How to draw photo with correct orientation in canvas after capture photo by using input[type='file'] in mobile web browser?

Question

I am making a simple web app in mobile which allow visitor to capture photo by using html5 input[type=file] element. Then I will display it on the web for preview, and then

Answer 1

Ben's great answer pointed me in the right direction but as far as I can tell the actual rotations are incorrect (at least they were for me) and don't cover all possible cases. The solution below worked for me. It is based on the one found in the JavaScript-Load-Image library (which I found via this great SO question). Note that I also had to translate the Canvas context to the center as it originates from the top left corner when rotating).

fileReader.onloadend = function() {

    var exif = EXIF.readFromBinaryFile(new BinaryFile(this.result));

    switch(exif.Orientation){

        case 2:
            // horizontal flip
            ctx.translate(canvas.width, 0);
            ctx.scale(-1, 1);
            break;
        case 3:
            // 180° rotate left
            ctx.translate(canvas.width, canvas.height);
            ctx.rotate(Math.PI);
            break;
        case 4:
            // vertical flip
            ctx.translate(0, canvas.height);
            ctx.scale(1, -1);
            break;
        case 5:
            // vertical flip + 90 rotate right
            ctx.rotate(0.5 * Math.PI);
            ctx.scale(1, -1);
            break;
        case 6:
            // 90° rotate right
            ctx.rotate(0.5 * Math.PI);
            ctx.translate(0, -canvas.height);
            break;
        case 7:
            // horizontal flip + 90 rotate right
            ctx.rotate(0.5 * Math.PI);
            ctx.translate(canvas.width, -canvas.height);
            ctx.scale(-1, 1);
            break;
        case 8:
            // 90° rotate left
            ctx.rotate(-0.5 * Math.PI);
            ctx.translate(-canvas.width, 0);
            break;


    }
};