我知道网上有这样做的例子,但每个例子都不一样,我自己的实现也不一样。我试图弄清楚我的实现有什么问题,因为它没有按预期工作。
代码片段:
var mousePressX = -1;
var mousePressY = -1;
document.getElementById("contextMenu").addEventListener("mousedown", function(event) {
mousePressX = event.clientX;
mousePressY = event.clientY;
}, false);
document.getElementById("contextMenu").addEventListener("mouseup", function(event) {
mousePressX = -1;
mousePressY = -1;
}, false);
document.getElementById("contextMenu").addEventListener("mousemove", function(event) {
if (mousePressX != -1 && mousePressY != -1) {
repositionElement(event.target, event.clientX, event.clientY);
}
}, false);
function repositionElement(element, currentMouseX, currentMouseY) {
element.style.left = element.offsetLeft + (currentMouseX - mousePressX) + 'px';
element.style.top = element.offsetTop + (currentMouseY - mousePressY) + 'px';
}
jsfiddle : http://jsfiddle.net/4rLctko8/
无法真正找出问题所在,但我注意到如果我更改以下行:
element.style.left = element.offsetLeft + (currentMouseX - mousePressX) + 'px';
element.style.top = element.offsetTop + (currentMouseY - mousePressY) + 'px';
到:
element.style.left = currentMouseX - mousePressX + 'px';
element.style.top = currentMouseY - mousePressY + 'px';
只有当元素被拖向正 x 轴(向右)和正 y 轴(向底部)并且当 mouseup 被触发时,它才会被正确拖动,它会被定位在附近的某个地方最左边的最上 Angular 区域(0,0 左右)
最佳答案
非常有趣,到目前为止只用 jQuery 完成过。稍微重写它并确保每个 mousemove 之后都删除了它的事件监听器 - 这将是内存泄漏,否则您可能会开始注意到:
var contextmenu = document.getElementById('contextMenu');
var initX, initY, mousePressX, mousePressY;
contextmenu.addEventListener('mousedown', function(event) {
initX = this.offsetLeft;
initY = this.offsetTop;
mousePressX = event.clientX;
mousePressY = event.clientY;
this.addEventListener('mousemove', repositionElement, false);
window.addEventListener('mouseup', function() {
contextmenu.removeEventListener('mousemove', repositionElement, false);
}, false);
}, false);
function repositionElement(event) {
this.style.left = initX + event.clientX - mousePressX + 'px';
this.style.top = initY + event.clientY - mousePressY + 'px';
}
似乎运作良好。 :-)
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编辑 - 我想我也会添加一个支持触摸的版本(尽管较新的设备似乎可以模拟鼠标事件)。不像 Jquery,你可以选择多个事件监听器,所以它主要是重复,只有触摸事件:
http://codepen.io/Shikkediel/pen/VLZKor?editors=011
var object = document.getElementById('element'),
initX, initY, firstX, firstY;
object.addEventListener('mousedown', function(e) {
e.preventDefault();
initX = this.offsetLeft;
initY = this.offsetTop;
firstX = e.pageX;
firstY = e.pageY;
this.addEventListener('mousemove', dragIt, false);
window.addEventListener('mouseup', function() {
object.removeEventListener('mousemove', dragIt, false);
}, false);
}, false);
object.addEventListener('touchstart', function(e) {
e.preventDefault();
initX = this.offsetLeft;
initY = this.offsetTop;
var touch = e.touches;
firstX = touch[0].pageX;
firstY = touch[0].pageY;
this.addEventListener('touchmove', swipeIt, false);
window.addEventListener('touchend', function(e) {
e.preventDefault();
object.removeEventListener('touchmove', swipeIt, false);
}, false);
}, false);
function dragIt(e) {
this.style.left = initX+e.pageX-firstX + 'px';
this.style.top = initY+e.pageY-firstY + 'px';
}
function swipeIt(e) {
var contact = e.touches;
this.style.left = initX+contact[0].pageX-firstX + 'px';
this.style.top = initY+contact[0].pageY-firstY + 'px';
}
关于javascript - 纯javascript可拖动元素,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/29703473/