如何Swiffy antialias画布? [英] How Swiffy antialias canvas?
问题描述
这是我的例子:
-
全画布,带遮罩。 Chrome超级肮脏: http://goo.gl/n8yB5h
-
和一个swiffy出口,有一个图片在面具内移动。 Chrome上的超级清洁:
http://www.creaktif.com/lab/test4。 html
我尝试了很多东西,包括绘制一个200%的canvas然后缩放,在绘制我的面具时添加更多的点,但是没有办法在我的画布上得到一个干净的面具。
Swiffy如何?
只是把我疯了。
谢谢。 :)
您可以使用 clip剪切路径到屏幕外画布中,并将其用作 ,或者使用alpha蒙版。
该掩模具有各种复合模式以获得抗锯齿边缘。在要剪辑的背景中绘制,设置复合模式(运算符)和绘制遮罩。根据操作符你可以切出中心或周围环境(目的地在
典型地等同于使用 clip()
)。
注意:下面的演示仅在Chrome / Opera中有用,因为Firefox / IE已经对剪辑掩码应用了抗锯齿功能 -
var ctxC = document.getElementById(clip)。getContext(2d) ; var ctxM = document.getElementById(mask)。getContext(2d); var w = ctxC.canvas.width,h = ctxC.canvas.height; var img = new Image(); img.onload = demo ; img.src =http://i.imgur.com/s9ksOb1.jpg\";function demo(){//定义剪辑路径ctxC.save(); createPath(ctxC); ctxC.clip(); ctxC.drawImage(this,0,0,w,h); ctxC.restore(); // create amatte/ alpha mask var matte = document.createElement(canvas),ctx = matte.getContext(2d); matte.width = w; matte.height = h; // fill the path instead:createPath(ctx); ctx.fill(); // color does not matter,alpha does //现在使用组合来剪辑ctxM.drawImage(this,0,0,w,h); // draw image ctxM.globalCompositeOperation =destination-in; // will keep bg where mask cover ctxM.drawImage(matte,0,0); ctxM.globalCompositeOperation =source-over; // default mode // zoom some details:zoom(ctxC); zoom(ctxM);} function createPath(ctx){var r = 88; ctx.beginPath(); ctx.moveTo(100 + r,90); ctx.arc(100,90,r,0,6.28);} function zoom(ctx){ctx.imageSmoothingEnabled = ctx.webkitImageSmoothingEnabled = ctx.mozImageSmoothingEnabled = false; ctx.drawImage(ctx.canvas,10,10,100,100,70,0,400,400);}
html,body {margin:4px 0 0 4px; overflow:hidden} canvas {background:#000; border:1px solid#000; margin:0 1px 0 0}
< canvas id =clipheight = 180& < / canvas>< canvas id =maskheight = 180>< / canvas>
$ b
I don't understand how swiffy succefully antialias clipping mask when it exports a flash animation that contains mask.
Here is my exemple :
Full canvas, with mask. Super dirty in Chrome : http://goo.gl/n8yB5h
And a swiffy export where there is a picture that move inside a mask. Super clean on Chrome : http://www.creaktif.com/lab/test4.html
I tried a lot of things, including draw a 200% canvas then scale it down, adding more points when I draw my mask, but no way to get a clean mask in my canvas.
How does swiffy ? It just turn me crazy.
Thanks. :)
Instead of using clip()
you can draw the clipping path into an off-screen canvas and use that as a "matte", or rather, an alpha mask.
Now you can use the mask with various composite modes to get anti-aliased edges. Draw in the background you want to clip, set a composite mode (operator) and draw in mask. Depending on operator you can cut out center or the surroundings (destination-in
is typical equivalent to using clip()
though).
Note: demo below is only useful in Chrome/Opera as Firefox/IE already apply anti-aliasing to the clip mask - here's a snapshot showing the difference:
var ctxC = document.getElementById("clip").getContext("2d");
var ctxM = document.getElementById("mask").getContext("2d");
var w = ctxC.canvas.width, h = ctxC.canvas.height;
var img = new Image();
img.onload = demo;
img.src = "http://i.imgur.com/s9ksOb1.jpg";
function demo() {
// define a clip path
ctxC.save();
createPath(ctxC);
ctxC.clip();
ctxC.drawImage(this, 0, 0, w, h);
ctxC.restore();
// create a "matte" / alpha mask
var matte = document.createElement("canvas"),
ctx = matte.getContext("2d");
matte.width = w;
matte.height = h;
// fill the path instead:
createPath(ctx);
ctx.fill(); // color doesn't matter, alpha does
// now use composition to "clip"
ctxM.drawImage(this, 0, 0, w, h); // draw image
ctxM.globalCompositeOperation = "destination-in"; // will keep bg where mask cover
ctxM.drawImage(matte, 0, 0);
ctxM.globalCompositeOperation = "source-over"; // default mode
// zoom some details:
zoom(ctxC);
zoom(ctxM);
}
function createPath(ctx) {
var r = 88;
ctx.beginPath();
ctx.moveTo(100 + r, 90);
ctx.arc(100,90,r, 0, 6.28);
}
function zoom(ctx) {
ctx.imageSmoothingEnabled =
ctx.webkitImageSmoothingEnabled =
ctx.mozImageSmoothingEnabled = false;
ctx.drawImage(ctx.canvas, 10, 10, 100, 100, 70,0, 400, 400);
}
html, body {margin:4px 0 0 4px;overflow:hidden}
canvas{background:#000;border:1px solid #000;margin:0 1px 0 0}
<canvas id="clip" height=180></canvas>
<canvas id="mask" height=180></canvas>
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