function line(x0, y0, x1, y1) { const dx = Math.abs(x1 - x0); // distancia em x const dy = Math.abs(y1 - y0); // distancia em y const sx = (x0 < x1) ? 1 : -1; // verifica x crescente ou decrescente const sy = (y0 < y1) ? 1 : -1; // verifica y crescente ou decrescente let err = dx - dy; // parametro de decisao, x ou y const res = []; // array resultado while (true) { res.push({ x: x0, y: y0 }); // coloca o ponto atual dentro do array if ((x0 === x1) && (y0 === y1)) break; // ultimo ponto const e2 = err * 2; // auxiliar para parametro de decisao if (e2 > -dy) { err -= dy; x0 += sx; } // decisao x if (e2 < dx) { err += dx; y0 += sy; } // decisao y } return res; } export const lineMP = (a, b) => line(a.x, a.y, b.x, b.y);什么意思
时间: 2024-02-05 08:04:12 浏览: 29
这是一个JavaScript函数,实现了计算两个点之间的直线上的所有点的坐标,并返回一个包含这些点的数组。该函数的输入参数为两个点的坐标,其中一个点表示为 (x0, y0),另一个点表示为 (x1, y1)。该函数的实现使用了Bresenham算法来生成直线上的点。具体地,该算法使用了一个参数 err,通过比较 err 与 dx、dy 的大小关系来决定下一个点是沿着 x 轴方向还是沿着 y 轴方向前进。该函数的输出结果是一个数组,其中包含了直线上的所有点的坐标。该函数的输出结果可以用于绘制直线、计算直线的长度等操作。
相关问题
// 获取页面元素 const chatbot = document.getElementById('chatbot'); const chatHeader = document.getElementById('chat-header'); const chatClose = document.getElementById('chat-close'); const chatMessages = document.getElementById('chat-messages'); const chatInput = document.getElementById('chat-input'); const chatInputBox = document.querySelector('#chat-input input'); const chatSend = document.getElementById('chat-send'); // 客服自动回复 function chatbotReply(message) { const reply = '这是客服自动回复的消息:' + message; const received = document.createElement('div'); received.className = 'message received'; received.textContent = reply; chatMessages.appendChild(received); chatMessages.scrollTop = chatMessages.scrollHeight; } // 用户发送消息 function sendMessage() { const message = chatInputBox.value; if (!message) { return; } const sent = document.createElement('div'); sent.className = 'message sent'; sent.textContent = message; chatMessages.appendChild(sent); chatMessages.scrollTop = chatMessages.scrollHeight; chatInputBox.value = ''; chatbotReply(message); } // 关闭客服窗口 chatClose.addEventListener('click', function() { chatbot.style.display = 'none'; }); // 发送消息 chatSend.addEventListener('click', function() { sendMessage(); }); chatInputBox.addEventListener('keydown', function(event) { if (event.key === 'Enter') { sendMessage(); } }); // 显示客服窗口 window.addEventListener('load', function() { chatbot.style.display = 'block'; });这个代码要加到1哪里
这段代码需要放在 `<script>` 标签中,并且需要放在HTML文件的 `<body>` 标签的末尾,确保页面其他元素都已加载完毕。通常情况下,它可以放在 `<body>` 标签的底部,就像这样:
```
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>My Website</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<!-- 这里是页面的主要内容 -->
<div id="chatbot">
<div id="chat-header">
<h3>智能客服</h3>
<button id="chat-close">×</button>
</div>
<div id="chat-body">
<div id="chat-messages">
<div class="message received">您好,有什么可以帮您的吗?</div>
</div>
<div id="chat-input">
<input type="text" placeholder="请输入您的问题">
<button id="chat-send">发送</button>
</div>
</div>
</div>
<script>
// 获取页面元素
const chatbot = document.getElementById('chatbot');
const chatHeader = document.getElementById('chat-header');
const chatClose = document.getElementById('chat-close');
const chatMessages = document.getElementById('chat-messages');
const chatInput = document.getElementById('chat-input');
const chatInputBox = document.querySelector('#chat-input input');
const chatSend = document.getElementById('chat-send');
// 客服自动回复
function chatbotReply(message) {
const reply = '这是客服自动回复的消息:' + message;
const received = document.createElement('div');
received.className = 'message received';
received.textContent = reply;
chatMessages.appendChild(received);
chatMessages.scrollTop = chatMessages.scrollHeight;
}
// 用户发送消息
function sendMessage() {
const message = chatInputBox.value;
if (!message) {
return;
}
const sent = document.createElement('div');
sent.className = 'message sent';
sent.textContent = message;
chatMessages.appendChild(sent);
chatMessages.scrollTop = chatMessages.scrollHeight;
chatInputBox.value = '';
chatbotReply(message);
}
// 关闭客服窗口
chatClose.addEventListener('click', function() {
chatbot.style.display = 'none';
});
// 发送消息
chatSend.addEventListener('click', function() {
sendMessage();
});
chatInputBox.addEventListener('keydown', function(event) {
if (event.key === 'Enter') {
sendMessage();
}
});
// 显示客服窗口
window.addEventListener('load', function() {
chatbot.style.display = 'block';
});
</script>
</body>
</html>
```
const ctx = wx.createCanvasContext('photo_canvas'); const SIZE = 200 const ratio = Math.max(res.width / SIZE, res.height / SIZE, 1) const smallWidth = Math.trunc(res.width / ratio) const smallHeight = Math.trunc(res.height / ratio) // 将宽高大小设置到页面的canvas元素(checkCanvas)上 ctx.drawImage(tempFilePaths[index], 0, 0, smallWidth, smallHeight) ctx.draw(false, function () { wx.canvasToTempFilePath({ width: smallWidth, height: smallHeight, destWidth: smallWidth, destHeight: smallHeight, canvasId: 'photo_canvas',请问怎么修改代码中的参数,让输出图片保持原始比列,而不是剪切图片或形变的图片
要让输出的图片保持原始比例,你可以修改代码如下:
```
const ctx = wx.createCanvasContext('photo_canvas');
const SIZE = 200;
const ratio = Math.max(res.width / SIZE, res.height / SIZE, 1);
const smallWidth = Math.trunc(res.width / ratio);
const smallHeight = Math.trunc(res.height / ratio);
const x = (smallWidth - res.width) / 2;
const y = (smallHeight - res.height) / 2;
ctx.drawImage(tempFilePaths[index], x, y, res.width, res.height, 0, 0, smallWidth, smallHeight);
ctx.draw(false, function () {
wx.canvasToTempFilePath({
width: smallWidth,
height: smallHeight,
destWidth: smallWidth,
destHeight: smallHeight,
canvasId: 'photo_canvas',
success: function (res) {
console.log(res.tempFilePath);
}
});
});
```
这里使用了`drawImage`方法的另一个重载版本,它可以指定在画布上绘制图像的位置和大小,以及将图像的哪一部分裁剪出来绘制。首先计算出在画布上绘制图像的起始坐标,使其居中显示,然后指定绘制的图像大小为原始大小,最后指定输出的图片大小为缩小后的大小。