android - 如何设置放大缩小和缩小默认缩放大小？

Question

我遵循本教程 http://www.allappsdevelopers.com/TopicDetail.aspx?TopicID=c16ed3b4-b422-43ba-b595-ee8e21dd1854问题是当我捕获图像时默认显示尺寸太大但所有放大缩小我如何将默认尺寸设置为正常图像尺寸？

public boolean onTouch(View v, MotionEvent event) {

   ImageView view = (ImageView) v;

   view.setScaleType(ImageView.ScaleType.MATRIX);

   float scale;



   // Dump touch event to log

   dumpEvent(event);



   // Handle touch events here...

   switch (event.getAction() & MotionEvent.ACTION_MASK) {



   case MotionEvent.ACTION_DOWN: //first finger down only

      savedMatrix.set(matrix);

      start.set(event.getX(), event.getY());

      Log.d(TAG, "mode=DRAG" );

      mode = DRAG;

      break;

   case MotionEvent.ACTION_UP: //first finger lifted

   case MotionEvent.ACTION_POINTER_UP: //second finger lifted

      mode = NONE;

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

      break;

   case MotionEvent.ACTION_POINTER_DOWN: //second finger down

      oldDist = spacing(event);

      Log.d(TAG, "oldDist=" + oldDist);

      if (oldDist > 5f) {

         savedMatrix.set(matrix);

         midPoint(mid, event);

         mode = ZOOM;

         Log.d(TAG, "mode=ZOOM" );

      }

      break;



   case MotionEvent.ACTION_MOVE:

      if (mode == DRAG) { //movement of first finger

         matrix.set(savedMatrix);

         if (view.getLeft() >= -392){

            matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);

         }
      }

      else if (mode == ZOOM) { //pinch zooming

         float newDist = spacing(event);

         Log.d(TAG, "newDist=" + newDist);

         if (newDist > 5f) {

            matrix.set(savedMatrix);

            scale = newDist / oldDist; /*thinking i need to play around  
with this value to limit it*/

            matrix.postScale(scale, scale, mid.x, mid.y);

         }

      }

      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);

}



/** 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());

}

Answer 1

float initialZoomLevel = 0.5f;
matrix.setScale(initialZoomLevel, initialZoomLevel);
view.setImageMatrix(matrix);

将其放入 ImageView 的构造函数/初始化方法中。这将导致图像立即以 1/2 大小显示。对图像的任何进一步修改都应该在同一个矩阵上完成

public boolean onTouch(View v, MotionEvent event) {
    matrix = view.getImageMatrix()
    //.. now do zooming, etc on this matrix
}

这样，图像的“默认”大小设置为原始大小的一半。希望这对您有所帮助!