How to Reference Buttons in the same Activity from a Custom View

Question

I am trying to make a simple drawing application, but am running into problems switching the paint color.Here is the tutorial I used to get to the point I am at. Here is my code: Drawing_View.java

public class Drawing_View extends View {
private Path path = new Path();
private Paint paint = new Paint();
public String paint_color = "#FFBB00";

public Drawing_View(Context context, AttributeSet attrs) {
    super(context, attrs);
    paint.setAntiAlias(true);
    paint.setStrokeWidth(5f);
    paint.setColor(Color.parseColor(paint_color));
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeJoin(Paint.Join.ROUND);


}

@Override
protected void onDraw(Canvas canvas) {
    canvas.drawPath(path, paint);

}

@Override
public boolean onTouchEvent(MotionEvent event) {
    float eventY = event.getY();
    float eventX = event.getX();
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            // Set a new starting point
            path.moveTo(eventX, eventY);
            return true;
        case MotionEvent.ACTION_MOVE:
            // Connect the points
            path.lineTo(eventX, eventY);
            break;
        default:
            return false;
    }

    invalidate();
    return true;
}
}

Here is the code for the activity the custom view sits inside. Drawing_Main.java

public class Drawing_Main extends ActionBarActivity {
Button green_light,green_dark,blue_light,blue_dark,blue_verydark,purple,magenta,red,orange_dark,orange_light,orange_lightest,yellow,black;
String btn_color_hex;
SharedPreferences.Editor editor = getSharedPreferences("paint_color", MODE_PRIVATE).edit();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_emoji_creation);
    green_light = (Button)findViewById(R.id.button1);
    green_dark = (Button)findViewById(R.id.button2);
    blue_light = (Button)findViewById(R.id.button3);
    blue_dark = (Button)findViewById(R.id.button4);
    blue_verydark = (Button)findViewById(R.id.button5);
    purple = (Button)findViewById(R.id.button6);
    magenta = (Button)findViewById(R.id.button7);
    red = (Button)findViewById(R.id.button8);
    orange_dark = (Button)findViewById(R.id.button9);
    orange_light = (Button)findViewById(R.id.button10);
    orange_lightest = (Button)findViewById(R.id.button11);
    yellow = (Button)findViewById(R.id.button12);
    black = (Button)findViewById(R.id.button13);
    green_light.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            btn_color_hex="#0fad00";
            editor.putString("paint_color_hex", btn_color_hex);
            editor.commit();


        }
    });
    green_dark.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    blue_light.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }

    });
    blue_dark.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    blue_verydark.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    purple.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    magenta.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    red.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    orange_light.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    orange_lightest.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    orange_dark.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    yellow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    black.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
}



@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_emojicreation, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

As you can see I started exploring the sharedPreferences option, after my attempt to create a service failed. If a Service is the best option, how can I make Drawing_View.java constantly listen for color changes? Thanks everyone!

Answer 1

You could add a setPaintColor method to your Drawing_View class. That way, you would not need to use SharedPreferences and you could just change the paint color in your onClickListeners.

Something like this should work:

In your Drawing_View class, add:

public void setPaintColor (String color) {
   paint.setColor(Color.parseColor(color));
}

In your onClickListener, call the setPaintColor method:

drawingView.setPaintColor(color);

I assume that your Drawing_View is already instantiated.

Update

You need to instantiate your Drawing_View the same way you instantiated the Buttons in your activity's onCreate method.

public class Drawing_Main extends ActionBarActivity {

...

Drawing_View drawingView;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_emoji_creation);
    drawingView = (Drawing_View)findViewById(R.id.drawing_view);
    green_light = (Button)findViewById(R.id.button1);
    ...    

I hope this helps.