = canvas.getContext('2d'),            clientWidth = document.documentElement.clientWidth,            canvasHeight = 0,            distance = 0,            photoCount = 0,            iconCount = 0;        // canvas中手机上一倍绘图会模糊，需采用两倍，pc端不会。            clientWidth = clientWidth > 480? 480 * 2 : clientWidth * 2;         option.photoData.forEach(function(item,index,picArr){            if (!index) {                item.distance = 0;            }else if(index){                distance += Math.floor(clientWidth / option.photoData[index - 1].width * option.photoData[index - 1].height)                item.distance = distance;            }            canvasHeight += Math.floor(clientWidth / item.width * item.height);            item.imgHeight = Math.floor(clientWidth / item.width * item.height);        })                console.log(option.photoData)        if (ctx) {            canvas.width = clientWidth;            canvas.height  = canvasHeight + clientWidth / 4 * 2                    ctx.fillStyle = '#fff'            ctx.fillRect(0, 0, canvas.width, canvas.height)            // 绘制图片文字            if(option.wordData.length){                option.wordData.forEach(function(item,index){                    ctx.fillStyle = item.color;                    ctx.font = 'normal normal ' + item.fontWeight + ' ' + calculate(item.fontSize) + 'px Microsoft YaHei';                    ctx.textAlign = 'left';                    ctx.fillText(item.word, calculate(item.left), canvasHeight + calculate(item.top));                    })            }            //按比例计算不同手机的百分比间距            function calculate(num){                return Math.floor(clientWidth * num / 750)            }            drawPhoto('photo0')            function drawPhoto(photoDom){                var photoDom = new Image();                    photoDom.setAttribute('crossOrigin', 'Anonymous');                photoDom.src = option.photoData[photoCount].photo;                photoDom.onload = function(){                    ctx.drawImage(photoDom, 0, option.photoData[photoCount].distance, clientWidth, option.photoData[photoCount].imgHeight);                    photoCount++;                    if (photoCount == option.photoData.length) {                        drawIcon('icon0')                        function drawIcon(iconDom){                            var iconDom = new Image();                                iconDom.setAttribute('crossOrigin', 'Anonymous');                            iconDom.src = option.iconData[iconCount].icon;                            iconDom.onload = function(){                                ctx.drawImage(iconDom, calculate(option.iconData[iconCount].left), canvasHeight + calculate(option.iconData[iconCount].top), calculate(option.iconData[iconCount].width), calculate(option.iconData[iconCount].height))                                iconCount++;                                if (iconCount == option.iconData.length) {                                    var imageURL = canvas.toDataURL("image/jpeg")                                    document.getElementsByClassName('shareImg')[0].setAttribute('src', imageURL)                                    //将闭包引用清除，释放内存;                                    drawPhoto = null;                                }else{                                    drawIcon('icon' + iconCount)                                }                            }                            }                                                     }else{                        drawPhoto('photo'+ photoCount)                                            }                    }                                                            }        }else{            console.log('不支持canvas')        }    }