Add the Box class for specifying the box of GMT embellishments

doc/api/index.rst

@@ -203,6 +203,16 @@ Xarray Integration
     GMTBackendEntrypoint
     GMTDataArrayAccessor
 
+Class-style Parameters
+----------------------
+
+.. currentmodule:: pygmt.params
+
+.. autosummary::
+    :toctree: generated
+
+    Box
+
 Enums
 -----
 

examples/gallery/embellishments/inset.py

@@ -10,6 +10,7 @@
 
 # %%
 import pygmt
+from pygmt.params import Box
 
 fig = pygmt.Figure()
 # Create the primary figure, setting the region to Madagascar, the land color
@@ -19,7 +20,7 @@
 # Create an inset, placing it in the Top Left (TL) corner with a width of 3.5 cm and
 # x- and y-offsets of 0.2 cm. The margin is set to 0, and the border is "gold" with a
 # pen size of 1.5 points.
-with fig.inset(position="jTL+w3.5c+o0.2c", margin=0, box="+p1.5p,gold"):
+with fig.inset(position="jTL+w3.5c+o0.2c", margin=0, box=Box(pen="1.5p,gold")):
     # Create a figure in the inset using coast. This example uses the azimuthal
     # orthogonal projection centered at 47E, 20S. The land color is set to
     # "gray" and Madagascar is highlighted in "red3".

examples/gallery/embellishments/inset_rectangle_region.py

@@ -10,6 +10,7 @@
 
 # %%
 import pygmt
+from pygmt.params import Box
 
 # Set the region of the main figure
 region = [137.5, 141, 34, 37]
@@ -34,7 +35,7 @@
 # a pen of "1p".
 with fig.inset(
     position="jBR+o0.1c",
-    box="+gwhite+p1p",
+    box=Box(fill="white", pen="1p"),
     region=[129, 146, 30, 46],
     projection="U54S/3c",
 ):

examples/gallery/embellishments/scalebar.py

@@ -44,6 +44,7 @@
 
 # %%
 import pygmt
+from pygmt.params import Box
 
 # Create a new Figure instance
 fig = pygmt.Figure()
@@ -105,7 +106,7 @@
     # Fill the box in white with a transparency of 30 percent, add a solid
     # outline in darkgray (gray30) with a thickness of 0.5 points, and use
     # rounded edges with a radius of 3 points
-    box="+gwhite@30+p0.5p,gray30,solid+r3p",
+    box=Box(fill="white@30", pen="0.5p,gray30,solid", radius="3p"),
 )
 
 fig.show()

examples/gallery/images/cross_section.py

@@ -14,6 +14,7 @@
 
 # %%
 import pygmt
+from pygmt.params import Box
 
 # Define region of study area
 # lon_min, lon_max, lat_min, lat_max in degrees East and North
@@ -44,9 +45,9 @@
     # corner with an offset ("+o") of 0.7 centimeters and 0.3 centimeters in x- or y-
     # directions, respectively; move the x-label above the horizontal colorbar ("+ml")
     position="jBR+o0.7c/0.8c+h+w5c/0.3c+ml",
-    # Add a box around the colobar with a fill ("+g") in "white" color and a
-    # transparency ("@") of 30 % and with a 0.8-points thick, black, outline ("+p")
-    box="+gwhite@30+p0.8p,black",
+    # Add a box around the colobar, filled in "white" and a 30% transparency, with a
+    # 0.8-points thick, black, outline.
+    box=Box(pen="0.8p,black", fill="white@30"),
     # Add x- and y-labels ("+l")
     frame=["x+lElevation", "y+lm"],
 )

examples/gallery/lines/hlines_vlines.py

@@ -12,6 +12,7 @@
 # In Cartesian coordinate systems lines are plotted as straight lines.
 
 import pygmt
+from pygmt.params import Box
 
 fig = pygmt.Figure()
 
@@ -31,7 +32,7 @@
 fig.hlines(
     y=[2, 3], xmin=[0, 1], xmax=[7, 7.5], pen="1.5p,dodgerblue3", label="Lines 7 & 8"
 )
-fig.legend(position="JBR+jBR+o0.2c", box="+gwhite+p1p")
+fig.legend(position="JBR+jBR+o0.2c", box=Box(pen="1p", fill="white"))
 
 fig.shift_origin(xshift="w+2c")
 

examples/tutorials/advanced/insets.py

@@ -10,6 +10,7 @@
 
 # %%
 import pygmt
+from pygmt.params import Box
 
 # %%
 # Prior to creating an inset figure, a larger figure must first be plotted. In
@@ -48,7 +49,7 @@
     water="lightblue",
     frame="a",
 )
-with fig.inset(position="jBL+w3c", box="+pblack+glightred"):
+with fig.inset(position="jBL+w3c", box=Box(pen="black", fill="lightred")):
     # pass is used to exit the with statement as no plotting methods are
     # called
     pass
@@ -72,7 +73,7 @@
     water="lightblue",
     frame="a",
 )
-with fig.inset(position="jBL+w3c+o0.5c/0.2c", box="+pblack+glightred"):
+with fig.inset(position="jBL+w3c+o0.5c/0.2c", box=Box(pen="black", fill="lightred")):
     pass
 fig.show()
 
@@ -97,7 +98,7 @@
 # parameters.
 with fig.inset(
     position="jBL+o0.5c/0.2c",
-    box="+pblack",
+    box=Box(pen="black"),
     region=[-80, -65, 35, 50],
     projection="M3c",
 ):

examples/tutorials/advanced/legends.py

@@ -10,6 +10,7 @@
 import io
 
 import pygmt
+from pygmt.params import Box
 
 # %%
 # Create an auto-legend
@@ -90,7 +91,7 @@
 
 # Add a box with a 2-points thick blue, solid outline and a white fill with a
 # transparency of 70 percentage ("@30").
-fig.legend(position="jTL+o0.3c/0.2c", box="+p2p,blue+gwhite@30")
+fig.legend(position="jTL+o0.3c/0.2c", box=Box(pen="2p,blue", fill="white@30"))
 
 fig.show()
 
@@ -152,7 +153,7 @@
 fig.basemap(region=[-5, 5, -5, 5], projection="M10c", frame=True)
 
 # Pass the io.StringIO object to the "spec" parameter
-fig.legend(spec=spec_io, position="jMC+w9c", box="+p1p,gray50+ggray95")
+fig.legend(spec=spec_io, position="jMC+w9c", box=Box(pen="1p,gray50", fill="gray95"))
 
 fig.show()
 

pygmt/params/__init__.py

@@ -0,0 +1,5 @@
+"""
+Classes for common parameters in PyGMT.
+"""
+
+from pygmt.params.box import Box

pygmt/params/base.py

@@ -0,0 +1,97 @@
+"""
+Base class for common parameters shared in PyGMT.
+"""
+
+
+class BaseParam:
+    """
+    Base class for parameters in PyGMT.
+
+    To define a new parameter class, inherit from this class and define the attributes
+    that correspond to the parameters you want to include.
+
+    The class should also implement the ``_aliases`` property, which returns a list of
+    ``Alias`` objects. Each ``Alias`` object represents a parameter and its value, and
+    the ``__str__`` method will concatenate these values into a single string that can
+    be passed to GMT.
+
+    Optionally, you can override the ``_validate`` method to perform any necessary
+    validation on the parameters after initialization.
+
+    Examples
+    --------
+    >>> from typing import Any
+    >>> import dataclasses
+    >>> from pygmt.params.base import BaseParam
+    >>> from pygmt.alias import Alias
+    >>>
+    >>> @dataclasses.dataclass(repr=False)
+    ... class Test(BaseParam):
+    ...     par1: Any = None
+    ...     par2: Any = None
+    ...     par3: Any = None
+    ...
+    ...     @property
+    ...     def _aliases(self):
+    ...         return [
+    ...             Alias(self.par1),
+    ...             Alias(self.par2, prefix="+a"),
+    ...             Alias(self.par3, prefix="+b", sep="/"),
+    ...         ]
+
+    >>> var = Test(par1="val1")
+    >>> str(var)
+    'val1'
+    >>> repr(var)
+    "Test(par1='val1')"
+
+    >>> var = Test(par1="val1", par2="val2", par3=("val3a", "val3b"))
+    >>> str(var)
+    'val1+aval2+bval3a/val3b'
+    >>> repr(var)
+    "Test(par1='val1', par2='val2', par3=('val3a', 'val3b'))"
+    """
+
+    def __post_init__(self):
+        """
+        Post-initialization method to _validate the _aliases property.
+        """
+        self._validate()
+
+    def _validate(self):
+        """
+        Validate the parameters of the object.
+
+        This method should be overridden in subclasses to perform any necessary
+        validation on the parameters.
+        """
+
+    @property
+    def _aliases(self):
+        """
+        List of Alias objects representing the parameters of this class.
+
+        This property must be implemented in subclasses to define the parameters
+        and their aliases.
+        """
+        msg = "The _aliases property must be implemented in subclasses."
+        raise NotImplementedError(msg)
+
+    def __str__(self):
+        """
+        String representation of the object that can be passed to GMT directly.
+        """
+        return "".join(
+            [alias._value for alias in self._aliases if alias._value is not None]
+        )
+
+    def __repr__(self):
+        """
+        String representation of the object.
+        """
+        params = ", ".join(
+            f"{k}={v!r}"
+            for k, v in vars(self).items()
+            if v is not None and v is not False
+        )
+        return f"{self.__class__.__name__}({params})"

pygmt/params/box.py

@@ -0,0 +1,125 @@
+"""
+The Box class for specifying the box around GMT embellishments.
+"""
+
+import dataclasses
+from collections.abc import Sequence
+
+from pygmt.alias import Alias
+from pygmt.exceptions import GMTValueError
+from pygmt.params.base import BaseParam
+
+
+@dataclasses.dataclass(repr=False)
+class Box(BaseParam):
+    """
+    Class for specifying the box around GMT embellishments.
+
+    Attributes
+    ----------
+    clearance
+        Set clearances between the embellishment and the box border. It can be either a
+        scalar value or a sequence of two/four values.
+
+        - a scalar value means a uniform clearance in all four directions.
+        - a sequence of two values means separate clearances in x- and y-directions.
+        - a sequence of four values means separate clearances for left/right/bottom/top.
+    fill
+        Fill for the box. Default is no fill.
+    pen
+        Pen attributes for the box outline.
+    radius
+        Draw a rounded rectangular border instead of sharp. Passing a value with unit
+        to control the corner radius [Default is ``"6p"``].
+    inner_gap
+        Gap between the outer and inner borders. Default is ``"2p"``.
+    inner_pen
+        Pen attributes for the inner border. Default to :gmt-term:`MAP_DEFAULT_PEN`.
+    shading_offset
+        Place an offset background shaded region behind the box. A sequence of two
+        values (dx, dy) indicates the shift relative to the foreground frame. Default is
+        ``("4p", "-4p")``.
+    shading_fill
+        Fill for the shading region. Default is ``"gray50"``.
+
+    Examples
+    --------
+    >>> from pygmt.params import Box
+    >>> str(Box(fill="red@20"))
+    '+gred@20'
+    >>> str(Box(clearance=(0.2, 0.2), fill="red@20", pen="blue"))
+    '+c0.2/0.2+gred@20+pblue'
+    >>> str(Box(clearance=(0.2, 0.2), pen="blue", radius=True))
+    '+c0.2/0.2+pblue+r'
+    >>> str(Box(clearance=(0.1, 0.2, 0.3, 0.4), pen="blue", radius="10p"))
+    '+c0.1/0.2/0.3/0.4+pblue+r10p'
+    >>> str(
+    ...     Box(
+    ...         clearance=0.2,
+    ...         pen="blue",
+    ...         radius="10p",
+    ...         shading_offset=("5p", "5p"),
+    ...         shading_fill="lightred",
+    ...     )
+    ... )
+    '+c0.2+pblue+r10p+s5p/5p/lightred'
+    >>> str(Box(clearance=0.2, inner_gap="2p", inner_pen="1p,red", pen="blue"))
+    '+c0.2+i2p/1p,red+pblue'
+    >>> str(Box(clearance=0.2, shading_offset=("5p", "5p"), shading_fill="lightred"))
+    '+c0.2+s5p/5p/lightred'
+    """
+
+    clearance: float | str | Sequence[float | str] | None = None
+    fill: str | None = None
+    inner_gap: float | str | None = None
+    inner_pen: str | None = None
+    pen: str | None = None
+    radius: str | bool = False
+    shading_offset: Sequence[float | str] | None = None
+    shading_fill: str | None = None
+
+    def _validate(self):
+        """
+        Validate the parameters.
+        """
+        # shading_offset must be a sequence of two values or None.
+        if self.shading_offset and (
+            not isinstance(self.shading_offset, Sequence)
+            or len(self.shading_offset) != 2
+        ):
+            raise GMTValueError(
+                self.shading_offset,
+                description="value for parameter 'shading_offset'",
+                reason="Must be a sequence of two values (dx, dy) or None.",
+            )
+
+    @property
+    def _innerborder(self) -> list[str | float] | None:
+        """
+        Inner border of the box, formatted as a list of 1-2 values, or None.
+        """
+        return [v for v in (self.inner_gap, self.inner_pen) if v is not None] or None
+
+    @property
+    def _shading(self) -> list[str | float] | None:
+        """
+        Shading for the box, formatted as a list of 1-3 values, or None.
+        """
+        _shading_offset = self.shading_offset or []
+        return [
+            v for v in (*_shading_offset, self.shading_fill) if v is not None
+        ] or None
+
+    @property
+    def _aliases(self):
+        """
+        Aliases for the parameter.
+        """
+        return [
+            Alias(self.clearance, prefix="+c", sep="/", size=(2, 4)),
+            Alias(self.fill, prefix="+g"),
+            Alias(self._innerborder, prefix="+i", sep="/", size=(1, 2)),
+            Alias(self.pen, prefix="+p"),
+            Alias(self.radius, prefix="+r"),
+            Alias(self._shading, prefix="+s", sep="/", size=(1, 2, 3)),
+        ]