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  • 移动端 js 实现图片上传 预览

    方法一:

    <html xmlns="http://www.w3.org/1999/xhtml">
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
            <title>测试页面</title>
            <script type="text/javascript">
            //图片预览功能
                function previewImage(file, imgNum)
                {
                    var MAXWIDTH = 200;
                    var MAXHEIGHT = 200;
                    var div = document.getElementById('preview' + imgNum);
                    if (file.files && file.files[0])
                    {
                        div.innerHTML = '<img id=imghead' + imgNum + '>';
                        var img = document.getElementById('imghead' + imgNum + '');
                        img.onload = function() {
                            var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
                            img.width = rect.width;
                            img.height = rect.height;
            //         img.style.marginLeft = rect.left+'px';
                            img.style.marginTop = rect.top + 'px';
                        }
                        var reader = new FileReader();
                        reader.onload = function(evt) {
                            img.src = evt.target.result;
                        }
                        reader.readAsDataURL(file.files[0]);
                    }
                    else //
                    {
                        var sFilter = 'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
                        file.select();
                        var src = document.selection.createRange().text;
                        div.innerHTML = '<img id=imghead' + imgNum + '>';
                        var img = document.getElementById('imghead2');
                        img.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
                        var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
                        status = ('rect:' + rect.top + ',' + rect.left + ',' + rect.width + ',' + rect.height);
                        div.innerHTML = "<div id=divhead" + imgNum + " style='" + rect.width + "px;height:" + rect.height + "px;margin-top:" + rect.top + "px;" + sFilter + src + ""'></div>";
                    }
                }
                function clacImgZoomParam(maxWidth, maxHeight, width, height) {
                    var param = {top: 0, left: 0,  width, height: height};
                    if (width > maxWidth || height > maxHeight)
                    {
                        rateWidth = width / maxWidth;
                        rateHeight = height / maxHeight;
    
                        if (rateWidth > rateHeight)
                        {
                            param.width = maxWidth;
                            param.height = Math.round(height / rateWidth);
                        } else
                        {
                            param.width = Math.round(width / rateHeight);
                            param.height = maxHeight;
                        }
                    }
                    param.left = Math.round((maxWidth - param.width) / 2);
                    param.top = Math.round((maxHeight - param.height) / 2);
                    return param;
                }
            </script>
        </head>
    
        <body>
            <div class="yanzRight">
                <input type="file" value="打开摄像头" title="摄像头" capture="camera" accept="image/*" onchange="previewImage(this, 5)" id="cameraInput">
                    <input style="margin-top:5px;float: left;" id="st18" name="evidence" onchange="previewImage(this, 5)" type="file"/>
                    <span class="dui" id="imgOrder_dui" style="display: none;"></span>
            </div>
            <div id="preview5" style="margin-left:150px;clear:both; padding-top:15px;">
                <img src="" alt="" id="imghead5" height="200" width="200" style="display:none;"/>
            </div>
        </body>
    </html>

    方法二:

    <html xmlns="http://www.w3.org/1999/xhtml">
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
            <title>测试页面</title>
            <script type="text/javascript">
                //下面用于多图片上传预览功能
                function setImagePreviews(avalue) {
                    var docObj = document.getElementById("doc");
                    var dd = document.getElementById("dd");
                    dd.innerHTML = "";
                    var fileList = docObj.files;
                    for (var i = 0; i < fileList.length; i++) {
                        dd.innerHTML += "<div style='float:left' > <img id='img" + i + "'  /> </div>";
                        var imgObjPreview = document.getElementById("img" + i);
                        if (docObj.files && docObj.files[i]) {
                            //火狐下,直接设img属性
                            imgObjPreview.style.display = 'block';
                            imgObjPreview.style.width = '150px';
                            imgObjPreview.style.height = '180px';
                            //imgObjPreview.src = docObj.files[0].getAsDataURL();
                            //火狐7以上版本不能用上面的getAsDataURL()方式获取,需要一下方式
                            imgObjPreview.src = window.URL.createObjectURL(docObj.files[i]);
                        }
                        else {
                            //IE下,使用滤镜
                            docObj.select();
                            var imgSrc = document.selection.createRange().text;
                            alert(imgSrc)
                            var localImagId = document.getElementById("img" + i);
                            //必须设置初始大小
                            localImagId.style.width = "150px";
                            localImagId.style.height = "180px";
                            //图片异常的捕捉,防止用户修改后缀来伪造图片
                            try {
                                localImagId.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
                                localImagId.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;
                            }
                            catch (e) {
                                alert("您上传的图片格式不正确,请重新选择!");
                                return false;
                            }
                            imgObjPreview.style.display = 'none';
                            document.selection.empty();
                        }
                    }
                    return true;
                }
            </script>
        </head>
        <body>
            <div style="margin :0px auto; 990px;">
                <input type="file"  name="file" id="doc" multiple="multiple"  style="150px;" onchange="javascript:setImagePreviews();" accept="image/*" />
                <div id="dd" style=" 990px;"></div>
            </div>
        </body>
    </html>
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  • 原文地址:https://www.cnblogs.com/webskill/p/5853259.html
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