Connect4 — 01: לוח שמצויר ומגיב למגע

package com.example.connect4.ui;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

/** Draws a six-by-seven board and reports column taps to its controller. */
public final class BoardView extends View {
    private static final int ROWS = 6;
    private static final int COLUMNS = 7;
    private final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private ColumnListener listener;

    /** Receives a zero-based column; the View does not apply game rules. */
    public interface ColumnListener { void onColumn(int column); }

    /** Called by Android when the custom View is inflated from XML. */
    public BoardView(Context context, AttributeSet attrs) {
        super(context, attrs);
        setContentDescription("Connect Four board. Tap a column to drop a disc.");
    }

    /** Connects the Activity's response to a board tap. */
    public void setColumnListener(ColumnListener listener) { this.listener = listener; }

    @Override protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        float size = cellSize();
        paint.setColor(0xff1565c0);
        canvas.drawRect(0, 0, size * COLUMNS, size * ROWS, paint);
        for (int row = 0; row < ROWS; row++) {
            for (int column = 0; column < COLUMNS; column++) {
                paint.setColor(0xffeeeeee);
                canvas.drawCircle((column + .5f) * size, (row + .5f) * size,
                        size * .38f, paint);
            }
        }
    }

    /** Uses the same geometry for drawing and hit testing. */
    private float cellSize() {
        return Math.min(getWidth() / (float) COLUMNS, getHeight() / (float) ROWS);
    }

    @Override public boolean onTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_UP) {
            float size = cellSize();
            float x = event.getX(), y = event.getY();
            if (size > 0 && x >= 0 && x < size * COLUMNS && y >= 0 && y < size * ROWS) {
                performClick();
                if (listener != null) listener.onColumn((int) (x / size));
            }
        }
        return true;
    }

    @Override public boolean performClick() { super.performClick(); return true; }
}