我正在尝试使用不同形状的背景图像。
目标是围绕多边形移动/旋转,使用多边形的形状裁剪背景,以某种方式将裁剪后的图像绘制在多边形上,并将裁剪的多边形保存为新图像。
到目前为止,我可以在画布上拖动和旋转(箭头键)多边形。
首先,我在旋转多边形时遇到问题:我希望它们在中心旋转。 第二,用多边形形状裁剪背景。
以下是jsbin的链接:http://jsbin.com/efoqav/1/edit
有什么想法吗?
感谢。
答案 0 :(得分:2)
以下是如何使用动力学多边形来剪切背景图像
首先,在动力学多边形中将背景图像用作fillPattern
。使填充不重复并通过多边形的x / y位置偏移图案:
var hexagon = new Kinetic.RegularPolygon({
x: 50,
y: 50,
sides: 6,
radius: 50,
fillPatternImage: img,
fillPatternRepeat: "no-repeat",
fillPatternOffset: [-50,-50],
stroke: 'black',
strokeWidth: 3,
draggable: true
});
然后当用户拖动多边形(或者用键击移动它)时,将fillPatternOffset
重新定位到多边形的当前位置。实质上,多边形内的填充将“跟随”拖动多边形。
hexagon.on('dragmove', function() {
var position=this.getAbsolutePosition();
var x=position.x;
var y=position.y
this.setFillPatternOffset(x,y);
layer.draw();
});
要围绕其中心(centerX,centerY)旋转多边形,请对每个动态多边形点执行此三角法,然后使用您的KineticPolygon.setPoints重置该形状。
// if the rotation angle is degrees, you must first convert it to radians:
var radianAngle = degreeAngle * Math.PI/180;
// modify each of your polygon points like this
var dx = centerX – pointX;
var dy = centerY – pointY;
var radius = Math.sqrt( dx*dx + dy*dy);
var rotatedX = centerX + radius * Math.cos(radianAngle);
var rotatedY = centerY + radius * Math.cos(radianAngle);
要将舞台保存到图像,您可以像这样使用stage.toDataURL:
// hide the background since you're just interested in the clip
background.hide();
// this saves the stage (your clipped polygon) to an image url
stage.toDataURL({
// just like an image object, you need an onload-ish callback
callback: function(dataUrl){
// testing -- put the image in an html img
var imgElement=document.getElementById("saved");
imgElement.src=dataUrl;
// reshow the background
background.show();
}
});
这是代码和小提琴:http://jsfiddle.net/m1erickson/eQYB8/
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.5.1.min.js"></script>
<style>
body{ background-color: ivory; padding:20px;}
img{border:1px solid red;}
</style>
<script>
$(function(){
// this just generates a sample image
var canvas=document.createElement("canvas");
var ctx=canvas.getContext("2d");
var count=0;
canvas.width=300;
canvas.height=300;
for(var x=0;x<10;x++){
for(var y=0;y<10;y++){
ctx.beginPath();
ctx.arc(x*30+15,y*30+15,15,0,Math.PI*2,false);
ctx.fillText(count++,x*30+11,y*30+18);
ctx.stroke();
}
}
var img=new Image();
img.onload=function(){
draw();
}
img.src=canvas.toDataURL();
function draw(){
var stage = new Kinetic.Stage({
container: 'container',
width: 300,
height: 300
});
var layer = new Kinetic.Layer();
stage.add(layer);
var background = new Kinetic.Image({
x: 0,
y: 0,
image: img,
width: 300,
height: 300,
opacity:.25
});
layer.add(background);
var hexagon = new Kinetic.RegularPolygon({
x: 50,
y: 50,
sides: 6,
radius: 50,
fillPatternImage: img,
fillPatternRepeat: "no-repeat",
fillPatternOffset: [-50,-50],
stroke: 'black',
strokeWidth: 3,
draggable: true
});
layer.add(hexagon);
layer.draw();
hexagon.on('dragmove', function() {
var position=this.getAbsolutePosition();
var x=position.x;
var y=position.y
this.setFillPatternOffset(x,y);
layer.draw();
});
$("#save").click(function(){
background.hide();
stage.toDataURL({
callback: function(dataUrl){
var imgElement=document.getElementById("saved");
imgElement.src=dataUrl;
background.show();
}
});
});
}
}); // end $(function(){});
</script>
</head>
<body>
<button id="save">Save</button><br><br>
<p>Drag the Polygon to your desired clip</p><br>
<div id="container"></div><br>
<p>Saved results without background</p>
<img id="saved" width=300 height=300/>
</body>
</html>