Android example source code file (TileView.java)

This example Android source code file (TileView.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, attributeset, bitmap, canvas, content, drawable, drawing, graphics, override, paint, tileview, typedarray, ui

The TileView.java Android example source code

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.snake;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;

import java.util.Map;

/**
 * TileView: a View-variant designed for handling arrays of "icons" or other
 * drawables.
 * 
 */
public class TileView extends View {

    /**
     * Parameters controlling the size of the tiles and their range within view.
     * Width/Height are in pixels, and Drawables will be scaled to fit to these
     * dimensions. X/Y Tile Counts are the number of tiles that will be drawn.
     */

    protected static int mTileSize;

    protected static int mXTileCount;
    protected static int mYTileCount;

    private static int mXOffset;
    private static int mYOffset;


    /**
     * A hash that maps integer handles specified by the subclasser to the
     * drawable that will be used for that reference
     */
    private Bitmap[] mTileArray; 

    /**
     * A two-dimensional array of integers in which the number represents the
     * index of the tile that should be drawn at that locations
     */
    private int[][] mTileGrid;

    private final Paint mPaint = new Paint();

    public TileView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TileView);

        mTileSize = a.getInt(R.styleable.TileView_tileSize, 12);
        
        a.recycle();
    }

    public TileView(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TileView);

        mTileSize = a.getInt(R.styleable.TileView_tileSize, 12);
        
        a.recycle();
    }

    
    
    /**
     * Rests the internal array of Bitmaps used for drawing tiles, and
     * sets the maximum index of tiles to be inserted
     * 
     * @param tilecount
     */
    
    public void resetTiles(int tilecount) {
    	mTileArray = new Bitmap[tilecount];
    }


    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        mXTileCount = (int) Math.floor(w / mTileSize);
        mYTileCount = (int) Math.floor(h / mTileSize);

        mXOffset = ((w - (mTileSize * mXTileCount)) / 2);
        mYOffset = ((h - (mTileSize * mYTileCount)) / 2);

        mTileGrid = new int[mXTileCount][mYTileCount];
        clearTiles();
    }

    /**
     * Function to set the specified Drawable as the tile for a particular
     * integer key.
     * 
     * @param key
     * @param tile
     */
    public void loadTile(int key, Drawable tile) {
        Bitmap bitmap = Bitmap.createBitmap(mTileSize, mTileSize, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        tile.setBounds(0, 0, mTileSize, mTileSize);
        tile.draw(canvas);
        
        mTileArray[key] = bitmap;
    }

    /**
     * Resets all tiles to 0 (empty)
     * 
     */
    public void clearTiles() {
        for (int x = 0; x < mXTileCount; x++) {
            for (int y = 0; y < mYTileCount; y++) {
                setTile(0, x, y);
            }
        }
    }

    /**
     * Used to indicate that a particular tile (set with loadTile and referenced
     * by an integer) should be drawn at the given x/y coordinates during the
     * next invalidate/draw cycle.
     * 
     * @param tileindex
     * @param x
     * @param y
     */
    public void setTile(int tileindex, int x, int y) {
        mTileGrid[x][y] = tileindex;
    }


    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        for (int x = 0; x < mXTileCount; x += 1) {
            for (int y = 0; y < mYTileCount; y += 1) {
                if (mTileGrid[x][y] > 0) {
                    canvas.drawBitmap(mTileArray[mTileGrid[x][y]], 
                    		mXOffset + x * mTileSize,
                    		mYOffset + y * mTileSize,
                    		mPaint);
                }
            }
        }

    }

}