Question

I want to be able to rotate, zoom and move an image in android framelayout and imageview. With the following code I am able to do it. But the view sometimes gets out of UI. As you can c I handle the rotation in ACTION_UP(90 degree rotation for each ACTION_UP) motionevent. following is my main.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent" >
   <ImageView android:id="@+id/imageView"
         android:layout_width="fill_parent"
         android:layout_height="fill_parent"
         android:src="@drawable/csf6a4_flipped"
         android:scaleType="matrix" >
   </ImageView>
</FrameLayout>

and following is my java file:

package com.example.rotatezoommove;



import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.os.Bundle;
import android.util.FloatMath;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class RotateZoomMove extends Activity implements OnTouchListener {
   private static final String TAG = "Touch";
   // These matrices will be used to move and zoom image
   Matrix matrix = new Matrix();
   Matrix savedMatrix = new Matrix();

   // We can be in one of these 3 states
   static final int NONE = 0;
   static final int DRAG = 1;
   static final int ZOOM = 2;
   int mode = NONE;

   // Remember some things for zooming
   PointF start = new PointF();
   PointF mid = new PointF();
   float oldDist = 1f;

   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      ImageView view = (ImageView) findViewById(R.id.imageView);
      view.setOnTouchListener(this);
   }

   @Override
   public boolean onTouch(View v, MotionEvent event) {
      ImageView view = (ImageView) v;
      int rotation = 25;
      // Dump touch event to log
      dumpEvent(event);

      // Handle touch events here...
      switch (event.getAction() & MotionEvent.ACTION_MASK) {
      case MotionEvent.ACTION_DOWN:
         savedMatrix.set(matrix);
         start.set(event.getX(), event.getY());
         Log.d(TAG, "mode=DRAG");
         mode = DRAG;
         break;



      case MotionEvent.ACTION_POINTER_DOWN:
         oldDist = spacing(event);
         Log.d(TAG, "oldDist=" + oldDist);
         if (oldDist > 10f) {
            savedMatrix.set(matrix);
            midPoint(mid, event);
            mode = ZOOM;
            Log.d(TAG, "mode=ZOOM");
         }
         break;

     case MotionEvent.ACTION_UP:

         mode = NONE;
         Log.d(TAG, "mode=NONE");
         savedMatrix.set(matrix);
         matrix.postRotate(90);

         break;


      case MotionEvent.ACTION_MOVE:
         if (mode == DRAG) {
            // ...
            matrix.set(savedMatrix);
            matrix.postTranslate(event.getX() - start.x,
                  event.getY() - start.y);
         }
         else if (mode == ZOOM) {
            float newDist = spacing(event);
            Log.d(TAG, "newDist=" + newDist);
            if (newDist > 10f) {
               matrix.set(savedMatrix);
               float scale = newDist / oldDist;
               matrix.postScale(scale, scale, mid.x, mid.y);
            }
         }
         break;
      }

      view.setImageMatrix(matrix);
      return true; // indicate event was handled
   }



/** Show an event in the LogCat view, for 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("[");
      for (int i = 0; i < 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(TAG, sb.toString());
   }

   /** Determine the space between the first two fingers */
   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);
   }

   /** Calculate the mid point of the first two 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);
   }
}

I guess I’m almost there. Can anyone suggest any solutions so that I can rotate, drag and zoom the image and keep the image within UI all the time?

Answer 1

call this method from inside from:

setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {

..........................................................

fixing();
setImageMatrix(savedMatrix2);

before the end of return

public void fixing()
{

float[] value = new float[9];
        matrix.getValues(value);

float[] savedValue = new float[9];
        savedMatrix2.getValues(savedValue);

int width = getWidth();
        int height = getHeight();

        Drawable d = getDrawable();
        if (d == null)  return;
        int imageWidth = d.getIntrinsicWidth();
        int imageHeight = d.getIntrinsicHeight();
        int scaleWidth = (int) (imageWidth * value[0]);
        int scaleHeight = (int) (imageHeight * value[4]);

// don't let the image go outside
        if (value[2] > width-1)   
            value[2] = width-10;
        else if (value[5] > height - 1)   
            value[5] = height - 10;
        else if (value[2] < -(scaleWidth-1))  
            value[2] = -(scaleWidth-10);
        else if (value[5] < -(scaleHeight-1))   
            value[5] = -(scaleHeight-10);

        // maximum zoom ratio: MAx
        if (value[0] > MAX_ZOOM || value[4] > MAX_ZOOM){
            value[0] = MAX_ZOOM;
            value[4] = MAX_ZOOM;
            //value[2] = savedValue[2];
            //value[5] = savedValue[5];
        }

        matrix.setValues(value); 
        savedMatrix2.set(matrix);
}