我能否像查找哪个坐标是我的间距的倍数一样,找到最靠近单击坐标的坐标?
可以。网格的整个目的就是可以使用简单的算术计算,而不必携带一大堆任意点的数组。
我从何处开始计算最接近的网格点坐标?
每个轴都进行简单的四舍五入除法即可。
#canvas { position: relative; width: 100px; height: 100px; border: solid red 1px; }
#nearest { position: absolute; width: 10px; height: 10px; background: yellow; }
<div id="canvas"><div id="nearest"></div></div>
var gridspacing= 10;
$('#canvas').mousemove(function(event) {
var pos= $(this).offset();
var gridx= Math.round((event.pageX-pos.left)/gridspacing);
var gridy= Math.round((event.pageY-pos.top)/gridspacing);
$('#nearest').css('left', (gridx-0.5)*gridspacing+'px').css('top', (gridy-0.5)*gridspacing+'px');
});
#canvas { position: relative; width: 100px; height: 100px; border: solid red 1px; }
#nearest { position: absolute; width: 10px; height: 10px; background: yellow; }
<div id="canvas"><div id="nearest"></div></div>
var
canvasOffset = $("div#canvas").offset(),
// Assuming that the space between the points is 10 pixels. Correct this if necessary.
cellSpacing = 10;
$("div#canvas").mousemove(function(event) {
event = event || window.event;
$("div#nearest").css({
top: Math.round((mouseCoordinate(event, "X") - canvasOffset.left) / cellSpacing) * cellSpacing + "px",
left: Math.round((mouseCoordinate(event, "Y") - canvasOffset.top) / cellSpacing) * cellSpacing + "px"
});
});
// Returns the one half of the current mouse coordinates relative to the browser window.
// Assumes the axis parameter to be uppercase: Either "X" or "Y".
function mouseCoordinate(event, axis) {
var property = (axis == "X") ? "scrollLeft" : "scrollTop";
if (event.pageX) {
return event["page"+axis];
} else {
return event["client"+axis] + (document.documentElement[property] ? document.documentElement[property] : document.body[property]);;
}
};
mouseCoordinate()函数是这两个函数的简化版本:
function mouseAxisX(event) {
if (event.pageX) {
return event.pageX;
} else if (event.clientX) {
return event.clientX + (document.documentElement.scrollLeft ? document.documentElement.scrollLeft : document.body.scrollLeft);
}
};
function mouseAxisY(event) {
if (event.pageY) {
return event.pageY;
} else if (event.clientY) {
return event.clientY + (document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop);
}
};
我非常喜欢你的项目想法,也许我会自己做类似的东西:D
$ (window) .resize(function(){canvasOffset = $(“#canvas”).offset()});
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xref=3; startxcoord=10; spacing=50; xcoord=(xref*spacing)+startxcoord;
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