Question

这是我试图实现放大和缩小图像的代码。它会变焦，但当它离开屏幕时会崩溃......当我缩小图像的大小时会缩小，然后它就会崩溃。我想将放大限制为一个级别，也缩小到原始位置。

当图像的中点改变时，它会继续缩放到屏幕的左上角......

请帮助实现这一目标....谢谢

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

在webview中显示图片。看这个例子......

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

您也可以使用此示例

         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);


        }
    }

最后在onDraw（）方法中调用// Image Scaling ....

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

Answer 3

如果您只想缩放，请使用ScaleGestureDetector.SimpleOnScaleGestureListener课程。这些方法可以很容易地使用矩阵调整缩放级别。

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

detector.getFocuxX()和detector.getFocusY()负责获取缩放中点，因此您无需自己计算。

保持浮动scaleFactor并使用scaleFactor *= detector.getScaleFactor()进行更新。这样您就可以控制最大和最小缩放级别。

示例代码：

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

动臂。你去吧。

放大和缩小

3 个答案: