From 0de0bf4c44e5600303c5fdf317bf498d120ac947 Mon Sep 17 00:00:00 2001
From: Luke Campagnola <ausqualius@yahoo.com>
Date: Thu, 28 Sep 2017 09:05:08 -0700
Subject: [PATCH] Fix: very small ellipse/circle ROIs have bad click areas

---
 pyqtgraph/graphicsItems/ROI.py | 42 ++++++++++++++++++++++++++++++----
 1 file changed, 37 insertions(+), 5 deletions(-)

diff --git a/pyqtgraph/graphicsItems/ROI.py b/pyqtgraph/graphicsItems/ROI.py
index 473506cf..850104c0 100644
--- a/pyqtgraph/graphicsItems/ROI.py
+++ b/pyqtgraph/graphicsItems/ROI.py
@@ -1725,10 +1725,18 @@ class EllipseROI(ROI):
     """
     def __init__(self, pos, size, **args):
         #QtGui.QGraphicsRectItem.__init__(self, 0, 0, size[0], size[1])
+        self.path = None
         ROI.__init__(self, pos, size, **args)
+        self.sigRegionChanged.connect(self._clearPath)
+        self._addHandles()
+        
+    def _addHandles(self):
         self.addRotateHandle([1.0, 0.5], [0.5, 0.5])
         self.addScaleHandle([0.5*2.**-0.5 + 0.5, 0.5*2.**-0.5 + 0.5], [0.5, 0.5])
             
+    def _clearPath(self):
+        self.path = None
+        
     def paint(self, p, opt, widget):
         r = self.boundingRect()
         p.setRenderHint(QtGui.QPainter.Antialiasing)
@@ -1764,8 +1772,27 @@ class EllipseROI(ROI):
         return arr * mask
     
     def shape(self):
-        self.path = QtGui.QPainterPath()
-        self.path.addEllipse(self.boundingRect())
+        if self.path is None:
+            path = QtGui.QPainterPath()
+            
+            # Note: Qt has a bug where very small ellipses (radius <0.001) do
+            # not correctly intersect with mouse position (upper-left and 
+            # lower-right quadrants are not clickable).
+            #path.addEllipse(self.boundingRect())
+            
+            # Workaround: manually draw the path.
+            br = self.boundingRect()
+            center = br.center()
+            r1 = br.width() / 2.
+            r2 = br.height() / 2.
+            theta = np.linspace(0, 2*np.pi, 24)
+            x = center.x() + r1 * np.cos(theta)
+            y = center.y() + r2 * np.sin(theta)
+            path.moveTo(x[0], y[0])
+            for i in range(1, len(x)):
+                path.lineTo(x[i], y[i])
+            self.path = path
+        
         return self.path
         
         
@@ -1782,10 +1809,15 @@ class CircleROI(EllipseROI):
     ============== =============================================================
     
     """
-    def __init__(self, pos, size, **args):
-        ROI.__init__(self, pos, size, **args)
+    def __init__(self, pos, size=None, radius=None, **args):
+        if size is None:
+            if radius is None:
+                raise TypeError("Must provide either size or radius.")
+            size = (radius*2, radius*2)
+        EllipseROI.__init__(self, pos, size, **args)
         self.aspectLocked = True
-        #self.addTranslateHandle([0.5, 0.5])
+        
+    def _addHandles(self):
         self.addScaleHandle([0.5*2.**-0.5 + 0.5, 0.5*2.**-0.5 + 0.5], [0.5, 0.5])