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# Copyright Crown and Cartopy Contributors
#
# This file is part of Cartopy and is released under the BSD 3-clause license.
# See LICENSE in the root of the repository for full licensing details.
"""
Define the SlippyImageArtist class, which interfaces with
:class:`cartopy.io.RasterSource` instances at draw time, for interactive
dragging and zooming of raster data.
"""
import matplotlib.artist
from matplotlib.image import AxesImage
class SlippyImageArtist(AxesImage):
"""
A subclass of :class:`~matplotlib.image.AxesImage` which provides an
interface for getting a raster from the given object with interactive
slippy map type functionality.
Kwargs are passed to the AxesImage constructor.
"""
def __init__(self, ax, raster_source, **kwargs):
self.raster_source = raster_source
# This artist fills the Axes, so should not influence layout.
kwargs.setdefault('in_layout', False)
super().__init__(ax, **kwargs)
self.cache = []
ax.figure.canvas.mpl_connect('button_press_event', self.on_press)
ax.figure.canvas.mpl_connect('button_release_event', self.on_release)
self.on_release()
def on_press(self, event=None):
self.user_is_interacting = True
def on_release(self, event=None):
self.user_is_interacting = False
self.stale = True
def get_window_extent(self, renderer=None):
return self.axes.get_window_extent(renderer=renderer)
@matplotlib.artist.allow_rasterization
def draw(self, renderer, *args, **kwargs):
if not self.get_visible():
return
ax = self.axes
window_extent = ax.get_window_extent()
[x1, y1], [x2, y2] = ax.viewLim.get_points()
if not self.user_is_interacting:
located_images = self.raster_source.fetch_raster(
ax.projection, extent=[x1, x2, y1, y2],
target_resolution=(window_extent.width, window_extent.height))
self.cache = located_images
for img, extent in self.cache:
self.set_array(img)
with ax.hold_limits():
self.set_extent(extent)
super().draw(renderer, *args, **kwargs)
def can_composite(self):
# As per https://github.com/SciTools/cartopy/issues/689, disable
# compositing multiple raster sources.
return False
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