第一篇:一个防御塔+多个野怪（简易版）
第二篇:防御塔随意放置
    自定义View，处理事件分发，up，move，down。
第三篇:防御塔随意放置+多组野怪
第四篇:多波野怪
第五篇:杀死野怪获得金币
第六篇:防御塔可升级,增强攻击力，增大射程

先上图片，防御塔放置，需要注意的是1、放置后刷新view会导致防御塔回到起点。2、防御塔一旦放置就无法移动，只能拆除，这才符合塔防的规则。问题会在下篇解决

1、创建TowerView，继承View

我这里命名为TowerView4，下面代码为通用继承View后的代码。

/**
 * author:liuzhitong
 * date:2022/9/2
 * description:
 */
public class TowerView4 extends View {

    public TowerView4(Context context) {
        this(context,null);
    }

    public TowerView4(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs,0);
    }

    public TowerView4(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        towerX = w/2;
        towerY = h/2;
        radius = towerX;
        screenWidth = getContext().getResources().getDisplayMetrics().widthPixels;
        screenHeight = getContext().getResources().getDisplayMetrics().heightPixels;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
    }

 我们需要知道防御塔的属性，x，y轴，半径（攻击范围）等

public int towerX,towerY;//防御塔坐标
private Paint paint;//防御塔范围画笔
public int radius;//防御塔攻击范围
public int lastX,lastY;//拖拽时down的坐标
private int offsetX;
private int offsetY;
private int screenWidth;//屏幕宽度
private int screenHeight;
private boolean move=true;//是否可移动
private int left;
private int top;

    public TowerView4(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        paint = new Paint();
        paint.setColor(0xffFFcAF9);
        paint.setAntiAlias(true);
        paint.setStrokeWidth(2f);
        paint.setStyle(Paint.Style.STROKE);

    }

 开始绘制出来

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.drawCircle(towerX,towerY,radius,paint);
    Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.pao1);
    canvas.drawBitmap(bitmap,towerX,towerY,paint);
}

 这里加了一个icon

然后拖拽我们需要在onTouchEvent中，移动很简单，我就直接上代码了

@Override
public boolean onTouchEvent(MotionEvent event) {
    int rawX = (int) event.getX();
    int rawY = (int) event.getY();
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            lastX = rawX;
            lastY = rawY;
            break;
        case MotionEvent.ACTION_MOVE:
            offsetX = rawX - lastX;
            offsetY = rawY - lastY;
            left = getLeft()+ offsetX;
            top = getTop()+ offsetY;
            int right=getRight()+ offsetX;
            int bottom =getBottom()+ offsetY;
            //左边距离边框为0
            if(getLeft()+ offsetX<=0){
                left = 0;
                right = towerX*2;
            }
            if(right >= screenWidth){
                right = screenWidth;
                left =screenWidth - radius*2;
            }

            layout(left, top,right,bottom);
            break;
        case MotionEvent.ACTION_UP:
            //确定是拖拽
            break;
    }
    return isMove();
}

ok，现在就可以拖拽了。

持续书写中........