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""" Defines the base class for various types of zoom tools.
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from numpy import allclose, inf
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# Enthought library imports
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from enthought.traits.api import Enum, Float, HasTraits
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class BaseZoomTool(HasTraits):
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""" Defines traits and methods to actually perform the logic of zooming
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# If the tool only applies to a particular axis, this attribute is used to
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# determine which mapper and range to use.
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axis = Enum("index", "value")
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# The maximum ratio between the original data space bounds and the zoomed-in
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# data space bounds. If None, then there is no limit (not advisable!).
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max_zoom_in_factor = Float(1e5, allow_none=True)
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# The maximum ratio between the zoomed-out data space bounds and the original
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# bounds. If None, then there is no limit.
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max_zoom_out_factor = Float(1e5, allow_none=True)
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def _zoom_limit_reached(self, orig_low, orig_high, new_low, new_high):
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""" Returns True if the new low and high exceed the maximum zoom
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orig_bounds = orig_high - orig_low
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if orig_bounds == inf:
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# There isn't really a good way to handle the case when the
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# original bounds were infinite, since any finite zoom
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# range will certainly exceed whatever zoom factor is set.
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# In this case, we just allow unbounded levels of zoom.
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new_bounds = new_high - new_low
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if allclose(orig_bounds, 0.0):
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if allclose(new_bounds, 0.0):
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if (new_bounds / orig_bounds) > self.max_zoom_out_factor or \
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(orig_bounds / new_bounds) > self.max_zoom_in_factor:
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#------------------------------------------------------------------------
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# Utility methods for computing axes, coordinates, etc.
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#------------------------------------------------------------------------
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def _get_mapper(self):
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""" Returns the mapper for the component associated with this tool.
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The zoom tool really only cares about this, so subclasses can easily
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customize SimpleZoom to work with all sorts of components just by
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overriding this method.
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if self.component is not None:
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return getattr(self.component, self.axis + "_mapper")
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def _get_axis_coord(self, event, axis="index"):
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""" Returns the coordinate of the event along the axis of interest
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to the tool (or along the orthogonal axis, if axis="value").
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event_pos = (event.x, event.y)
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return event_pos[ self._determine_axis() ]
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return event_pos[ 1 - self._determine_axis() ]
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def _determine_axis(self):
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""" Determines whether the index of the coordinate along the axis of
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interest is the first or second element of an (x,y) coordinate tuple.
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if self.axis == "index":
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if self.component.orientation == "h":
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else: # self.axis == "value"
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if self.component.orientation == "h":
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def _map_coordinate_box(self, start, end):
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""" Given start and end points in screen space, returns corresponding
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low and high points in data space.
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for axis_index, mapper in [(0, self.component.x_mapper), \
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(1, self.component.y_mapper)]:
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low_val = mapper.map_data(start[axis_index])
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high_val = mapper.map_data(end[axis_index])
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if low_val > high_val:
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low_val, high_val = high_val, low_val
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low[axis_index] = low_val
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high[axis_index] = high_val
added
removed
enthought/chaco/tools/base_zoom_tool.py
