Imviz: astrowidget API for center_on and offset_to

jdaviz/configs/imviz/helper.py

@@ -2,10 +2,20 @@
 import re
 from copy import deepcopy
 
+from astropy.coordinates import SkyCoord
+from astropy.utils.introspection import minversion
+from astropy.wcs import NoConvergence
+from astropy.wcs.wcsapi import BaseHighLevelWCS
+from echo import delay_callback
+from glue.core import BaseData
+
+from jdaviz.core.events import SnackbarMessage
 from jdaviz.core.helpers import ConfigHelper
 
 __all__ = ['Imviz']
 
+ASTROPY_LT_4_3 = not minversion('astropy', '4.3')
+
 
 class Imviz(ConfigHelper):
     """Imviz Helper class"""
@@ -79,6 +89,102 @@ def load_data(self, data, parser_reference=None, **kwargs):
             self.app.load_data(
                 data, parser_reference=parser_reference, **kwargs)
 
+    def center_on(self, point):
+        """Centers the view on a particular point.
+
+        Parameters
+        ----------
+        point : tuple or `~astropy.coordinates.SkyCoord`
+            If tuple of ``(X, Y)`` is given, it is assumed
+            to be in data coordinates and 0-indexed.
+
+        Raises
+        ------
+        AttributeError
+            Sky coordinates are given but image does not have a valid WCS.
+
+        """
+        viewer = self.app.get_viewer("viewer-1")
+
+        if isinstance(point, SkyCoord):
+            i_top = get_top_layer_index(viewer)
+            image = viewer.layers[i_top].layer
+            if hasattr(image, 'coords') and isinstance(image.coords, BaseHighLevelWCS):
+                try:
+                    pix = image.coords.world_to_pixel(point)  # 0-indexed X, Y
+                except NoConvergence as e:  # pragma: no cover
+                    self.app.hub.broadcast(SnackbarMessage(
+                        f'{point} is likely out of bounds: {repr(e)}',
+                        color="warning", sender=self.app))
+                    return
+            else:
+                raise AttributeError(f'{image.label} does not have a valid WCS')
+        else:
+            pix = point
+
+        # Disallow centering outside of display.
+        if (pix[0] < viewer.state.x_min or pix[0] > viewer.state.x_max
+                or pix[1] < viewer.state.y_min or pix[1] > viewer.state.y_max):
+            self.app.hub.broadcast(SnackbarMessage(
+                f'{pix} is out of bounds', color="warning", sender=self.app))
+            return
+
+        with delay_callback(viewer.state, 'x_min', 'x_max', 'y_min', 'y_max'):
+            width = viewer.state.x_max - viewer.state.x_min
+            height = viewer.state.y_max - viewer.state.y_min
+            viewer.state.x_min = pix[0] - (width * 0.5)
+            viewer.state.y_min = pix[1] - (height * 0.5)
+            viewer.state.x_max = viewer.state.x_min + width
+            viewer.state.y_max = viewer.state.y_min + height
+
+    def offset_to(self, dx, dy, skycoord_offset=False):
+        """Move the center to a point that is given offset
+        away from the current center.
+
+        Parameters
+        ----------
+        dx, dy : float or `~astropy.units.Quantity`
+            Offset value. The presence of unit depends on ``skycoord_offset``.
+
+        skycoord_offset : bool
+            If `True`, offset (lon, lat) must be given as ``Quantity``.
+            Otherwise, they are in pixel values (float).
+
+        Raises
+        ------
+        AttributeError
+            Sky offset is given but image does not have a valid WCS.
+
+        """
+        viewer = self.app.get_viewer("viewer-1")
+        width = viewer.state.x_max - viewer.state.x_min
+        height = viewer.state.y_max - viewer.state.y_min
+
+        if skycoord_offset:
+            i_top = get_top_layer_index(viewer)
+            image = viewer.layers[i_top].layer
+            if hasattr(image, 'coords') and isinstance(image.coords, BaseHighLevelWCS):
+                # To avoid distortion headache, assume offset is relative to
+                # displayed center.
+                x_cen = viewer.state.x_min + (width * 0.5)
+                y_cen = viewer.state.y_min + (height * 0.5)
+                sky_cen = image.coords.pixel_to_world(x_cen, y_cen)
+                if ASTROPY_LT_4_3:
+                    from astropy.coordinates import SkyOffsetFrame
+                    new_sky_cen = sky_cen.__class__(
+                        SkyOffsetFrame(dx, dy, origin=sky_cen.frame).transform_to(sky_cen))
+                else:
+                    new_sky_cen = sky_cen.spherical_offsets_by(dx, dy)
+                self.center_on(new_sky_cen)
+            else:
+                raise AttributeError(f'{image.label} does not have a valid WCS')
+        else:
+            with delay_callback(viewer.state, 'x_min', 'x_max', 'y_min', 'y_max'):
+                viewer.state.x_min += dx
+                viewer.state.y_min += dy
+                viewer.state.x_max = viewer.state.x_min + width
+                viewer.state.y_max = viewer.state.y_min + height
+
 
 def split_filename_with_fits_ext(filename):
     """Split a ``filename[ext]`` input into filename and FITS extension.
@@ -125,3 +231,12 @@ def split_filename_with_fits_ext(filename):
     data_label = os.path.basename(s[0])
 
     return filepath, ext, data_label
+
+
+def get_top_layer_index(viewer):
+    """Get index of the top visible layer in Imviz.
+    This is because when blinked, first layer might not be top visible layer.
+
+    """
+    return [i for i, lyr in enumerate(viewer.layers)
+            if lyr.visible and isinstance(lyr.layer, BaseData)][-1]

jdaviz/configs/imviz/plugins/tools.py

@@ -4,7 +4,6 @@
 from echo import delay_callback
 
 from glue.config import viewer_tool
-from glue.core import BaseData
 from glue_jupyter.bqplot.common.tools import Tool
 from glue.viewers.common.tool import CheckableTool
 from glue.plugins.wcs_autolinking.wcs_autolinking import wcs_autolink, WCSLink
@@ -119,6 +118,7 @@ def deactivate(self):
         self.viewer.remove_event_callback(self.on_mouse_or_key_event)
 
     def on_mouse_or_key_event(self, data):
+        from jdaviz.configs.imviz.helper import get_top_layer_index
 
         event = data['event']
 
@@ -141,8 +141,7 @@ def on_mouse_or_key_event(self, data):
             y = event_y / (self.viewer.state.y_max - self.viewer.state.y_min)
 
             # When blinked, first layer might not be top layer
-            i_top = [i for i, lyr in enumerate(self.viewer.layers)
-                     if lyr.visible and isinstance(lyr.layer, BaseData)][-1]
+            i_top = get_top_layer_index(self.viewer)
             state = self.viewer.layers[i_top].state
 
             # https://github.com/glue-viz/glue/blob/master/glue/viewers/image/qt/contrast_mouse_mode.py
@@ -154,8 +153,7 @@ def on_mouse_or_key_event(self, data):
 
         elif event == 'dblclick':
             # When blinked, first layer might not be top layer
-            i_top = [i for i, lyr in enumerate(self.viewer.layers)
-                     if lyr.visible and isinstance(lyr.layer, BaseData)][-1]
+            i_top = get_top_layer_index(self.viewer)
             state = self.viewer.layers[i_top].state
 
             # Restore defaults that are applied on load

jdaviz/configs/imviz/plugins/viewers.py

@@ -62,6 +62,12 @@ def on_mouse_or_key_event(self, data):
             x = data['domain']['x']
             y = data['domain']['y']
 
+            if x is None or y is None:  # Out of bounds
+                self.label_mouseover.pixel = ""
+                self.label_mouseover.world = ""
+                self.label_mouseover.value = ""
+                return
+
             maxsize = int(np.ceil(np.log10(np.max(image.shape)))) + 3
 
             fmt = 'x={0:0' + str(maxsize) + '.1f} y={1:0' + str(maxsize) + '.1f}'

jdaviz/configs/imviz/tests/test_astrowidgets_api.py

@@ -0,0 +1,86 @@
+import numpy as np
+import pytest
+from astropy import units as u
+from astropy.io import fits
+from astropy.wcs import WCS
+from numpy.testing import assert_allclose
+
+
+class TestAstrowidgetsAPI:
+    @pytest.fixture(autouse=True)
+    def setup_class(self, imviz_app):
+        hdu = fits.ImageHDU(np.zeros((10, 10)), name='SCI')
+
+        # Apply some celestial WCS from
+        # https://learn.astropy.org/rst-tutorials/celestial_coords1.html
+        hdu.header.update({'CTYPE1': 'RA---TAN',
+                           'CUNIT1': 'deg',
+                           'CDELT1': -0.0002777777778,
+                           'CRPIX1': 1,
+                           'CRVAL1': 337.5202808,
+                           'NAXIS1': 10,
+                           'CTYPE2': 'DEC--TAN',
+                           'CUNIT2': 'deg',
+                           'CDELT2': 0.0002777777778,
+                           'CRPIX2': 1,
+                           'CRVAL2': -20.833333059999998,
+                           'NAXIS2': 10})
+
+        # Data with WCS
+        imviz_app.load_data(hdu, data_label='has_wcs')
+
+        # Data without WCS
+        imviz_app.load_data(hdu, data_label='no_wcs')
+        imviz_app.app.data_collection[1].coords = None
+
+        self.wcs = WCS(hdu.header)
+        self.imviz = imviz_app
+        self.viewer = imviz_app.app.get_viewer('viewer-1')
+
+    def test_center_offset_pixel(self):
+        self.imviz.center_on((0, 1))
+        assert_allclose(self.viewer.state.x_min, -5)
+        assert_allclose(self.viewer.state.y_min, -4)
+        assert_allclose(self.viewer.state.x_max, 5)
+        assert_allclose(self.viewer.state.y_max, 6)
+
+        self.imviz.offset_to(1, -1)
+        assert_allclose(self.viewer.state.x_min, -4)
+        assert_allclose(self.viewer.state.y_min, -5)
+        assert_allclose(self.viewer.state.x_max, 6)
+        assert_allclose(self.viewer.state.y_max, 5)
+
+    def test_center_offset_sky(self):
+        # Blink to the one with WCS because the last loaded data is shown.
+        self.viewer.blink_once()
+
+        sky = self.wcs.pixel_to_world(0, 1)
+        self.imviz.center_on(sky)
+        assert_allclose(self.viewer.state.x_min, -5)
+        assert_allclose(self.viewer.state.y_min, -4)
+        assert_allclose(self.viewer.state.x_max, 5)
+        assert_allclose(self.viewer.state.y_max, 6)
+
+        dsky = 0.1 * u.arcsec
+        self.imviz.offset_to(dsky, dsky, skycoord_offset=True)
+        assert_allclose(self.viewer.state.x_min, -5.100000000142565)
+        assert_allclose(self.viewer.state.y_min, -3.90000000002971)
+        assert_allclose(self.viewer.state.x_max, 4.899999999857435)
+        assert_allclose(self.viewer.state.y_max, 6.09999999997029)
+
+        # astropy requires Quantity
+        with pytest.raises(u.UnitTypeError):
+            self.imviz.offset_to(0.1, 0.1, skycoord_offset=True)
+
+        # Cannot pass Quantity without specifying skycoord_offset=True
+        with pytest.raises(u.UnitConversionError):
+            self.imviz.offset_to(dsky, dsky)
+
+        # Blink to the one without WCS
+        self.viewer.blink_once()
+
+        with pytest.raises(AttributeError, match='does not have a valid WCS'):
+            self.imviz.center_on(sky)
+
+        with pytest.raises(AttributeError, match='does not have a valid WCS'):
+            self.imviz.offset_to(dsky, dsky, skycoord_offset=True)

jdaviz/configs/imviz/tests/test_parser.py

@@ -6,7 +6,7 @@
 from astropy.utils.data import download_file
 from astropy.wcs import WCS
 
-from jdaviz.configs.imviz.helper import Imviz, split_filename_with_fits_ext
+from jdaviz.configs.imviz.helper import split_filename_with_fits_ext
 from jdaviz.configs.imviz.plugins.parsers import (
     HAS_JWST_ASDF, parse_data, _validate_fits_image2d, _validate_bunit,
     _parse_image)
@@ -18,11 +18,6 @@
     HAS_SKIMAGE = False
 
 
-@pytest.fixture
-def imviz_app():
-    return Imviz()
-
-
 @pytest.mark.parametrize(
     ('filename', 'ans'),
     [('/path/to/cache/contents', ['/path/to/cache/contents', None, 'contents']),

jdaviz/conftest.py

@@ -11,7 +11,7 @@
 import numpy as np
 from specutils import Spectrum1D
 from jdaviz.configs.specviz.helper import SpecViz
-
+from jdaviz.configs.imviz.helper import Imviz
 
 SPECTRUM_SIZE = 10  # length of spectrum
 
@@ -45,6 +45,11 @@ def spectrum1d():
     return Spectrum1D(spectral_axis=spec_axis, flux=flux, uncertainty=uncertainty)
 
 
+@pytest.fixture
+def imviz_app():
+    return Imviz()
+
+
 try:
     from pytest_astropy_header.display import PYTEST_HEADER_MODULES, TESTED_VERSIONS
 except ImportError: