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""" Defines the PanTool class.
"""
# Enthought library imports
from enable.enable_traits import Pointer
from traits.api import Bool, Enum, Float, Tuple
from drag_tool import DragTool
class ViewportPanTool(DragTool):
""" A tool that enables the user to pan around a viewport by clicking a
mouse button and dragging.
"""
# The cursor to use when panning.
drag_pointer = Pointer("hand")
# Scaling factor on the panning "speed".
speed = Float(1.0)
# The modifier key that, if depressed when the drag is initiated, constrains
# the panning to happen in the only direction of largest initial motion.
# It is possible to permanently restrict this tool to always drag along one
# direction. To do so, set constrain=True, constrain_key=None, and
# constrain_direction to the desired direction.
constrain_key = Enum(None, "shift", "control", "alt")
# Constrain the panning to one direction?
constrain = Bool(False)
# The direction of constrained draw. A value of None means that the user
# has initiated the drag and pressed the constrain_key, but hasn't moved
# the mouse yet; the magnitude of the components of the next mouse_move
# event will determine the constrain_direction.
constrain_direction = Enum(None, "x", "y")
# (x,y) of the point where the mouse button was pressed.
_original_xy = Tuple
# Data coordinates of **_original_xy**. This may be either (index,value)
# or (value,index) depending on the component's orientation.
_original_data = Tuple
# Was constrain=True triggered by the **contrain_key**? If False, it was
# set programmatically.
_auto_constrain = Bool(False)
#------------------------------------------------------------------------
# Inherited BaseTool traits
#------------------------------------------------------------------------
# The tool is not visible (overrides BaseTool).
visible = False
def drag_start(self, event):
self._original_xy = (event.x, event.y)
if self.constrain_key is not None:
if getattr(event, self.constrain_key + "_down"):
self.constrain = True
self._auto_constrain = True
self.constrain_direction = None
event.window.set_pointer(self.drag_pointer)
event.window.set_mouse_owner(self, event.net_transform())
event.handled = True
return
def dragging(self, event):
""" Handles the mouse being moved when the tool is in the 'panning'
state.
"""
if self._auto_constrain and self.constrain_direction is None:
# Determine the constraint direction
if abs(event.x - self._original_xy[0]) > abs(event.y - self._original_xy[1]):
self.constrain_direction = "x"
else:
self.constrain_direction = "y"
new_position = self.component.view_position[:]
for direction, ndx in [("x", 0), ("y", 1)]:
if self.constrain and self.constrain_direction != direction:
continue
origpos = self._original_xy[ndx]
eventpos = getattr(event, direction)
delta = self.speed * (eventpos - origpos)
if self.component.enable_zoom:
delta /= self.component.zoom
new_position[ndx] -= delta
if self.constrain:
self.component.view_position[self.constrain_direction] = \
new_position[self.constrain_direction]
else:
self.component.view_position = new_position
event.handled = True
self._original_xy = (event.x, event.y)
self.component.request_redraw()
return
def drag_end(self, event):
if self._auto_constrain:
self.constrain = False
self.constrain_direction = None
event.window.set_pointer("arrow")
if event.window.mouse_owner == self:
event.window.set_mouse_owner(None)
event.handled = True
return
# EOF
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