WIP on curve for a Line

Author: derek-richard

CHANGES.txt

@@ -5,9 +5,10 @@ protograf Changes
 ------------------
 - Add example for Grid and Line connections
 - Allow Card Images to use sequence value
+- Patch error when card copies run across pages
 - [PLANNED-1] Enable curve for a Line
-- [PLANNED-2] Enable non-curve Line connections to Ellipse shapes
 - [PLANNED-2] Add Circle/Dot end for an arrowhead
+- [PLANNED-2] Enable non-curve Line connections to Ellipse shapes
 - [PLANNED-2] Enable Line connections to Stadium shapes
 - [PLANNED-2] Enable Line connections to Rhombus shapes
 - [PLANNED-2] Enable Line connections to Text shapes

protograf/base.py

@@ -385,7 +385,7 @@ def __init__(
         # ---- line
         self.connections = self.defaults.get("connections", None)
         self.connections_style = self.defaults.get("connections_style", None)
-        self.curve = self.defaults.get("curve", None)
+        self.curve = self.defaults.get("curve", 0.0)
         # ---- line / bezier
         self.x_1 = self.defaults.get("x1", 0.0)
         self.y_1 = self.defaults.get("y1", 0.0)
@@ -1043,7 +1043,7 @@ def __init__(self, _object: muShape = None, canvas: BaseCanvas = None, **kwargs)
         # ---- line
         self.connections = kwargs.get("connections", base.connections)
         self.connections_style = kwargs.get("connections_style", base.connections_style)
-        self.curve = kwargs.get("curve", base.curve)
+        self.curve = self.kw_float(kwargs.get("curve", base.curve))
         # ---- line / bezier / sector
         self.x_1 = self.kw_float(kwargs.get("x1", base.x_1))
         self.y_1 = self.kw_float(kwargs.get("y1", base.y_1))

protograf/shapes.py

@@ -21,7 +21,7 @@
 
 # local
 from protograf import globals
-from protograf.shapes_utils import set_cached_dir, draw_line
+from protograf.shapes_utils import set_cached_dir, draw_line, draw_line_curve
 from protograf.base import (
     BaseShape,
     get_cache,
@@ -1187,7 +1187,7 @@ def draw(self, cnv=None, off_x=0, off_y=0, ID=None, **kwargs):
         kwargs = self.kwargs | kwargs
         cnv = cnv if cnv else globals.canvas  # a new Page/Shape may now exist
         super().draw(cnv, off_x, off_y, ID, **kwargs)  # unit-based props
-        x, y, x_1, y_1 = None, None, None, None
+        x, y, x_1, y_1, ccx, ccy = None, None, None, None, None, None
         # ---- EITHER connections draw
         if self.connections:
             conns = self.draw_connections(
@@ -1249,9 +1249,18 @@ def draw(self, cnv=None, off_x=0, off_y=0, ID=None, **kwargs):
                     raise ValueError(
                         f'Cannot calculate rotation point "{self.rotation_point}"', True
                     )
-            # ---- draw line
-            # breakpoint()
-            klargs = draw_line(cnv, Point(x, y), Point(x_1, y_1), shape=self, **kwargs)
+            # ---- draw straight line
+            if not self.curve:
+                klargs = draw_line(
+                    cnv, Point(x, y), Point(x_1, y_1), shape=self, **kwargs
+                )
+            else:
+                # ---- draw curve line
+                if kwargs.get("wave_height") or kwargs.get("wave_style"):
+                    feedback("A line cannot use a wave and curve together", True)
+                klargs, ccx, ccy = draw_line_curve(
+                    cnv, Point(x, y), Point(x_1, y_1), self.curve, **kwargs
+                )
             self.set_canvas_props(cnv=cnv, index=ID, **klargs)  # shape.finish()
             # ---- arrowhead
             self.draw_arrow(cnv, Point(x, y), Point(x_1, y_1), **kwargs)
@@ -1262,7 +1271,10 @@ def draw(self, cnv=None, off_x=0, off_y=0, ID=None, **kwargs):
             conn = conns[0]
             x, y = conn[0].x, conn[0].y
             x_1, y_1 = conn[1].x, conn[1].y
-            cx, cy = (x_1 + x) / 2.0, (y_1 + y) / 2.0
+            if ccx and ccy:
+                cx, cy = ccx, ccy  # centre of point of curve line
+            else:
+                cx, cy = (x_1 + x) / 2.0, (y_1 + y) / 2.0
             # ---- * centre shapes (with offsets)
             if self.centre_shapes:
                 _, _angle = geoms.angles_from_points(Point(x_1, y_1), Point(x, y))

protograf/shapes_utils.py

@@ -14,7 +14,7 @@
 from protograf.base import (
     BaseShape,
 )
-from protograf.utils import tools
+from protograf.utils import geoms, tools
 from protograf.utils.tools import _lower
 from protograf.utils.constants import (
     BGG_IMAGES,
@@ -68,8 +68,6 @@ def draw_line(
     """
     result = False
     if start and end and cnv:
-        if kwargs.get("wave_height") and kwargs.get("curve"):
-            feedback("A line cannot use a wave_style and curve together", True)
         if kwargs.get("wave_height"):
             _height = tools.as_float(kwargs.get("wave_height", 0.5), "wave_height")
             try:
@@ -102,3 +100,50 @@ def draw_line(
         klargs["fill"] = None
         return klargs
     return kwargs
+
+
+def draw_line_curve(
+    cnv=None,
+    start: Point = None,
+    end: Point = None,
+    curve_height: float = None,
+    **kwargs,
+) -> dict:
+    """Draw a curved line on the canvas (Page) between two points for a Shape.
+
+    Args:
+
+        cnv (PyMuPDF Page object):
+            where the line is drawn
+        start (Point):
+            start of the line
+        end (Point):
+            end of the line
+        curve_height (float):
+            height of curve above centre point of line
+
+    Returns:
+        kwargs (modified for styled lines)
+    """
+    result = False
+    if start and end and curve_height:
+        curve_centre = geoms.fraction_along_line(start, end, 0.5)
+        _, rotation = geoms.angles_from_points(start, end)
+        adjust = 90 if curve_height < 0 else -90
+        u_curve_height = tools.unit(curve_height)
+        curve_point = geoms.point_from_angle(
+            curve_centre, abs(u_curve_height), rotation + adjust
+        )
+        ccentre, _ = geoms.centre_radius_from_points(start, curve_point, end)
+        angle_width = geoms.circle_angle_between_points(start, end, ccentre)
+        # feedback(f'***Line Curve: {start=} {end=} {u_curve_height=} {angle_width=}')
+        cnv.draw_sector(  # anti-clockwise from end pt; 90° default
+            (ccentre.x, ccentre.y), (end.x, end.y), angle_width, fullSector=False
+        )
+        result = True
+    if result:
+        klargs = copy.copy(kwargs)
+        klargs["closed"] = False
+        klargs["fill"] = None  # may want to allow this? curve_fill?
+        return klargs, curve_point.x, curve_point.y
+    return kwargs, None, None

protograf/utils/geoms.py

@@ -731,7 +731,7 @@ def line_intersection_point(
 
 def bezier_arc_segment(
     cx: float, cy: float, rx: float, ry: float, theta0: float, theta1: float
-):
+) -> tuple:
     """Compute the control points for a Bezier arc with angles theta1-theta0 <= 90.
 
     Points are computed for an arc with angle theta increasing in the
@@ -782,7 +782,7 @@ def bezier_arc_segment(
     return (x0, y0), (x1, y1, x2, y2, x3, y3)
 
 
-def circle_angles(radius: float, chord: float):
+def circle_angles(radius: float, chord: float) -> float:
     """Calculate interior angles of isosceles triangle formed inside a circle.
 
     Source:
@@ -799,7 +799,46 @@ def circle_angles(radius: float, chord: float):
     return math.degrees(top), base, base
 
 
-def equilateral_height(side: Any):
+def circle_angle_between_points(start: Point, end: Point, centre: Point) -> float:
+    """Calculate angles between two points lying on a circle of known centre.
+
+    Args:
+        start: coordinates of first point
+        end: coordinates of seconf point
+        centre: coordinates of circle's centre
+
+    Returns:
+        angle (degrees)
+
+    Source:
+        Google AI!
+
+    Doc Test:
+
+    >>> P1 = Point(15, 10)
+    >>> P2 = Point(10, 15)
+    >>> C0 = Point(10, 10)
+    >>> circle_angle_between_points(P1, P2, C0)
+    90.0
+    """
+
+    # # Center of the circle
+    # h, k = 10, 10
+
+    # # Two points on the circle
+    # x1, y1 = 15, 10
+    # x2, y2 = 10, 15
+
+    # Subtract the center from each point
+    angle1 = math.atan2(start.y - centre.y, start.x - centre.x)
+    angle2 = math.atan2(end.y - centre.y, end.x - centre.x)
+    # Calculate the difference and normalize
+    diff = math.degrees(angle2 - angle1)
+    angle_between = diff % 360
+    return angle_between
+
+
+def equilateral_height(side: Any) -> float:
     """Calculate height of equilateral triangle from a side.
 
     Doc Test: