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Question

我希望制作一个相当复杂的 CustomSeekBar。我发现的教程对我帮助不大，这对我来说是新的领域。

我的目标是这样的：https://morgazmo99-yahoo-com.tinytake.com/sf/MjIwMjM2XzEzNzI5MzQ

我需要将所有获取、设置、侦听和更新代码包含在我的 CustomSeekBar 类中。 textViewA 和 textViewB 应该被重写的 onProgressChanged 方法自动更新，尽管每个都需要一个 OnClickListener 来向这些视图添加额外的数据。

我想我已经很接近了，但我不知道如何将视图封装到我的 CustomSeekBar 类中。我在尝试设置 TextView 时遇到了 NPE，我基本上理解原因，但我确定我希望 CustomSeekBar 组件来管理这些 TextView。

我真的只是在寻找有关如何在我的自定义类中正确更新来自 OnProgressChanged 的​​ TextViews 的帮助。代码如下：

到目前为止，我的 XML 工作正常。

<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/textViewTitle"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Center of Gravity"
    android:layout_alignParentStart="true"
    android:layout_alignParentLeft="true"
    android:layout_marginStart="@dimen/seekbar_margin"
    android:layout_marginLeft="@dimen/seekbar_margin"
    android:layout_marginTop="14dp" />

<com.sample.myapp.CustomSeekBar

    android:id="@+id/customseekBar"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_below="@+id/textViewTitle"
    android:progressDrawable="@android:color/transparent"
    android:max="100"
    android:progress="50"/>

<TextView

    android:id="@+id/textViewA"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="A"
    android:layout_alignParentStart="true"
    android:layout_alignParentLeft="true"
    android:layout_below="@+id/customseekBar"
    android:layout_marginStart="@dimen/seekbar_margin"
    android:layout_marginLeft="@dimen/seekbar_margin"
    android:layout_marginTop="@dimen/seekbar_text_padding"
    android:clickable="true"/>

<TextView

    android:id="@+id/textViewB"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="B"
    android:layout_alignParentEnd="true"
    android:layout_alignParentRight="true"
    android:layout_below="@+id/customseekBar"
    android:layout_marginEnd="@dimen/seekbar_margin"
    android:layout_marginRight="@dimen/seekbar_margin"
    android:layout_marginTop="@dimen/seekbar_text_padding"
    android:clickable="true"/>

</RelativeLayout>

我确实有一个 CustomSeekBar 类正在到达那里：

package com.sample.myapp;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.widget.SeekBar;

public class CustomSeekBar extends SeekBar implements SeekBar.OnSeekBarChangeListener {

private Rect rect;
private Paint paint;
private int seekbar_height, textViewAPercentage, textViewBPercentage;
private String textViewTitleText, textViewAText, textViewBText;;

private TextView textViewA, textViewB, textViewTitle;

public CustomSeekBar(Context context) {

    super(context);
    setOnSeekBarChangeListener(this);

}

public CustomSeekBar(Context context, AttributeSet attrs) {

    super(context, attrs);
    setOnSeekBarChangeListener(this);
    rect = new Rect();
    paint = new Paint();
    seekbar_height = 6;

}

public CustomSeekBar(Context context, AttributeSet attrs, int defStyle) {

    super(context, attrs, defStyle);
    setOnSeekBarChangeListener(this);

}

public void setTextViewTitleText(String string) {
    this.textViewTitleText = string;
}

public String getTextA() {
    return textViewAText;
}

public void setTextA(String string) {
    this.textViewAText = string;
}

public String getTextB() {
    return textViewBText;
}

public void setTextB(String string) {
    this.textViewBText = string;
}

@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

    int seekBarMax = seekBar.getMax();
    textViewAPercentage = (seekBarMax / progress) * 100;
    textViewBPercentage = ((seekBarMax - progress) / seekBarMax) * 100;

    String A, B;

    if (textViewAText != null) A = String.valueOf(textViewAPercentage) + "\n" + textViewAText;
    else A = String.valueOf(textViewAPercentage);

    if (textViewBText != null) B = String.valueOf(textViewBPercentage) + "\n" + textViewBText;
    else B = String.valueOf(textViewBPercentage);

    textViewA = (TextView) findViewById(R.id.textViewA);
    textViewB = (TextView) findViewById(R.id.textViewB);

    textViewA.setText(A);
    textViewB.setText(B);

}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {

}

@Override
public void onStopTrackingTouch(SeekBar seekBar) {

}

@Override
protected synchronized void onDraw(Canvas canvas) {

    rect.set(0 + getThumbOffset(), (getHeight() / 2) - (seekbar_height / 2), getWidth() - getThumbOffset(), (getHeight() / 2) + (seekbar_height / 2));
    paint.setColor(Color.GRAY);
    canvas.drawRect(rect, paint);
    if (this.getProgress() > 50) {

        rect.set(getWidth() / 2,  (getHeight() / 2) - (seekbar_height / 2), getWidth() / 2 + (getWidth() / 100) * (getProgress() - 50), getHeight() / 2 + seekbar_height / 2));

        paint.setColor(Color.CYAN);
        canvas.drawRect(rect, paint);

    }

    if (this.getProgress() < 50) {

        rect.set(getWidth() / 2 - ((getWidth() / 100) * (50 - getProgress())), (getHeight() / 2) - (seekbar_height / 2), getWidth() / 2, getHeight() / 2 + (seekbar_height / 2));

        paint.setColor(Color.CYAN);
        canvas.drawRect(rect, paint);

    }

    super.onDraw(canvas);

}

}

Answer 1

使用以下代码

interface iSeekChangeListener {
   public void onChange(String a, String b);
}

在您的活动类中实现 iSeekChangeListener 并覆盖 onChange()，如下所示

 @Override
    public void onChange(String a, String b) {

        textViewA.setText(a);
        textViewB.setText(b);
    }

在您的 CustomSeekBar 类中设置监听器

  public void setListener(iSeekChangeListener customSeekActivty) {

        this.customSeekListener = customSeekActivty;
    }

在您的活动中，您需要设置监听器

customSeekBar.setListener(this);

在 CustomSeekBar 的 onProgressChange() 中

if (customSeekListener != null)
            customSeekListener.onChange(A, B);