To Examples

Drawing1 Example

Goal

• Set up a derived class MyView from the base class View. Override the onDraw method to draw in a MyView object.

Directions

1. Create a project named Drawing1. Leave the layout and activity files with their default names.
2. Set up a linear layout with these attributes set: id to layout, layout width and height to match_parent, orientation set to vertical, and layout margin to 32dp.
3. Create a MyView class with this code:
   

   package it372.drawing1;
   import android.content.Context;
   import android.graphics.Canvas;
   import android.graphics.Color;
   import android.graphics.Paint;
   import android.view.View;
   
   public class MyView extends View {
   
       public MyView(Context context) {
           super(context);
       }
   
       @Override
       public void onDraw(Canvas canvas) {
           Paint paint = new Paint( );
           canvas.drawColor(
               Color.parseColor("#ffa0a0"));
           paint.setColor(Color.BLUE);
           canvas.drawCircle(100, 100, 50, paint);
           paint.setStrokeWidth(10);
           System.out.println(canvas.getWidth());
           System.out.println(canvas.getHeight());
           canvas.drawLine(150, 150, 300, 300, paint);
           paint.setTextSize(50.0f);
           paint.setColor(Color.WHITE);
           canvas.drawText("Test Drawing", 200, 100, paint);
       }
   }
   

4. Add these lines to the activity code file:
   

   LinearLayout layout = (LinearLayout) findViewById(R.id.layout);
   MyView mv = new MyView(this);
   layout.addView(mv);
   

5. Run your app to test it. Here is the emulator screenshot.
6. Here are the final files for the layout, MyView class, and activity:
       activity_main.xml   MyView.java    MainActivity.java