Android开发之底图局部加载移动的方法示例

public class MapMgr {
  public static MapMgr mapMgr = null;
  private int map_num = 28;
  private int b_x = 0;
  private int b_y = 0;
  private int width = 0;
  private int height = 0;
  private Bitmap bmpView = null;
  //create by danielinbiti，前提，你图片确实比屏幕大，如果不比屏幕大，下面注释行修改一下即可。
  public static void init(int width,int height){
    if(mapMgr==null){
      mapMgr = new MapMgr(width,height);
    }
  }
  public static MapMgr getInstance(){
    return mapMgr;
  }
  public MapMgr(int width,int height){
    this.width = width;
    this.height = height;
    Bitmap bmp = PicMgr.getInstance().getBackGroundBitmap();
    b_x = (bmp.getWidth()-width)/2;//保证图片比屏幕大
    b_y = (bmp.getHeight()-height)/2;
    bmpView = Bitmap.createBitmap(bmp, b_x, b_y, width, height);
  }
  public void logic(){
  }
  public void mapDown(){
    Bitmap bmp = PicMgr.getInstance().getBackGroundBitmap();
    if(b_y+height<bmp.getHeight()){
      b_y = b_y + bmp.getHeight()/map_num;
      if(b_y+height>bmp.getHeight()){
        b_y = bmp.getHeight() - height;
      }
    }
    bmpView = Bitmap.createBitmap(bmp, b_x, b_y, width, height);
  }
  public void mapUp(){
    Bitmap bmp = PicMgr.getInstance().getBackGroundBitmap();
    if(b_y>0){
      b_y = b_y - bmp.getHeight()/map_num;
      if(b_y<0){
        b_y = 0;
      }
    }
    bmpView = Bitmap.createBitmap(bmp, b_x, b_y, width, height);
  }
  public void mapLeft(){
    Bitmap bmp = PicMgr.getInstance().getBackGroundBitmap();
    if(b_x>0){
      b_x = b_x - bmp.getWidth()/map_num;
      if(b_x<0){
        b_x = 0;
      }
    }
    bmpView = Bitmap.createBitmap(bmp, b_x, b_y, width, height);
  }
  public void mapRight(){
    Bitmap bmp = PicMgr.getInstance().getBackGroundBitmap();
    if(b_x+width<bmp.getWidth()){
      b_x = b_x + bmp.getWidth()/map_num;
      if(b_x+width>bmp.getWidth()){
        b_x = bmp.getHeight() - width;
      }
    }
    bmpView = Bitmap.createBitmap(bmp, b_x, b_y, width, height);
  }
  public void draw(Canvas canvas){
    Paint paint = new Paint();
    if(bmpView!=null){
      canvas.drawBitmap(bmpView,0, 0, paint);
    }
  }
}

public void onKeyDownDeal(int keyCode){
    if(keyCode==KeyEvent.KEYCODE_DPAD_UP){
      MapMgr.getInstance().mapUp();
    }else if(keyCode==KeyEvent.KEYCODE_DPAD_DOWN){
      MapMgr.getInstance().mapDown();
    }else if(keyCode==KeyEvent.KEYCODE_DPAD_LEFT){
      MapMgr.getInstance().mapLeft();
    }else if(keyCode==KeyEvent.KEYCODE_DPAD_RIGHT){
      MapMgr.getInstance().mapRight();
    }
}