【Android游戏开发之四】Android 游戏框架（一个游戏角色在屏幕行走的demo）

原文地址： http://blog.csdn.net/xiaominghimi/archive/2010/12/21/6090631.aspx

 

    其实上一篇分析surfaceview的文章就是一个简单的游戏框架了，当然这里再强调一下，简单的游戏框架，所以不要高手们不要乱喷~

    这个Demo是给群里一童鞋写的一个对图片操作以及按键处理，游戏简单框架的一个demo，这里放出给大家分享~   

package com.himi;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.Log;
import android.view.KeyEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;

public class MySurfaceView extends SurfaceView implements Callback, Runnable {
    private Thread th = new Thread(this);
    private SurfaceHolder sfh;
    private int SH, SW;
    private Canvas canvas;
    private Paint p;
    private Paint p2;
    private Resources res;
    private Bitmap bmp;
    private int bmp_x = 100, bmp_y = 100;
    private boolean UP, DOWN, LEFT, RIGHT;
    private int animation_up[] = { 3, 4, 5 };
    private int animation_down[] = { 0, 1, 2 };
    private int animation_left[] = { 6, 7, 8 };
    private int animation_right[] = { 9, 10, 11 };
    private int animation_init[] = animation_down;
    private int frame_count;

    public MySurfaceView(Context context) {
        super(context);
        this.setKeepScreenOn(true);
        res = this.getResources();
        bmp = BitmapFactory.decodeResource(res, R.drawable.enemy1);
        sfh = this.getHolder();
        sfh.addCallback(this);
        p = new Paint();
        p.setColor(Color.YELLOW);
        p2 = new Paint();
        p2.setColor(Color.RED);
        p.setAntiAlias(true);
        setFocusable(true);//备注1

    }

    public void surfaceCreated(SurfaceHolder holder) {
        SH = this.getHeight();
        SW = this.getWidth();
        th.start();
    }

    public void draw() {
        canvas = sfh.lockCanvas();
        canvas.drawRect(0, 0, SW, SH, p);//备注2

        canvas.save();//备注3

        canvas.drawText("Himi", bmp_x-2, bmp_y-10, p2);
        canvas.clipRect(bmp_x, bmp_y, bmp_x + bmp.getWidth() / 13, bmp_y+bmp.getHeight());
        if (animation_init == animation_up) {
            canvas.drawBitmap(bmp, bmp_x - animation_up[frame_count] * (bmp.getWidth() / 13), bmp_y, p);
        } else if (animation_init == animation_down) {
            canvas.drawBitmap(bmp, bmp_x - animation_down[frame_count] * (bmp.getWidth() / 13), bmp_y, p);
        } else if (animation_init == animation_left) {
            canvas.drawBitmap(bmp, bmp_x - animation_left[frame_count] * (bmp.getWidth() / 13), bmp_y, p);
        } else if (animation_init == animation_right) {
            canvas.drawBitmap(bmp, bmp_x - animation_right[frame_count] * (bmp.getWidth() / 13), bmp_y, p);
        }
        canvas.restore();//备注3

        sfh.unlockCanvasAndPost(canvas);
    }

    public void cycle() {
        if (DOWN) {
            bmp_y += 5;
        } else if (UP) {
            bmp_y -= 5;
        } else if (LEFT) {
            bmp_x -= 5;
        } else if (RIGHT) {
            bmp_x += 5;
        }
        if (DOWN || UP || LEFT || RIGHT) {
            if (frame_count < 2) {
                frame_count++;
            } else {
                frame_count = 0;
            }
        }
        if (DOWN == false && UP == false && LEFT == false && RIGHT == false) {
            frame_count = 0;
        }
    }

    @Override
    public boolean onKeyDown(int key, KeyEvent event) {
        if (key == KeyEvent.KEYCODE_DPAD_UP) {
            if (UP == false) {
                animation_init = animation_up;
            }
            UP = true;
        } else if (key == KeyEvent.KEYCODE_DPAD_DOWN) {
            if (DOWN == false) {
                animation_init = animation_down;
            }
            DOWN = true;
        } else if (key == KeyEvent.KEYCODE_DPAD_LEFT) {
            if (LEFT == false) {
                animation_init = animation_left;
            }
            LEFT = true;
        } else if (key == KeyEvent.KEYCODE_DPAD_RIGHT) {
            if (RIGHT == false) {
                animation_init = animation_right;
            }
            RIGHT = true;
        }
        return super.onKeyDown(key, event);
    }

    /* (non-Javadoc)
     * @see android.view.View#onKeyUp(int, android.view.KeyEvent)
     */
    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        if (DOWN) {
            DOWN = false;
        } else if (UP) {
            UP = false;
        } else if (LEFT) {
            LEFT = false;
        } else if (RIGHT) {
            RIGHT = false;
        }
        return super.onKeyUp(keyCode, event);
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub

        while (true) {
            draw();
            cycle();
            try {
                Thread.sleep(100);
            } catch (Exception ex) {
            }
        }
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // TODO Auto-generated method stub

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // TODO Auto-generated method stub


    }

}

备注1

   此方法是用来响应按键！如果是自己定义一个继承自View的类,重新实现onKeyDown方法后,只有当该View获得焦点时才会调用onKeyDown方法,Actvity中的onKeyDown方法是当所有控件均没有处理该按键事件时,才会调用.

 备注2

   这里也是对屏幕进行刷屏操作，其实这也只是一种，之前文章里我也用到drawRGB的方法同样实现，当然也可以用fillRect等来刷屏。

    那么这里我想说下，在继承view中，因为onDraw方法是系统自动调用的，不像在surfaceview这里这样去在run里面自己去不断调用，在view中我们可以抵用 invalidate()/postInvalidate() 这两种方法实现让系统调用onDraw方法，这里也是和surfaceview中的不同之一！

 备注3

   这里canvas.save();和canvas.restore();是两个相互匹配出现的，作用是用来保存画布的状态和取出保存的状态的。这里稍微解释一下，

   当我们对画布进行旋转，缩放，平移等操作的时候其实我们是想对特定的元素进行操作，比如图片，一个矩形等，但是当你用canvas的方法来进行这些操作的时候，其实是对整个画布进行了操作，那么之后在画布上的元素都会受到影响，所以我们在操作之前调用canvas.save()来保存画布当前的状态，当操作之后取出之前保存过的状态，这样就不会对其他的元素进行影响

对于 canvas.save();和canvas.restore();  还有不少童鞋不懂，OK、我再补充点：

代码段1：

public void draw() {
  Canvas canvas = sfh.lockCanvas();
  canvas.drawColor(Color.BLACK);
  canvas.drawBitmap(bmp1, 0,0,paint);
  canvas.save();
  canvas.scale(1.5f, 1.5f);
  canvas.restore();
  canvas.drawBitmap(bmp2, 0,0,paint);
  sfh.unlockCanvasAndPost(canvas);
}

代码段2：

public void draw() {
  Canvas canvas = sfh.lockCanvas();
  canvas.drawColor(Color.BLACK);
  canvas.drawBitmap(bmp1, 0,0,paint);
  canvas.scale(1.5f, 1.5f);
  canvas.drawBitmap(bmp2, 0,0,paint);
  sfh.unlockCanvasAndPost(canvas);
}

上面这两个代码片段中我们都假设有两张图片 bmp1和bmp2，并且都画在画布上!

那么代码段1和代码段2的不同:

代码段1中我们进行画布缩放的之前保存了画布状态，做了缩放操作之后又取出之前保存的状态，这样做是为了保证bmp2正常画出来不受到缩放的影响！

代码段2里，画了bmp1后就执行了缩放操作，并且没有保存状态！紧接着画了bmp2，那么bmp2也会一样受到缩放的影响！！

所以我们如果单独处理一张图片的时候，而且不想影响其他部分的绘制，那么应该如下来做：

public void draw() {
    Canvas canvas = sfh.lockCanvas();
    canvas.drawColor(Color.BLACK);
    canvas.drawBitmap(bmp1, 0,0,paint);
    canvas.save();
    canvas.scale(1.5f, 1.5f);
    canvas.drawBitmap(bmp2, 0,0,paint);
    canvas.restore();
    sfh.unlockCanvasAndPost(canvas);
  }

 Himi(Android游戏demo+人物行走).rar