我完全不了解Canvas元素。我能够在画布上画线,但不能清除特定的线条,整个画布变成空白。
尝试过以下方法: HTML:
<canvas id="cvs" width="400" height="400"></canvas>
<hr />
<input type="submit" id="reDrowA" value="Draw A" />
<input type="submit" id="reDrowB" value="Draw B" />
<hr />
<input type="submit" id="clearA" value="Clear A" />
<input type="submit" id="clearB" value="Clear B" />
脚本
$(document).ready(function(){
canvas = document.getElementById("cvs");
$("#reDrowA").on("click",function(){
a = canvas.getContext('2d');
a.translate(0.5, 0.5);
a.beginPath();
a.setLineDash([2,10]);
a.moveTo(10,10);
a.lineTo(300,10);
a.lineTo(300,300);
a.stroke();
});
$("#reDrowB").on("click",function(){
b = canvas.getContext('2d');
b.translate(0.5, 0.5);
b.beginPath();
b.setLineDash([2,10]);
b.moveTo(10,10);
b.lineTo(10,300);
b.lineTo(300,300);
b.stroke();
});
$("#clearA").on("click",function(){
a.clearRect(0, 0, canvas.width, canvas.height);
});
$("#clearB").on("click",function(){
b.clearRect(0, 0, canvas.width, canvas.height);
});
});
Fiddle: http://jsfiddle.net/8YNvu/