在文本视图android上捏缩放

Question

你好朋友我已经完成了缩放缩放textview,它的工作正常,但问题是当我缩小textview位置发生变化时我希望textview的位置在放大和缩小期间是固定的,这是我的代码

public class MainActivity extends Activity {

    TextView scaleGesture;
    ScaleGestureDetector scaleGestureDetector;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        scaleGesture = (TextView)findViewById(R.id.article);
        scaleGesture.setText("this is some text");
        scaleGestureDetector = new ScaleGestureDetector(this, new simpleOnScaleGestureListener());
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // TODO Auto-generated method stub
        scaleGestureDetector.onTouchEvent(event);
        return true;
    }

    public class simpleOnScaleGestureListener extends
            SimpleOnScaleGestureListener {

        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            // TODO Auto-generated method stub
            float size = scaleGesture.getTextSize();
            Log.d("TextSizeStart", String.valueOf(size));

            float factor = detector.getScaleFactor();
            Log.d("Factor", String.valueOf(factor));


            float product = size*factor;
            Log.d("TextSize", String.valueOf(product));
            scaleGesture.setTextSize(TypedValue.COMPLEX_UNIT_PX, product);

            size = scaleGesture.getTextSize();
            Log.d("TextSizeEnd", String.valueOf(size));
            return true;
        }
    }
}

Answer 1

我这样做了:

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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/mytv"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="This is my sample text for pinch zoom demo, you can zoom in and out using pinch zoom, thanks" />

</RelativeLayout>

MainActivity.java:

import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.TextView;

public class MyTextViewPinchZoomClass extends Activity implements OnTouchListener {

    final static float STEP = 200;
    TextView mytv;
    float mRatio = 1.0f;
    int mBaseDist;
    float mBaseRatio;
    float fontsize = 13;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mytv = (TextView) findViewById(R.id.mytv);
        mytv.setTextSize(mRatio + 13);
    }

    public boolean onTouchEvent(MotionEvent event) {
        if (event.getPointerCount() == 2) {
            int action = event.getAction();
            int pureaction = action & MotionEvent.ACTION_MASK;
            if (pureaction == MotionEvent.ACTION_POINTER_DOWN) {
                mBaseDist = getDistance(event);
                mBaseRatio = mRatio;
            } else {
                float delta = (getDistance(event) - mBaseDist) / STEP;
                float multi = (float) Math.pow(2, delta);
                mRatio = Math.min(1024.0f, Math.max(0.1f, mBaseRatio * multi));
                mytv.setTextSize(mRatio + 13);
            }
        }
        return true;
    }

    int getDistance(MotionEvent event) {
        int dx = (int) (event.getX(0) - event.getX(1));
        int dy = (int) (event.getY(0) - event.getY(1));
        return (int) (Math.sqrt(dx * dx + dy * dy));
    }

    public boolean onTouch(View v, MotionEvent event) {
        return false;
    }
}

完成

Answer 2

public class MainActivity extends Activity {

TextView scaleGesture;
ScaleGestureDetector scaleGestureDetector;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    scaleGesture = (TextView)findViewById(R.id.article);
    scaleGesture.setText("this is some text");
    scaleGestureDetector = new ScaleGestureDetector(this, new simpleOnScaleGestureListener());
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}


@Override
public boolean onTouchEvent(MotionEvent event) {
    // TODO Auto-generated method stub
    scaleGestureDetector.onTouchEvent(event);
    return true;
}

public class simpleOnScaleGestureListener extends
        SimpleOnScaleGestureListener {

    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        // TODO Auto-generated method stub
        float size = scaleGesture.getTextSize();
        Log.d("TextSizeStart", String.valueOf(size));

        float factor = detector.getScaleFactor();
        Log.d("Factor", String.valueOf(factor));


        float product = size*factor;
        Log.d("TextSize", String.valueOf(product));
        scaleGesture.setTextSize(TypedValue.COMPLEX_UNIT_PX, product);

        size = scaleGesture.getTextSize();
        Log.d("TextSizeEnd", String.valueOf(size));
        return true;
    }
}
 }

视图

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<TextView
    android:id="@+id/article"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />