我使用了来自here的sketch.min.js文件。在此通过单击橡皮擦链接应擦除画布。
因为我不想在橡皮擦链接和画布上点击两次，所以如果点击橡皮擦链接则需要擦除画布。
我使用的代码如下：
<!DOCTYPE html>
<html>
<head>
<title></title>
<script src="http://code.jquery.com/jquery-3.1.1.min.js"></script>
</head>
<body>
<div class="tools">
<a href="#tools_sketch" data-tool="marker">Marker</a>
<a href="#tools_sketch" data-tool="eraser">Eraser</a>
</div>
<canvas id="tools_sketch" width="800" height="300" style="background:#eee;"></canvas>
<script type="text/javascript">
var __slice = Array.prototype.slice;
(function(a) {
var b;
return a.fn.sketch = function() {
var c, d, e;
d = arguments[0],
c = 2 <= arguments.length ? __slice.call(arguments, 1) : [],
this.length > 1 && a.error("Sketch.js can only be called on one element at a time."),
e = this.data("sketch");
if (typeof d != "string" || !e)
return e ? e : (this.data("sketch", new b(this.get(0),d)),
this);
if (!e[d])
return a.error("Sketch.js did not recognize the given command.");
if (typeof e[d] == "function")
return e[d].apply(e, c);
if (c.length === 0)
return e[d];
if (c.length === 1)
return e[d] = c[0]
}
,
b = function() {
function b(b, c) {
this.el = b,
this.canvas = a(b),
this.context = b.getContext("2d"),
this.options = a.extend({
toolLinks: !0,
defaultTool: "marker",
defaultColor: "#134543",
defaultSize: 3
}, c),
this.painting = !1,
this.color = this.options.defaultColor,
this.size = this.options.defaultSize,
this.tool = this.options.defaultTool,
this.actions = [],
this.action = [],
this.canvas.bind("click mousedown mouseup mousemove mouseleave mouseout touchstart touchmove touchend touchcancel", this.onEvent),
this.options.toolLinks && a("body").delegate('a[href="#' + this.canvas.attr("id") + '"]', "click", function(b) {
var c, d, e, f, g, h, i;
d = a(this),
c = a(d.attr("href")),
f = c.data("sketch"),
i = ["color", "size", "tool"];
for (g = 0,
h = i.length; g < h; g++)
e = i[g],
d.attr("data-" + e) && f.set(e, a(this).attr("data-" + e));
return a(this).attr("data-download") && f.download(a(this).attr("data-download")),!1
})
}
return b.prototype.download = function(a) {
var b;
return a || (a = "png"),
a === "jpg" && (a = "jpeg"),
b = "image/" + a,
window.open(this.el.toDataURL(b))
}
,
b.prototype.set = function(a, b) {
return this[a] = b,
this.canvas.trigger("sketch.change" + a, b)
}
,
b.prototype.startPainting = function() {
return this.painting = !0,
this.action = {
tool: this.tool,
color: this.color,
size: parseFloat(this.size),
events: []
}
}
,
b.prototype.stopPainting = function() {
return this.action && this.actions.push(this.action),
this.painting = !1,
this.action = null ,
this.redraw()
}
,
b.prototype.onEvent = function(b) {
return b.originalEvent && b.originalEvent.targetTouches && (b.pageX = b.originalEvent.targetTouches[0].pageX,
b.pageY = b.originalEvent.targetTouches[0].pageY),
a.sketch.tools[a(this).data("sketch").tool].onEvent.call(a(this).data("sketch"), b),
b.preventDefault(),
!1
}
,
b.prototype.redraw = function() {
var b;
this.el.width = this.canvas.width(),
this.context = this.el.getContext("2d"),
b = this,
a.each(this.actions, function() {
if (this.tool)
return a.sketch.tools[this.tool].draw.call(b, this)
});
if (this.painting && this.action)
return a.sketch.tools[this.action.tool].draw.call(b, this.action)
}
,
b
}(),
a.sketch = {
tools: {}
},
a.sketch.tools.marker = {
onEvent: function(a) {
switch (a.type) {
case "mousedown":
case "touchstart":
this.startPainting();
break;
case "mouseup":
case "mouseout":
case "mouseleave":
case "touchend":
case "touchcancel":
this.stopPainting()
}
if (this.painting)
return this.action.events.push({
x: a.pageX - this.canvas.offset().left,
y: a.pageY - this.canvas.offset().top,
event: a.type
}),
this.redraw()
},
draw: function(a) {
var b, c, d, e, f;
this.context.lineJoin = "round",
this.context.lineCap = "round",
this.context.beginPath(),
this.context.moveTo(a.events[0].x, a.events[0].y),
f = a.events;
for (d = 0,
e = f.length; d < e; d++)
b = f[d],
this.context.lineTo(b.x, b.y),
c = b;
return this.context.strokeStyle = a.color,
this.context.lineWidth = a.size,
this.context.stroke()
}
},
a.sketch.tools.eraser = {
onEvent: function(b) {
return a.sketch.tools.marker.onEvent.call(this, b)
},
draw: function(b) {
var c;
return c = this.context.globalCompositeOperation,
this.context.globalCompositeOperation = "copy",
b.color = "rgba(0,0,0,0)",
a.sketch.tools.marker.draw.call(this, b),
this.context.globalCompositeOperation = c
}
}
})(jQuery)
$(function() {
$('#tools_sketch').sketch({defaultColor: "#ff0"});
});
</script>
</body>
</html>
答案 0 :(得分：1)
最后，我得到了一个问题的解决方案：
只需将此代码if(f.tool=="eraser"){ f.startPainting();}放在此行代码d.attr("data-" + e) && f.set(e, a(this).attr("data-" + e));之后。