如何放大/缩小ImageView（不使用画布）android

Question

我正在开发应用程序，在其中我必须旋转，拖放n和放大/缩小图像（较小的一个）到另一个图像（较大的一个）。我已完成旋转并拖动拖放，但无法实现放大/缩小。我知道如何在画布上做，但在我的应用程序中，我没有使用画布。 任何帮助将不胜感激..........

感谢 Davender

Answer 1

看看下面的代码，让我知道，如果有帮助。

public class Touch 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(); 
PointF start = new PointF(); 
public static PointF mid = new PointF(); 

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

float oldDist; 

private float[] matrixValues = new float[9]; 

@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; 

    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_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; 

    case MotionEvent.ACTION_UP: 
    case MotionEvent.ACTION_POINTER_UP: 

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

    // Perform the transformation 
    view.setImageMatrix(matrix); 

    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); 
} 

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); 
} 

}

以下是main.xml中的文件

<?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/yourimage" 
      android:scaleType="matrix"> 
    </ImageView> 
    </FrameLayout> 

更换ImageView的（yourimage）的SRC属性的价值，你在你的项目中有形象的名字。