一、创建DrawView类
public class DrawView extends View {
public float currentX = 40 ;
public float currentY = 50 ;
//定义并创建画笔
Paint p = new Paint();
public DrawView(Context context) {
super(context);
}
public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//创建画笔颜色
p.setColor(Color.RED);
//绘制一个小圆(作为小球)
canvas.drawCircle(currentX,currentY,15,p);
}
//为该组件的触碰事件重写事件处理方法
@Override
public boolean onTouchEvent(MotionEvent event) {
//修改currentX,currentY两个属性
currentX = event.getX();
currentY = event.getY();
//通知当前组件绘制自己
invalidate();
//返回ture表名该处理方法已经处理该事件
return true;
}
}
二、在Activity里:
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//获取布局文件中的LinearLayout容器
LinearLayout root = findViewById(R.id.root);
//创建DrawView组件
DrawView drawView = new DrawView(this);
//设置自定义组建的最小宽度、高度
drawView.setMinimumWidth(0);
drawView.setMinimumHeight(0);
root.addView(drawView);
}
}
三、给LinearLayout设置ID:
android:id="@+id/root"