Allow toggling use of additional fallback fonts (#6095)

frontend/apps/reader/modules/readerfont.lua

@@ -49,11 +49,15 @@ function ReaderFont:init()
                 event = "ChangeLineSpace", args = "decrease" },
         }
     end
-    -- build face_table for menu
+    -- Build face_table for menu
     self.face_table = {}
-    if Device:isAndroid() or Device:isDesktop() or Device:isEmulator() then
-        table.insert(self.face_table, require("ui/elements/font_settings"):getMenuTable())
-    end
+    -- Font settings
+    table.insert(self.face_table, {
+        text = _("Font settings"),
+        sub_item_table = self:getFontSettingsTable(),
+        separator = true,
+    })
+    -- Font list
     local face_list = cre.getFontFaces()
     for k,v in ipairs(face_list) do
         table.insert(self.face_table, {
@@ -82,20 +86,6 @@ function ReaderFont:init()
         })
         face_list[k] = {text = v}
     end
-    if self:hasFontsTestSample() then
-        self.face_table[#self.face_table].separator = true
-        table.insert(self.face_table, {
-            text = _("Generate fonts test HTML document"),
-            callback = function()
-                UIManager:show(ConfirmBox:new{
-                    text = _("Would you like to generate an HTML document showing some sample text rendered with each available font?");
-                    ok_callback = function()
-                        self:buildFontsTestDocument()
-                    end
-                })
-            end
-        })
-    end
     self.ui.menu:registerToMainMenu(self)
 end
 
@@ -346,24 +336,79 @@ function ReaderFont:onAdjustFontSize(ges, direction)
     return true
 end
 
-function ReaderFont:hasFontsTestSample()
-    local font_test_sample = require("datastorage"):getSettingsDir() .. "/fonts-test-sample.html"
-    local lfs = require("libs/libkoreader-lfs")
-    return lfs.attributes(font_test_sample, "mode") == "file"
+function ReaderFont:getFontSettingsTable()
+    local settings_table = {}
+
+    if Device:isAndroid() or Device:isDesktop() or Device:isEmulator() then
+        for _, item in ipairs(require("ui/elements/font_settings"):getSystemFontMenuItems()) do
+            table.insert(settings_table, item)
+        end
+        settings_table[#settings_table].separator = true
+    end
+
+    table.insert(settings_table, {
+        text = _("Use additional fallback fonts"),
+        checked_func = function()
+            return G_reader_settings:nilOrTrue("additional_fallback_fonts")
+        end,
+        callback = function()
+        G_reader_settings:flipNilOrTrue("additional_fallback_fonts")
+            self.ui.document:setupFallbackFontFaces()
+            self.ui:handleEvent(Event:new("UpdatePos"))
+        end,
+        help_text = T(_([[
+Enable additional fallback fonts, for the most complete script and language coverage.
+These fonts will be used in this order:
+
+%1
+
+You can set a preferred fallback font with a long-press on a font name, and it will be used before these.
+If that font happens to be part of this list already, it will be used first.]]),
+            table.concat(self.ui.document.fallback_fonts, "\n")),
+        separator = true,
+    })
+
+    table.insert(settings_table, {
+        text = _("Generate font test document"),
+        callback = function()
+            UIManager:show(ConfirmBox:new{
+                text = _("Would you like to generate an HTML document showing some sample text rendered with each available font?");
+                ok_callback = function()
+                    self:buildFontsTestDocument()
+                end
+            })
+        end,
+    })
+    return settings_table
 end
 
+-- Default sample file
+local FONT_TEST_DEFAULT_SAMPLE_PATH = "frontend/ui/elements/font-test-sample-default.html"
+-- Users can set their own sample file, that will be used if found
+local FONT_TEST_USER_SAMPLE_PATH = require("datastorage"):getSettingsDir() .. "/font-test-sample.html"
+-- This document will be generated in the home or default directory
+local FONT_TEST_FINAL_FILENAME = "font-test.html"
+
 function ReaderFont:buildFontsTestDocument()
-    local font_test_sample = require("datastorage"):getSettingsDir() .. "/fonts-test-sample.html"
-    local f = io.open(font_test_sample, "r")
-    if not f then return nil end
-    local html_sample = f:read("*all")
-    f:close()
+    local html_sample
+    local f = io.open(FONT_TEST_USER_SAMPLE_PATH, "r")
+    if f then
+        html_sample = f:read("*all")
+        f:close()
+    end
+    if not html_sample then
+        f = io.open(FONT_TEST_DEFAULT_SAMPLE_PATH, "r")
+        if not f then return nil end
+        html_sample = f:read("*all")
+        f:close()
+    end
     local dir = G_reader_settings:readSetting("home_dir")
     if not dir then dir = require("apps/filemanager/filemanagerutil").getDefaultDir() end
     if not dir then dir = "." end
-    local fonts_test_path = dir .. "/fonts-test-all.html"
-    f = io.open(fonts_test_path, "w")
-    -- Using <section><title>...</title></section> allows for a TOC to be built
+    local font_test_final_path = dir .. "/" .. FONT_TEST_FINAL_FILENAME
+    f = io.open(font_test_final_path, "w")
+    if not f then return end
+    -- Using <section><title>...</title></section> allows for a TOC to be built by crengine
     f:write(string.format([[
 <?xml version="1.0" encoding="UTF-8"?>
 <html>
@@ -400,10 +445,10 @@ a { color: black; }
     f:write("</body></html>\n")
     f:close()
     UIManager:show(ConfirmBox:new{
-        text = T(_("Document created as:\n%1\n\nWould you like to read it now?"), BD.filepath(fonts_test_path)),
+        text = T(_("Document created as:\n%1\n\nWould you like to read it now?"), BD.filepath(font_test_final_path)),
         ok_callback = function()
             UIManager:scheduleIn(1.0, function()
-                self.ui:switchDocument(fonts_test_path)
+                self.ui:switchDocument(font_test_final_path)
             end)
         end,
     })

frontend/document/credocument.lua

@@ -639,6 +639,13 @@ function CreDocument:setupFallbackFontFaces()
             seen_fonts[font_name] = true
         end
     end
+    if G_reader_settings:isFalse("additional_fallback_fonts") then
+        -- Keep the first fallback font (user set or first from self.fallback_fonts),
+        -- as crengine won't reset its current set when provided with an empty string
+        for i=#fallbacks, 2, -1 do
+            table.remove(fallbacks, i)
+        end
+    end
     -- We use '|' as the delimiter (which is less likely to be found in font
     -- names than ',' or ';', without the need to have to use quotes.
     local s_fallbacks = table.concat(fallbacks, "|")

frontend/ui/elements/font-test-sample-default.html

@@ -0,0 +1,62 @@
+<p><b>Leonardo di ser Piero da Vinci</b> (Italian: [leoˈnardo di
+ˌsɛr ˈpjɛːro da (v)ˈvintʃi]; 14/15 April 1452 – 2
+May 1519), known as Leonardo da Vinci, was an Italian polymath of the
+Renaissance whose areas of interest included «invention, drawing,
+painting, sculpture, architecture, science, music, mathematics,
+engineering, literature, anatomy, geology, astronomy, botany,
+paleontology, and cartography». He has been variously called the
+father of palaeontology, ichnology, and architecture, and is widely
+considered one of the greatest painters of all time (despite perhaps
+only 15 of his paintings having survived).</p>
+
+<p>Leonardo is renowned primarily as a painter. The <i>Mona Lisa</i>
+is the most famous of his works <a href="#footnote34"><sup>34</sup></a>
+and the most popular portrait ever made. <i>The Last Supper</i>
+is the most reproduced religious painting of all
+time<a href="#footnote35"><sup>35</sup></a> and his
+Vitruvian Man drawing is regarded as a cultural icon as
+well<a href="#footnote36"><sup>36</sup></a>. Salvator Mundi was
+sold for a world record $450.3 million at a Christie's auction
+in New York, 15 November 2017, the <a href="nolink">highest price</a>
+ever paid for a work of art. <i>Leonardo's paintings and preparatory
+drawings—together with his notebooks, which contain sketches,
+scientific diagrams, and his thoughts on the nature of
+painting—compose a contribution to later generations of artists
+rivalled only by that of his contemporary Michelangelo.</i></p>
+<p>&nbsp;</p>
+
+<div>Above is some random text to appreciate lines height, and how
+much height or pages the same text occupy with each font &mdash;
+with bits in bold and italic, numbers and footnote links.</div>
+<div>&nbsp;</div>
+
+<div>These are some numbers ans possibly ambiguous letters and symbols:<br/>
+427, 809, 1635, 1IlLi, oO0, _-=+*#$~,;:!()[]{} "'«»</div>
+<div>&nbsp;</div>
+
+<div>Next are some bits to appreciate this font's OpenType features:<br/>
+This might show some ligatures: afflicting filling.<br/>
+<span style="font-variant: small-caps ">This line might be in Small Caps</span>.<br/>
+Lining numbers <span style="font-variant: lining-nums">123456</span> vs
+<span style="font-variant: oldstyle-nums">123456</span> oldstyle numbers.
+</div>
+<div>&nbsp;</div>
+
+<div>Finally, some words in various scripts to see how the baseline
+and height of this font and those of the fallback fonts compare: 
+a few classic greek words are νους, intelligence, ειδος, form,
+and λογος, which have nothing to do with the following text
+in simplified chinese <span lang="zh-CN">关门吃及刃</span>,
+and the same text in traditional chinese <span lang="zh-Hant">关门吃及刃</span>
+or in japanese <span lang="ja">关门吃及刃</span>.
+Nothing in common either with these RTL and BiDi bits
+in hebrew סֶּלַע ססס
+and in arabic الرحيم (123 456) الْحَمْدُ and وال (بااتي: abcd) من.
+This should be enough to appreciate this font.</div>
+<div>&nbsp;</div>
+
+<div>This is some sample content. You can have this document generated
+with some text of yours in your prefered language(s) by creating and
+adding it to a file named:<br/>
+<code>koreader/settings/font-test-sample.html</code>
+</div>

frontend/ui/elements/font_settings.lua

@@ -77,7 +77,7 @@ function FontSettings:getPath()
     return getUserDir()
 end
 
-function FontSettings:getMenuTable()
+function FontSettings:getSystemFontMenuItems()
     local t = {{
         text = _("Enable system fonts"),
         checked_func = usesSystemFonts,
@@ -98,11 +98,7 @@ function FontSettings:getMenuTable()
         })
     end
 
-    return {
-        text = _("Font settings"),
-        separator = true,
-        sub_item_table = t
-    }
+    return t
 end
 
 return FontSettings