GLViewWidget.itemsAt() now measures y from top of widget.

CHANGELOG

@@ -15,6 +15,8 @@ pyqtgraph-0.9.9  [unreleased]
     - Renamed GraphicsView signals to avoid collision with ViewBox signals that
       are wrapped in PlotWidget: sigRangeChanged => sigDeviceRangeChanged and
       sigTransformChanged => sigDeviceTransformChanged.
+    - GLViewWidget.itemsAt() now measures y from top of widget to match mouse 
+      event position.
 
   New Features:
     - Added ViewBox.setLimits() method

pyqtgraph/opengl/GLViewWidget.py

@@ -129,6 +129,12 @@ class GLViewWidget(QtOpenGL.QGLWidget):
         return tr
 
     def itemsAt(self, region=None):
+        """
+        Return a list of the items displayed in the region (x, y, w, h)
+        relative to the widget.        
+        """
+        region = (region[0], self.height()-(region[1]+region[3]), region[2], region[3])
+        
         #buf = np.zeros(100000, dtype=np.uint)
         buf = glSelectBuffer(100000)
         try:
@@ -140,12 +146,12 @@ class GLViewWidget(QtOpenGL.QGLWidget):
             
         finally:
             hits = glRenderMode(GL_RENDER)
-
+            
         items = [(h.near, h.names[0]) for h in hits]
         items.sort(key=lambda i: i[0])
         
         return [self._itemNames[i[1]] for i in items]
-        
+    
     def paintGL(self, region=None, viewport=None, useItemNames=False):
         """
         viewport specifies the arguments to glViewport. If None, then we use self.opts['viewport']
@@ -294,6 +300,17 @@ class GLViewWidget(QtOpenGL.QGLWidget):
         
     def mouseReleaseEvent(self, ev):
         pass
+        # Example item selection code:
+        #region = (ev.pos().x()-5, ev.pos().y()-5, 10, 10)
+        #print(self.itemsAt(region))
+        
+        ## debugging code: draw the picking region
+        #glViewport(*self.getViewport())
+        #glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT )
+        #region = (region[0], self.height()-(region[1]+region[3]), region[2], region[3])
+        #self.paintGL(region=region)
+        #self.swapBuffers()
+        
         
     def wheelEvent(self, ev):
         if (ev.modifiers() & QtCore.Qt.ControlModifier):