text drawing

src/ifcblenderexport/blenderbim/bim/decoration.py

@@ -1,7 +1,10 @@
 """Viewport decorations"""
+import math
 from bpy.types import SpaceView3D
+from mathutils import Vector
 import bpy
 import blf
+from bpy_extras.view3d_utils import location_3d_to_region_2d
 
 
 class ViewDecorator(object):
@@ -15,7 +18,10 @@ class ViewDecorator(object):
 
     @classmethod
     def uninstall(cls):
-        SpaceView3D.draw_handler_remove(cls.installed, 'WINDOW')
+        try:
+            SpaceView3D.draw_handler_remove(cls.installed, 'WINDOW')
+        except ValueError:
+            pass
         cls.installed = None
 
 
@@ -25,23 +31,79 @@ class DimensionDecorator(ViewDecorator):
     - puts metric text next to each segment
     """
 
-    def __init__(self, scene, context):
-        self.scene = scene
+    def __init__(self, props, context):
         self.context = context
-        self.font_id = 0
+        self.props = props
+        self.font_id = 0  # TODO: take font from styles
         self.dpi = context.preferences.system.dpi
-        print("Created decorator", scene)
 
     def __call__(self):
         # get active drawing, if any
-        if self.scene.active_drawing_index is None or len(self.scene.drawings) == 0:
+        if self.props.active_drawing_index is None or len(self.props.drawings) == 0:
             return
-        drawing = self.scene.drawings[self.scene.active_drawing_index]
+        drawing = self.props.drawings[self.props.active_drawing_index]
         collection = bpy.data.collections.get("IfcGroup/" + drawing.name)
+        # get curve object
         if 'IfcAnnotation/Dimension' not in collection.all_objects:
             return
-        curve = collection.all_objects['IfcAnnotation/Dimension'].data
-        text = repr(curve)
-        blf.position(self.font_id, 100, 100, 0)
-        blf.size(self.font_id, 10, self.dpi)
+        curve = collection.all_objects['IfcAnnotation/Dimension']
+
+        for segm in self.iter_segments(curve):
+            self.draw_label(segm)
+            self.draw_arrow(segm)
+
+    def iter_segments(self, curve):
+        """Yields each segment converted to world coords
+        (v0, v1, length)
+        """
+        for spline in curve.data.splines:
+            points = [curve.matrix_world @ p.co for p in spline.points]
+            for i in range(len(points)-1):
+                p0 = points[i]
+                p1 = points[i+1]
+                length = (p1 - p0).length
+                yield (p0, p1, length)
+
+    def draw_label(self, segm):
+        """Draw text of segment length
+        aligned and centered at segment middle
+        """
+        p0, p1, length = segm
+
+        # convert to view coords
+        region = self.context.region
+        region3d = self.context.region_data
+        p0 = location_3d_to_region_2d(region, region3d, p0)
+        p1 = location_3d_to_region_2d(region, region3d, p1)
+
+        text = f"{length:.2f}"
+
+        ang = -Vector((1, 0)).angle_signed(p1 - p0)
+        cos = math.cos(ang)
+        sin = math.sin(ang)
+
+        # midpoint
+        pos = p0 + (p1 - p0) * .5
+
+        # TODO: take font size from styles
+        blf.size(self.font_id, 16, self.dpi)
+        w, h = blf.dimensions(self.font_id, text)
+
+        # align centered
+        pos -= Vector((cos, sin)) * w * 0.5
+
+        # add padding
+        # TODO: take padding from styles and adjust to line width
+        pos += Vector((-sin, cos)) * 4
+
+        # TODO: handle overlapping of text with arrows for narrow segments
+
+        blf.enable(self.font_id, blf.ROTATION)
+        blf.position(self.font_id, pos.x, pos.y, 0)
+
+        blf.rotation(self.font_id, ang)
         blf.draw(self.font_id, text)
+        blf.disable(self.font_id, blf.ROTATION)
+
+    def draw_arrow(self, segm):
+        pass