顺利滚动

Question

我需要Android设备中的图像滚动。我用缩放完成了以下代码。它适用于缩放，但不能轻松滚动。 这是我的代码详细信息。我需要做出改变的地方请帮忙。

package pipe.support.calculator;


import android.app.Activity;
import android.content.res.Resources;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.SystemClock;
import android.util.DisplayMetrics;
import android.util.FloatMath;
import android.util.Log;

import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.Window;
import android.widget.ImageView;

public class ZoomActivity extends Activity implements OnTouchListener { 

    ImageView view;
    Matrix  matrix = new Matrix();
    Matrix  savedMatrix = new Matrix();
    PointF  start = new PointF();
    PointF  mid = new PointF();
    float   oldDist = 0;
    int     width = 0;
    int     height = 0;
    float   fitScaleX = 1.0f;
    float   fitScaleY = 1.0f;

    static final int STATE_NONE = 0;
    static final int STATE_DRAG = 1;
    static final int STATE_ZOOM = 2;
    int mode = STATE_NONE;
    long doubleClickStartTime = 0;
    boolean doubleClickFlag = false;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);   
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.chart);        
        view = (ImageView) findViewById(R.id.imageViewChart);
        view.setOnTouchListener(this);

        getFitScale();      

        matrix.postScale(fitScaleX, fitScaleY, 0, 0);
        view.setImageMatrix(matrix);
    }

    public void onStart() {
        super.onStart();


    }

    private void getFitScale() {        
        try{
        Resources rs = getResources();     
        Drawable dw = rs.getDrawable(R.drawable.chartid);

        width =  dw.getIntrinsicWidth();
        height = dw.getIntrinsicHeight();
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);

        fitScaleX = (float)dm.widthPixels / (float)width;
        fitScaleY = fitScaleX;
        }catch(Exception exception)
        {
            exception.printStackTrace();
        }
    }   

    public boolean onTouch(View v, MotionEvent event)
    {       
        // Handle touch events here...
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
             savedMatrix.set(matrix);
             start.set(event.getX(), event.getY());
             mode = STATE_DRAG; 
             break;
        case MotionEvent.ACTION_UP:
            mode = STATE_NONE;
             // for Auto Fitting
             if(doubleClickFlag == false)
                 doubleClickStartTime = SystemClock.uptimeMillis();

             if(doubleClickFlag) { 
                 if(SystemClock.uptimeMillis() - doubleClickStartTime < 500) {
                    matrix.reset();
                    matrix.postScale(fitScaleX, fitScaleY, 0, 0);
                 } else {
                    doubleClickStartTime = SystemClock.uptimeMillis();
                    doubleClickFlag = false;
                 }
             }

             if(doubleClickFlag == false)
                 doubleClickFlag = true;
             else
                 doubleClickFlag = false;
             break;
        case MotionEvent.ACTION_POINTER_UP:
             mode = STATE_NONE;  
             break;
        case MotionEvent.ACTION_MOVE:
             if (mode == STATE_DRAG) {
                 float dx = event.getX() - start.x;
                 float dy = event.getY() - start.y;
                 float[] values = new float[9];              

                 matrix.set(savedMatrix);
                 matrix.getValues(values);

                 if(values[Matrix.MTRANS_X]+ dx < view.getWidth() - width * values[Matrix.MSCALE_X]) {                  
                    dx = view.getWidth()  - values[Matrix.MTRANS_X] - width * values[Matrix.MSCALE_X];
                 }               
                 else if(values[Matrix.MTRANS_X]+ dx > 0) {
                     dx = 0 - values[Matrix.MTRANS_X];
                 }

                 if(values[Matrix.MTRANS_Y] + dy  < view.getHeight() - height*values[Matrix.MSCALE_Y]) {                     
                    dy = view.getHeight() - height * values[Matrix.MSCALE_Y] - values[Matrix.MTRANS_Y];
                 }
                 else if(values[Matrix.MTRANS_Y] + dy > 0) {
                     dy = 0 - values[Matrix.MTRANS_Y];
                 }

                 matrix.postTranslate(dx, dy);
             }
             else if (mode == STATE_ZOOM) {
                  float newDist = spacing(event);
                  matrix.set(savedMatrix);

                  if (newDist > 10f) {
                     float[] values = new float[9];              

                     matrix.set(savedMatrix);
                     matrix.getValues(values);

                     float scale = newDist / oldDist;

                     if(values[Matrix.MSCALE_X] * scale > 3.0f ||
                        values[Matrix.MSCALE_Y] * scale > 3.0f   ) {
                        matrix.reset();
                        matrix.postScale(3.0f, 3.0f, 0, 0);
                     }
                     else if(values[Matrix.MSCALE_X] * scale < fitScaleX ||
                             values[Matrix.MSCALE_Y] * scale < fitScaleY) {
                        matrix.reset();
                        matrix.postScale(fitScaleX, fitScaleY, 0, 0);
                     }
                     else {
                         matrix.postScale(scale, scale, 0, 0);
                     }
                  }
               }
             break;

        case MotionEvent.ACTION_POINTER_DOWN:
             oldDist = spacing(event);

             if (oldDist > 10f) {
                 savedMatrix.set(matrix);
                 midPoint(mid, event);
                 mode = STATE_ZOOM;            
             }
             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);
    }
}