Cómo hacer zoom en una vista de texto en android?

Question

¿Alguien me puede guiar para realizar zoom en & operaciones en múltiples vistas en android? Necesito realizar un acercamiento de & operaciones en el toque de la imagen, vistas de texto. ¿Cuál debería ser el diseño de mi padre? Aquí está el código para acercar o alejar una imagen al tocar la vista de la imagen. ¿Cómo hago zoom en una vista de texto? Por favor, ayúdame.

// These matrices will be used to scale points of the image 
Matrix matrix = new Matrix(); 
Matrix savedMatrix = new Matrix(); 

// The 3 states (events) which the user is trying to perform 
static final int NONE = 0; 
static final int DRAG = 1; 
static final int ZOOM = 2; 
int mode = NONE; 

// these PointF objects are used to record the point(s) the user is touching 
PointF start = new PointF(); 
PointF mid = new PointF(); 
float oldDist = 1f; 

private void zoom(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 only 
     savedMatrix.set(matrix); 
     start.set(event.getX(), event.getY()); 

     mode = DRAG; 
     break; 

    case MotionEvent.ACTION_UP: // first finger lifted 

    case MotionEvent.ACTION_POINTER_UP: // second finger lifted 

     mode = NONE; 

     break; 

    case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down 

     oldDist = spacing(event); 

     if (oldDist > 5f) 
     { 
      savedMatrix.set(matrix); 
      midPoint(mid, event); 
      mode = ZOOM; 

     } 
     break; 

    case MotionEvent.ACTION_MOVE: 

     if (mode == DRAG) 
     { 
      matrix.set(savedMatrix); 
      matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); // create the transformation in the matrix of points 
     } 
     else if (mode == ZOOM) 
     { 
      // pinch zooming 
      float newDist = spacing(event); 

      if (newDist > 5f) 
      { 
       matrix.set(savedMatrix); 
       scale = newDist/oldDist; // setting the scaling of the 
       // 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 the transformation on screen 

} 

/* 
* -------------------------------------------------------------------------- 
* Method: spacing Parameters: MotionEvent Returns: float Description: 
* 
* checks the spacing between the two 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 the midpoint between the 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); 
} 

Answer 1

Para acercar la vista de texto, puede usar el mismo código que tiene para z de una imagen. Pero debe cambiar la vista de texto a una vista de imagen y luego realizar operaciones de acercamiento. Aquí está el enlace para convertir TextView a imageview Converting a TextView->Bitmap->ImageView, and nothing's showing up

Answer 2

Lo anterior es bueno, pero que a la misma de la siguiente manera ::

En alcrear() debe instialize su TextView y establecer evento ontouch en él como a continuación

TextView tv = (TextView)findViewById(R.id.name); 
tv.setText("text"); 
tv.setOnTouchListener(this); 

aquí es el código completo incluyendo su código :::

public class MyTextView extends Activity implements OnTouchListener{ 
    private static final String TAG = "Touch"; 
     @SuppressWarnings("unused") 
     private static final float MIN_ZOOM = 1f,MAX_ZOOM = 1f; 

     // These matrices will be used to scale points of the image 
     Matrix matrix = new Matrix(); 
     Matrix savedMatrix = new Matrix(); 

     // The 3 states (events) which the user is trying to perform 
     static final int NONE = 0; 
     static final int DRAG = 1; 
     static final int ZOOM = 2; 
     int mode = NONE; 

     // these PointF objects are used to record the point(s) the user is 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); 
    TextView iv = new TextView(this); 
    iv.setText("text"); 
    iv.setOnTouchListener(this); 
    setContentView(iv); 
} 
@Override 
public boolean onTouch(View v, MotionEvent event) { 
    // TODO Auto-generated method stub 
    ImageView view = (ImageView) v; 
    view.setScaleType(ImageView.ScaleType.MATRIX); 
    float scale; 

    dumpEvent(event); 
    // Handle touch events here... 

    switch (event.getAction() & 255) 
    { 
     case MotionEvent.ACTION_DOWN: // first finger down only 
              savedMatrix.set(matrix); 
              start.set(event.getX(), event.getY()); 
              Log.d(TAG, "mode=DRAG"); // write to LogCat 
              mode = DRAG; 
              break; 

     case MotionEvent.ACTION_UP: // first finger lifted 

     case 6: // second finger lifted 

              mode = NONE; 
              Log.d(TAG, "mode=NONE"); 
              break; 

     case 5: // first and 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 the transformation in the 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 the scaling of the 
                       // 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 the transformation on screen 

    return true; // indicate event was handled 
} 
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 the midpoint between the 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); 
} 

/** 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("Touch Events ---------", sb.toString()); 
} 
} 

Answer 3

first you should convert Textview to imageview.Next you should apply sample image view drag functionality. 
    ----------------------------- 



      TextView tv = new TextView(this); 
      FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(
        FrameLayout.LayoutParams.FILL_PARENT, 
        FrameLayout.LayoutParams.FILL_PARENT); 

      tv.setLayoutParams(layoutParams); 
      tv.setText("Text"); 
      tv.setTextColor(Color.BLACK); 
      tv.setBackgroundColor(Color.TRANSPARENT); 

      Bitmap testB; 

      testB = Bitmap.createBitmap(80, 100, Bitmap.Config.ARGB_8888); 
      Canvas c = new Canvas(testB); 
      tv.layout(30, 40, 200, 100); 
      tv.draw(c); 

      ImageView iv = (ImageView) findViewById(R.id.imageView); 
      iv.setLayoutParams(layoutParams); 
      iv.setBackgroundColor(Color.GRAY);`enter code here` 
      iv.setImageBitmap(testB); 
      iv.setMaxHeight(80); 
      iv.setMaxWidth(200); 

      iv.setOnTouchListener(this); 

Answer 4

he encontrado una solución muy simple de implementar zoom in/out en vista de texto. Tal vez ayuda a alguien

package com.app; 

import android.os.Bundle; 
import android.util.TypedValue; 
import android.view.MotionEvent; 
import android.widget.TextView; 
import android.support.v7.app.AppCompatActivity; 
import android.view.View; 


public class MyActivity extends AppCompatActivity implements View.OnTouchListener{ 

    public static final int TEXT_MAX_SIZE = 140; 
    public static final int TEXT_MIN_SIZE = 40; 
    private static final int STEP = 4; 

    private int mBaseDistZoomIn; 
    private int mBaseDistZoomOut; 

    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.my_activity); 

     . 
     . 
     . 
     TextView viewById = (TextView) findViewById(R.id.some_text_view); 
     viewById.setOnTouchListener(this); 
    } 

    @Override 
    public boolean onTouch(View v, MotionEvent event) { 
     if (event.getPointerCount() == 2) { 
      TextView viewById = (TextView) findViewById(R.id.some_text_view); 
      int action = event.getAction(); 
      int pure = action & MotionEvent.ACTION_MASK; 

      if (pure == MotionEvent.ACTION_POINTER_DOWN 
        && viewById.getTextSize() <= TEXT_MAX_SIZE 
        && viewById.getTextSize() >= TEXT_MIN_SIZE) { 

       mBaseDistZoomIn = getDistanceFromEvent(event); 
       mBaseDistZoomOut = getDistanceFromEvent(event); 

      } else { 
       int currentDistance = getDistanceFromEvent(event); 
       if (currentDistance > mBaseDistZoomIn) { 
        float finalSize = viewById.getTextSize() + STEP; 
        if (finalSize > TEXT_MAX_SIZE) { 
         finalSize = TEXT_MAX_SIZE; 
        } 
        viewById.setTextSize(TypedValue.COMPLEX_UNIT_PX, finalSize); 
       } else { 
        if (currentDistance < mBaseDistZoomOut) { 
         float finalSize = viewById.getTextSize() - STEP; 
         if (finalSize < TEXT_MIN_SIZE) { 
          finalSize = TEXT_MIN_SIZE; 
         } 
         viewById.setTextSize(TypedValue.COMPLEX_UNIT_PX, finalSize); 
        } 
       } 
      } 
      return true; 
     } 
     return false; 
    } 


    // good function to get the distance between the multiple touch 
    int getDistanceFromEvent(MotionEvent event) { 
     int dx = (int) (event.getX(0) - event.getX(1)); 
     int dy = (int) (event.getY(0) - event.getY(1)); 
     return (int) (Math.sqrt(dx * dx + dy * dy)); 
    } 
}