>背景 ：
1.用户点击蒙版并在蒙版上上传自己的图像....
2.上传图片后，用户可以拖动上传的图片。
要求 ：
我觉得拖动非常慢，我真的很想让它超级快和流畅......
码笔 ： https://codepen.io/kidsdial/pen/QPoRyM
小提琴 ： https://jsfiddle.net/kidsdial1/g58nrf7e/
以下是片段：
var target;
const imageUrl = "https://i.imgur.com/RzEm1WK.png";
let jsonData = {
"layers": [{
"x": 0,
"height": 612,
"layers": [{
"x": 160,
"src": "ax0HVTs.png",
"y": 291,
"height": 296,
"width": 429,
"name": "mask_1"
},
{
"x": 25,
"src": "hEM2kEP.png",
"height": 324,
"width": 471,
"y": 22,
"name": "mask_2"
}
],
"y": 0,
"width": 612
}]
};
const containerElement = $('#container');
const fileUp = $('#fileup');
$(function() {
// Upload image onclick mask image
containerElement.click(function(e) {
var res = e.target;
target = res.id;
console.log(target);
if (e.target.getContext) {
// click only inside Non Transparent part
var pixel = e.target.getContext('2d').getImageData(e.offsetX, e.offsetY, 1, 1).data;
if (pixel[3] === 255) {
setTimeout(() => {
$('#fileup').click();
}, 20);
}
}
});
// Fetch mask images from json file - IGNORE this code
function getAllSrc(layers) {
let arr = [];
layers.forEach(layer => {
if (layer.src) {
arr.push({
src: layer.src,
x: layer.x,
y: layer.y,
height: layer.height,
width: layer.width,
name: layer.name
});
} else if (layer.layers) {
let newArr = getAllSrc(layer.layers);
if (newArr.length > 0) {
newArr.forEach(({
src,
x,
y,
height,
width,
name
}) => {
arr.push({
src,
x: (layer.x + x),
y: (layer.y + y),
height,
width,
name: (name)
});
});
}
}
});
return arr;
}
function json(data)
{
var width = 0;
var height = 0;
let arr = getAllSrc(data.layers);
let layer1 = data.layers;
width = layer1[0].width;
height = layer1[0].height;
let counter = 0;
let table = [];
// container dimensions
containerElement.css('width', width + "px").css('height', height + "px").addClass('temp');
//end
for (let {
src,
x,
y,
name
} of arr) {
//Get Height and width of mask image [ edit button ]
var ImagePosition = arr;
//code end
var mask = $(".container").mask({
imageUrl: imageUrl,
// Fetch Mask images
maskImageUrl: 'https://i.imgur.com/' + src,
// end
onMaskImageCreate: function(img) {
// Mask image positions
img.css({
"position": "absolute",
"left": x + "px",
"top": y + "px"
});
// end
},
id: counter
});
table.push(mask);
fileup.onchange = function() {
let mask2 = table[target];
const newImageLoadedId = mask2.loadImage(URL.createObjectURL(fileup.files[0]));
document.getElementById('fileup').value = "";
};
counter++;
}
}
json(jsonData);
}); // end of function
// Image code
(function($) {
var JQmasks = [];
$.fn.mask = function(options) {
// This is the easiest way to have default options.
var settings = $.extend({
// These are the defaults.
maskImageUrl: undefined,
imageUrl: undefined,
scale: 1,
id: new Date().getUTCMilliseconds().toString(),
x: 0, // image start position
y: 0, // image start position
onMaskImageCreate: function(div) {},
}, options);
var container = $(this);
let prevX = 0,
prevY = 0,
draggable = false,
img,
canvas,
context,
image,
timeout,
initImage = false,
startX = settings.x,
startY = settings.y,
div;
container.mousePosition = function(event) {
return {
x: event.pageX || event.offsetX,
y: event.pageY || event.offsetY
};
}
container.selected = function(ev) {
var pos = container.mousePosition(ev);
var item = $(".masked-img canvas").filter(function() {
var offset = $(this).offset()
var x = pos.x - offset.left;
var y = pos.y - offset.top;
var d = this.getContext('2d').getImageData(x, y, 1, 1).data;
return d[0] > 0
});
JQmasks.forEach(function(el) {
var id = item.length > 0 ? $(item).attr("id") : "";
if (el.id == id)
el.item.enable();
else el.item.disable();
});
};
container.enable = function() {
draggable = true;
$(canvas).attr("active", "true");
div.css({
"z-index": 2
});
}
container.disable = function() {
draggable = false;
$(canvas).attr("active", "false");
div.css({
"z-index": 1
});
}
container.getImagePosition = function() {
return {
x: settings.x,
y: settings.y,
scale: settings.scale
};
};
// Drag uploaded image
container.onDragStart = function(evt) {
if (evt.target.getContext) {
var pixel = evt.target.getContext('2d').getImageData(evt.offsetX, evt.offsetY, 1, 1).data;
$(canvas).attr("active", "true");
container.selected(evt);
prevX = evt.clientX;
prevY = evt.clientY;
var img = new Image();
evt.originalEvent.dataTransfer.setDragImage(img, 10, 10);
evt.originalEvent.dataTransfer.setData('text/plain', 'anything');
}
};
container.onDragOver = function(evt) {
if (evt.target.getContext) {
var pixel = evt.target.getContext('2d').getImageData(evt.offsetX, evt.offsetY, 1, 1).data;
if (pixel[3] === 255) {
if (draggable && $(canvas).attr("active") === "true") {
var x = settings.x + evt.clientX - prevX;
var y = settings.y + evt.clientY - prevY;
if (x == settings.x && y == settings.y)
return; // position has not changed
settings.x += evt.clientX - prevX;
settings.y += evt.clientY - prevY;
prevX = evt.clientX;
prevY = evt.clientY;
clearTimeout(timeout);
timeout = setTimeout(function() {
container.updateStyle();
renderInnerImage();
}, 20);
}
} else {
evt.stopPropagation();
return false;
}
}
};
// end
container.updateStyle = function() {
return new Promise((resolve, reject) => {
context.beginPath();
context.globalCompositeOperation = "source-over";
image = new Image();
image.setAttribute('crossOrigin', 'anonymous');
image.src = settings.maskImageUrl;
image.onload = function() {
canvas.width = image.width;
canvas.height = image.height;
context.drawImage(image, 0, 0, image.width, image.height);
div.css({
"width": image.width,
"height": image.height
});
resolve();
};
});
};
function renderInnerImage() {
img = new Image();
img.setAttribute('crossOrigin', 'anonymous');
img.src = settings.imageUrl;
img.onload = function() {
settings.x = settings.x == 0 && initImage ? (canvas.width - (img.width * settings.scale)) / 2 : settings.x;
settings.y = settings.y == 0 && initImage ? (canvas.height - (img.height * settings.scale)) / 2 : settings.y;
context.globalCompositeOperation = 'source-atop';
context.drawImage(img, settings.x, settings.y, img.width * settings.scale, img.height * settings.scale);
initImage = false;
};
}
// change the draggable image
container.loadImage = function(imageUrl) {
console.log("load");
settings.y = startY;
settings.x = startX;
prevX = prevY = 0;
settings.imageUrl = imageUrl;
initImage = true;
container.updateStyle().then(renderInnerImage);
// sirpepole Add this
return settings.id;
};
container.loadMaskImage = function(imageUrl, from) {
canvas = document.createElement("canvas");
context = canvas.getContext('2d');
canvas.setAttribute("draggable", "true");
canvas.setAttribute("id", settings.id);
settings.maskImageUrl = imageUrl;
div = $("<div/>", {
"class": "masked-img"
}).append(canvas);
// div.find("canvas").on('touchstart mousedown', function(event)
div.find("canvas").on('dragstart', function(event) {
if (event.handled === false) return;
event.handled = true;
container.onDragStart(event);
});
div.find("canvas").on('touchend mouseup', function(event) {
if (event.handled === false) return;
event.handled = true;
container.selected(event);
});
div.find("canvas").bind("dragover", container.onDragOver);
container.append(div);
if (settings.onMaskImageCreate)
settings.onMaskImageCreate(div);
container.loadImage(settings.imageUrl);
};
container.loadMaskImage(settings.maskImageUrl);
JQmasks.push({
item: container,
id: settings.id
})
// Edit image
div.addClass('masked-img' + settings.id);
// end
return container;
};
}(jQuery));.container {
background: silver;
position: relative;
}
.container img {
position: absolute;
top: 0;
bottom: 250px;
left: 0;
right: 0;
margin: auto;
z-index: 999;
}
.masked-img {
overflow: hidden;
position: relative;
}
.pip {
display: inline-block;
margin: 0;
position: absolute;
}<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js">
</script>
<input id="fileup" name="fileup" type="file" style="display:none" >
<div id="container"class="container">
</div>我展示了你的代码，为了拖动，你正在使用JavaScript的超时功能。
你的JS中有这段代码
container.onDragOver = function(evt) {
if (evt.target.getContext) {
var pixel = evt.target.getContext('2d').getImageData(evt.offsetX, evt.offsetY, 1, 1).data;
if (pixel[3] === 255) {
if (draggable && $(canvas).attr("active") === "true") {
var x = settings.x + evt.clientX - prevX;
var y = settings.y + evt.clientY - prevY;
if (x == settings.x && y == settings.y)
return; // position has not changed
settings.x += evt.clientX - prevX;
settings.y += evt.clientY - prevY;
prevX = evt.clientX;
prevY = evt.clientY;
clearTimeout(timeout);
timeout = setTimeout(function() {
container.updateStyle();
renderInnerImage();
}, 20);
}
} else {
evt.stopPropagation();
return false;
}
}
};
只需在下面的代码中替换您需要的时间
timeout = setTimeout(function() {
container.updateStyle();
renderInnerImage();
}, 20);
20 替换为 1，您的拖动速度将增加。