缩放系列（二）：所有子控件也随着缩放、手势缩放、多点触控layout

下面是一个功能强大的改造的例子：

可以实现以下需求：

1.两个手指进行缩放布局

2.所有子控件也随着缩放，

3.子控件该有的功能不能丢失（像button有可被点击的功能，缩放后不能丢失该功能）

运行效果图：

java代码如下

MainActivity.java:

public class MainActivity extends ActionBarActivity {
    private ScaleGestureDetector mScaleGestureDetector = null;
    private View view;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // setContentView(R.layout.test);
        view = View.inflate(this, R.layout.activity_main, null);
        setContentView(view);

        mScaleGestureDetector = new ScaleGestureDetector(this,
                new ScaleGestureListener());

    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // 返回给ScaleGestureDetector来处理
        return mScaleGestureDetector.onTouchEvent(event);
    }

    public class ScaleGestureListener implements
            ScaleGestureDetector.OnScaleGestureListener {

        private float scale;
        private float preScale = 1;// 默认前一次缩放比例为1

        @Override
        public boolean onScale(ScaleGestureDetector detector) {

            float previousSpan = detector.getPreviousSpan();
            float currentSpan = detector.getCurrentSpan();
            if (currentSpan < previousSpan) {
                // 缩小
                // scale = preScale-detector.getScaleFactor()/3;
                scale = preScale - (previousSpan - currentSpan) / 1000;
            } else {
                // 放大
                // scale = preScale+detector.getScaleFactor()/3;
                scale = preScale + (currentSpan - previousSpan) / 1000;
            }

            // 缩放view
            ViewHelper.setScaleX(view, scale );// x方向上缩小
            ViewHelper.setScaleY(view, scale );// y方向上缩小

            return false;
        }

        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) {
            // 一定要返回true才会进入onScale()这个函数
            return true;
        }

        @Override
        public void onScaleEnd(ScaleGestureDetector detector) {
            preScale = scale;//记录本次缩放比例
        }
    }
}

布局文件(activity_main.xml)：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="@drawable/home_tools"
    >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="测试" />

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/abc_ic_voice_search_api_holo_light" />

    <ImageButton
        android:id="@+id/imageButton1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/selector_button2" />

    <ImageButton
        android:id="@+id/imageButton2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/selector_button1"
        android:layout_gravity="center"
        />

</LinearLayout>

selector_button1.xml：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:drawable="@drawable/home_tools" android:state_pressed="true"></item>
    <item android:drawable="@drawable/home_*"></item>
</selector>

selector_button2.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:drawable="@drawable/home_sysoptimize" android:state_pressed="true"></item>
    <item android:drawable="@drawable/home_taskmanager"></item>
</selector>

如果想要整个布局能够移动，可以看下面的帖子：

http://www.cnblogs.com/johnsonwei/p/5831925.html