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WIP dummy viewer
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‎src/astro_image_display_api/dummy_viewer.py‎

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import os
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from dataclasses import dataclass, field
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from pathlib import Path
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from typing import Any
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from astropy.coordinates import SkyCoord
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from astropy.nddata import CCDData, NDData
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from astropy.table import Table, vstack
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from astropy.units import Quantity, get_physical_type
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from astropy.wcs import WCS
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from numpy.typing import ArrayLike
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from .interface_definition import ImageViewerInterface
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@dataclass
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class ImageViewer:
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"""
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This viewer does not do anything except making changes to its internal
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state to simulate the behavior of a real viewer.
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"""
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# These are attributes, not methods. The type annotations are there
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# to make sure Protocol knows they are attributes. Python does not
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# do any checking at all of these types.
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click_center: bool = False
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click_drag: bool = True
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scroll_pan: bool = False
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image_width: int = 0
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image_height: int = 0
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zoom_level: float = 1
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is_marking: bool = False
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stretch_options: tuple = ("linear", "log", "sqrt")
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autocut_options: tuple = ("minmax", "zscale", "asinh", "percentile")
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cursor: str = ImageViewerInterface.ALLOWED_CURSOR_LOCATIONS[0]
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marker: Any = "marker"
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cuts: Any = (0, 1)
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stretch: str = "linear"
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# viewer: Any
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# Allowed locations for cursor display
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ALLOWED_CURSOR_LOCATIONS: tuple = ImageViewerInterface.ALLOWED_CURSOR_LOCATIONS
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# List of marker names that are for internal use only
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RESERVED_MARKER_SET_NAMES: tuple = ImageViewerInterface.RESERVED_MARKER_SET_NAMES
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# Default marker name for marking via API
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DEFAULT_MARKER_NAME: str = ImageViewerInterface.DEFAULT_MARKER_NAME
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# Default marker name for interactive marking
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DEFAULT_INTERACTIVE_MARKER_NAME: str = ImageViewerInterface.DEFAULT_INTERACTIVE_MARKER_NAME
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# some internal variable for keeping track of viewer state
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_interactive_marker_name: str = ""
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_previous_click_center: bool = False
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_previous_click_drag: bool = True
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_previous_scroll_pan: bool = False
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_previous_marker: Any = ""
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_markers: dict[str, Table] = field(default_factory=dict)
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_wcs: WCS | None = None
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_center: tuple[float, float] = (0.0, 0.0)
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# The methods, grouped loosely by purpose
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# Methods for loading data
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def load_fits(self, file: str | os.PathLike) -> None:
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"""
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Load a FITS file into the viewer.
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Parameters
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----------
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file : str or `astropy.io.fits.HDU`
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The FITS file to load. If a string, it can be a URL or a
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file path.
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"""
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ccd = CCDData.read(file)
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self._wcs = ccd.wcs
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self.image_height, self.image_width = ccd.shape
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# Totally made up number...as currently defined, zoom_level means, esentially, ratio
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# of image size to viewer size.
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self.zoom_level = 1.0
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self.center_on((self.image_width / 2, self.image_height / 2))
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def load_array(self, array: ArrayLike) -> None:
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"""
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Load a 2D array into the viewer.
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Parameters
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----------
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array : array-like
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The array to load.
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"""
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self.image_height, self.image_width = array.shape
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# Totally made up number...as currently defined, zoom_level means, esentially, ratio
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# of image size to viewer size.
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self.zoom_level = 1.0
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self.center_on((self.image_width / 2, self.image_height / 2))
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def load_nddata(self, data: NDData) -> None:
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"""
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Load an `astropy.nddata.NDData` object into the viewer.
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Parameters
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----------
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data : `astropy.nddata.NDData`
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The NDData object to load.
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"""
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self._wcs = data.wcs
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self.image_height, self.image_width = data.shape
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# Totally made up number...as currently defined, zoom_level means, esentially, ratio
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# of image size to viewer size.
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self.zoom_level = 1.0
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self.center_on((self.image_width / 2, self.image_height / 2))
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# Saving contents of the view and accessing the view
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def save(self, filename: str | os.PathLike, overwrite: bool = False) -> None:
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"""
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Save the current view to a file.
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Parameters
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----------
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filename : str or `os.PathLike`
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The file to save to. The format is determined by the
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extension.
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overwrite : bool, optional
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If `True`, overwrite the file if it exists. Default is
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`False`.
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"""
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p = Path(filename)
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p.write_text("This is a dummy file. The viewer does not save anything.")
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# Marker-related methods
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def start_marking(self, marker_name: str | None = None, marker: Any = None) -> None:
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"""
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Start interactive marking of points on the image.
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Parameters
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----------
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marker_name : str, optional
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The name of the marker set to use. If not given, a unique
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name will be generated.
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"""
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self.is_marking = True
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self._previous_click_center = self.click_center
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self._previous_click_drag = self.click_drag
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self._previous_marker = self.marker
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self._previous_scroll_pan = self.scroll_pan
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self.click_center = False
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self.click_drag = False
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self.scroll_pan = True
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self._interactive_marker_name = marker_name if marker_name else self.DEFAULT_INTERACTIVE_MARKER_NAME
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self.marker = marker if marker else self.DEFAULT_INTERACTIVE_MARKER_NAME
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def stop_marking(self, clear_markers: bool = False) -> None:
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"""
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Stop interactive marking of points on the image.
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Parameters
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----------
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clear_markers : bool, optional
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If `True`, clear the markers that were created during
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interactive marking. Default is `False`.
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"""
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self.is_marking = False
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self.click_center = self._previous_click_center
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self.click_drag = self._previous_click_drag
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self.scroll_pan = self._previous_scroll_pan
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self.marker = self._previous_marker
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if clear_markers:
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self.remove_markers(self._interactive_marker_name)
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def add_markers(self, table: Table, x_colname: str = 'x', y_colname: str = 'y',
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skycoord_colname: str = 'coord', use_skycoord: bool = False,
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marker_name: str | None = None) -> None:
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"""
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Add markers to the image.
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Parameters
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----------
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table : `astropy.table.Table`
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The table containing the marker positions.
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x_colname : str, optional
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The name of the column containing the x positions. Default
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is ``'x'``.
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y_colname : str, optional
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The name of the column containing the y positions. Default
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is ``'y'``.
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skycoord_colname : str, optional
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The name of the column containing the sky coordinates. If
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given, the ``use_skycoord`` parameter is ignored. Default
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is ``'coord'``.
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use_skycoord : bool, optional
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If `True`, the ``skycoord_colname`` column will be used to
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get the marker positions. Default is `False`.
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marker_name : str, optional
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The name of the marker set to use. If not given, a unique
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name will be generated.
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"""
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if use_skycoord:
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coords = table[skycoord_colname]
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if self._wcs is not None:
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x, y = self._wcs.world_to_pixel(coords)
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else:
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raise ValueError("WCS is not set. Cannot convert to pixel coordinates.")
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else:
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x = table[x_colname]
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y = table[y_colname]
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if marker_name in self.RESERVED_MARKER_SET_NAMES:
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raise ValueError(f"Marker name {marker_name} not allowed.")
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marker_name = marker_name if marker_name else self.DEFAULT_MARKER_NAME
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if marker_name in self._markers:
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marker_table = self._markers[marker_name]
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else:
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marker_table = Table(names=["x", "y", "marker name"],
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dtype=[float, float, str])
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to_add = table[x_colname, y_colname]
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to_add[marker_name] = marker_name
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self._markers[marker_name] = vstack([marker_table, to_add])
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def reset_markers(self) -> None:
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"""
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Remove all markers from the image.
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"""
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self._markers = {}
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def remove_markers(self, marker_name: str | list[str] | None = None) -> None:
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"""
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Remove markers from the image.
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Parameters
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----------
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marker_name : str, optional
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The name of the marker set to remove. If the value is ``"all"``,
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then all markers will be removed.
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"""
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if isinstance(marker_name, str):
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if marker_name in self._markers:
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del self._markers[marker_name]
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elif marker_name == "all":
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self._markers = {}
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elif isinstance(marker_name, list):
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for name in marker_name:
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if name in self._markers:
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del self._markers[name]
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def get_markers(self, x_colname: str = 'x', y_colname: str = 'y',
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skycoord_colname: str = 'coord',
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marker_name: str | list[str] | None = None) -> Table:
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"""
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Get the marker positions.
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Parameters
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----------
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x_colname : str, optional
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The name of the column containing the x positions. Default
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is ``'x'``.
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y_colname : str, optional
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The name of the column containing the y positions. Default
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is ``'y'``.
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skycoord_colname : str, optional
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The name of the column containing the sky coordinates. Default
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is ``'coord'``.
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marker_name : str or list of str, optional
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The name of the marker set to use. If that value is ``"all"``,
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then all markers will be returned.
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Returns
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-------
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table : `astropy.table.Table`
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The table containing the marker positions. If no markers match the
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``marker_name`` parameter, an empty table is returned.
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"""
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if isinstance(marker_name, str):
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if marker_name == "all":
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marker_name = self._markers.keys()
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else:
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marker_name = [marker_name]
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to_stack = [self._markers[name] for name in marker_name if name in self._markers]
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result = vstack(to_stack) if to_stack else Table(names=["x", "y", "coord", "marker name"])
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return result.rename_columns(["x", "y", "coord"], [x_colname, y_colname, skycoord_colname])
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# Methods that modify the view
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def center_on(self, point: tuple | SkyCoord):
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"""
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Center the view on the point.
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Parameters
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----------
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tuple or `~astropy.coordinates.SkyCoord`
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If tuple of ``(X, Y)`` is given, it is assumed
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to be in data coordinates.
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"""
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# currently there is no way to get the position of the center, but we may as well make
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# note of it
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if isinstance(point, SkyCoord):
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if self._wcs is not None:
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point = self._wcs.world_to_pixel(point)
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else:
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raise ValueError("WCS is not set. Cannot convert to pixel coordinates.")
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self._center = point
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def offset_by(self, dx: float | Quantity, dy: float | Quantity) -> None:
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"""
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Move the center to a point that is given offset
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away from the current center.
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Parameters
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----------
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dx, dy : float or `~astropy.units.Quantity`
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Offset value. Without a unit, assumed to be pixel offsets.
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If a unit is attached, offset by pixel or sky is assumed from
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the unit.
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"""
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# Convert to quantity to make the rest of the processing uniform
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dx = Quantity(dx)
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dy = Quantity(dy)
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# This raises a UnitConversionError if the units are not compatible
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dx.to(dy.unit)
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# Do we have an angle or pixel offset?
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if get_physical_type(dx) == "angle":
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# This is a sky offset
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if self._wcs is not None:
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old_center_coord = self._wcs.pixel_to_world(self._center[0], self._center[1])
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new_center = old_center_coord.spherical_offsets_byt(dx, dy)
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self.center_on(new_center)
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else:
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raise ValueError("WCS is not set. Cannot convert to pixel coordinates.")
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else:
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# This is a pixel offset
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new_center = (self._center[0] + dx.value, self._center[1] + dy.value)
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self.center_on(new_center)
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def zoom(self) -> None:
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"""
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Zoom in or out by the given factor.
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Parameters
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----------
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val : int
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The zoom level to zoom the image.
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See `zoom_level`.
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"""
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raise NotImplementedError

‎tests/test_astro_image_display_api.py‎

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"ImageWidgetAPITest does not access these attributes/methods:\n "
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f"{"\n".join(attr for attr, present in zip(required_attributes, attr_present) if not present)}. "
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)
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def test_instance():
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image = ImageViewer()
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assert isinstance(image, ImageViewerInterface)
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class TestDummyViewer(ImageWidgetAPITest):
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image_widget_class = ImageViewer

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