이미지의 시작점과 끝점
<p>我正在尝试设置图像的起点和终点。所以我有我的画布和图像，当我将图像放入画布时，我希望当我将鼠标悬停在起点/终点时，它会亮起一个小红色圆圈，这意味着我可以与其他图像创建连接。例如：<strong>1) 拖动图像。 2) 将图像放入画布内。 3）鼠标悬停到起点/终点，小红点亮起。</strong>
</p>
<p>如您所见，红点仅在悬停时出现。另一个问题，但如果你解决第一个问题很酷，图像不会跟随烤架（正方形）。
这是 html/js 的示例</p>
<p>
<pre class="brush:js;toolbar:false;">const resistor = document.getElementById('component_circuit_resistor');
const condensator = document.getElementById('component_circuit_condensator');
const tranistor = document.getElementById('component_circuit_tranistor');
const alimentator = document.getElementById('component_circuit_alimentator');
const circuit = document.getElementById('components_circuit');
const back_button = document.getElementById('back-button');
const clear_button = document.getElementById('clear-button');
const draggable = document.querySelectorAll('.draggable');
const container = document.querySelectorAll('.container');
const canvas = document.getElementById('canvas');
const foward_button = document.getElementById('foward-button');
/** EDIT START */
const draggableImages = document.querySelectorAll('img[draggable]');
for (let i = 0; i < draggableImages.length; i++)
draggableImages[i].ondragstart = (ev) => {
ev.dataTransfer.setData('text/plain', i.toString());
};
canvas.ondragover = (ev) => ev.preventDefault(); // IMPORTANT
const orderStack = [];
const deletedOrderStack = [];
const drawnImageData = [];
const deletedImageData = [];
canvas.ondrop = (ev) => {
const index = parseInt(ev.dataTransfer.getData('text/plain'));
const img = draggableImages[index];
const x = ev.clientX - canvas.offsetLeft - img.width / 2;
const y = ev.clientY - canvas.offsetTop - img.height / 2;
const squareSize = 10; // adjust this to match the size of your squares
const maxSize = 75; // maximum size of the image
const aspectRatio = img.width / img.height;
let width = maxSize;
let height = maxSize / aspectRatio;
if (height > maxSize) {
height = maxSize;
width = height * aspectRatio;
}
const snappedX = Math.round(x / squareSize) * squareSize;
const snappedY = Math.round(y / squareSize) * squareSize;
ctx.drawImage(img, snappedX, snappedY, width, height);
drawnImageData.push(ctx.getImageData(0, 0, canvas.width, canvas.height));
orderStack.push(1);
deletedImageData.length = 0;
deletedOrderStack.length = 0;
back_button.disabled = false;
back_button.style.cursor = 'pointer';
clear_button.disabled = false;
clear_button.style.cursor = 'pointer';
foward_button.disabled = true;
foward_button.style.cursor = 'not-allowed';
return false;
};
clear_button.disabled = true;
clear_button.style.cursor = 'not-allowed';
foward_button.disabled = true;
foward_button.style.cursor = 'not-allowed';
back_button.disabled = true;
back_button.style.cursor = 'not-allowed';
/** EDIT END */
canvas.width = 1900;
canvas.height = 1000;
canvas.style.backgroundColor = 'white';
circuit.appendChild(canvas);
canvas.style.borderRadius = '10px';
canvas.style.marginLeft = 'auto';
canvas.style.marginRight = 'auto';
canvas.style.display = 'block';
const ctx = canvas.getContext('2d');
//const circles = [];
const lines = [];
const lines_c = [];
var deletedLines = [];
function drawSquares() {
const squareSize = 10;
const numColumns = Math.floor(canvas.width / squareSize);
const numRows = Math.floor(canvas.height / squareSize);
ctx.fillStyle = "#FAF9F9";
ctx.strokeStyle = "#F4F1F0";
ctx.lineWidth = 1;
for (let i = 0; i < numColumns; i++) {
for (let j = 0; j < numRows; j++) {
const x = i * squareSize;
const y = j * squareSize;
if (i % 10 === 0 && j % 10 === 0) {
ctx.lineWidth = 2.6;
ctx.fillStyle = "#F1ECEB";
ctx.strokeStyle = "#E6E0DE"; // set the stroke color to a darker shade
ctx.strokeRect(x, y, squareSize * 10, squareSize * 10);
ctx.fillStyle = "#F4F1F0";
ctx.strokeStyle = "#F4F1F0"; // reset the stroke color
ctx.lineWidth = 1;
} else {
ctx.strokeRect(x, y, squareSize, squareSize);
}
}
}
}
drawSquares();</pre>
<pre class="brush:html;toolbar:false;"><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@48,400,0,0" />
<link rel="stylesheet" href="style.css">
<!-- <title>From Circuit to Breadboard</title> -->
</head>
<body>
<div class="container">
<div class="components">
<div id="components_circuit">
<h3 id ="h3_componenti_circuit">Componenti:</h3>
<ul id="components_circuit_border">
<li><img id ="component_circuit_resistor" src="https://www.elprocus.com/wp-content/uploads/Resistor-Symbol-768x288.png" height="50" draggable="true"></li>
<br><br>
<li><img id = "component_circuit_condensator" src="https://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Capacitor_Symbol_alternative.svg/1280px-Capacitor_Symbol_alternative.svg.png" height="50" draggable="true"></li>
<br><br>
<li><img id="component_circuit_transistor" src="images/circuit_transistor.png" height="50" draggable="true"></li>
<br><br>
<li><img id="component_circuit_alimentator" src="images/circuit_alimentator.png" height="50" draggable="true"></li>
</ul>
<div class = "elementi_disegno">
<h1 id ="h1_disegna">Disegna il tuo circuito!</h1>
<button id="back-button">Indietro
<span class="material-symbols-outlined">undo</span>
</button>
<button id="foward-button">Avanti
<span class="material-symbols-outlined">redo</span>
</button>
<button id="clear-button">Clear All
<span class="material-symbols-outlined">delete</span>
</button>
<canvas id = "canvas" class = "dropzone"></canvas>
</div>
</div>
<script src="script.js"></script>
</body>
</html></pre>
</p>
<p>提供的代码可能在 stackoverflow 上不起作用，请在本地尝试。如果您使用其他图像，请提供链接。</p>
