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

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：