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

本站文章均为 李华明Himi 原创,转载务必在明显处注明：（作者新浪微博： @李华明Himi ) 
转载自【黑米GameDev街区】 原文链接: http://www.himigame.com/android-game/298.html 

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，以不要高手们不要乱喷哦  ~

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~

packagecom.himi;
importandroid.content.Context;
importandroid.content.res.Resources;
importandroid.graphics.Bitmap;
importandroid.graphics.BitmapFactory;
importandroid.graphics.Canvas;
importandroid.graphics.Color;
importandroid.graphics.Paint;
importandroid.util.Log;
importandroid.view.KeyEvent;
importandroid.view.SurfaceHolder;
importandroid.view.SurfaceView;
importandroid.view.SurfaceHolder.Callback;
publicclass MySurfaceView extendsSurfaceView implementsCallback, Runnable {
    privateThread th = newThread(this);
    privateSurfaceHolder sfh;
    privateint SH, SW;
    privateCanvas canvas;
    privatePaint p;
    privatePaint p2;
    privateResources res;
    privateBitmap bmp;
    privateint bmp_x = 100, bmp_y = 100;
    privateboolean UP, DOWN, LEFT, RIGHT;
    privateint animation_up[] = { 3,4,5};
    privateint animation_down[] = { 0,1,2};
    privateint animation_left[] = { 6,7,8};
    privateint animation_right[] = { 9,10,11};
    privateint animation_init[] = animation_down;
    privateint frame_count;
    publicMySurfaceView(Context context) {
        super(context);
        this.setKeepScreenOn(true);
        res = this.getResources();
        bmp = BitmapFactory.decodeResource(res, R.drawable.enemy1);
        sfh = this.getHolder();
        sfh.addCallback(this);
        p = newPaint();
        p.setColor(Color.YELLOW);
        p2 = newPaint();
        p2.setColor(Color.RED);
        p.setAntiAlias(true);
        setFocusable(true); //备注1
    }
    publicvoid surfaceCreated(SurfaceHolder holder) {
        SH = this.getHeight();
        SW = this.getWidth();
        th.start();
    }
    publicvoid 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);
        }elseif (animation_init == animation_down) {
            canvas.drawBitmap(bmp, bmp_x - animation_down[frame_count] * (bmp.getWidth() / 13), bmp_y, p);
        }elseif (animation_init == animation_left) {
            canvas.drawBitmap(bmp, bmp_x - animation_left[frame_count] * (bmp.getWidth() / 13), bmp_y, p);
        }elseif (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);
    }
    publicvoid cycle() {
        if(DOWN) {
            bmp_y += 5;
        }elseif (UP) {
            bmp_y -= 5;
        }elseif (LEFT) {
            bmp_x -= 5;
        }elseif (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
    publicboolean onKeyDown(intkey, KeyEvent event) {
        if(key == KeyEvent.KEYCODE_DPAD_UP) {
            if(UP == false) {
                animation_init = animation_up;
            }
            UP = true;
        }elseif (key == KeyEvent.KEYCODE_DPAD_DOWN) {
            if(DOWN == false) {
                animation_init = animation_down;
            }
            DOWN = true;
        }elseif (key == KeyEvent.KEYCODE_DPAD_LEFT) {
            if(LEFT == false) {
                animation_init = animation_left;
            }
            LEFT = true;
        }elseif (key == KeyEvent.KEYCODE_DPAD_RIGHT) {
            if(RIGHT == false) {
                animation_init = animation_right;
            }
            RIGHT = true;
        }
        returnsuper.onKeyDown(key, event);
    }
    /* (non-Javadoc)
     * @see android.view.View#onKeyUp(int, android.view.KeyEvent)
     */
    @Override
    publicboolean onKeyUp(intkeyCode, KeyEvent event) {
        if(DOWN) {
            DOWN = false;
        }elseif (UP) {
            UP = false;
        }elseif (LEFT) {
            LEFT = false;
        }elseif (RIGHT) {
            RIGHT = false;
        }
        returnsuper.onKeyUp(keyCode, event);
    }
    @Override
    publicvoid run() {
        // TODO Auto-generated method stub
        while(true) {
            draw();
            cycle();
            try{
                Thread.sleep(100);
            }catch(Exception ex) {
            }
        }
    }
    @Override
    publicvoid surfaceChanged(SurfaceHolder holder, intformat, intwidth, intheight) {
        // TODO Auto-generated method stub
    }
    @Override
    publicvoid 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：

publicvoid 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：

publicvoid 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：

publicvoid 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);
  }

          本章源码下载： ”Himi-Android游戏框架源码.rar”      下载地址： http://vdisk.weibo.com/s/hq1dQ