手势缩放（一）

 效果：字体缩放（无数倍），目前我自定义有个倍数，不过有点BUG;而且scroollveiw滑动冲突没解决；

1.   activity_main.xml

<ScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="11sp"
        android:scrollbars="vertical"
        />

</ScrollView>

2.   MainActivity.java

TextView textView = (TextView) findViewById(R.id.textView);
textView.setMovementMethod(ScrollingMovementMethod.getInstance());
textView.setText("道德三皇五帝,\n" + "功名夏后商周.\n" + "英雄五霸闹春秋,\n" + "顷刻兴亡过手.\n"
        + "青史几行名姓,\n" + "北邙无数荒丘.\n" + "前人田地后人收,\n" + "说甚龙争虎斗." + "道德三皇五帝,\n" + "功名夏后商周.\n" + "英雄五霸闹春秋,\n" + "顷刻兴亡过手.\n"
        + "青史几行名姓,\n" + "北邙无数荒丘.\n" + "前人田地后人收,\n" + "说甚龙争虎斗." + "道德三皇五帝,\n" + "功名夏后商周.\n" + "英雄五霸闹春秋,\n" + "顷刻兴亡过手.\n"
        + "青史几行名姓,\n" + "北邙无数荒丘.\n" + "前人田地后人收,\n" + "说甚龙争虎斗." + "道德三皇五帝,\n" + "功名夏后商周.\n" + "英雄五霸闹春秋,\n" + "顷刻兴亡过手.\n"
        + "青史几行名姓,\n" + "北邙无数荒丘.\n" + "前人田地后人收,\n" + "说甚龙争虎斗." + "道德三皇五帝,\n" + "功名夏后商周.\n" + "英雄五霸闹春秋,\n" + "顷刻兴亡过手.\n"
        + "青史几行名姓,\n" + "北邙无数荒丘.\n" + "前人田地后人收,\n" + "说甚龙争虎斗." + "道德三皇五帝,\n" + "功名夏后商周.\n" + "英雄五霸闹春秋,\n" + "顷刻兴亡过手.\n"
        + "青史几行名姓,\n" + "北邙无数荒丘.\n" + "前人田地后人收,\n" + "说甚龙争虎斗." + "道德三皇五帝,\n" + "功名夏后商周.\n" + "英雄五霸闹春秋,\n" + "顷刻兴亡过手.\n"
        + "青史几行名姓,\n" + "北邙无数荒丘.\n" + "前人田地后人收,\n" + "说甚龙争虎斗." + "道德三皇五帝,\n" + "功名夏后商周.\n" + "英雄五霸闹春秋,\n" + "顷刻兴亡过手.\n"
        + "青史几行名姓,\n" + "北邙无数荒丘.\n" + "前人田地后人收,\n" + "说甚龙争虎斗.");
textView.getParent().requestDisallowInterceptTouchEvent(true);
textView.setOnTouchListener(new ZoomListenter());

 

3.   ZoomListenter.java

import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.TextView;

public class ZoomListenter implements OnTouchListener {

   private int mode = 0;
   float oldDist;
   float textSize = 0;
   TextView textView;
   final static float defaultTextSize = 11.0f;
   public boolean onTouch(View v, MotionEvent event) {
      textView = (TextView) v;
      if (textSize == 0) {
         textSize = textView.getTextSize();
      }
      switch (event.getAction() & MotionEvent.ACTION_MASK) {
         case MotionEvent.ACTION_DOWN:
            mode = 1;
            break;
         case MotionEvent.ACTION_UP:
            mode = 0;
            break;
         case MotionEvent.ACTION_POINTER_UP:
            mode -= 1;
            break;
         case MotionEvent.ACTION_POINTER_DOWN:
            oldDist = spacing(event);
            mode += 1;
            break;

         case MotionEvent.ACTION_MOVE:
            if (mode >= 2) {
               float newDist = spacing(event);
               if (newDist > oldDist + 1) {
                  if (textSize < defaultTextSize*3){
                  zoom(newDist / oldDist);
                  oldDist = newDist;
                  }

               }
               if (newDist < oldDist - 1) {
                  if (textSize > defaultTextSize){
                  zoom(newDist / oldDist);
                  oldDist = newDist;
                  }
               }
            }
            break;
      }
      return true;
   }
   private void zoom(float f) {
         textView.setTextSize(textSize *= f);
   }
   private float spacing(MotionEvent event) {
      float x = event.getX(0) - event.getX(1);
      float y = event.getY(0) - event.getY(1);
      //平方根
      return (float) Math.sqrt(x * x + y * y);
   }



}