我想拖放图像，然后在 Canvas 上显示该图像，但我真的不知道该怎么做。但这是我尝试过的:
var canvas = document.getElementById("canvas2");
var c = canvas.getContext("2d");
//console.log(canvas)
canvas.ondrop = function(e){
e.preventDefault();
c.drawImage(e.dataTransfer.files[0], 0, 0, c.canvas.width, c.canvas.height);
}
canvas.ondragover = function(e){
console.log("test")
return false;
}#canvas2{
position:relative;
z-index:100;
margin-top: 100px;
border:1px solid #000000;
}<html lang="en">
<head>
<!-- <meta http-equiv="refresh" content="5" > -->
<meta charset="UTF-8">
<title>Document</title>
<link rel="stylesheet" href="./style.css">
</head>
<body>
<!-- <label for="GridCheck">Grid:</label> -->
<!-- <input type="checkbox" id="GridCheck" onclick="GridToggle('canvas1')"> -->
<div class="canvasContainer">
<canvas id = "canvas2" class="canvas"></canvas>
</div>
<script src="main.js"></script>
</body>
</html>我知道问题是“c.drawImage(e.dataTransfer.files[0], 0, 0, c.canvas.width, c.canvas.height);”部分。我是否需要实际上传图像才能访问它并在 Canvas 上显示它？我很困惑...
最佳答案
你可以这样做，尽管它可能与你所说的有点不同，我认为你可以对其进行足够的编辑，使其像你想要的那样:
代码
const fill = document.querySelector('.fill');
const empties = document.querySelectorAll('.empty');
fill.addEventListener('dragstart', dragStart);
fill.addEventListener('dragend', dragEnd);
for (const empty of empties) {
empty.addEventListener('dragover', dragOver);
empty.addEventListener('dragenter', dragEnter);
empty.addEventListener('dragleave', dragLeave);
empty.addEventListener('drop', dragDrop);
}
function dragStart() {
this.className += ' hold';
setTimeout(() => (this.className = 'invisible'), 0);
}
function dragEnd() {
this.className = 'fill';
}
function dragOver(e) {
e.preventDefault();
}
function dragEnter(e) {
e.preventDefault();
this.className += ' hovered';
}
function dragLeave() {
this.className = 'empty';
}
function dragDrop() {
this.className = 'empty';
this.append(fill);
}body {
background: #1a911a;
}
.fill {
background-image: url('https://source.unsplash.com/random/150x150');
position: relative;
height: 150px;
width: 150px;
top: 5px;
left: 5px;
cursor: pointer;
}
.hold {
border: solid 5px #ccc;
}
.empty {
display: grid;
height: 160px;
width: 160px;
margin: 10px;
border: solid 3px red;
background: white;
grid-row: 1/4;
grid-column: 3/4;
}
.hovered {
background: #f4f4f4;
border-style: dashed;
}<!DOCTYPE HTML>
<html lang="en">
<head>
<script src="(Filename).js"></script>
<title>Drag and Drop</title>
</head>
<body>
<div class="empty">
<div class="fill" draggable="true"> </div>
</div>
<div class="empty"></div>
</body>
</html>关于javascript - 拖放图像，在 Canvas 上显示该图像，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/66837015/