Create raster PDF pages to match input page size

Previously we produced a raster image, then multiplied image width
by DPI to get the page size. However if there is rounding the
page size may not match exactly. In this modified approach we
constrain the page size to match.

src/ocrmypdf/_pipeline.py

@@ -588,12 +588,17 @@ def create_pdf_page_from_image(image: Path, page_context: PageContext):
     # except that the hocr renderer does not understand non-square DPI. The
     # sandwich renderer would be fine.
     output_file = page_context.get_path('visible.pdf')
-    dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
-    layout_fun = img2pdf.get_fixed_dpi_layout_fun(dpi)
+
+    pageinfo = page_context.pageinfo
+    pagesize = 72.0 * float(pageinfo.width_inches), 72.0 * float(pageinfo.height_inches)
+    if pageinfo.rotation % 180 == 90:
+        pagesize = pagesize[1], pagesize[0]
 
     # This create a single page PDF
     with open(image, 'rb') as imfile, open(output_file, 'wb') as pdf:
         log.debug('convert')
+
+        layout_fun = img2pdf.get_layout_fun(pagesize)
         img2pdf.convert(
             imfile, with_pdfrw=False, layout_fun=layout_fun, outputstream=pdf
         )