BUG: Improve placement of CallTipWidget

Only the vertical placement of the CallTipWidget was being checked.
Now add checks for horizontal placement as well.

IPython/frontend/qt/console/call_tip_widget.py

@@ -1,230 +1,262 b''
 # Standard library imports
 import re
 from textwrap import dedent
 from unicodedata import category
 
 # System library imports
 from IPython.external.qt import QtCore, QtGui
 
 
 class CallTipWidget(QtGui.QLabel):
     """ Shows call tips by parsing the current text of Q[Plain]TextEdit.
     """
 
     #--------------------------------------------------------------------------
     # 'QObject' interface
     #--------------------------------------------------------------------------
 
     def __init__(self, text_edit):
         """ Create a call tip manager that is attached to the specified Qt
             text edit widget.
         """
         assert isinstance(text_edit, (QtGui.QTextEdit, QtGui.QPlainTextEdit))
         super(CallTipWidget, self).__init__(None, QtCore.Qt.ToolTip)
 
         self._hide_timer = QtCore.QBasicTimer()
         self._text_edit = text_edit
 
         self.setFont(text_edit.document().defaultFont())
         self.setForegroundRole(QtGui.QPalette.ToolTipText)
         self.setBackgroundRole(QtGui.QPalette.ToolTipBase)
         self.setPalette(QtGui.QToolTip.palette())
 
         self.setAlignment(QtCore.Qt.AlignLeft)
         self.setIndent(1)
         self.setFrameStyle(QtGui.QFrame.NoFrame)
         self.setMargin(1 + self.style().pixelMetric(
                 QtGui.QStyle.PM_ToolTipLabelFrameWidth, None, self))
         self.setWindowOpacity(self.style().styleHint(
                 QtGui.QStyle.SH_ToolTipLabel_Opacity, None, self, None) / 255.0)
 
     def eventFilter(self, obj, event):
         """ Reimplemented to hide on certain key presses and on text edit focus
             changes.
         """
         if obj == self._text_edit:
             etype = event.type()
 
             if etype == QtCore.QEvent.KeyPress:
                 key = event.key()
                 if key in (QtCore.Qt.Key_Enter, QtCore.Qt.Key_Return):
                     self.hide()
                 elif key == QtCore.Qt.Key_Escape:
                     self.hide()
                     return True
 
             elif etype == QtCore.QEvent.FocusOut:
                 self.hide()
 
             elif etype == QtCore.QEvent.Enter:
                 self._hide_timer.stop()
 
             elif etype == QtCore.QEvent.Leave:
                 self._leave_event_hide()
 
         return super(CallTipWidget, self).eventFilter(obj, event)
 
     def timerEvent(self, event):
         """ Reimplemented to hide the widget when the hide timer fires.
         """
         if event.timerId() == self._hide_timer.timerId():
             self._hide_timer.stop()
             self.hide()
 
     #--------------------------------------------------------------------------
     # 'QWidget' interface
     #--------------------------------------------------------------------------
 
     def enterEvent(self, event):
         """ Reimplemented to cancel the hide timer.
         """
         super(CallTipWidget, self).enterEvent(event)
         self._hide_timer.stop()
 
     def hideEvent(self, event):
         """ Reimplemented to disconnect signal handlers and event filter.
         """
         super(CallTipWidget, self).hideEvent(event)
         self._text_edit.cursorPositionChanged.disconnect(
             self._cursor_position_changed)
         self._text_edit.removeEventFilter(self)
 
     def leaveEvent(self, event):
         """ Reimplemented to start the hide timer.
         """
         super(CallTipWidget, self).leaveEvent(event)
         self._leave_event_hide()
 
     def paintEvent(self, event):
         """ Reimplemented to paint the background panel.
         """
         painter = QtGui.QStylePainter(self)
         option = QtGui.QStyleOptionFrame()
         option.initFrom(self)
         painter.drawPrimitive(QtGui.QStyle.PE_PanelTipLabel, option)
         painter.end()
 
         super(CallTipWidget, self).paintEvent(event)
 
     def setFont(self, font):
         """ Reimplemented to allow use of this method as a slot.
         """
         super(CallTipWidget, self).setFont(font)
 
     def showEvent(self, event):
         """ Reimplemented to connect signal handlers and event filter.
         """
         super(CallTipWidget, self).showEvent(event)
         self._text_edit.cursorPositionChanged.connect(
             self._cursor_position_changed)
         self._text_edit.installEventFilter(self)
 
     #--------------------------------------------------------------------------
     # 'CallTipWidget' interface
     #--------------------------------------------------------------------------
 
     def show_call_info(self, call_line=None, doc=None, maxlines=20):
         """ Attempts to show the specified call line and docstring at the
             current cursor location. The docstring is possibly truncated for
             length.
         """
         if doc:
             match = re.match("(?:[^\n]*\n){%i}" % maxlines, doc)
             if match:
                 doc = doc[:match.end()] + '\n[Documentation continues...]'
         else:
             doc = ''
 
         if call_line:
             doc = '\n\n'.join([call_line, doc])
         return self.show_tip(doc)
 
     def show_tip(self, tip):
         """ Attempts to show the specified tip at the current cursor location.
         """
         # Attempt to find the cursor position at which to show the call tip.
         text_edit = self._text_edit
         document = text_edit.document()
         cursor = text_edit.textCursor()
         search_pos = cursor.position() - 1
         self._start_position, _ = self._find_parenthesis(search_pos,
                                                          forward=False)
         if self._start_position == -1:
             return False
 
         # Set the text and resize the widget accordingly.
         self.setText(tip)
         self.resize(self.sizeHint())
 
         # Locate and show the widget. Place the tip below the current line
-        # unless it would be off the screen. In that case, place it above
-        # the current line.
+        # unless it would be off the screen.  In that case, decide the best
+        # location based trying to minimize the  area that goes off-screen.
         padding = 3 # Distance in pixels between cursor bounds and tip box.
         cursor_rect = text_edit.cursorRect(cursor)
         screen_rect = QtGui.qApp.desktop().screenGeometry(text_edit)
         point = text_edit.mapToGlobal(cursor_rect.bottomRight())
         point.setY(point.y() + padding)
         tip_height = self.size().height()
+        tip_width = self.size().width()
+
+        vertical = 'bottom'
+        horizontal = 'Right'
         if point.y() + tip_height > screen_rect.height():
-            point = text_edit.mapToGlobal(cursor_rect.topRight())
+            point_ = text_edit.mapToGlobal(cursor_rect.topRight())
+            # If tip is still off screen, check if point is in top or bottom
+            # half of screen.
+            if point_.y() - tip_height < padding:
+                # If point is in upper half of screen, show tip below it.
+                # otherwise above it.
+                if 2*point.y() < screen_rect.height():
+                    vertical = 'bottom'
+                else:
+                    vertical = 'top'
+            else:
+                vertical = 'top'
+        if point.x() + tip_width > screen_rect.width():
+            point_ = text_edit.mapToGlobal(cursor_rect.topRight())
+            # If tip is still off-screen, check if point is in the right or
+            # left half of the screen.
+            if point_.x() - tip_width < padding:
+                if 2*point.x() < screen_rect.width():
+                    horizontal = 'Right'
+                else:
+                    horizontal = 'Left'
+            else:
+                horizontal = 'Left'
+        pos = getattr(cursor_rect, '%s%s' %(vertical, horizontal))
+        point = text_edit.mapToGlobal(pos())
+        if vertical == 'top':
             point.setY(point.y() - tip_height - padding)
+        if horizontal == 'Left':
+            point.setX(point.x() - tip_width - padding)
+
         self.move(point)
         self.show()
         return True
 
     #--------------------------------------------------------------------------
     # Protected interface
     #--------------------------------------------------------------------------
 
     def _find_parenthesis(self, position, forward=True):
         """ If 'forward' is True (resp. False), proceed forwards
             (resp. backwards) through the line that contains 'position' until an
             unmatched closing (resp. opening) parenthesis is found. Returns a
             tuple containing the position of this parenthesis (or -1 if it is
             not found) and the number commas (at depth 0) found along the way.
         """
         commas = depth = 0
         document = self._text_edit.document()
         char = document.characterAt(position)
         # Search until a match is found or a non-printable character is
         # encountered.
         while category(char) != 'Cc' and position > 0:
             if char == ',' and depth == 0:
                 commas += 1
             elif char == ')':
                 if forward and depth == 0:
                     break
                 depth += 1
             elif char == '(':
                 if not forward and depth == 0:
                     break
                 depth -= 1
             position += 1 if forward else -1
             char = document.characterAt(position)
         else:
             position = -1
         return position, commas
 
     def _leave_event_hide(self):
         """ Hides the tooltip after some time has passed (assuming the cursor is
             not over the tooltip).
         """
         if (not self._hide_timer.isActive() and
             # If Enter events always came after Leave events, we wouldn't need
             # this check. But on Mac OS, it sometimes happens the other way
             # around when the tooltip is created.
             QtGui.qApp.topLevelAt(QtGui.QCursor.pos()) != self):
             self._hide_timer.start(300, self)
 
     #------ Signal handlers ----------------------------------------------------
 
     def _cursor_position_changed(self):
         """ Updates the tip based on user cursor movement.
         """
         cursor = self._text_edit.textCursor()
         if cursor.position() <= self._start_position:
             self.hide()
         else:
             position, commas = self._find_parenthesis(self._start_position + 1)
             if position != -1:
                 self.hide()