Merge pull request matplotlib#3194 from lkilcher/annotate_bbox_DArrow

Annotate bbox darrow

Author: tacaswell

doc/users/annotations_guide.rst

@@ -46,6 +46,8 @@ keyword arguments. Currently, following box styles are implemented.
   ==========   ==============   ==========================
   Class        Name             Attrs
   ==========   ==============   ==========================
+  Circle       ``circle``       pad=0.3
+  DArrow       ``darrow``       pad=0.3
   LArrow       ``larrow``       pad=0.3
   RArrow       ``rarrow``       pad=0.3
   Round        ``round``        pad=0.3,rounding_size=None

examples/pylab_examples/fancybox_demo2.py

@@ -2,13 +2,14 @@
 import matplotlib.pyplot as plt
 
 styles = mpatch.BoxStyle.get_styles()
+spacing = 1.2
 
-figheight = (len(styles)+.5)
+figheight = (spacing * len(styles) + .5)
 fig1 = plt.figure(1, (4/1.5, figheight/1.5))
 fontsize = 0.3 * 72
 
-for i, (stylename, styleclass) in enumerate(styles.items()):
-    fig1.text(0.5, (float(len(styles)) - 0.5 - i)/figheight, stylename,
+for i, stylename in enumerate(sorted(styles.keys())):
+    fig1.text(0.5, (spacing * (float(len(styles)) - i) - 0.5)/figheight, stylename,
               ha="center",
               size=fontsize,
               transform=fig1.transFigure,

lib/matplotlib/patches.py

@@ -2003,6 +2003,57 @@ def transmute(self, x0, y0, width, height, mutation_size):
 
     _style_list["rarrow"] = RArrow
 
+    class DArrow(_Base):
+        """
+        (Double) Arrow Box
+        """
+        # This source is copied from LArrow,
+        # modified to add a right arrow to the bbox.
+
+        def __init__(self, pad=0.3):
+            self.pad = pad
+            super(BoxStyle.DArrow, self).__init__()
+
+        def transmute(self, x0, y0, width, height, mutation_size):
+
+            # padding
+            pad = mutation_size * self.pad
+
+            # width and height with padding added.
+            # The width is padded by the arrows, so we don't need to pad it.
+            height = height + 2. * pad
+
+            # boundary of the padded box
+            x0, y0 = x0 - pad, y0 - pad
+            x1, y1 = x0 + width, y0 + height
+
+            dx = (y1 - y0)/2.
+            dxx = dx * .5
+            # adjust x0.  1.4 <- sqrt(2)
+            x0 = x0 + pad / 1.4
+
+            cp = [(x0 + dxx, y0), (x1, y0),  # bot-segment
+                  (x1, y0 - dxx), (x1 + dx + dxx, y0 + dx),
+                  (x1, y1 + dxx),  # right-arrow
+                  (x1, y1), (x0 + dxx, y1),  # top-segment
+                  (x0 + dxx, y1 + dxx), (x0 - dx, y0 + dx),
+                  (x0 + dxx, y0 - dxx),  # left-arrow
+                  (x0 + dxx, y0), (x0 + dxx, y0)]  # close-poly
+
+            com = [Path.MOVETO, Path.LINETO,
+                   Path.LINETO, Path.LINETO,
+                   Path.LINETO,
+                   Path.LINETO, Path.LINETO,
+                   Path.LINETO, Path.LINETO,
+                   Path.LINETO,
+                   Path.LINETO, Path.CLOSEPOLY]
+
+            path = Path(cp, com)
+
+            return path
+
+    _style_list['darrow'] = DArrow
+
     class Round(_Base):
         """
         A box with round corners.

lib/matplotlib/tests/baseline_images/test_arrow_patches/boxarrow_test_image.png

@@ -30,6 +30,27 @@ def test_fancyarrow():
             ax.tick_params(labelleft=False, labelbottom=False)
 
 
+@image_comparison(baseline_images=['boxarrow_test_image'], extensions=['png'])
+def test_boxarrow():
+
+    styles = matplotlib.patches.BoxStyle.get_styles()
+
+    n = len(styles)
+    spacing = 1.2
+
+    figheight = (n * spacing + .5)
+    fig1 = plt.figure(1, figsize=(4 / 1.5, figheight / 1.5))
+
+    fontsize = 0.3 * 72
+
+    for i, stylename in enumerate(sorted(styles.keys())):
+        fig1.text(0.5, ((n - i) * spacing - 0.5)/figheight, stylename,
+                  ha="center",
+                  size=fontsize,
+                  transform=fig1.transFigure,
+                  bbox=dict(boxstyle=stylename, fc="w", ec="k"))
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule(argv=['-s', '--with-doctest'], exit=False)