问题

我想在Flutter中绘制一个梯形形状，就像这样：

现在我正在使用Rrect绘制一个椭圆形状，与之类似，

这是我用于绘制第二张图片（得到一个椭圆形状）的代码：

 @override
  void paint(Canvas canvas, Offset offset, ImageConfiguration cfg) {
    final Offset circleOffset =
        offset + Offset(cfg.size!.width / 2, cfg.size!.height + 8);
    canvas.drawRRect(
        RRect.fromRectAndRadius(
          Rect.fromCenter(center: circleOffset, width: 50, height: 5),
          Radius.circular(radius),
        ),
        _paint);
  }

 @override
  void paint(Canvas canvas, Offset offset, ImageConfiguration cfg) {
    final Offset circleOffset =
        offset + Offset(cfg.size!.width / 2, cfg.size!.height + 8);
    canvas.drawRRect(
        RRect.fromRectAndRadius(
          Rect.fromCenter(center: circleOffset, width: 50, height: 5),
          Radius.circular(radius),
        ),
        _paint);
  }

答案1

得分: 0

使用RRect.fromRectAndCorners，
```Rect rect,
  {
    Radius topLeft = Radius.circular(10),
    ///左上角的曲线或半径，我的情况下是10
    Radius topRight = Radius.circular(10),
    ///右上角的曲线或半径，我的情况下是10
    Radius bottomRight = Radius.zero,
    ///右下角的曲线或半径，我的情况下是零
    Radius bottomLeft = Radius.zero
    ///左下角的曲线或半径，我的情况下是零
  }

所以我的最终代码如下

@override
void paint(Canvas canvas, Offset offset, ImageConfiguration cfg) {
    final Offset circleOffset =
        offset + Offset(cfg.size!.width / 2, cfg.size!.height + 8);
    canvas.drawRRect(
      RRect.fromRectAndCorners(
        Rect.fromCenter(center: circleOffset, width: 50, height: 5),
        bottomLeft: Radius.zero,
        bottomRight: Radius.zero,
        topLeft: Radius.circular(radius),
        topRight: Radius.circular(radius),
      ),
      _paint,
    );
  }

可以在文档这里中找到更多详细信息。

<details>
<summary>英文:</summary>

using Rrect.fromRectAndCorners, 
```Rect rect,
  {
    Radius topLeft = Radius.circular(10),
    ///top left corner curve or radius, in my case it is 10
    Radius topRight = Radius.circular(10),
    ///top right corner curve or radius, in my case it is 10
    Radius bottomRight = Radius.zero,
    ///bottom left corner curve or radius, in my case it is zero
    Radius bottomLeft = Radius.zero
    ///bottom right corner curve or radius, in my case it is zero
  }

so my final code looks like

@override
  void paint(Canvas canvas, Offset offset, ImageConfiguration cfg) {
    final Offset circleOffset =
        offset + Offset(cfg.size!.width / 2, cfg.size!.height + 8);
    canvas.drawRRect(
      RRect.fromRectAndCorners(
        Rect.fromCenter(center: circleOffset, width: 50, height: 5),
        bottomLeft: Radius.zero,
        bottomRight: Radius.zero,
        topLeft: Radius.circular(radius),
        topRight: Radius.circular(radius),
      ),
      _paint,
    );
  }

will get more details in the documentation here

https://api.flutter.dev/flutter/dart-ui/RRect/RRect.fromRectAndCorners.html

Thanks for help.