Javascript 通过鼠标进行HTML画布平移
代码笔: 使用画布,我在画布上创建了数千个圆,画布填充了整个视口。我添加了一些平移功能,但在鼠标释放后,我遇到了重绘问题 基本上,用户可以拖动画布(代码方面,这是可行的),但在视觉上它不会显示任何平移,在鼠标释放时,画布会在其原始位置重新绘制,因此看起来好像什么都没有发生过 JS:Javascript 通过鼠标进行HTML画布平移,javascript,jquery,html,canvas,Javascript,Jquery,Html,Canvas,代码笔: 使用画布,我在画布上创建了数千个圆,画布填充了整个视口。我添加了一些平移功能,但在鼠标释放后,我遇到了重绘问题 基本上,用户可以拖动画布(代码方面,这是可行的),但在视觉上它不会显示任何平移,在鼠标释放时,画布会在其原始位置重新绘制,因此看起来好像什么都没有发生过 JS: ctx.setTransform覆盖由ctx.translate()完成的(0,0)点的重新映射。因此,您应该删除行ctx.setTransform(1,0,0,1,0,0)从draw()函数中 $(document
ctx.setTransform
覆盖由ctx.translate()
完成的(0,0)点的重新映射。因此,您应该删除行ctx.setTransform(1,0,0,1,0,0)代码>从draw()函数中
$(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;
}
});