Question

所以就像一个graphics.FillEllipse，但中间有一个洞。我需要通过在它们周围放一个环来突出显示一些圆形图标，并且由于较大程序的限制，很难/不可能简单地将FillEllipse放在它们下面以使其看起来像是一个洞。

Answer 1

// Create a brush
SolidBrush b = new SolidBrush(Color.Blue);

// Clear your Graphics object (defined externally)
gfx.Clear(Color.White);

// You need a path for the outer and inner circles
GraphicsPath path1 = new GraphicsPath();
GraphicsPath path2 = new GraphicsPath();

// Define the paths (where X, Y, and D are chosen externally)
path1.AddEllipse((float)(X - D / 2), (float)(Y - D / 2), (float)D, (float)D);
path2.AddEllipse((float)(X - D / 4), (float)(Y - D / 4), (float)(D / 2), (float)(D / 2));

// Create a region from the Outer circle.
Region region = new Region(path1);

// Exclude the Inner circle from the region
region.Exclude(path2);

// Draw the region to your Graphics object
gfx.FillRegion(b, region);

Answer 2

使用GDI +，您可以绘制一个笔宽较高的圆圈，使其看起来像甜甜圈。中心没有任何东西，所以你将能够看透它。

Answer 3

您可以创建一个区域，该区域基于您使用FillEllipse绘制的内容，并使用Region的Exclude方法通过使用另一个对FillEllipse的调用返回的另一个GraphicsPath来删除您不想要的区域。 / p>

然后，您只需将生成的区域叠加在您希望它所包围的区域之上。

Answer 4

基于user263134回答：

    g.FillRegion(Brushes.Black, GetRingRegion(center, innerRadius, outherRadius));

    public static RectangleF GetRectangle(PointF center, float radius)
    {
        var rectangle = new RectangleF(center.X - radius, center.Y - radius,radius * 2, radius * 2);
        return rectangle;
    }

    public static Region GetRingRegion(PointF center, float innerRadius, float outherRadius)
    {
        // You need a path for the outer and inner circles
        var path1 = new GraphicsPath();
        var path2 = new GraphicsPath();

        // Define the paths (where X, Y, and D are chosen externally)
        path1.AddEllipse(GetRectangle(center,outherRadius));
        path2.AddEllipse(GetRectangle(center, innerRadius));

        // Create a region from the Outer circle.
        Region region = new Region(path1);

        // Exclude the Inner circle from the region
        region.Exclude(path2);

        return region;
    }

Answer 5

关于sth答案的最重要的事情是最灵活的答案，那就是需要处理GraphicsPath和Brush，因此将它们的声明放在using语句中，如下所示：

// Clear your Graphics object (defined externally)
gfx.Clear(Color.White);

// You need a path for the outer and inner circles
using (GraphicsPath path1 = new GraphicsPath(), path2 = new GraphicsPath())
  {
  // Define the paths (where X, Y, and D are chosen externally)
  path1.AddEllipse((float)(X - D / 2), (float)(Y - D / 2), (float)D, (float)D);
  path2.AddEllipse((float)(X - D / 4), (float)(Y - D / 4), (float)(D / 2), (float)(D / 2));

  // Create a region from the Outer circle.
  Region region = new Region(path1);

  // Exclude the Inner circle from the region
  region.Exclude(path2);

  // Create a brush
  using (SolidBrush b = new SolidBrush(Color.Blue))
    {
    // Draw the region to your Graphics object
    gfx.FillRegion(b, region);
    }
  }

这将确保在不再需要它们时将其丢弃。

using是确保即使发生异常也可以调用Dispose方法的最佳方法。

用C＃轻松画出空心圆环形状的任何方法

5 个答案: