web前端——實現上傳圖片預覽功能
阿新 • • 發佈：2018-12-31
function previewImage(file) {
var MAXWIDTH = 100;
var MAXHEIGHT = 100;
//var div = document.getElementById('preview');
if (file.files && file.files[0]) {
//div.innerHTML = '<img id=imghead>';
var img = document.getElementById('imghead');
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]);
uploadPhoto();
} else {
var sFilter = 'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
file.select();
var src = document.selection.createRange().text;
// div.innerHTML = '<img id=imghead>';
var img = document.getElementById('imghead');
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 style='width:"+rect.width+"px;height:"+rect.height+"px;margin-top:"+rect.top+"px;margin-left:"+rect.left+"px;"+sFilter+src+"\"'></div>";
uploadPhoto();
}
}
function clacImgZoomParam(maxWidth, maxHeight, width, height) {
var param = {
top: 0,
left: 0,
width: 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;
}
var MAXWIDTH = 100;
var MAXHEIGHT = 100;
//var div = document.getElementById('preview');
if (file.files && file.files[0]) {
//div.innerHTML = '<img id=imghead>';
var img = document.getElementById('imghead');
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]);
uploadPhoto();
} else {
var sFilter = 'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
file.select();
var src = document.selection.createRange().text;
// div.innerHTML = '<img id=imghead>';
var img = document.getElementById('imghead');
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 style='width:"+rect.width+"px;height:"+rect.height+"px;margin-top:"+rect.top+"px;margin-left:"+rect.left+"px;"+sFilter+src+"\"'></div>";
uploadPhoto();
}
}
function clacImgZoomParam(maxWidth, maxHeight, width, height) {
var param = {
top: 0,
left: 0,
width: 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;
}