Figure.logo: Add parameters position/width/height to specify logo position and dimensions

examples/gallery/embellishments/gmt_logo.py

@@ -7,12 +7,12 @@
 
 # %%
 import pygmt
+from pygmt.params import Position
 
 fig = pygmt.Figure()
 fig.basemap(region=[0, 10, 0, 2], projection="X6c", frame=True)
 
 # Add the GMT logo in the Top Right (TR) corner of the current plot, scaled up to be 3
 # centimeters wide and offset by 0.3 cm in x-direction and 0.6 cm in y-direction.
-fig.logo(position="jTR+o0.3c/0.6c+w3c")
-
+fig.logo(position=Position("TR", offset=(0.3, 0.6)), width="3c")
 fig.show()

pygmt/src/_common.py

@@ -7,7 +7,8 @@
 from pathlib import Path
 from typing import Any, ClassVar, Literal
 
-from pygmt.exceptions import GMTValueError
+from pygmt.exceptions import GMTInvalidInput, GMTValueError
+from pygmt.params.position import Position
 from pygmt.src.which import which
 
 
@@ -244,3 +245,113 @@ def from_params(
             if set(param_list).issubset(set(params)):
                 return cls(convention, component=component)  # type: ignore[arg-type]
         raise GMTValueError(params, description="focal mechanism parameters")
+
+
+def _parse_position(
+    position: Position | Sequence[float | str] | str | None,
+    kwdict: dict[str, Any],
+    default: Position | None,
+) -> Position | str:
+    """
+    Parse the "position" parameter for embellishment-plotting functions.
+
+    Parameters
+    ----------
+    position
+        The position argument to parse. It can be one of the following:
+
+        - A :class:`pygmt.params.Position` object.
+        - A sequence of two values representing x and y coordinates in plot coordinates.
+        - A 2-character justification code.
+        - A raw GMT command string (for backward compatibility).
+        - ``None``, in which case the default position is used.
+    kwdict
+        The keyword arguments dictionary that conflicts with ``position`` if
+        ``position`` is given as a raw GMT command string.
+    default
+        The default Position object to use if ``position`` is ``None``.
+
+    Returns
+    -------
+    position
+        The parsed Position object or raw GMT command string.
+
+    Examples
+    --------
+    >>> from pygmt.params import Position
+    >>> _parse_position(
+    ...     Position((3, 3), cstype="mapcoords"),
+    ...     kwdict={"width": None, "height": None},
+    ...     default=Position((0, 0), cstype="plotcoords"),
+    ... )
+    Position(refpoint=(3, 3), cstype='mapcoords')
+
+    >>> _parse_position(
+    ...     (3, 3),
+    ...     kwdict={"width": None, "height": None},
+    ...     default=Position((0, 0), cstype="plotcoords"),
+    ... )
+    Position(refpoint=(3, 3), cstype='plotcoords')
+    >>> _parse_position(
+    ...     "TL",
+    ...     kwdict={"width": None, "height": None},
+    ...     default=Position((0, 0), cstype="plotcoords"),
+    ... )
+    Position(refpoint='TL', cstype='inside')
+
+    >>> _parse_position(
+    ...     None,
+    ...     kwdict={"width": None, "height": None},
+    ...     default=Position((0, 0), cstype="plotcoords"),
+    ... )
+    Position(refpoint=(0, 0), cstype='plotcoords')
+
+    >>> _parse_position(
+    ...     "x3c/4c+w2c",
+    ...     kwdict={"width": None, "height": None},
+    ...     default=Position((0, 0), cstype="plotcoords"),
+    ... )
+    'x3c/4c+w2c'
+
+    >>> _parse_position(
+    ...     "x3c/4c+w2c",
+    ...     kwdict={"width": 2, "height": None},
+    ...     default=Position((0, 0), cstype="plotcoords"),
+    ... )
+    Traceback (most recent call last):
+        ...
+    pygmt.exceptions.GMTInvalidInput: Parameter 'position' is given with a raw GMT...
+
+    >>> _parse_position(
+    ...     123,
+    ...     kwdict={"width": None, "height": None},
+    ...     default=Position((0, 0), cstype="plotcoords"),
+    ... )
+    Traceback (most recent call last):
+        ...
+    pygmt.exceptions.GMTInvalidInput: Invalid type for parameter 'position':...
+    """
+
+    _valid_anchors = {f"{h}{v}" for v in "TMB" for h in "LCR"} | {
+        f"{v}{h}" for v in "TMB" for h in "LCR"
+    }
+    match position:
+        case str() if position in _valid_anchors:  # Anchor code
+            position = Position(position, cstype="inside")
+        case str():  # Raw GMT command string.
+            if any(v is not None for v in kwdict.values()):
+                msg = (
+                    "Parameter 'position' is given with a raw GMT command string, and "
+                    f"conflicts with parameters {', '.join(repr(c) for c in kwdict)}."
+                )
+                raise GMTInvalidInput(msg)
+        case Sequence() if len(position) == 2:  # A sequence of x and y coordinates.
+            position = Position(position, cstype="plotcoords")
+        case Position():  # Already a Position object.
+            pass
+        case None if default is not None:  # Set default position.
+            position = default
+        case _:
+            msg = f"Invalid type for parameter 'position': {type(position)}."
+            raise GMTInvalidInput(msg)
+    return position

pygmt/src/inset.py

@@ -109,7 +109,7 @@ def inset(
     Examples
     --------
     >>> import pygmt
-    >>> from pygmt.params import Box
+    >>> from pygmt.params import Box, Position
     >>>
     >>> # Create the larger figure
     >>> fig = pygmt.Figure()
@@ -126,9 +126,8 @@ def inset(
     ...         dcw="MG+gred",
     ...     )
     ...
-    >>> # Map elements outside the "with" statement are plotted in the main
-    >>> # figure
-    >>> fig.logo(position="jBR+o0.2c+w3c")
+    >>> # Map elements outside the "with" statement are plotted in the main figure
+    >>> fig.logo(position=Position("BR", offset=0.2), width="3c")
     >>> fig.show()
     """
     self._activate_figure()

pygmt/src/logo.py

@@ -5,38 +5,51 @@
 from collections.abc import Sequence
 from typing import Literal
 
+from pygmt._typing import AnchorCode
 from pygmt.alias import Alias, AliasSystem
 from pygmt.clib import Session
-from pygmt.helpers import build_arg_list, fmt_docstring, use_alias
-from pygmt.params import Box
+from pygmt.exceptions import GMTInvalidInput
+from pygmt.helpers import build_arg_list, fmt_docstring
+from pygmt.params import Box, Position
+from pygmt.src._common import _parse_position
 
 
 @fmt_docstring
-@use_alias(D="position")
-def logo(
+def logo(  # noqa: PLR0913
     self,
+    position: Position | Sequence[float | str] | AnchorCode | None = None,
+    width: float | str | None = None,
+    height: float | str | None = None,
+    box: Box | bool = False,
+    style: Literal["standard", "url", "no_label"] = "standard",
     projection: str | None = None,
     region: Sequence[float | str] | str | None = None,
-    style: Literal["standard", "url", "no_label"] = "standard",
-    box: Box | bool = False,
     verbose: Literal["quiet", "error", "warning", "timing", "info", "compat", "debug"]
     | bool = False,
     panel: int | Sequence[int] | bool = False,
-    transparency: float | None = None,
     perspective: float | Sequence[float] | str | bool = False,
+    transparency: float | None = None,
     **kwargs,
 ):
-    r"""
+    """
     Plot the GMT logo.
 
-    By default, the GMT logo is 2 inches wide and 1 inch high and
-    will be positioned relative to the current plot origin.
-    Use various options to change this and to place a transparent or
-    opaque rectangular map panel behind the GMT logo.
+    .. figure:: https://docs.generic-mapping-tools.org/6.6/_images/GMT_coverlogo.png
+       :alt: GMT logo
+       :align: center
+       :width: 300px
+
+    By default, the GMT logo is 2 inches wide and 1 inch high and will be positioned
+    relative to the current plot origin.
 
     Full GMT docs at :gmt-docs:`gmtlogo.html`.
 
-    $aliases
+    **Aliases:**
+
+    .. hlist::
+       :columns: 3
+
+       - D = position, **+w**: width, **+h**: height
        - F = box
        - J = projection
        - R = region
@@ -48,12 +61,22 @@ def logo(
 
     Parameters
     ----------
-    $projection
-    $region
-    position : str
-        [**g**\|\ **j**\|\ **J**\|\ **n**\|\ **x**]\ *refpoint*\
-        **+w**\ *width*\ [**+j**\ *justify*]\ [**+o**\ *dx*\ [/*dy*]].
-        Set reference point on the map for the image.
+    position
+        Position of the GMT logo on the plot. It can be specified in multiple ways:
+
+        - A :class:`pygmt.params.Position` object to fully control the reference point,
+          anchor point, and offset.
+        - A sequence of two values representing the x and y coordinates in plot
+          coordinates, e.g., ``(1, 2)`` or ``("1c", "2c")``.
+        - A :doc:`2-character justification code </techref/justification_codes>` for a
+          position inside the plot, e.g., ``"TL"`` for Top Left corner inside the plot.
+
+        If not specified, defaults to the lower-left corner of the plot (position
+        ``(0, 0)`` with anchor ``"BL"``).
+    width
+    height
+        Width or height of the GMT logo. Since the aspect ratio is fixed, only one of
+        the two can be specified. [Default is 2 inches wide and 1 inch high].
     box
         Draw a background box behind the logo. If set to ``True``, a simple rectangular
         box is drawn using :gmt-term:`MAP_FRAME_PEN`. To customize the box appearance,
@@ -65,14 +88,32 @@ def logo(
         - ``"standard"``: The text label "The Generic Mapping Tools".
         - ``"no_label"``: Skip the text label.
         - ``"url"``: The URL to the GMT website.
+    $projection
+    $region
     $verbose
     $panel
-    $transparency
     $perspective
+    $transparency
     """
     self._activate_figure()
 
+    position = _parse_position(
+        position,
+        kwdict={"width": width, "height": height},
+        default=Position((0, 0), cstype="plotcoords"),  # Default to (0,0) in plotcoords
+    )
+
+    # width and height are mutually exclusive.
+    if width is not None and height is not None:
+        msg = "Cannot specify both 'width' and 'height'."
+        raise GMTInvalidInput(msg)
+
     aliasdict = AliasSystem(
+        D=[
+            Alias(position, name="position"),
+            Alias(height, name="height", prefix="+h"),
+            Alias(width, name="width", prefix="+w"),
+        ],
         F=Alias(box, name="box"),
         S=Alias(
             style, name="style", mapping={"standard": "l", "url": "u", "no_label": "n"}

pygmt/tests/baseline/test_logo_default_position.png.dvc

@@ -0,0 +1,5 @@
+outs:
+- md5: 6fa301eb7cd0e467285160cf261f9a10
+  size: 44372
+  hash: md5
+  path: test_logo_default_position.png

pygmt/tests/test_logo.py

@@ -4,6 +4,8 @@
 
 import pytest
 from pygmt import Figure
+from pygmt.exceptions import GMTInvalidInput
+from pygmt.params import Position
 
 
 @pytest.mark.benchmark
@@ -17,12 +19,54 @@ def test_logo():
     return fig
 
 
+@pytest.mark.mpl_image_compare
+def test_logo_default_position():
+    """
+    Test that the default position is at the plot origin when no position is specified.
+    """
+    fig = Figure()
+    fig.basemap(region=[0, 10, 0, 10], projection="X10c", frame=True)
+    fig.logo()
+    return fig
+
+
 @pytest.mark.mpl_image_compare
 def test_logo_on_a_map():
     """
     Plot the GMT logo at the upper right corner of a map.
     """
     fig = Figure()
     fig.basemap(region=[-90, -70, 0, 20], projection="M15c", frame=True)
-    fig.logo(position="jTR+o0.25c/0.25c+w7.5c", box=True)
+    fig.logo(position=Position("TR", offset=(0.25, 0.25)), width="7.5c", box=True)
     return fig
+
+
+@pytest.mark.mpl_image_compare(filename="test_logo_on_a_map.png")
+def test_logo_position_deprecated_syntax():
+    """
+    Test that passing the deprecated GMT CLI syntax string to 'position' works.
+    """
+    fig = Figure()
+    fig.basemap(region=[-90, -70, 0, 20], projection="M15c", frame=True)
+    fig.logo(position="jTR+o0.25/0.25+w7.5c", box=True)
+    return fig
+
+
+def test_logo_width_and_height():
+    """
+    Test that an error is raised when both width and height are specified.
+    """
+    fig = Figure()
+    with pytest.raises(GMTInvalidInput):
+        fig.logo(width="5c", height="5c")
+
+
+def test_logo_position_mixed_syntax():
+    """
+    Test that an error is raised when mixing new and deprecated syntax in 'position'.
+    """
+    fig = Figure()
+    with pytest.raises(GMTInvalidInput):
+        fig.logo(position="jTL", width="5c")
+    with pytest.raises(GMTInvalidInput):
+        fig.logo(position="jTL", height="6c")