Android DataBinding 学习（二）

dataBinding(二)

【1】在布局中使用vm变量进行资源判断

场景：点击按钮，对应的圆和按钮本身的背景颜色发生改变，不需要单独在代码中设置其背景色，可以直接在布局中镶嵌

VM：

public  class TestVM {
    public ObservableBoolean isGreenGradient = new ObservableBoolean();
}

布局文件：

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

    <data>

        <import type="android.view.View" />

        <variable
            name="viewModel"
            type="com.tzbc.databindtest.TestVM" />
    </data>

    <LinearLayout
        android:id="@+id/linearLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_horizontal"
        android:orientation="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dp"
            android:gravity="center"
            android:orientation="horizontal">

            <ImageView
                android:id="@+id/ivGradient"
                android:layout_width="150dp"
                android:layout_height="150dp"
                android:background="@{viewModel.isGreenGradient ? @drawable/green_gradient : @drawable/yellow_gradient}" />

            <Button
                android:id="@+id/btGradient"
                android:layout_width="wrap_content"
                android:layout_height="50dp"
                android:layout_marginLeft="20dp"
                android:background="@{viewModel.isGreenGradient ? @drawable/button_green_bg : @drawable/button_yellow_bg}"
                android:paddingLeft="10dp"
                android:paddingRight="10dp"
                android:text="@string/gradientText"
                android:textColor="@color/yellowEnd"
                android:textSize="12sp" />
        </LinearLayout>

        <View
            android:layout_width="match_parent"
            android:layout_height="2dp"
            android:layout_marginLeft="20dp"
            android:layout_marginTop="30dp"
            android:layout_marginRight="20dp"
            android:background="@drawable/view_line" />

    </LinearLayout>
</layout>

activity：

package com.tzbc.databindtest;

import android.os.Bundle;
import android.view.View;

import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;

import com.tzbc.databindtest.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private static final String TAG = "tzbc";
    private TestVM testVM;

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

        ActivityMainBinding activityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        testVM = new TestVM();
        testVM.isGreenGradient.set(true);
        activityMainBinding.setViewModel(testVM);

        activityMainBinding.btGradient.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btGradient:
                testVM.isGreenGradient.set(!testVM.isGreenGradient.get());
                break;
        }
    }

}

资源文件：

string:

<string name="gradientText">click to change gradient</string>
<string name="gradientGreen">Green</string>
<string name="gradientYellow">Yellow</string>

view_line:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <solid android:color="@color/black"/>

</shape>

<color name="black">#1A000000</color>
<color name="buttonBg">#569DA7</color>
<color name="buttonBg1">#F1A12B</color>
<color name="greenStart">#15611B</color>
<color name="greenMiddle">#60C964</color>
<color name="greenEnd">#83CC30</color>
<color name="yellowStart">#FF9800</color>
<color name="yellowMiddle">#E6CE08</color>
<color name="yellowEnd">#FAED82</color>

green_gradient:

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

    <gradient
        android:endColor="@color/greenEnd"
        android:startColor="@color/greenStart" />
</shape>

yellow_gradient:

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

    <gradient
        android:endColor="@color/yellowEnd"
        android:startColor="@color/yellowStart" />
</shape>

button_green_bg:

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

    <solid android:color="@color/buttonBg" />
    <corners android:radius="20dp" />
</shape>

button_yellow_bg:

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

    <solid android:color="@color/buttonBg1" />
    <corners android:radius="20dp" />
</shape>