Javascript function to Rotate a base64 image by X degrees and return new base64

Question

I want a javascript function that will rotate a base64 image by X degrees and return the new base64 image.

Example I wish to call a function with something like:

Answer 1

I a little bit generalized method above to convert base64Image string without any dependencies clockwise or counterclockwise

      /**
       * Rotates base64 image string iether 
       * clockwise or counterclockwise
       *
       * @param isClockwise - true or false
       *
       * WARNING!!! Method not null save - assumes all input data are valid
       */
      function rotateBase64Image90deg(base64Image, isClockwise) {
            // create an off-screen canvas
            var offScreenCanvas = document.createElement('canvas');
            offScreenCanvasCtx = offScreenCanvas.getContext('2d');

            // cteate Image
            var img = new Image();
            img.src = base64Image;

            // set its dimension to rotated size
            offScreenCanvas.height = img.width;
            offScreenCanvas.width = img.height;

            // rotate and draw source image into the off-screen canvas:
            if (isClockwise) { 
                offScreenCanvasCtx.rotate(90 * Math.PI / 180);
                offScreenCanvasCtx.translate(0, -offScreenCanvas.width);
            } else {
                offScreenCanvasCtx.rotate(-90 * Math.PI / 180);
                offScreenCanvasCtx.translate(-offScreenCanvas.height, 0);
            }
            offScreenCanvasCtx.drawImage(img, 0, 0);

            // encode image to data-uri with base64
            return offScreenCanvas.toDataURL("image/jpeg", 100);
      }