在API版本16之前检测SeekBar中的拇指位置 [英] Detecting thumb position in SeekBar prior to API version 16

问题描述

基本上，我需要检测SeekBar中进度何时发生变化，并在拇指上方绘制一个文本视图以指示进度值.

Basically, I need to detect when the progress changes in the SeekBar and draw a text view on top of the thumb indicating the progress value.

我通过实现OnSeekBarChangeListener来做到这一点 在public void onProgressChanged(SeekBar seekBar, int progress, boolean b)方法上，我调用Rect thumbRect = seekBar.getThumb().getBounds();确定拇指的位置.

I do this by implementing a OnSeekBarChangeListener and on the public void onProgressChanged(SeekBar seekBar, int progress, boolean b) method, I call Rect thumbRect = seekBar.getThumb().getBounds(); to determine where the thumb is positioned.

这工作得很好，但是显然getThumb()仅在API级别16+(Android 4.1)中可用，导致在早期版本中出现NoSuchMethodError.

This works perfectly fine, but apparently getThumb() is only available in API level 16+ (Android 4.1), causing a NoSuchMethodError on earlier versions.

任何想法如何解决此问题?

Any idea how to work around this issue?

推荐答案

我能够使用自己的类来获取Thumb:

I was able to use my own class to get the 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，此操作非常完美:

In the activity this works perfectly:

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

    }
}

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