NGUI Touch Drag and constrain the drag area

usingUnityengine;usingSystem.Collections; Public classUdragmanager:monobehaviour { PublicTransform Target; PrivateVector3 offset; PrivateBounds Bounds;  Public Static floatImageWidth;  Public Static floatImageHeight;  Public Static floatScreenWidth;  Public Static floatScreenHeight;  Public Static floatM_noffect; voidStart () {initconfig (); }    voidinitconfig () {imagewidth=2490; ImageHeight=1536; ScreenWidth=2048; ScreenHeight=1536;//imagewidth = this.transform.localscale.x;//imageheight = this.transform.localscale.y;//screenwidth = screen.width;//screenheight = screen.height;M_noffect= ImageHeight-ScreenHeight; }        voidOnpress (BOOLpressed) {        if(target = =NULL)return; if(pressed) {bounds=nguimath.calculaterelativewidgetbounds (Target.transform); Vector3 position=UICamera.currentCamera.WorldToScreenPoint (target.position); Offset=NewVector3 (Input.mouseposition.x-(position.x-bounds.size.x/2), INPUT.MOUSEPOSITION.Y-(POSITION.Y-BOUNDS.SIZE.Y/2), 0f); }    }        voidOndrag (Vector2 delta) {Vector3 currentpoint=NewVector3 (Input.mouseposition.x-offset.x, INPUT.MOUSEPOSITION.Y-Offset.y, 0f); Currentpoint.x+ = bounds.size.x/2; Currentpoint.y+ = bounds.size.x/2; Currentpoint.z=2; Target.position=UICamera.currentCamera.ScreenToWorldPoint (currentpoint); }    voidUpdate () {if( This. transform.localposition.x > (-screenwidth)) {             This. transform.localposition =NewVector3 (-screenwidth, This. TRANSFORM.LOCALPOSITION.Y, This. transform.localposition.z); }        if( This. transform.localposition.x < (-imagewidth)) {             This. transform.localposition =NewVector3 (-imagewidth, This. TRANSFORM.LOCALPOSITION.Y, This. transform.localposition.z); }        if( This. transform.localposition.y >0)        {             This. transform.localposition =NewVector3 ( This. transform.localposition.x,0, This. transform.localposition.z); }        if( This. TRANSFORM.LOCALPOSITION.Y < (-m_noffect)) {             This. transform.localposition =NewVector3 ( This. Transform.localposition.x,-m_noffect, This. transform.localposition.z); }    }}

NGUI Touch Drag and constrain the drag area