Figure.image: Add parameters position/width/height/dpi/replicate to specify image position and properties

Author: seisman

examples/gallery/images/image.py

@@ -6,23 +6,25 @@
 many formats (e.g., png, jpg, eps, pdf) on a figure. We must specify the filename via
 the ``imagefile`` parameter or simply use the filename as the first argument. You can
 also use a full URL pointing to your desired image. The ``position`` parameter allows
-us to set a reference point on the map for the image.
+us to place the image at a specific location on the plot.
 """
 
 # %%
 from pathlib import Path
 
 import pygmt
+from pygmt.params import Position
 
 fig = pygmt.Figure()
 fig.basemap(region=[0, 2, 0, 2], projection="X10c", frame=True)
 
-# Place and center ("+jCM") the image "needle.jpg" provided by GMT to the position
-# ("+g") 1/1 on the current plot, scale it to a width of 8 centimeters ("+w") and draw
-# a rectangular border around it
+# Place the center of the image "needle.jpg" provided by GMT to the position (1, 1) on
+# the current plot, scale it to a width of 8 centimeters and draw a rectangular border
+# around it.
 fig.image(
     imagefile="https://oceania.generic-mapping-tools.org/cache/needle.jpg",
-    position="g1/1+w8c+jCM",
+    position=Position((1, 1), cstype="mapcoords", anchor="MC"),
+    width="8c",
     box=True,
 )
 

pygmt/src/image.py

@@ -5,18 +5,24 @@
 from collections.abc import Sequence
 from typing import Literal
 
-from pygmt._typing import PathLike
+from pygmt._typing import AnchorCode, PathLike
 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.params import Box, Position
+from pygmt.src._common import _parse_position
 
 
 @fmt_docstring
-@use_alias(D="position", G="bitcolor")
+@use_alias(G="bitcolor")
 def image(  # noqa: PLR0913
     self,
     imagefile: PathLike,
+    position: Position | Sequence[float | str] | AnchorCode | None = None,
+    width: float | str | None = None,
+    height: float | str | None = None,
+    dpi: float | str | None = None,
+    replicate: int | Sequence[int] | None = None,
     box: Box | bool = False,
     monochrome: bool = False,
     invert: bool = False,
@@ -33,10 +39,10 @@ def image(  # noqa: PLR0913
     r"""
     Plot raster or EPS images.
 
-    Reads Encapsulated PostScript (EPS) or raster image files and plots them. The
-    image can be scaled arbitrarily, and 1-bit raster images can be:
+    Reads an Encapsulated PostScript file or a raster image file and plot it on a map.
+    The image can be scaled arbitrarily, and 1-bit raster images can be:
 
-    - inverted, i.e., black pixels (on) becomes white (off) and vice versa.
+    - inverted, i.e., black pixels (on) become white (off) and vice versa.
     - colorized, by assigning different foreground and background colors.
     - made transparent where either the back- or foreground is painted.
 
@@ -50,6 +56,7 @@ def image(  # noqa: PLR0913
 
     $aliases
        - B = frame
+       - D = position, **+w**: width/height, **+r**: dpi, **+n**: replicate
        - F = box
        - I = invert
        - J = projection
@@ -66,11 +73,34 @@ def image(  # noqa: PLR0913
         An Encapsulated PostScript (EPS) file or a raster image file. An EPS file must
         contain an appropriate BoundingBox. A raster file can have a depth of 1, 8, 24,
         or 32 bits and is read via GDAL.
-    position : str
-        [**g**\|\ **j**\|\ **J**\|\ **n**\|\ **x**]\ *refpoint*\ **+r**\ *dpi*\
-        **+w**\ [**-**]\ *width*\ [/*height*]\ [**+j**\ *justify*]\
-        [**+n**\ *nx*\ [/*ny*]]\ [**+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 bottom-left corner of the plot (position
+        ``(0, 0)`` with anchor ``"BL"``).
+    width
+    height
+        Width (and height) of the image in plot coordinates (inches, cm, etc.). If
+        ``height`` (or ``width``) is set to 0, then the original aspect ratio of the
+        image is maintained. If ``width`` (or ``height``) is negative, the absolute
+        value is used to interpolate image to the device resolution using the PostScript
+        image operator. If neither dimensions nor ``dpi`` are set then revert to the
+        default dpi [:gmt-term:`GMT_GRAPHICS_DPU`].
+    dpi
+        Set the dpi of the image in dots per inch, or append **c** to indicate this is
+        dots per cm.
+    replicate
+        *nx* or (*nx*, *ny*).
+        Replicate the (scaled) image *nx* times in the horizontal direction, and *ny*
+        times in the vertical direction. If a single integer *nx* is given, *ny* = *nx*.
+        [Default is (1, 1)].
     box
         Draw a background box behind the image. If set to ``True``, a simple rectangular
         box is drawn using :gmt-term:`MAP_FRAME_PEN`. To customize the box appearance,
@@ -104,7 +134,24 @@ def image(  # noqa: PLR0913
     """
     self._activate_figure()
 
+    position = _parse_position(
+        position,
+        kwdict={"width": width, "height": height, "dpi": dpi, "replicate": replicate},
+        default=Position((0, 0), cstype="plotcoords"),  # Default to (0,0) in plotcoords
+    )
+
+    # width is required when only height is given.
+    if width is None and height is not None:
+        width = 0
+
     aliasdict = AliasSystem(
+        D=[
+            Alias(position, name="position"),
+            Alias(width, name="width", prefix="+w"),  # +wwidth/height
+            Alias(height, name="height", prefix="/"),
+            Alias(replicate, name="replicate", prefix="+n", sep="/", size=2),
+            Alias(dpi, name="dpi", prefix="+r"),
+        ],
         F=Alias(box, name="box"),
         M=Alias(monochrome, name="monochrome"),
         I=Alias(invert, name="invert"),

pygmt/tests/baseline/test_image.png.dvc

@@ -1,4 +1,5 @@
 outs:
-- md5: d7d0d71a44a232d5907dbd44f7a08f18
-  size: 30811
+- md5: 3bafd31eb0374ec175c1283c95ab0530
+  size: 24065
   path: test_image.png
+  hash: md5

pygmt/tests/baseline/test_image_complete.png.dvc

@@ -0,0 +1,5 @@
+outs:
+- md5: b2984015b085a78cda9c90fbd500b97e
+  size: 64696
+  hash: md5
+  path: test_image_complete.png

pygmt/tests/test_image.py

@@ -4,7 +4,8 @@
 
 import pytest
 from pygmt import Figure
-from pygmt.params import Box
+from pygmt.exceptions import GMTInvalidInput
+from pygmt.params import Box, Position
 
 
 @pytest.mark.mpl_image_compare
@@ -13,5 +14,53 @@ def test_image():
     Place images on map.
     """
     fig = Figure()
-    fig.image(imagefile="@circuit.png", position="x0/0+w2c", box=Box(pen="thin,blue"))
+    fig.image(imagefile="@circuit.png")
     return fig
+
+
+@pytest.mark.mpl_image_compare
+def test_image_complete():
+    """
+    Test all parameters of image.
+    """
+    fig = Figure()
+    fig.image(
+        imagefile="@circuit.png",
+        position=Position((0, 0)),
+        width="4c",
+        height="0",
+        replicate=(2, 1),
+        dpi="300",
+        box=Box(pen="thin,blue"),
+    )
+    return fig
+
+
+@pytest.mark.mpl_image_compare(filename="test_image_complete.png")
+def test_image_position_deprecated_syntax():
+    """
+    Test that passing the deprecated GMT CLI syntax string to 'position' works.
+    """
+    fig = Figure()
+    fig.image(
+        imagefile="@circuit.png",
+        position="x0/0+w4c/0c+n2/1+r300",
+        box=Box(pen="thin,blue"),
+    )
+    return fig
+
+
+def test_image_position_mixed_syntax():
+    """
+    Test that an error is raised when 'position' is given as a raw GMT CLI string
+    and conflicts with other parameters.
+    """
+    fig = Figure()
+    with pytest.raises(GMTInvalidInput):
+        fig.image(imagefile="@circuit.png", position="x0/0", width="4c")
+    with pytest.raises(GMTInvalidInput):
+        fig.image(imagefile="@circuit.png", position="x0/0", height="3c")
+    with pytest.raises(GMTInvalidInput):
+        fig.image(imagefile="@circuit.png", position="x0/0", dpi="300")
+    with pytest.raises(GMTInvalidInput):
+        fig.image(imagefile="@circuit.png", position="x0/0", replicate=(2, 1))