Add fanchart option with overhang

A fanchart consisting of half a circle fills paper with aspect ratio
1:2. Common paper and screens have larger aspect ratios (e.g. 16:9 or
1:1.41). By adding an overhang to the fanchart, more space can be used.

gramps/plugins/drawreport/fanchart.py

@@ -30,7 +30,7 @@
 # python modules
 #
 #------------------------------------------------------------------------
-from math import pi, cos, sin, log10, acos
+from math import pi, cos, sin, log10, acos, asin, degrees, radians
 
 def log2(val):
     """
@@ -69,6 +69,7 @@ from gramps.gen.display.name import displayer as _nd
 FULL_CIRCLE = 0
 HALF_CIRCLE = 1
 QUAR_CIRCLE = 2
+OVERHANG = 3
 
 BACKGROUND_WHITE = 0
 BACKGROUND_GEN = 1
@@ -96,10 +97,9 @@ def draw_wedge(doc, style, centerx, centery, radius, start_angle,
 
     path = []
 
-    degreestoradians = pi / 180.0
+    radiansdelta = radians(0.5)
-    radiansdelta = degreestoradians / 2
+    sangle = radians(start_angle)
-    sangle = start_angle * degreestoradians
+    eangle = radians(end_angle)
-    eangle = end_angle * degreestoradians
     while eangle < sangle:
         eangle = eangle + 2 * pi
     angle = sangle
@@ -162,7 +162,8 @@ class FanChart(Report):
         that come in the options class.
 
         maxgen       - Maximum number of generations to include.
-        circle       - Draw a full circle, half circle, or quarter circle.
+        circle       - Draw a full circle, half circle, half circle with
+                       overhang or quarter circle.
         background   - Background color is generation dependent or white.
         radial       - Print radial texts roundabout or as upright as possible.
         draw_empty   - draw background when there is no information
@@ -244,6 +245,23 @@ class FanChart(Report):
             _y_ = self.doc.get_usable_height()
             min_xy = min(_x_, _y_)
 
+        elif self.circle == OVERHANG:
+            if self.doc.get_usable_height() < self.doc.get_usable_width() and \
+               self.doc.get_usable_height() > self.doc.get_usable_width() / 2:
+                # Determine overhang angle to fill the paper
+                radius = self.doc.get_usable_width() / 2
+                _overhang_height_ = self.doc.get_usable_height() - radius
+                overhang_angle = degrees(asin(_overhang_height_ / radius))
+            else:
+                overhang_angle = 25.0
+            max_angle = 180 + 2 * overhang_angle
+            start_angle = 180 - overhang_angle
+            max_circular = 3
+            _x_ = (self.doc.get_usable_width()/2.0)
+            _overhang_height_ = sin(radians(overhang_angle)) * _x_
+            _y_ = self.doc.get_usable_height() - _overhang_height_
+            min_xy = min(_x_, _y_)
+
         else:  # quarter circle
             max_angle = 90.0
             start_angle = 270
@@ -308,8 +326,13 @@ class FanChart(Report):
 
         # title
         mark = IndexMark(title, INDEX_TYPE_TOC, 1)
-        self.doc.center_text('FC-Graphic-title', title,
+        titlex = self.doc.get_usable_width() / 2
-                             self.doc.get_usable_width() / 2, 0, mark)
+        if self.circle == OVERHANG:
+            titley = self.doc.get_usable_height() - _overhang_height_ / 2
+        else:
+            titley = 0
+        self.doc.center_text('FC-Graphic-title', title, titlex, titley, mark)
+
         # wheel
         for generation in range(0, min(max_circular, self.max_generations)):
             self.draw_circular(_x_, _y_,
@@ -373,7 +396,7 @@ class FanChart(Report):
 
             if self.circle == FULL_CIRCLE:
                 return [name, val]
-            elif self.circle == HALF_CIRCLE:
+            elif self.circle in (HALF_CIRCLE, OVERHANG):
                 return [name, val]
             else:
                 if (name != "") and (val != ""):
@@ -384,7 +407,7 @@ class FanChart(Report):
         elif generation == 6:
             if self.circle == FULL_CIRCLE:
                 return [p_pn.get_first_name(), p_pn.get_surname(), val]
-            elif self.circle == HALF_CIRCLE:
+            elif self.circle in (HALF_CIRCLE, OVERHANG):
                 return [p_pn.get_first_name(), p_pn.get_surname(), val]
             else:
                 if (p_pn.get_first_name() != "") and (p_pn.get_surname() != ""):
@@ -620,7 +643,7 @@ class FanChart(Report):
         if circle == FULL_CIRCLE:
             rad1 = size * ((generation * 2) - 5)
             rad2 = size * ((generation * 2) - 3)
-        elif circle == HALF_CIRCLE:
+        elif circle in (HALF_CIRCLE, OVERHANG):
             rad1 = size * ((generation * 2) - 3)
             rad2 = size * ((generation * 2) - 1)
         else:  # quarter circle
@@ -698,9 +721,10 @@ class FanChartOptions(MenuReportOptions):
         circle = EnumeratedListOption(_('Type of graph'), HALF_CIRCLE)
         circle.add_item(FULL_CIRCLE, _('full circle'))
         circle.add_item(HALF_CIRCLE, _('half circle'))
+        circle.add_item(OVERHANG, _('overhang'))
         circle.add_item(QUAR_CIRCLE, _('quarter circle'))
         circle.set_help(_("The form of the graph: full circle, half circle,"
-                          " or quarter circle."))
+                          " half circle with overhang or quarter circle."))
         menu.add_option(category_name, "circle", circle)
 
         background = EnumeratedListOption(_('Background color'), BACKGROUND_GEN)