基于Android DataBinding的InverseBindingMethod改进SeekBar双向绑定（正向/反向）数据绑定

在前文《使用Android BindingAdapter与InverseBindingAdapter实现SeekBar双向（正向/反向）数据绑定》（链接：http://blog.csdn.net/zhangphil/article/details/77839555 ）基础上，用InverseBindingMethod改进双向绑定实现方案。

老规矩，先建立数据模型，PhilProgress.java：

package zhangphil.test;

import android.databinding.BaseObservable;
import android.databinding.ObservableInt;

/**
 * Created by Phil on 2017/9/4.
 */

public class PhilProgress extends BaseObservable {
    public ObservableInt porgress = new ObservableInt();
}

重写SeekBar，PhilSeekBar.java：

package zhangphil.test;

import android.content.Context;
import android.databinding.InverseBindingListener;
import android.databinding.InverseBindingMethod;
import android.databinding.InverseBindingMethods;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.SeekBar;

/**
 * Created by Phil on 2017/9/4.
 */

@InverseBindingMethods({@InverseBindingMethod(type = PhilSeekBar.class, attribute = "progress", event = "progressAttrChanged")})

public class PhilSeekBar extends SeekBar {
    private String TAG = "调试输出";

    private int progress = 0;
    private InverseBindingListener mInverseBindingListener;

    public PhilSeekBar(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
                progress = i;

                //触发反向数据的传递
                if (mInverseBindingListener != null) {
                    mInverseBindingListener.onChange();
                }
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });
    }

    public void setProgress(int p) {
        Log.d(TAG, "setProgress:" + p);

        if (progress != p) {
            progress = p;

            //这一句代码可以解决初始化阶段进度条显示的值正确，但没有及时更新UI的问题。
            //super.setProgress(progress);
        }
    }

    public int getProgress() {
        Log.d(TAG, "getProgress:" + progress);

        return progress;
    }

    public void setProgressAttrChanged(InverseBindingListener inverseBindingListener) {
        if (inverseBindingListener != null) {
            mInverseBindingListener = inverseBindingListener;
        }
    }
}

写布局activity_main.xml使用PhilSeekBar:

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>
        <variable
            name="progress"
            type="zhangphil.test.PhilProgress" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <zhangphil.test.PhilSeekBar
            style="?android:attr/progressBarStyleHorizontal"
            android:layout_width="match_parent"
            android:layout_height="30dp"
            app:progress="@={progress.porgress}" />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="@{String.valueOf(progress.porgress)}"
            android:textColor="@android:color/holo_blue_light"
            android:textSize="50dp" />

    </LinearLayout>
</layout>

测试的MainActivity.java:

package zhangphil.test;

import android.app.Activity;
import android.databinding.DataBindingUtil;
import android.os.Bundle;

import zhangphil.test.databinding.ActivityMainBinding;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);

        final PhilProgress progress = new PhilProgress();
        binding.setProgress(progress);

        //设置一个初始值作为演示 数据 -> View
        //这是最常见的进度设置。
        progress.porgress.set(21);
    }
}

代码初始运行结果：

注意到虽然进度条显示到了21，但是却没有彩色着色，在PhilSeekBar的setProgress方法里面，启用super.setProgress可以解决这个问题。


手指拖动后的结果显示：