我正在开发一个Android网页应用程序,在HTML5画布上,用户可以使用触摸事件进行绘制。我希望将这些内容保存在本地SD卡中,而不需要使用任何服务器端脚本(如PHP等)来实现。
我正在使用一个名为magictouch.js
的示例:
<canvas id="example" height=450 width=300></canvas>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script type="text/javascript" src="magictouch.js"></script>
<script>
var CanvasDrawr = function(options) {
var canvas = document.getElementById(options.id),
ctxt = canvas.getContext("2d");
var img = canvas.toDataURL("image/png");
ctxt.lineWidth = options.size || Math.ceil(Math.random() * 35);
ctxt.lineCap = options.lineCap || "round";
ctxt.pX = undefined;
ctxt.pY = undefined;
var lines = [,,];
var offset = $(canvas).offset();
var self = {
//bind click events
init: function() {
canvas.addEventListener('touchstart', self.preDraw, false);
canvas.addEventListener('touchmove', self.draw, false);
},
preDraw: function(event) {
$.each(event.touches, function(i, touch) {
var id = touch.identifier;
lines[id] = { x : this.pageX - offset.left,
y : this.pageY - offset.top,
color : options.color || ["black"]
};
});
event.preventDefault();
},
draw: function(event) {
var e = event, hmm = {};
$.each(event.touches, function(i, touch) {
var id = touch.identifier;
var moveX = this.pageX - offset.left - lines[id].x,
moveY = this.pageY - offset.top - lines[id].y;
var ret = self.move(id, moveX, moveY);
lines[id].x = ret.x;
lines[id].y = ret.y;
});
event.preventDefault();
},
move: function(i, changeX, changeY) {
ctxt.strokeStyle = lines[i].color;
ctxt.beginPath();
ctxt.moveTo(lines[i].x, lines[i].y);
ctxt.lineTo(lines[i].x + changeX, lines[i].y + changeY);
ctxt.stroke();
ctxt.closePath();
return { x: lines[i].x + changeX, y: lines[i].y + changeY };
}
};
return self.init();
};
$(function(){
var super_awesome_multitouch_drawing_canvas_thingy = new CanvasDrawr({id:"example", size: 2 });
console.log('loaded');
});
</script>
</body>
但是我在互联网上看到的所有例子都使用了一个在服务器上的php脚本来解码并将画布保存为图片。而实际上,我只想在我的Android设备上,通过使用HTML5/Javascript,在我的SD卡中完成这个过程...
谢谢。
var img64 = canvas.toDataURL("image/png").replace(/data:image\/png;base64,/, ''); var img_ok = decode_base64(img); navigator.notification.alert(img_ok); writer.write(img_ok, true); writer.close();
}但是我的 PNG 文件已经损坏了。 :/ - dany