Android游戏之文件读写类和绘图类设计

1、基础知识：

A. FileInputStream

http://developer.android.com/reference/java/io/FileInputStream.html
B. FileOutputStream
http://developer.android.com/reference/java/io/FileOutputStream.html
C. Environment.getExternalStorageDirectory()
http://developer.android.com/reference/android/os/Environment.html#getExternalStorageDirectory()
D. Bitmap
http://developer.android.com/reference/android/graphics/Bitmap.html
E. Canvas
http://developer.android.com/reference/android/graphics/Canvas.html
F. Paint
http://developer.android.com/reference/android/graphics/Paint.html
G. Rect
http://developer.android.com/reference/android/graphics/Rect.html

2、设计文件读写接口FileIO和文件读写类AndroidFileIO

package com.badlogic.androidgames.framework;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public interface FileIO {
    public InputStream readAsset(String fileName) throws IOException;

    public InputStream readFile(String fileName) throws IOException;

    public OutputStream writeFile(String fileName) throws IOException;
}

package com.badlogic.androidgames.framework.impl;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.res.AssetManager;
import android.os.Environment;

import com.badlogic.androidgames.framework.FileIO;

public class AndroidFileIO implements FileIO {
    AssetManager assets;
    String externalStoragePath;

    public AndroidFileIO(AssetManager assets) {
        this.assets = assets;
        this.externalStoragePath = Environment.getExternalStorageDirectory()
                .getAbsolutePath() + File.separator;
    }

    @Override
    public InputStream readAsset(String fileName) throws IOException {
        return assets.open(fileName);
    }

    @Override
    public InputStream readFile(String fileName) throws IOException {
        return new FileInputStream(externalStoragePath + fileName);
    }

    @Override
    public OutputStream writeFile(String fileName) throws IOException {
        return new FileOutputStream(externalStoragePath + fileName);
    }
}

3. 设计像素接口Pixmap，绘图接口Graphics，像素类AndroidPixmap和绘图类AndroidGraphics

package com.badlogic.androidgames.framework;

import com.badlogic.androidgames.framework.Graphics.PixmapFormat;

public interface Pixmap {
    public int getWidth();

    public int getHeight();

    public PixmapFormat getFormat();

    public void dispose();
}

package com.badlogic.androidgames.framework;

public interface Graphics {
    public static enum PixmapFormat {
        ARGB8888, ARGB4444, RGB565
    }

    public Pixmap newPixmap(String fileName, PixmapFormat format);

    public void clear(int color);

    public void drawPixel(int x, int y, int color);

    public void drawLine(int x, int y, int x2, int y2, int color);

    public void drawRect(int x, int y, int width, int height, int color);

    public void drawPixmap(Pixmap pixmap, int x, int y, int srcX, int srcY,
            int srcWidth, int srcHeight);

    public void drawPixmap(Pixmap pixmap, int x, int y);

    public int getWidth();

    public int getHeight();
}

package com.badlogic.androidgames.framework.impl;

import android.graphics.Bitmap;

import com.badlogic.androidgames.framework.Graphics.PixmapFormat;
import com.badlogic.androidgames.framework.Pixmap;

public class AndroidPixmap implements Pixmap {
    Bitmap bitmap;
    PixmapFormat format;
    
    public AndroidPixmap(Bitmap bitmap, PixmapFormat format) {
        this.bitmap = bitmap;
        this.format = format;
    }

    @Override
    public int getWidth() {
        return bitmap.getWidth();
    }

    @Override
    public int getHeight() {
        return bitmap.getHeight();
    }

    @Override
    public PixmapFormat getFormat() {
        return format;
    }

    @Override
    public void dispose() {
        bitmap.recycle();
    }      
}

package com.badlogic.androidgames.framework.impl;

import java.io.IOException;
import java.io.InputStream;

import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Rect;

import com.badlogic.androidgames.framework.Graphics;
import com.badlogic.androidgames.framework.Pixmap;

public class AndroidGraphics implements Graphics {
    AssetManager assets;
    Bitmap frameBuffer;
    Canvas canvas;
    Paint paint;
    Rect srcRect = new Rect();
    Rect dstRect = new Rect();

    public AndroidGraphics(AssetManager assets, Bitmap frameBuffer) {
        this.assets = assets;
        this.frameBuffer = frameBuffer;
        this.canvas = new Canvas(frameBuffer);
        this.paint = new Paint();
    }

    @Override
    public Pixmap newPixmap(String fileName, PixmapFormat format) {
        Config config = null;
        if (format == PixmapFormat.RGB565)
            config = Config.RGB_565;
        else if (format == PixmapFormat.ARGB4444)
            config = Config.ARGB_4444;
        else
            config = Config.ARGB_8888;

        Options options = new Options();
        options.inPreferredConfig = config;

        InputStream in = null;
        Bitmap bitmap = null;
        try {
            in = assets.open(fileName);
            bitmap = BitmapFactory.decodeStream(in);
            if (bitmap == null)
                throw new RuntimeException("Couldn‘t load bitmap from asset ‘"
                        + fileName + "‘");
        } catch (IOException e) {
            throw new RuntimeException("Couldn‘t load bitmap from asset ‘"
                    + fileName + "‘");
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                }
            }
        }

        if (bitmap.getConfig() == Config.RGB_565)
            format = PixmapFormat.RGB565;
        else if (bitmap.getConfig() == Config.ARGB_4444)
            format = PixmapFormat.ARGB4444;
        else
            format = PixmapFormat.ARGB8888;

        return new AndroidPixmap(bitmap, format);
    }

    @Override
    public void clear(int color) {
        canvas.drawRGB((color & 0xff0000) >> 16, (color & 0xff00) >> 8,
                (color & 0xff));
    }

    @Override
    public void drawPixel(int x, int y, int color) {
        paint.setColor(color);
        canvas.drawPoint(x, y, paint);
    }

    @Override
    public void drawLine(int x, int y, int x2, int y2, int color) {
        paint.setColor(color);
        canvas.drawLine(x, y, x2, y2, paint);
    }

    @Override
    public void drawRect(int x, int y, int width, int height, int color) {
        paint.setColor(color);
        paint.setStyle(Style.FILL);
        canvas.drawRect(x, y, x + width - 1, y + width - 1, paint);
    }

    @Override
    public void drawPixmap(Pixmap pixmap, int x, int y, int srcX, int srcY,
            int srcWidth, int srcHeight) {
        srcRect.left = srcX;
        srcRect.top = srcY;
        srcRect.right = srcX + srcWidth - 1;
        srcRect.bottom = srcY + srcHeight - 1;

        dstRect.left = x;
        dstRect.top = y;
        dstRect.right = x + srcWidth - 1;
        dstRect.bottom = y + srcHeight - 1;

        canvas.drawBitmap(((AndroidPixmap) pixmap).bitmap, srcRect, dstRect,
                null);
    }
    
    @Override
    public void drawPixmap(Pixmap pixmap, int x, int y) {
        canvas.drawBitmap(((AndroidPixmap)pixmap).bitmap, x, y, null);
    }

    @Override
    public int getWidth() {
        return frameBuffer.getWidth();
    }

    @Override
    public int getHeight() {
        return frameBuffer.getHeight();
    }
}

4. 另外基于openGL ES的绘图类GLGraphics（之前的绘图类AndroidGraphics是基于像素绘图）

package com.badlogic.androidgames.framework.impl;

import javax.microedition.khronos.opengles.GL10;

import android.opengl.GLSurfaceView;

public class GLGraphics {
    GLSurfaceView glView;
    GL10 gl;
    
    GLGraphics(GLSurfaceView glView) {
        this.glView = glView;
    }
    
    public GL10 getGL() {
        return gl;
    }
    
    void setGL(GL10 gl) {
        this.gl = gl;
    }
    
    public int getWidth() {
        return glView.getWidth();
    }
    
    public int getHeight() {
        return glView.getHeight();
    }
}

本文浅述了“beginning-android-games”书本的相关基础知识和相关类的设计分析，
书本和源码：http://download.csdn.net/detail/yangzhenping/8420261
本篇中的类实现来自“beginning-android-games\ch07-gl-basics”