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""" Defines the LegendTool class.
"""
# Enthought library imports
from traits.api import Bool, Enum
from enable.tools.drag_tool import DragTool
class LegendTool(DragTool):
""" A tool for interacting with legends.
Attach this tool to a legend by setting the tool's **component**
to the legend.
"""
# The mouse button that initiates the drag.
drag_button = Enum("left", "right")
# Whether to change the legend's **align** property in accord with
# the quadrant into which it is dropped.
auto_align = Bool(True)
def is_draggable(self, x, y):
""" Returns whether the (x,y) position is in a region that is OK to
drag.
Overrides DragTool.
"""
if self.component:
legend = self.component
return (x >= legend.x and x <= legend.x2 and \
y >= legend.y and y <= legend.y2)
else:
return False
def drag_start(self, event):
""" Called when the drag operation starts.
Implements DragTool.
"""
if self.component:
self.original_padding = self.component.padding
event.window.set_mouse_owner(self, event.net_transform())
event.handled = True
return
def dragging(self, event):
""" This method is called for every mouse_move event that the tool
receives while the user is dragging the mouse.
Implements DragTool. Moves the legend by aligning it to a corner of its
overlay component.
"""
# To properly move a legend (which aligns itself to a corner of its overlay
# component), we need to modify the padding amounts as opposed to modifying
# the position directly.
if self.component:
legend = self.component
valign, halign = legend.align
left, right, top, bottom = self.original_padding
dy = int(event.y - self.mouse_down_position[1])
if valign == "u":
# we subtract dy because if the mouse moves downwards, dy is
# negative but the top padding has increased
legend.padding_top = top - dy
else:
legend.padding_bottom = bottom + dy
dx = int(event.x - self.mouse_down_position[0])
if halign == "r":
legend.padding_right = right - dx
else:
legend.padding_left = left + dx
event.handled = True
legend.request_redraw()
return
def drag_end(self, event):
""" Called when a mouse event causes the drag operation to end.
Implements DragTool.
"""
# Make sure we have both a legend and that the legend is overlaying
# a component
if self.auto_align and self.component and self.component.component:
# Determine which boundaries of the legend's overlaid component are
# closest to the center of the legend
legend = self.component
component = legend.component
left = int(legend.x - component.x)
right = int(component.x2 - legend.x2)
if left < right:
halign = "l"
legend.padding_left = left
else:
halign = "r"
legend.padding_right = right
bottom = int(legend.y - component.y)
top = int(component.y2 - legend.y2)
if bottom < top:
valign = "l"
legend.padding_bottom = bottom
else:
valign = "u"
legend.padding_top = top
legend.align = valign + halign
if event.window.mouse_owner == self:
event.window.set_mouse_owner(None)
event.handled = True
legend.request_redraw()
return
# EOF
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