Java 在 Android 中绘制片段

Drawing in a Fragment in Android

提问by Peter Barnett

I have the following code:

我有以下代码：

import android.app.Fragment;
import android.graphics.Rect;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AlphaAnimation;
import android.widget.TextView;

public class MainFragment extends Fragment {

protected AlphaAnimation fadeIn = new AlphaAnimation(0.0f , 1.0f ); 


public MainFragment(){}


public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.main_fragment, container, false);
    String fontPath = "fonts/roboto.ttf";
    Typeface font = Typeface.createFromAsset(getActivity().getAssets(), fontPath);

    TextView txt1 = (TextView) rootView.findViewById(R.id.headerTextView);
    txt1.setTypeface(font); 

    TextView txt2 = (TextView) rootView.findViewById(R.id.instructions);
    txt2.setTypeface(font);


    txt1.startAnimation(fadeIn);
    txt2.startAnimation(fadeIn);
    fadeIn.setDuration(1400);
    fadeIn.setFillAfter(true);

    Rect rectangle = new Rect(200, 56, 200, 112);


    return rootView;
  }
}

I'm trying to draw a rectangle, but for the life of me can't figure it out. I've looked everywhere for the onDraw() method, but I don't believe that is possible in a fragment.

我正在尝试绘制一个矩形，但我一生都无法弄清楚。我到处寻找 onDraw() 方法，但我不相信在片段中这是可能的。

采纳答案by Libin

There is no difference in drawing a Rectanglein Activityor Fragment. You just need a Viewadded to your layout. You can draw anything as you wish.

Rectangle在Activity或中绘制 a 没有区别Fragment。您只需要View添加到您的布局。你可以随心所欲地画任何东西。

Create a custom view and override the onDraw()like this to create a rectangle.

创建一个自定义视图并覆盖onDraw()这样的内容以创建一个矩形。

  private class Rectangle extends View{
    Paint paint = new Paint();

    public Rectangle(Context context) {
        super(context);
    }
    @Override
    public void onDraw(Canvas canvas) {
        paint.setColor(Color.GREEN);
        Rect rect = new Rect(20, 56, 200, 112);
        canvas.drawRect(rect, paint );
    }
 }

Now add this view into your layout , it could be the layout set in Fragment or Activity.

现在将此视图添加到您的布局中，它可能是Fragment or Activity.

RelativeLayout relativeLayout = (RelativeLayout) rootView.findViewById(R.id.container);
relativeLayout.addView(new Rectangle(getActivity()));

ie, R.id.container is the layout id.

即，R.id.container 是布局 ID。

回答by mrres1

Create your own RelativeLayoutclass, in this case MyRelativeLayout(which extends the RelativeLayout class).

RelativeLayout在本例中创建您自己的类MyRelativeLayout（它扩展了 RelativeLayout 类）。

Then implement the onDrawfeature and add your square.

然后实现该onDraw功能并添加您的方块。

During the Fragment's onCreateViewmethod, return the MyRelativeLayout.

在Fragment的onCreateView方法中，返回MyRelativeLayout。

Read the comments.

阅读评论。

public class MainFragment extends Fragment
{
    protected AlphaAnimation fadeIn = new AlphaAnimation(0.0f, 1.0f);

    public MainFragment() { }

    /*
     *  Create a custom RelativeLayout and implement the inherited 'onDraw' 
     *  method
     */
    class MyRelativeLayout extends RelativeLayout
    {
        public MyRelativeLayout(Context context)
        {
            super(context);
        }

        @Override
        protected void onDraw(Canvas canvas)
        {
            /*
             *  Draw your rectangle
             */
            Rect rectangle = new Rect(200, 56, 200, 112);

            Paint paint = new Paint();
            paint.setAntiAlias(true);
            paint.setColor(Color.BLACK);

            canvas.drawRect(rectangle, paint);

            super.onDraw(canvas);
        }
    }

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState)
    {

        /*
         *  Create the layout
         */
        MyRelativeLayout layout = new MyRelativeLayout(getActivity());
        layout.setLayoutParams(
            new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 
                                       ViewGroup.LayoutParams.MATCH_PARENT));

        /*
         *  Inflate your xml view
         */
        View rootView = 
            inflater.inflate(R.layout.main_fragment, container, false);

        String fontPath = "fonts/roboto.ttf";
        Typeface font = 
            Typeface.createFromAsset(getActivity().getAssets(), fontPath);

        TextView txt1 = (TextView) rootView.findViewById(R.id.headerTextView);
        txt1.setTypeface(font);

        TextView txt2 = (TextView) rootView.findViewById(R.id.instructions);
        txt2.setTypeface(font);

        txt1.startAnimation(fadeIn);
        txt2.startAnimation(fadeIn);

        fadeIn.setDuration(1400);
        fadeIn.setFillAfter(true);

        /*
         *  Add your view to the MyRelativeLayout you made, 'layout'
         */
        layout.addView(rootView);

        /*
         *  Return the 'layout' instead of just the 'rootView'
         */
        return layout;
    }
}