zoomable android textview

目标=把helloworld的文字变成可以缩放的。

测试=需要能实体手机，虚拟机似乎不能进行触摸缩放测试。

版本=android 2.3.3，target=android-10

参考了网上例子。

关键点

=============main.xml

<TextView android:id="@+id/text"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:text="@string/hello" />

=============A1Activity.java

public void onCreate中，加入：

TextView textView = (TextView) findViewById(R.id.text);

textView.setOnTouchListener(this);

加入public boolean onTouch和相关变量

public boolean onTouch中，最后return true;是关键。

关键文件代码

=============main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <TextView android:id="@+id/text"        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:text="@string/hello" /></LinearLayout>

=============A1Activity.java

package com.ex.a1205;import android.app.Activity;import android.os.Bundle;import android.util.FloatMath;import android.util.Log;import android.util.TypedValue;import android.view.MotionEvent;import android.view.View;import android.view.View.OnTouchListener;import android.widget.TextView;public class A1Activity extends Activity implements OnTouchListener {  private static final String TAG = "textZoom";  // We can be in one of these 2 states  static final int NONE = 0;  static final int ZOOM = 1;  int mode = NONE;  static final int MIN_FONT_SIZE = 20;  static final int MAX_FONT_SIZE = 150;  float oldDist = 1f;  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);    TextView textView = (TextView) findViewById(R.id.text);    textView.setOnTouchListener(this);  }  public boolean onTouch(View v, MotionEvent event) {    TextView textView = (TextView) findViewById(R.id.text);    switch (event.getAction() & MotionEvent.ACTION_MASK) {    case MotionEvent.ACTION_POINTER_DOWN:      oldDist = spacing(event);      Log.d(TAG, "oldDist=" + oldDist);      if (oldDist > 10f) {        mode = ZOOM;      }      break;    case MotionEvent.ACTION_POINTER_UP:      mode = NONE;      break;    case MotionEvent.ACTION_MOVE:      if (mode == ZOOM) {        float newDist = spacing(event);        if (newDist > 10f) {          float scale = newDist / oldDist;          if (scale > 1) {            scale = 1.1f;          } else if (scale < 1) {            scale = 0.95f;          }          float currentSize = textView.getTextSize() * scale;          if ((currentSize < MAX_FONT_SIZE && currentSize > MIN_FONT_SIZE)              || (currentSize >= MAX_FONT_SIZE && scale < 1)              || (currentSize <= MIN_FONT_SIZE && scale > 1)) {            textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, currentSize);          }        }      }      break;    }    return true;  }  /** 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);  }}

执行结果

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