HTML5画布，用户绘图调整大小并旋转

Question

I have a canvas on which the user can draw with some sort of pen. The canvas height is slightly larger than the width. The actual size depends on several variables. I want to give the user the ability to rotate his/her drawing. I'm creating a new canvas on which i draw the old canvas rotated.

Below is how i did 180 degrease.

if(rotation==180){
    ctx.translate(canvas.width/2, canvas.height/2);
    ctx.rotate(Math.PI);
    ctx.translate(-canvas.width/2, -canvas.height/2);
    ctx.drawImage(drawing,0,0);
}

Now for the 90 degrease I also have to do a resize because otherwise it won´t fit anymore. I'm not even sure where to start. Any ideas on how to do this?

Answer 1

u can use CSS3 for rotation:like

h1
{
rotation-point:50% 50%;
rotation:180deg;
}

Answer 2

See this posts

HTML5 canvas image rotate left rotate right

http://phptechworld.blogspot.in/2012/10/html5-canvas-image-rotation.html