在API版本16之前检测SeekBar中的拇指位置

Question

基本上,我需要检测SeekBar中进度何时发生变化,并在拇指顶部绘制一个文本视图,指示进度值.

我这样做是通过实现一个OnSeekBarChangeListener 和public void onProgressChanged(SeekBar seekBar, int progress, boolean b)方法,我打电话Rect thumbRect = seekBar.getThumb().getBounds();确定拇指的位置.

这非常好用,但显然getThumb()只能在API级别16+(Android 4.1)中使用,导致NoSuchMethodError早期版本.

知道如何解决这个问题吗？

Answer 1

我能够使用自己的类来获取Thumb:

MySeekBar.java

package mobi.sherif.seekbarthumbposition;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.widget.SeekBar;

public class MySeekBar extends SeekBar {

    public MySeekBar(Context context) {
        super(context);
    }
    public MySeekBar(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public MySeekBar(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    Drawable mThumb;
    @Override
    public void setThumb(Drawable thumb) {
        super.setThumb(thumb);
        mThumb = thumb;
    }
    public Drawable getSeekBarThumb() {
        return mThumb;
    }

}

在活动中,这完美地运作:

package mobi.sherif.seekbarthumbposition;

import android.app.Activity;
import android.graphics.Rect;
import android.os.Bundle;
import android.util.Log;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;

public class MainActivity extends Activity implements OnSeekBarChangeListener {
    MySeekBar mSeekBar;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mSeekBar = (MySeekBar) findViewById(R.id.seekbar);
        mSeekBar.setOnSeekBarChangeListener(this);
    }
    @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean b) {
        Rect thumbRect = mSeekBar.getSeekBarThumb().getBounds();
        Log.v("sherif", "(" + thumbRect.left + ", " + thumbRect.top + ", " + thumbRect.right + ", " + thumbRect.bottom + ")");
    }
    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {
        // TODO Auto-generated method stub

    }
    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {
        // TODO Auto-generated method stub

    }
}