android pinch zoom

Question

My layout contains buttons  textviews  etc  Is it possible to implement pinch zoom in my layout

User · Answer

I have created a project for basic pinch-zoom that supports Android 2 1   Available here

User · Answer

For android 2 2   api level8   you can use ScaleGestureDetector   you need a member   private ScaleGestureDetector mScaleDetector    in your constructor  or onCreate    you add   mScaleDetector   new ScaleGestureDetector context  new OnScaleGestureListener          Override     public void onScaleEnd ScaleGestureDetector detector               Override     public boolean onScaleBegin ScaleGestureDetector detector            return true             Override     public boolean onScale ScaleGestureDetector detector            Log d LOG KEY   zoom ongoing  scale      detector getScaleFactor             return false              You override onTouchEvent    Override public boolean onTouchEvent MotionEvent event        mScaleDetector onTouchEvent event       return true      If you draw your View by hand  in the onScale   you probably do store the scale factor in a member  then call invalidate   and use the scale factor when drawing in your onDraw    Otherwise you can directly modify font sizes or things like that in the onScale

User · Answer

There is also this project that does the job and worked perfectly for me  https   github com chrisbanes PhotoView

User · Answer

In honeycomb  API level 11  it is possible  We can use setScalaX and setScaleY with pivot point I have explained it here Zooming a view completely Pinch Zoom to view completely

User · Answer

I implemented a pinch zoom for my TextView  using this tutorial  The resulting code is this   private GestureDetector gestureDetector  private View OnTouchListener gestureListener    and in onCreate            Zoom handlers     gestureDetector   new GestureDetector new MyGestureDetector         gestureListener   new View OnTouchListener                 We can be in one of these 2 states         static final int NONE   0          static final int ZOOM   1          int mode   NONE           static final int MIN FONT SIZE   10          static final int MAX FONT SIZE   50           float oldDist   1f            Override         public boolean onTouch View v  MotionEvent event                TextView textView    TextView  findViewById R id text                switch  event getAction    amp  MotionEvent ACTION MASK                    case MotionEvent ACTION POINTER DOWN                      oldDist   spacing event                       Log d TAG   oldDist     oldDist                       if  oldDist  gt  10f                           mode   ZOOM                         Log d TAG   mode ZOOM                                               break                  case MotionEvent ACTION POINTER UP                      mode   NONE                      break                  case MotionEvent ACTION MOVE                      if  mode    ZOOM                            float newDist   spacing event                              If you want to tweak font scaling  this is the place to go                          if  newDist  gt  10f                                float scale   newDist   oldDist                               if  scale  gt  1                                    scale   1 1f                                else if  scale  lt  1                                    scale   0 95f                                                             float currentSize   textView getTextSize     scale                              if   currentSize  lt  MAX FONT SIZE  amp  amp  currentSize  gt  MIN FONT SIZE                                         currentSize  gt   MAX FONT SIZE  amp  amp  scale  lt  1                                          currentSize  lt   MIN FONT SIZE  amp  amp  scale  gt  1                                     textView setTextSize TypedValue COMPLEX UNIT PX  currentSize                                                                                                     break                                return false              Magic constants 1 1 and 0 95 were chosen empirically  using scale variable for this purpose made my TextView behave kind of weird

User · Answer

Updated Answer Code can be found here   official-doc Answer Outdated Check out the following links which may help you Best examples are provided in the below links  which you can refactor to meet your requirements   implementing-the-pinch-zoom-gestur  Android-pinch  GestureDetector SimpleOnGestureListener

User · Answer

I have an open source library that does this very well  It s a four gesture library that comes with an out-of-the-box pan zoom setting  You can find it here  https   bitbucket org warwick hacergestov3 Or you can download the demo app here  https   play google com store apps details id com WarwickWestonWright HacerGestoV3Demo This is a pure canvas library so it can be used in pretty any scenario  Hope this helps

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