var sx = Math.min(this.canvasEl.width - this.thumbEl.getWidth(), this.thumbEl.getLeft(true) - this.previewEl.getLeft(true));
var sy = Math.min(this.canvasEl.height - this.thumbEl.getHeight(), this.thumbEl.getTop(true) - this.previewEl.getTop(true));
var sx = Math.min(this.canvasEl.width - this.thumbEl.getWidth(), this.thumbEl.getLeft(true) - this.previewEl.getLeft(true));
var sy = Math.min(this.canvasEl.height - this.thumbEl.getHeight(), this.thumbEl.getTop(true) - this.previewEl.getTop(true));