我想拖放一张卡片的图像在javascript的画布上,但mouseup事件似乎没有工作,即使它在main()内部。一旦卡被选中,它会围绕着鼠标,但当我放开鼠标时它似乎并没有放开。我也知道,图像是从不清除屏幕重复。Javascript mouseup和mousedown事件
function main(){
var ctx = cvs.getContext("2d");
var img = new Image();
img.src = "allcards.png";
var imgX = 75;
var imgY = 75;
draw();
function draw(){
ctx.drawImage(img,0,0,97,129,imgX,imgY,100,100);
}
cvs.addEventListener("mouseup", function(ev){
greaterX = false;
lessX = false;
greaterY = false;
lessY = false;
}
);
cvs.addEventListener("mousedown", function(ev){
if(ev.clientX <= (imgX + 97)){
var greaterX = true;
}
if(ev.clientY <= (imgY + 129)){
var greaterY = true;
}
if(ev.clientX >= imgX){
var lessX = true;
}
if(ev.clientY >= imgY){
var lessY = true;
}
if(greaterX == true)
if(greaterY == true)
if(lessX == true)
if(lessY == true)
cvs.addEventListener("mousemove", function(ev){
var offsetX = (ev.clientX - imgX);
var offsetY = (ev.clientY - imgY);
imgX = imgX + offsetX;
imgY = imgY + offsetY;
draw();
});
});
};
你不能使用JQuery?它会处理他为你粘贴的所有代码:http://jqueryui.com/demos/draggable/ –
@Lando OP正在使用Canvas,屏幕上放置的图像仅使用代码创建。 jQuery的DOM选择器将[没有帮助](http://jsfiddle.net/SeRcf/)。 – Polyov