Copy width/height calculating logic from kaleido

plotly/io/_kaleido.py

@@ -376,13 +376,31 @@ def to_image(
             if defaults.mathjax:
                 kopts["mathjax"] = defaults.mathjax
 
-            # TODO: Refactor to make it possible to use a shared Kaleido instance here
+            width = (
+                width
+                or fig_dict.get("layout", {}).get("width")
+                or fig_dict.get("layout", {})
+                .get("template", {})
+                .get("layout", {})
+                .get("width")
+                or defaults.default_width
+            )
+            height = (
+                height
+                or fig_dict.get("layout", {}).get("height")
+                or fig_dict.get("layout", {})
+                .get("template", {})
+                .get("layout", {})
+                .get("height")
+                or defaults.default_height
+            )
+
             img_bytes = kaleido.calc_fig_sync(
                 fig_dict,
                 opts=dict(
                     format=format or defaults.default_format,
-                    width=width or defaults.default_width,
-                    height=height or defaults.default_height,
+                    width=width,
+                    height=height,
                     scale=scale or defaults.default_scale,
                 ),
                 topojson=defaults.topojson,

tests/test_optional/test_kaleido/test_kaleido.py

@@ -4,6 +4,7 @@
 from pathlib import Path
 import tempfile
 from unittest.mock import patch
+import xml.etree.ElementTree as ET
 
 from pdfrw import PdfReader
 from PIL import Image
@@ -16,6 +17,26 @@
 fig = {"data": [], "layout": {"title": {"text": "figure title"}}}
 
 
+def create_figure(width=None, height=None):
+    """Create a simple figure with optional layout dimensions."""
+    layout = {}
+    if width:
+        layout["width"] = width
+    if height:
+        layout["height"] = height
+
+    return go.Figure(data=[go.Scatter(x=[1, 2, 3], y=[1, 2, 3])], layout=layout)
+
+
+def parse_svg_dimensions(svg_bytes):
+    """Parse width and height from SVG bytes."""
+    svg_str = svg_bytes.decode("utf-8")
+    root = ET.fromstring(svg_str)
+    width = root.get("width")
+    height = root.get("height")
+    return int(width) if width else None, int(height) if height else None
+
+
 def check_image(path_or_buffer, size=(700, 500), format="PNG"):
     if format == "PDF":
         img = PdfReader(path_or_buffer)
@@ -314,3 +335,42 @@ def test_get_chrome():
 
             # Verify that kaleido.get_chrome_sync was called
             mock_get_chrome.assert_called_once()
+
+
+def test_width_height_priority():
+    """Test width/height priority: arguments > layout.width/height > defaults."""
+
+    # Test case 1: Arguments override layout
+    fig = create_figure(width=800, height=600)
+    svg_bytes = pio.to_image(fig, format="svg", width=1000, height=900)
+    width, height = parse_svg_dimensions(svg_bytes)
+    assert width == 1000 and height == 900, (
+        "Arguments should override layout dimensions"
+    )
+
+    # Test case 2: Layout dimensions used when no arguments
+    fig = create_figure(width=800, height=600)
+    svg_bytes = pio.to_image(fig, format="svg")
+    width, height = parse_svg_dimensions(svg_bytes)
+    assert width == 800 and height == 600, (
+        "Layout dimensions should be used when no arguments provided"
+    )
+
+    # Test case 3: Partial override (only width argument)
+    fig = create_figure(width=800, height=600)
+    svg_bytes = pio.to_image(fig, format="svg", width=1200)
+    width, height = parse_svg_dimensions(svg_bytes)
+    assert width == 1200 and height == 600, (
+        "Width argument should override layout, height should use layout"
+    )
+
+    # Test case 4: Defaults used when no layout or arguments
+    fig = create_figure()
+    svg_bytes = pio.to_image(fig, format="svg")
+    width, height = parse_svg_dimensions(svg_bytes)
+    assert width == pio.defaults.default_width, (
+        "Default width should be used when no layout or argument"
+    )
+    assert height == pio.defaults.default_height, (
+        "Default height should be used when no layout or argument"
+    )