HTML5 Canvas显示本地图片实例1、Canvas预览图片实例1

    <input    type="file" />
    <canvas       height="500"></canvas>
    <script >
        //读取本地文件
        var inputOne = document.getElementById('fileOne');
        inputOne.onchange = function() {
            //1.获取选中的文件列表
            var fileList =inputOne.files;
            var file = fileList[0];
            //读取文件内容
            var reader = newFileReader();
            reader.readAsDataURL(file);
            reader.onload = function(e) {
                //将结果显示到canvas
showCanvas(reader.result);
            }
        }
        //指定图片内容显示
        functionshowCanvas(dataUrl) {
            console.info(dataUrl);
            var canvas = document.getElementById('canvasOne');
            var ctx = canvas.getContext('2d');
            //加载图片
            var img = newImage();
            img.onload = function() {
                ctx.drawImage(img, 0, 0, img.width, img.height);
            }
            img.src =dataUrl;
            //document.body.appendChild(img);
}
    </script>