Fixed chaco aspect_ratio example

Plot_LayoutTrouble_fixed.py

# from https://github.com/SDiot/chaco_troubles/blob/master/Plot_LayoutTrouble.py

""" Simple example to show a problem with the Layout

    HOW TO:
        1) Run Plot_LayoutTrouple.py
        2) Zoom by creating a rectangular box with the left click so that the aspect_ratio is changed
        3) Click on Reset Asp. Ratio
        4) Click on Reset View ===> the plot is not taking all the room it could!
        5) Resize the window ===> the plot is now taking all the room it can!
"""

#-------------------------------------------------------------------------------
# Force Qt4 since issue with wx when clicking the window close button
from traits.etsconfig.api import ETSConfig
ETSConfig.toolkit = 'qt4'
#-------------------------------------------------------------------------------
from enable.api import ComponentEditor
from chaco.api import Plot, ArrayPlotData, OverlayPlotContainer
from chaco.tools.api import ZoomTool, PanTool
from traits.api import HasTraits, Instance, Button, Bool, Any
from traitsui.api import View, UItem, Item, HGroup, VGroup

#-------------------------------------------------------------------------------
class TestPlot(HasTraits):

    plot = Instance(Plot)
    container = Instance(OverlayPlotContainer)
    plotdata = Instance(ArrayPlotData)

    # Button to reset the view to the nice original plot
    reset_view = Button(label='Reset View')
    reset_asp_ratio= Button(label='Reset Asp. Ratio')

    view = View(
                VGroup(
                    UItem('container', editor=ComponentEditor(), resizable=True, width = .8, height = .8,),
                    HGroup(
                        Item("reset_asp_ratio", label="Reset Asp. Ratio", show_label=False),
                        Item("reset_view", label="Reset View", show_label=False),
                        ),
                    ),
                resizable=True, width=.6, height=.8,
                )

    #---------------------------------------------------------------------------
    def _plotdata_default(self):
        self.plotdata = ArrayPlotData()
        self.plotdata.set_data("x1", [0, 1, 1, 0])
        self.plotdata.set_data("y1", [0, 0, 1, 1])
        self.plotdata.set_data("x2", [1, 2, 2, 1])
        self.plotdata.set_data("y2", [0, 0, 1, 1])
        self.plotdata.set_data("x3", [0, 1, 1, 0])
        self.plotdata.set_data("y3", [1, 1, 2, 2])
        self.plotdata.set_data("x4", [1, 2, 2, 1])
        self.plotdata.set_data("y4", [1, 1, 2, 2])
        return self.plotdata

    #---------------------------------------------------------------------------
    def _plot_default(self):

        self.plot = Plot(self.plotdata)
        self.plot.plot( ("x1", "y1"), type='polygon', face_color='auto' )
        self.plot.plot( ("x2", "y2"), type='polygon', face_color='auto'  )
        self.plot.plot( ("x3", "y3"), type='polygon', face_color='auto'  )
        self.plot.plot( ("x4", "y4"), type='polygon', face_color='auto'  )
        self.plot.aspect_ratio =  1.0

        # Add Pan & ZoomTool
        zoom = ZoomTool(self.plot, tool_mode="box",always_on=True,)
        self.plot.overlays.append(zoom)
        return self.plot

    def _container_default(self):
        outer_container = OverlayPlotContainer()
        outer_container.add(self.plot)
        return outer_container

    #---------------------------------------------------------------------------
    def _reset_asp_ratio_fired(self):
        x_lo = self.plot.x_axis.mapper.range.low
        x_hi = self.plot.x_axis.mapper.range.high
        y_lo = self.plot.y_axis.mapper.range.low
        y_hi = self.plot.y_axis.mapper.range.high
        self.plot.aspect_ratio = (x_hi-x_lo)/(y_hi-y_lo)
        self.plot.invalidate_and_redraw()

    #---------------------------------------------------------------------------
    def _reset_view_fired(self):
        self.plot.x_axis.mapper.range.set(low=0, high=2)
        self.plot.y_axis.mapper.range.set(low=0, high=2)
        self.plot.aspect_ratio = 1.0
        self.plot.invalidate_and_redraw()


#-------------------------------------------------------------------------------
if __name__ == '__main__':
    tst = TestPlot()
    tst.configure_traits()