feat(draw): continue paths on initial Enter

Start LINE, PLINE, ARC, and SPLINE from the latest path endpoint when Enter accepts the first point. Fall back to the active UCS origin.\n\nRefs #610

src/modules/draw/draw/arc.rs

@@ -369,6 +369,9 @@ impl CadCommand for ArcCommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -467,6 +470,9 @@ impl CadCommand for Arc3PCommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.pts.is_empty()
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -564,6 +570,9 @@ impl CadCommand for ArcSCECommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -664,6 +673,9 @@ impl CadCommand for ArcSCACommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -787,6 +799,9 @@ impl CadCommand for ArcSCLCommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -886,6 +901,9 @@ impl CadCommand for ArcSEACommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -961,6 +979,9 @@ impl CadCommand for ArcSERCommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -1074,6 +1095,9 @@ impl CadCommand for ArcSEDCommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -1160,6 +1184,9 @@ impl CadCommand for ArcCSACommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
@@ -1279,6 +1306,9 @@ impl CadCommand for ArcCSLCommand {
     fn on_enter(&mut self) -> CmdResult {
         CmdResult::Cancel
     }
+    fn enter_accepts_default_start(&self) -> bool {
+        self.step == 0
+    }
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }

src/modules/draw/draw/line.rs

@@ -150,6 +150,10 @@ impl CadCommand for LineCommand {
         CmdResult::Cancel
     }
 
+    fn enter_accepts_default_start(&self) -> bool {
+        self.points.is_empty()
+    }
+
     fn on_escape(&mut self) -> CmdResult {
         CmdResult::Cancel
     }

src/modules/draw/draw/polyline.rs

@@ -355,6 +355,10 @@ impl CadCommand for PlineCommand {
         }
     }
 
+    fn enter_accepts_default_start(&self) -> bool {
+        self.vertices.is_empty()
+    }
+
     fn on_escape(&mut self) -> CmdResult {
         match self.live_handle {
             Some(handle) => CmdResult::FinalizeLiveEntity(handle),

src/modules/draw/draw/spline.rs

@@ -143,6 +143,10 @@ impl CadCommand for SplineCommand {
         }
     }
 
+    fn enter_accepts_default_start(&self) -> bool {
+        self.pts.is_empty()
+    }
+
     fn on_escape(&mut self) -> CmdResult {
         match self.build(false) {
             Some(e) => CmdResult::CommitAndExit(e),