<!--
可以把他理解为绝对定位
Top 距离顶端
Left 距离左边
ZIndex Z坐标轴
-->
<Canvas>
<Button Background="Beige" Width="100" Height="100"></Button>
<Button Background="Blue" Canvas.Left="50" Canvas.Top="50" Width="100" Height="100"></Button>
<Button Background="Chartreuse" Canvas.ZIndex="1" Canvas.Left="100" Canvas.Top="100" Width="100" Height="100"></Button>
<Button Background="Red" Canvas.Left="150" Canvas.Top="150" Width="100" Height="100"></Button>
<!--图形系列(Canvas里面用的比较多):背景用Fill来填充-->
<!--正方形-->
<Rectangle Width="300" Height="300" Fill="Yellow" Opacity="0.7" Canvas.ZIndex="-1"></Rectangle>
<!--矩形-->
<Rectangle Width="300" Height="200" Fill="Yellow" Opacity="0.7" Canvas.Top="50" Canvas.ZIndex="-1"></Rectangle>
<!--圆形-->
<Ellipse Width="100" Height="100" Fill="Pink" Opacity="0.9" Canvas.ZIndex="9" Canvas.Left="120" Canvas.Top="120"></Ellipse>
<!--椭圆-->
<Ellipse Width="100" Height="50" Fill="Black" Opacity="0.1" Canvas.ZIndex="9" Canvas.Left="120" Canvas.Top="150"></Ellipse>
</Canvas>