我找到了android data binding with a custom view的解释,但这对我不起作用,因为我不太了解这一点,而且我的情况有点不同。
我的想法:
我需要帆布,所以我可以在上面绘画。
我创建了一个扩展View类的类(CustomView)。在CustomView类中,我创建了负责绘制的服务实例,并且在重写的onDraw
方法中,我将canvas传递给服务类,以便应用程序可以绘制。
问题:
在活动中我使用了setContentView(new CustomView());
,但如果我想使用MVVM设计模式,这将不起作用。
我如何将它们分开并使其与MVVM数据绑定一起使用?
我不明白设置CustomView的方式和位置,以便可以通过数据绑定查看来获取/绑定它?
请耐心等待我,我是Android新手,没有足够的经验。 谢谢:))
答案 0 :(得分:3)
我建议这个解决方案:
Activity.java
package com.example.myapplication;
import android.databinding.DataBindingUtil;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import com.example.myapplication.databinding.ActivityBinding;
import java.util.Arrays;
public class Activity extends AppCompatActivity
{
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
//Do magic with binding
ActivityBinding binding = DataBindingUtil.setContentView(this, R.layout.activity);
CustomViewModel viewModel = new CustomViewModel();
binding.setVariable(BR.vm, viewModel);
binding.executePendingBindings();
//Fill model
viewModel.backgroundFill.set(Color.WHITE);
viewModel.setCircleModels(Arrays.asList(new CircleModel(0, 0), new CircleModel(200, 400)));
}
}
CustomView.java
package com.example.myapplication;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.support.annotation.ColorInt;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;
import java.util.Collections;
import java.util.List;
public class CustomView extends View
{
private Paint mPaint = new Paint();
private int backgroundFill;
private List<CircleModel> circleModels = Collections.emptyList();
public CustomView(Context context, @Nullable AttributeSet attrs)
{
super(context, attrs);
mPaint.setStyle(Paint.Style.FILL);
}
@Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
mPaint.setColor(backgroundFill);
canvas.drawPaint(mPaint);
mPaint.setColor(Color.BLUE);
for(CircleModel model : circleModels)
canvas.drawCircle(model.getX(), model.getY(), 100, mPaint);
}
public void setBackgroundFill(@ColorInt int backgroundFill)
{
this.backgroundFill = backgroundFill;
}
public void setCircles(List<CircleModel> circles)
{
circleModels = circles;
}
}
CustomViewModel.java
package com.example.myapplication;
import android.databinding.BaseObservable;
import android.databinding.Bindable;
import android.databinding.ObservableInt;
import java.util.ArrayList;
import java.util.List;
public class CustomViewModel extends BaseObservable
{
public final ObservableInt backgroundFill = new ObservableInt();
@Bindable
private List<CircleModel> circleModels = new ArrayList<>();
public List<CircleModel> getCircleModels()
{
return circleModels;
}
public void setCircleModels(List<CircleModel> circleModels)
{
this.circleModels = circleModels;
notifyPropertyChanged(BR.circleModels);
}
}
CircleModel.java
public class CircleModel
{
private int x;
private int y;
public CircleModel(int x, int y)
{
this.x = x;
this.y = y;
}
public int getX() { return x; }
public int getY() { return y; }
}
activity.xml
<?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="vm"
type="com.example.myapplication.CustomViewModel" />
</data>
<android.support.design.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.example.myapplication.CustomView
android:id="@+id/canvas"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:backgroundFill="@{vm.backgroundFill}"
app:circles="@{vm.circleModels}"/>
<!--Setters in CustomView-->
<!--app:backgroundFill="@{vm.backgroundFill}"-->
<!--app:circles="@{vm.circleModels}"-->
</android.support.design.widget.CoordinatorLayout>
</layout>
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