okular: use chromium's zoom factors

okular_zoom_factors.patch

From 64e83c7326c9cbb4d41158aebe08c228490470cb Mon Sep 17 00:00:00 2001
From: Ivan Kozik <ivan@ludios.org>
Date: Tue, 15 Jan 2019 21:36:28 +0000
Subject: [PATCH] okular: use chromium's zoom factors

---
 pkgs/applications/kde/okular.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkgs/applications/kde/okular.nix b/pkgs/applications/kde/okular.nix
index 39fb232b342..031fef97e29 100644
--- a/pkgs/applications/kde/okular.nix
+++ b/pkgs/applications/kde/okular.nix
@@ -18,6 +18,12 @@ mkDerivation {
     kwindowsystem libkexiv2 libspectre libzip phonon poppler qca-qt5
     qtdeclarative qtsvg threadweaver kcrash
   ] ++ lib.optional (!stdenv.isAarch64) chmlib;
+  postPatch = ''
+    # Okular doesn't have enough zoom factors, going down from e.g. 100% to 75%,
+    # so replace the zoom factors with those from Chromium.
+    factors="{0.25, 1 / 3.0, 0.5, 2 / 3.0, 0.75, 0.8, 0.9, 1.0, 1.1, 1.25, 1.5, 1.75, 2.0, 2.5, 3.0, 4.0, 5.0}"
+    sed -i -r "s@^static const float kZoomValues\[\] = .*@static const float kZoomValues[] = $factors;@g" ui/pageview.cpp
+  '';
   meta = with lib; {
     homepage = http://www.kde.org;
     license = with licenses; [ gpl2 lgpl21 fdl12 bsd3 ];
-- 
2.18.1