A5 page dimensions fix #1699 (#1703)

Author: Lucas-C

CHANGELOG.md

@@ -20,6 +20,7 @@ This can also be enabled programmatically with `warnings.simplefilter('default',
 ### Added
 * support for SVG `<linearGradient>` and `<radialGradient>` elements - _cf._ [issue #1580](https://github.com/py-pdf/fpdf2/issues/1580) - thanks to @Ani07-05
 ### Fixed
+* the `A5` value that could be specified as page `format` to the `FPDF` constructor was slightly incorrect, and the corresponding page dimensions have been fixed. This could lead to a minor change in your documents dimensions if you used this `A5` page format. - _cf._ [issue #1699](https://github.com/py-pdf/fpdf2/issues/1699)
 * a bug when rendering empty tables with `INTERNAL` layout, that caused an extra border to be rendered due to an erroneous use of `list.index()` - _cf._ [issue #1669](https://github.com/py-pdf/fpdf2/issues/1669)
 ### Changed
 * improved performance when rendering paths, SVGs, and opaque raster images with an alpha channel - _cf._ [PR #1675](https://github.com/py-pdf/fpdf2/pull/1675)

fpdf/fpdf.py

@@ -165,9 +165,9 @@ class Image:
 FPDF_VERSION = "2.8.5"
 __version__ = FPDF_VERSION
 PAGE_FORMATS = {
-    "a3": (841.89, 1190.55),
-    "a4": (595.28, 841.89),
-    "a5": (420.94, 595.28),
+    "a3": (841.89, 1190.55),  # 297mm × 420mm
+    "a4": (595.28, 841.89),  # 210mm × 297mm
+    "a5": (419.53, 595.28),  # 148mm x 210mm
     "letter": (612, 792),
     "legal": (612, 1008),
 }
@@ -219,6 +219,11 @@ def get_page_format(format, k=None):
     if isinstance(format, str):
         format = format.lower()
         if format in PAGE_FORMATS:
+            if format == "a5":
+                warnings.warn(
+                    # This warning should be removed in the next release:
+                    "Dimensions for page format A5 were fixed in release 2.8.5"
+                )
             return PAGE_FORMATS[format]
         raise FPDFPageFormatException(format, unknown=True)