From 31b0c321fc256fc293adef2e6d2abfd014acab15 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 31 Jan 2023 19:26:42 +0530
Subject: [PATCH] DRYer

---
 src/pyj/read_book/paged_mode.pyj | 15 ++-------------
 src/pyj/read_book/viewport.pyj   | 18 +++++++++++++++++-
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/src/pyj/read_book/paged_mode.pyj b/src/pyj/read_book/paged_mode.pyj
index 3b417a6b2e..707355d273 100644
--- a/src/pyj/read_book/paged_mode.pyj
+++ b/src/pyj/read_book/paged_mode.pyj
@@ -33,7 +33,7 @@ from read_book.cfi import (
 )
 from read_book.globals import current_spine_item, get_boss, rtl_page_progression
 from read_book.settings import opts
-from read_book.viewport import scroll_viewport, line_height, rem_size
+from read_book.viewport import scroll_viewport, line_height, rem_size, get_unit_size_in_pixels
 from utils import (
     get_elem_data, set_elem_data
 )
@@ -155,18 +155,7 @@ def cps_by_em_size():
         if fs is 0:
             ans = cps_by_em_size.ans = 16
         else:
-            d = document.createElement('span')
-            d.style.position = 'absolute'
-            d.style.visibility = 'hidden'
-            d.style.width = '1rem'
-            d.style.fontSize = '1rem'
-            d.style.paddingTop = d.style.paddingBottom = d.style.paddingLeft = d.style.paddingRight = '0'
-            d.style.marginTop = d.style.marginBottom = d.style.marginLeft = d.style.marginRight = '0'
-            d.style.borderStyle = 'none'
-            document.body.appendChild(d)
-            w = d.clientWidth
-            document.body.removeChild(d)
-            ans = cps_by_em_size.ans = max(2, w)
+            ans = cps_by_em_size.ans = max(2, get_unit_size_in_pixels('rem'))
         cps_by_em_size.at_font_size = fs
     return ans
 
diff --git a/src/pyj/read_book/viewport.pyj b/src/pyj/read_book/viewport.pyj
index d4d73d4452..ecc7dfbfd9 100644
--- a/src/pyj/read_book/viewport.pyj
+++ b/src/pyj/read_book/viewport.pyj
@@ -330,6 +330,22 @@ for attr in FUNCTIONS:
         scroll_viewport['paged_' + attr] = scroll_viewport[attr]
 viewport_mode_changer(scroll_viewport.set_mode)
 
+
+def get_unit_size_in_pixels(unit):
+    d = document.createElement('span')
+    d.style.position = 'absolute'
+    d.style.visibility = 'hidden'
+    d.style.width = f'1{unit}'
+    d.style.fontSize = f'1{unit}'
+    d.style.paddingTop = d.style.paddingBottom = d.style.paddingLeft = d.style.paddingRight = '0'
+    d.style.marginTop = d.style.marginBottom = d.style.marginLeft = d.style.marginRight = '0'
+    d.style.borderStyle = 'none'
+    document.body.appendChild(d)
+    ans = d.clientWidth
+    document.body.removeChild(d)
+    return ans
+
+
 def rem_size(reset):
     if reset:
         rem_size.ans = None
@@ -344,7 +360,7 @@ def rem_size(reset):
         d.style.marginTop = d.style.marginBottom = d.style.marginLeft = d.style.marginRight = '0'
         d.style.borderStyle = 'none'
         document.body.appendChild(d)
-        rem_size.ans = d.clientWidth
+        rem_size.ans = max(2, d.clientWidth)
         document.body.removeChild(d)
     return rem_size.ans