Question

How can I construct this scenario?

I want to build a game where the game board is a canvas controlled by a custom View but within a ScrollView. The game board is potentially much bigger than the screen and I want to scale, scroll around the game. However, I want all the advantages of the UI outside the game board to include Buttons, TextViews, ImageViews, etc.

Here’s the outline code of what I imagine should work. Am I wrong in thinking I can use both
my own onDraw and expect buttons and other widgets to be managed by Android? Must I implement
all my own UI ? Just trying to deal with a Button (see below) fails me Here’s the XML where I want my custom view surrounded by other UI elements.

I’ve looked at a lot of other examples and tutorials but have yet to see a custom view placed with an activity with UI elements around it.

My main activity

// Activity 
public class gameStartActivity extends Activity { 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.game); 
    } 
} 

My custom view

// gameView.java 
public class gameView extends View { 
  public gameView(Context context) { 
    super(context); 
    setFocusable(true); //necessary for getting the touch events 
   InitBoardView(); 
 } 
private void InitBoardView(){ 
    Button myButton = (Button)findViewById(R.id.editname); 
-----> fails at this point as myButton is null 
    myButton.setOnClickListener(doSomething); 
} 
@Override 
protected void onDraw(Canvas canvas) { 
  super.onDraw(canvas); 
 canvas.drawBitmap(face, getPaddingLeft(), getPaddingTop(),paint); 
} 
@Override 
protected void onMeasure(int widthMeasureSpec,int heightMeasureSpec) 
{ 
  super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
  final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 
  final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 
  setMeasuredDimension(xSize, ySize); 
} 

game.xml

 <ScrollView 
        android:layout_width="240dp" 
       android:layout_height="600dp" 
    <com.android.example.game.gameView 
        android:layout_width="match_parent" 
        android:layout_height="match_parent"/> 
  </ScrollView> 
  <TextView 
     android:id="@+id/sometext 
     android:layout_width="120dp" 
     android:layout_height= "wrap_content" 
     android:layout_weight="1" 
     android:visibility="gone"/> 
  <Button 
     android:id="@+id/editname" 
     android:text="DoIt" 
     android:layout_height="wrap_content" 
     android:layout_width="wrap_content"> 
 </Button> 

Answer 1

findViewById() would work in a custom view only if:
– You extend from ViewGroup (or another subclass of ViewGroup)
– The Button is a child of your custom view

A better way of doing this would be to find the button in the Activity and set its listener there. You could also have a setButton(Button view) method in your custom view and have the activity do the following:

((MyCustomView) findViewById(R.id.myCustomView)).setButton((Button) findViewById(R.id.myButton));