[英]HTML Canvas Panning via Mouse
Codepen: https ://codepen.io/anon/pen/EvNqyY
使用“畫布”,我在畫布上創建了數千個圓,並且畫布填充了整個視口。 我添加了一些平移功能,但是釋放鼠標后重新繪制存在問題。
基本上,用戶可以拖動畫布(在代碼方面,這是可行的),但是在視覺上它不會顯示任何平移,並且在釋放鼠標時,畫布會以其原始位置重新繪制,因此好像什么也沒發生。
JS:
$(document).ready(function() {
var canvas = document.querySelector('canvas');
var ctx = canvas.getContext("2d");
var global = {
scale: 1,
offset: {
x: 0,
y: 0,
},
};
var panning = {
start: {
x: null,
y: null,
},
offset: {
x: 0,
y: 0,
},
};
var systems = '../js/json/eveSystems.json';
fitToContainer(canvas);
$.getJSON(systems, function(data) {
function draw() {
ctx.setTransform(1, 0, 0, 1, 0, 0);
ctx.clearRect(0, 0, canvas.width, canvas.height);
data.forEach(function(systemData) {
var coordX = systemData.position.x / 100000000000000;
var coordY = systemData.position.y / 100000000000000;
ctx.beginPath();
ctx.arc(coordX,coordY,20,0,2*Math.PI);
ctx.stroke();
});
}
draw();
canvas.addEventListener("mousedown", startPan);
function pan() {
ctx.setTransform(1, 0, 0, 1, 0, 0);
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.translate(panning.offset.x, panning.offset.y);
console.log(panning.offset.x);
draw();
}
function startPan(e) {
window.addEventListener("mousemove", trackMouse);
window.addEventListener("mousemove", pan);
window.addEventListener("mouseup", endPan);
panning.start.x = e.clientX;
panning.start.y = e.clientY;
}
function endPan(e) {
window.removeEventListener("mousemove", trackMouse);
window.removeEventListener("mousemove", pan);
window.removeEventListener("mouseup", endPan);
panning.start.x = null;
panning.start.y = null;
global.offset.x = panning.offset.x;
global.offset.y = panning.offset.y;
}
function trackMouse(e) {
var offsetX = e.clientX - panning.start.x;
var offsetY = e.clientY - panning.start.y;
panning.offset.x = global.offset.x + offsetX;
panning.offset.y = global.offset.y + offsetY;
}
});
function fitToContainer(canvas){
canvas.style.width ='100%';
canvas.style.height='100%';
canvas.width = canvas.offsetWidth;
canvas.height = canvas.offsetHeight;
}
});
ctx.setTransform
覆蓋ctx.translate()
完成的(0,0)點的重新映射。 因此,您應刪除ctx.setTransform(1, 0, 0, 1, 0, 0);
從您的draw()函數。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.