解决缺少弧线和实心长方形的问题：处理线的宽度constant_width，增加lwpolyline转圆弧的代码

src/qelmt/arc.rs

@@ -1,5 +1,6 @@
 use super::{two_dec, ScaleEntity};
 use dxf::entities;
+use dxf::entities::LwPolyline;
 use simple_xml_builder::XMLElement;
 
 #[derive(Debug)]
@@ -130,3 +131,100 @@ impl ScaleEntity for Arc {
         self.y + self.height
     }
 }
+
+// 在 mod.rs 中添加从 LwPolyline 转换为 Arc 的方法
+impl TryFrom<&LwPolyline> for Arc {
+    type Error = String;
+
+    fn try_from(lwpolyline: &LwPolyline) -> Result<Self, Self::Error> {
+        // 检查顶点数量，必须是2个顶点才能形成圆弧
+        if lwpolyline.vertices.len() != 2 {
+            return Err(format!("Arc conversion requires exactly 2 vertices, got {}", lwpolyline.vertices.len()));
+        }
+
+        let v1 = &lwpolyline.vertices[0];
+        let v2 = &lwpolyline.vertices[1];
+        
+        // 检查第一个顶点是否有bulge值
+        if v1.bulge == 0.0 {
+            return Err("No bulge value found for arc conversion".to_string());
+        }
+
+        // 计算弦长和中点
+        let chord_length = ((v2.x - v1.x).powi(2) + (v2.y - v1.y).powi(2)).sqrt();
+        let mid_x = (v1.x + v2.x) / 2.0;
+        let mid_y = (v1.y + v2.y) / 2.0;
+        
+        // 根据bulge值计算圆弧参数
+        // bulge = tan(angle/4)，其中angle是圆弧的包含角
+        let bulge = v1.bulge;
+        let included_angle = 4.0 * bulge.atan(); // 圆弧包含角（弧度）
+        
+        // 计算半径
+        let radius = chord_length / (2.0 * (included_angle / 2.0).sin());
+        
+        // 计算圆心位置
+        // 弦的方向向量
+        let chord_dx = v2.x - v1.x;
+        let chord_dy = v2.y - v1.y;
+        
+        // 弦的垂直方向（向左旋转90度）
+        let perp_dx = -chord_dy;
+        let perp_dy = chord_dx;
+        let perp_length = (perp_dx * perp_dx + perp_dy * perp_dy).sqrt();
+        
+        // 标准化垂直向量
+        let unit_perp_x = perp_dx / perp_length;
+        let unit_perp_y = perp_dy / perp_length;
+        
+        // 计算圆心到弦中点的距离
+        let center_distance = radius * (included_angle / 2.0).cos();
+        
+        // 根据bulge的符号确定圆心位置
+        let center_x = if bulge > 0.0 {
+            mid_x + center_distance * unit_perp_x
+        } else {
+            mid_x - center_distance * unit_perp_x
+        };
+        let center_y = if bulge > 0.0 {
+            mid_y + center_distance * unit_perp_y
+        } else {
+            mid_y - center_distance * unit_perp_y
+        };
+        
+        // 计算起始角度和结束角度
+        let start_angle = (v1.y - center_y).atan2(v1.x - center_x);
+        let end_angle = (v2.y - center_y).atan2(v2.x - center_x);
+        
+        // 将弧度转换为度数
+        let mut start_angle_deg = start_angle.to_degrees();
+        let mut end_angle_deg = end_angle.to_degrees();
+        
+        // 标准化角度到0-360度范围
+        if start_angle_deg < 0.0 {
+            start_angle_deg += 360.0;
+        }
+        if end_angle_deg < 0.0 {
+            end_angle_deg += 360.0;
+        }
+        
+        // 计算角度跨度
+        let arc_angle = included_angle.to_degrees().abs();
+        
+        // 创建Arc对象
+        Ok(Arc {
+            x: center_x - radius, // 边界框左上角x坐标
+            y: -center_y - radius, // 边界框左上角y坐标（y轴翻转）
+            width: radius * 2.0,  // 边界框宽度
+            height: radius * 2.0, // 边界框高度
+            start: start_angle_deg, // 起始角度（度）
+            angle: arc_angle,     // 圆弧角度跨度（度）
+            style: if lwpolyline.thickness > 0.1 {
+                "line-style:normal;line-weight:normal;filling:none;color:black"
+            } else {
+                "line-style:normal;line-weight:thin;filling:none;color:black"
+            }.into(),
+            antialias: false,
+        })
+    }
+}

src/qelmt/mod.rs

@@ -819,6 +819,21 @@ impl<'a> ObjectsBuilder<'a> {
             EntityType::LwPolyline(lwpolyline) => match lwpolyline.vertices.len() {
                 0 | 1 => Err("Error empty LwPolyline"),
                 2 => {
+                    if lwpolyline.vertices[0].bulge != 0.0 {
+                        match Arc::try_from(lwpolyline) {
+                            Ok(mut arc) => {
+                                arc.update_line_style(&update_line_style);
+                                arc.scale(self.scale_fact.x, self.scale_fact.y);
+                                arc.x += self.offset.x;
+                                arc.y -= self.offset.y;
+                                return Ok(Objects::Arc(arc));
+                            }
+                            Err(_) => {
+                                // Arc转换失败，继续执行下面的Line转换
+                            }
+                        }
+                    }
+
                     let mut line = Line::try_from(lwpolyline)?;
 
                     // 根据line_type_name更新线型样式