放大和縮小

Question

這裏是我想實現放大和縮小的圖像的代碼。它得到放大，但是當它熄滅屏幕它就會崩潰...還當我縮小圖像的尺寸縮小，再後來得到它墜毀。我想限制放大到一個級別，也縮小到原來的位置。

，並繼續擴展到屏幕的中間點的圖像變化的左上角...

請幫助實現這一....謝謝

package com.imageviewzoomactivity; 

import android.app.Activity; 
import android.graphics.Matrix; 
import android.graphics.PointF; 
import android.graphics.drawable.Drawable; 
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 ImageViewZoomActivityActivity 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(); 
    Matrix savedMatrix2 = new Matrix(); 

    private static final int WIDTH = 0; 
    private static final int HEIGHT = 1; 
    // 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); 
    } 

Answer 1

顯示圖像在web視圖中。看到這個例子...

String html = new String(); 
html = ("<html><BODY ><table style='margin-top:100px;' align='center'><tr><td><img src=\""+path+"\" width=\""+800+"px\" height=\""+800+"px\" ></td></tr></table> </BODY></html>"); 

webView1.loadDataWithBaseURL("file:///sdcard/data/data/com.dharani.jorTablet.Fragments/", 
     html, 
     "text/html", 
     "utf-8", 
     ""); 

Answer 2

你可以用這個例子也

  float mScaleFactor1=1.f; 
    float gx=0,gy=0; 


    //Code for Image Scaling............ 
    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener { 

     @Override 
     public boolean onScale(ScaleGestureDetector detector) { 
      mScaleFactor1 *= detector.getScaleFactor(); 




      gx = detector.getFocusX(); 
      gy = detector.getFocusY(); 





      return true; 
     } 

     @Override 
     public void onScaleEnd(ScaleGestureDetector detector) { 
      // TODO Auto-generated method stub 
      super.onScaleEnd(detector); 


     } 
    } 

終於在的onDraw（）方法調用這個//圖像縮放....

**canvas.scale(gx, gy);** 

Answer 3

如果你只想縮放，使用ScaleGestureDetector.SimpleOnScaleGestureListener類。這是使用矩陣調整縮放級別的真正簡單方法。

public boolean onScale(ScaleGestureDetector detector){ 
     ... 
    } 

detector.getFocuxX()和detector.getFocusY()照顧越來越變焦中點，所以你不必計算出自己。

保持一個浮動scaleFactor和更新與scaleFactor *= detector.getScaleFactor()。這樣您可以控制最大和最小縮放級別。

示例代碼：

public boolean onScale(ScaleGestureDetector detector) { 
    //update the current scale 
    scaleFactor *= detector.getScaleFactor(); 
    matrix.setScale(scaleFactor, scaleFactor) 
} 

繁榮。你走了。