def stop_filter(self, post_processing):
"""
Save the plot in the current canvas as a image and apply
the *post_processing* function.
def post_processing(image, dpi):
# ny, nx, depth = image.shape
# image (numpy array) has RGBA channels and has a depth of 4.
...
# create a new_image (numpy array of 4 channels, size can be
# different). The resulting image may have offsets from
# lower-left corner of the original image
return new_image, offset_x, offset_y
The saved renderer is restored and the returned image from
post_processing is plotted (using draw_image) on it.
"""
orig_img = np.asarray(self.buffer_rgba())
slice_y, slice_x = cbook._get_nonzero_slices(orig_img[..., 3])
cropped_img = orig_img[slice_y, slice_x]
self._renderer = self._filter_renderers.pop()
self._update_methods()
if cropped_img.size:
img, ox, oy = post_processing(cropped_img / 255, self.dpi)
gc = self.new_gc()
if img.dtype.kind == 'f':
img = np.asarray(img * 255., np.uint8)
self._renderer.draw_image(gc, slice_x.start + ox,
int(self.height) - slice_y.stop + oy,
img[::-1])
def stop_rasterizing(self):
"""
Exit "raster" mode. All of the drawing that was done since
the last `start_rasterizing` call will be copied to the
vector backend by calling draw_image.
"""
self._renderer = self._vector_renderer
height = self._height * self.dpi
img = np.asarray(self._raster_renderer.buffer_rgba())
slice_y, slice_x = cbook._get_nonzero_slices(img[..., 3])
cropped_img = img[slice_y, slice_x]
if cropped_img.size:
gc = self._renderer.new_gc()
# TODO: If the mixedmode resolution differs from the figure's
# dpi, the image must be scaled (dpi->_figdpi). Not all
# backends support this.
self._renderer.draw_image(
gc, slice_x.start * self._figdpi / self.dpi,
(height - slice_y.stop) * self._figdpi / self.dpi,
cropped_img[::-1])
self._raster_renderer = None
# restore the figure dpi.
self.figure.set_dpi(self._figdpi)
if self._bbox_inches_restore: # when tight bbox is used
r = process_figure_for_rasterizing(self.figure,
self._bbox_inches_restore,
self._figdpi)
self._bbox_inches_restore = r
def get_content_extents(self):
orig_img = np.asarray(self.buffer_rgba())
slice_y, slice_x = cbook._get_nonzero_slices(orig_img[..., 3])
return (slice_x.start, slice_y.start, slice_x.stop - slice_x.start,
slice_y.stop - slice_y.start)
