如果我有一个600 x 400的网格，具有10 x 10像素的正方形，如下所示:
/**
* draws grid to screen
*/
function drawgrid(context)
{
for(var x = 0.5; x < 600; x += 10)
{
context.moveTo(x, 0);
context.lineTo(x, 400);
}
for(var y = 0.5; y < 400; y += 10)
{
context.moveTo(0, y);
context.lineTo(600, y);
}
context.strokeStyle = "#eee";
context.stroke();
}
/**
* Creates a canvas element, loads images, adds events, and draws the canvas for the first time.
*/
function prepareCanvas()
{
var context = document.getElementById('canvas').getContext("2d");
drawgrid(context);
}
如何将鼠标悬停在各个正方形上并突出显示鼠标悬停的正方形。就像用红色框突出显示鼠标悬停的网格正方形一样。
最佳答案
请参见下面的代码。调整事件的坐标
<body>
<canvas id=canvas height=400 width=600
onmousemove="over()" style="cursor:crosshair">
</canvas>
</body>
<script type="text/javascript">
<!--
var grid;
function prepareCanvasGrid()
{
var cnv = document.getElementById('canvas');
grid = new CanvasGrid(cnv.getContext("2d"),cnv.offsetLeft, cnv.offsetTop);
}
function CanvasGrid(context,x,y) {
this.sq = [];
this.dirty = [];
this.ctx = context;
this.x = x;
this.y = y;
this.init = function(){
for(var x = 0.5; x < 600; x += 50) {
for(var y = 0.5; y < 400; y += 50) {
var s = new square(x,y, context);
this.sq.push(s);
}
}
}
this.draw = function(){
this.ctx.clearRect(0,0,600,400);
for(var i=0; i < this.sq.length; i++)
this.sq[i].draw();
}
this.clean = function(){
for(var i=0; i < this.dirty.length; i++)
this.dirty[i].draw();
this.dirty = [];
}
this.over = function(ex,ey){
ex = ex - this.x;
ey = ey - this.y;
for(var i=0; i < this.sq.length; i++) {
if(this.sq[i].eleAtPoint(ex,ey)){
this.clean(); // clean up
this.dirty.push(this.sq[i]);
this.sq[i].over();
break;
}
}
}
this.init();
this.draw();
}
function square(x,y, ctx){
this.ctx = ctx;
this.x = x;
this.y = y;
this.h = 50;
this.w = 50;
this.draw = function(){
this.ctx.strokeStyle = "#eee";
this.ctx.strokeRect(this.x, this.y, this.w, this.w);
this.ctx.fillStyle = "#fff";
this.ctx.fillRect(this.x, this.y, this.w, this.w);
}
this.over = function() {
this.ctx.fillStyle = "red";
this.ctx.fillRect(this.x, this.y, this.w, this.w);
}
this.eleAtPoint = function(ex,ey){
if(ex < this.x + this.w && ex > this.x
&& ey > this.y && ey < this.y + this.h)
return true;
return false;
}
}
function over(){
var e = window.event;
grid.over(e.clientX ,e.clientY);
}
prepareCanvasGrid();
//-->
</script>
更新了代码以提高性能
关于javascript - 如何在HTML 5中创建鼠标悬停突出显示框？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/7583482/