Question

您好我正在尝试创建一个应用程序，您可以在其中放大和平移校园站点地图。我有这个工作，但遇到了限制你可以平移和缩放多少的问题。我需要帮助设置平移和缩放边界。
任何帮助将不胜感激，

提前致谢
这是代码。

package com.scott;

import android.app.Activity;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.os.Bundle;
import android.util.FloatMath;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ImageView;

public class Touch extends Activity implements OnTouchListener,OnClickListener {
   private static final String TAG = "Touch";

   Matrix matrix = new Matrix();
   Matrix savedMatrix = new Matrix();
   static final int NONE = 0;
   static final int DRAG = 1;
   static final int ZOOM = 2;
   int mode = NONE;

   PointF start = new PointF();
   PointF mid = new PointF();
   float oldDist = 1f;

   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.touch);
      ImageView view = (ImageView) findViewById(R.id.imageView);
      view.setOnTouchListener(this);

     Button buttonClose =(Button)findViewById(R.id.buttonClose);
     buttonClose.setOnClickListener(this); 

   }

   @Override
   public boolean onTouch(View v, MotionEvent event) {
      ImageView view = (ImageView) v;


      dumpEvent(event);

      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:
      case MotionEvent.ACTION_POINTER_UP:
         mode = NONE;
         Log.d(TAG, "mode=NONE");
         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; 
   }

   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());
   }

   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);
   }

@Override
public void onClick(View src) {
    switch(src.getId()){ 
    case R.id.buttonClose:
        finish(); 
        break; 

    }   
    }
}

Answer 1

你可以用postTranslate来调整这个方法，你应该在自己的postScale和postTranslate之后调用这个方法

private void adjustPan(){
        float[] matrixValues = new float[9];
        matrix.getValues(matrixValues);
        float currentY = matrixValues[Matrix.MTRANS_Y];
        float currentX = matrixValues[Matrix.MTRANS_X];
        float currentScale = matrixValues[Matrix.MSCALE_X];
        float currentHeight = bitmap.getHeight() * currentScale;
        float currentWidth =  bitmap.getWidth() * currentScale;
        float newX = currentX;
        float newY = currentY;

        RectF drawingRect = new RectF(newX, newY, newX + currentWidth,
                        newY + currentHeight);
        float diffUp = Math.min(displayRect.bottom - drawingRect.bottom,
                        displayRect.top - drawingRect.top);
        float diffDown = Math.max(displayRect.bottom - drawingRect.bottom,
                        displayRect.top - drawingRect.top);
        float diffLeft = Math.min(displayRect.left - drawingRect.left,
                        displayRect.right - drawingRect.right);
        float diffRight = Math.max(displayRect.left - drawingRect.left,
                        displayRect.right - drawingRect.right);

        float x = 0, y = 0;

        if (diffUp > 0) 
                y += diffUp;
        if (diffDown < 0) 
                y += diffDown;
        if (diffLeft > 0) 
                x += diffLeft;
        if (diffRight < 0) 
                x += diffRight;

        if(currentWidth < displayRect.width())
                x = -currentX + (displayRect.width() - currentWidth) / 2;
        if(currentHeight<displayRect.height())
                y = -currentY + (displayRect.height() - currentHeight) / 2;

        matrix.postTranslate(x, y);
}

其中displayRect是一个看起来像这样的RectF：

         displayRect = new RectF();
     displayRect.set(0, 0, displaywidth, displayheight);

至于你的最大最小变焦，你需要在你的postScale之前做这样的事情：

             float[] f = new float[9];
         matrix.getValues(f);
         float currentScale = f[Matrix.MSCALE_X];

         if (scale * currentScale > maxZoom) 
                 scale = maxZoom / currentScale;
           else if (scale * currentScale < minZoom) 
                 scale = minZoom / currentScale;

其中minZoom是：

minZoom = Math.min(displayRect.width()/bitmap.getWidth(), displayRect.height()/bitmap.getHeight());

和maxZoom就是你喜欢的。

希望这有点帮助。

（原文取自某处，现在找不到链接）

限制平移和缩放

1 个答案: