0000908: Ability to lock snap angle in Draft by pressing L

By pressing the L key while drawing with the Draft workbench, the
current angle shown on screen is kept, until L is pressed again.

src/Mod/Draft/DraftGui.py

@@ -1139,7 +1139,10 @@ class DraftToolBar:
             self.displayPoint()
         elif txt.endsWith("z"):
             self.constrain("z")
-            self.displayPoint()    
+            self.displayPoint()
+        elif txt.endsWith("l"):
+            self.constrain("angle")
+            self.displayPoint()
         elif txt.endsWith("c"):
             if self.closeButton.isVisible():
                 self.closeLine()
@@ -1362,7 +1365,9 @@ class DraftToolBar:
             FreeCADGui.Snapper.showradius()
 
     def constrain(self,val):
-        if self.mask == val:
+        if val == "angle":
+            FreeCADGui.Snapper.setAngle()
+        elif self.mask == val:
             self.mask = None
             if hasattr(FreeCADGui,"Snapper"):
                 FreeCADGui.Snapper.mask = None

src/Mod/Draft/DraftSnap.py

@@ -764,6 +764,13 @@ class Snapper:
             self.toolbar.hide()
         self.mask = None
         self.lastArchPoint = None
+        
+    def setAngle(self):
+        "keeps the current angle"
+        if isinstance(self.mask,FreeCAD.Vector):
+            self.mask = None
+        elif self.trackLine.Visible:
+            self.mask = self.trackLine.p2().sub(self.trackLine.p1())
 
     def constrain(self,point,basepoint=None,axis=None):
         '''constrain(point,basepoint=None,axis=None: Returns a
@@ -809,8 +816,15 @@ class Snapper:
                 self.constraintAxis = FreeCAD.DraftWorkingPlane.u
             elif self.affinity == "y":
                 self.constraintAxis = FreeCAD.DraftWorkingPlane.v
-            else:
+            elif self.affinity == "z":
                 self.constraintAxis = FreeCAD.DraftWorkingPlane.axis
+            elif isinstance(self.affinity,FreeCAD.Vector):
+                self.constraintAxis = self.affinity
+            else:
+                self.constraintAxis = None
+                
+        if not self.constraintAxis:
+            return point
                 
         # calculating constrained point
         cdelta = DraftVecUtils.project(delta,self.constraintAxis)