imageview - Add limit to zoom-in and zoom-out in android -

i have imageview can zoomed. have code works well, problem want add limit maximum , minimum zooming levels.

import android.annotation.targetapi; import android.app.actionbar; import android.app.activity; import android.graphics.matrix; import android.graphics.pointf; import android.os.build; import android.os.bundle; import android.util.floatmath; import android.util.log; import android.view.menuitem; import android.view.motionevent; import android.view.view; import android.view.view.ontouchlistener; import android.widget.imageview;  @targetapi(build.version_codes.honeycomb) public class reach extends activity implements ontouchlistener {     private static final string tag = "touch";     @suppresswarnings("unused")     private static final float min_zoom = 1f,max_zoom = 1f;  // these matrices used scale points of image matrix matrix = new matrix(); matrix savedmatrix = new matrix();  // 3 states (events) user trying perform static final int none = 0; static final int drag = 1; static final int zoom = 2; int mode = none;  // these pointf objects used record point(s) user touching pointf start = new pointf(); pointf mid = new pointf(); float olddist = 1f;  @override protected void oncreate(bundle savedinstancestate) {     // todo auto-generated method stub     super.oncreate(savedinstancestate);     setcontentview(r.layout.reach_us);     int currentapiversion = android.os.build.version.sdk_int;      if (currentapiversion >= android.os.build.version_codes.honeycomb)      {          // run code specific api levels above honeycomb (api 11+)            actionbar actionbar = getactionbar();         actionbar.setdisplayhomeasupenabled(true);     }     imageview view=(imageview)findviewbyid(r.id.map);     view.setontouchlistener(this); }  @override public boolean onoptionsitemselected(menuitem item) {      switch (item.getitemid()) {      case android.r.id.home: {         this.finish();          return true;     }      default:         return super.onoptionsitemselected(item);     } } @override public boolean ontouch(view v, motionevent event)  {     imageview view = (imageview) v;     view.setscaletype(imageview.scaletype.matrix);     float scale;      dumpevent(event);     // handle touch events here...      switch (event.getaction() & motionevent.action_mask)      {     case motionevent.action_down:   // first finger down         savedmatrix.set(matrix);         start.set(event.getx(), event.gety());         log.d(tag, "mode=drag"); // write logcat         mode = drag;         break;      case motionevent.action_up: // first finger lifted      case motionevent.action_pointer_up: // second finger lifted          mode = none;         log.d(tag, "mode=none");         break;      case motionevent.action_pointer_down: // first , second finger down          olddist = spacing(event);         log.d(tag, "olddist=" + olddist);         if (olddist > 5f) {             savedmatrix.set(matrix);             midpoint(mid, event);             mode = zoom;             log.d(tag, "mode=zoom");         }         break;      case motionevent.action_move:          if (mode == drag)          {              matrix.set(savedmatrix);             matrix.posttranslate(event.getx() - start.x, event.gety() - start.y); // create transformation in matrix  of points         }          else if (mode == zoom)          {              // pinch zooming             float newdist = spacing(event);             log.d(tag, "newdist=" + newdist);             if (newdist > 5f)              {                 matrix.set(savedmatrix);                 scale = newdist / olddist; // setting scaling of                 // matrix...if scale > 1 means                 // zoom in...if scale < 1 means                 // zoom out                 matrix.postscale(scale, scale, mid.x, mid.y);             }         }         break;     }      view.setimagematrix(matrix); // display transformation on screen      return true; // indicate event handled }  /*  * --------------------------------------------------------------------------  * method: spacing parameters: motionevent returns: float description:  * checks spacing between 2 fingers on touch  * ----------------------------------------------------  */  private float spacing(motionevent event)  {     float x = event.getx(0) - event.getx(1);     float y = event.gety(0) - event.gety(1);     return floatmath.sqrt(x * x + y * y); }  /*  * --------------------------------------------------------------------------  * method: midpoint parameters: pointf object, motionevent returns: void  * description: calculates midpoint between 2 fingers  * ------------------------------------------------------------  */  private void midpoint(pointf point, motionevent event)  {     float x = event.getx(0) + event.getx(1);     float y = event.gety(0) + event.gety(1);     point.set(x / 2, y / 2); }  /** show event in logcat view, debugging */ private void dumpevent(motionevent event)  {     string names[] = { "down", "up", "move", "cancel", "outside","pointer_down", "pointer_up", "7?", "8?", "9?" };     stringbuilder sb = new stringbuilder();     int action = event.getaction();     int actioncode = action & motionevent.action_mask;     sb.append("event action_").append(names[actioncode]);      if (actioncode == motionevent.action_pointer_down || actioncode == motionevent.action_pointer_up)      {         sb.append("(pid ").append(action >> motionevent.action_pointer_id_shift);         sb.append(")");     }      sb.append("[");     (int = 0; < event.getpointercount(); i++)      {         sb.append("#").append(i);         sb.append("(pid ").append(event.getpointerid(i));         sb.append(")=").append((int) event.getx(i));         sb.append(",").append((int) event.gety(i));         if (i + 1 < event.getpointercount())             sb.append(";");     }      sb.append("]");     log.d("touch events ---------", sb.tostring()); } } 

i have seen lot of question & answers linked this, no 1 helps me. please give me solution. in advance

i got solution this. not seems perfect one. add methods given below after switch cases , before view.setimagematrix(matrix); here methods:

private void limitzoom(matrix m) {          float[] values = new float[9];         m.getvalues(values);         float scalex = values[matrix.mscale_x];         float scaley = values[matrix.mscale_y];         if(scalex > max_zoom) {             scalex = max_zoom;         } else if(scalex < min_zoom) {             scalex = min_zoom;         }          if(scaley > max_zoom) {             scaley = max_zoom;         } else if(scaley < min_zoom) {             scaley = min_zoom;         }          values[matrix.mscale_x] = scalex;         values[matrix.mscale_y] = scaley;          m.setvalues(values);     }      private void limitdrag(matrix m) {         float[] values = new float[9];         m.getvalues(values);         float transx = values[matrix.mtrans_x];         float transy = values[matrix.mtrans_y];         float scalex = values[matrix.mscale_x];         float scaley = values[matrix.mscale_y];          imageview iv = (imageview)findviewbyid(r.id.map);         rect bounds = iv.getdrawable().getbounds();         int viewwidth = getresources().getdisplaymetrics().widthpixels;         int viewheight = getresources().getdisplaymetrics().heightpixels;          int width = bounds.right - bounds.left;         int height = bounds.bottom - bounds.top;          float minx = (-width + 20) * scalex;          float miny = (-height + 20) * scaley;          if(transx > (viewwidth - 20)) {             transx = viewwidth - 20;         } else if(transx < minx) {             transx = minx;         }          if(transy > (viewheight - 80)) {             transy = viewheight - 80;         } else if(transy < miny) {             transy = miny;         }          values[matrix.mtrans_x] = transx;         values[matrix.mtrans_y] = transy;          m.setvalues(values);      } 

is there other solution better one?