Add 2-bit compressed rendering for large UI fonts

Refactor UI font generation to support different rendering modes based on size. Small UI fonts (12pt) use 1-bit rendering for crisp display and reduced flash usage. Large UI fonts (14pt) now use 2-bit compressed rendering to stay smooth when scaled up on touch/high-density boards. Extract font generation logic into reusable generate_ui_font() function.

lib/EpdFont/builtinFonts/all.h

@@ -37,3 +37,5 @@
 #include <builtinFonts/ubuntu_10_regular.h>
 #include <builtinFonts/ubuntu_12_bold.h>
 #include <builtinFonts/ubuntu_12_regular.h>
+#include <builtinFonts/ubuntu_14_bold.h>
+#include <builtinFonts/ubuntu_14_regular.h>

lib/EpdFont/scripts/build-font-ids.sh

@@ -94,6 +94,13 @@ ruby -rdigest -e 'puts [
 ].map{|f| Digest::SHA256.hexdigest(File.read(f)).to_i(16) }.sum % (2 ** 32) - (2 ** 31)'
 ))"
 
+echo "#define UI_14_FONT_ID ($(
+ruby -rdigest -e 'puts [
+  "./ubuntu_14_regular.h",
+  "./ubuntu_14_bold.h",
+].map{|f| Digest::SHA256.hexdigest(File.read(f)).to_i(16) }.sum % (2 ** 32) - (2 ** 31)'
+))"
+
 echo "#define SMALL_FONT_ID ($(
 ruby -rdigest -e 'puts [
   "./notosans_8_regular.h",

lib/EpdFont/scripts/convert-builtin-fonts.sh

@@ -28,23 +28,42 @@ for size in ${NOTOSANS_FONT_SIZES[@]}; do
   done
 done
 
+# Small UI chrome (button devices, uiScale 1.0). Rendered 1-bit: crisp at these
+# sizes and half the flash of 2-bit.
 UI_FONT_SIZES=(10 12)
+# Larger UI chrome substituted in on touch/high-density boards via the uiScale
+# remap (see src/main.cpp setupFonts). Rendered 2-bit so it stays smooth when
+# enlarged. Touch boards use uiScale 1.2, so UI_12 -> 14.4 -> 14 is the size the
+# remap actually lands on; add larger sizes here if a board adopts a higher scale.
+UI_FONT_SIZES_LARGE=(14)
 UI_FONT_STYLES=("Regular" "Bold")
 
+# Ubuntu lacks the Latin Extended Additional block (U+1EA0-U+1EF9) used for
+# Vietnamese tone marks. Append a Vietnamese-only Ubuntu cut so those glyphs are
+# filled from it while every glyph Ubuntu already has stays unchanged (fontstack
+# is ordered by descending priority). NotoSansHebrew fills U+05D0-U+05EA so the
+# Hebrew UI translation renders in menus and settings.
+generate_ui_font() {
+  local size="$1" style="$2" extra_flags="$3"
+  local font_name="ubuntu_${size}_$(echo $style | tr '[:upper:]' '[:lower:]')"
+  local font_path="../builtinFonts/source/Ubuntu/Ubuntu-${style}.ttf"
+  local hebrew_path="../builtinFonts/source/NotoSansHebrew/NotoSansHebrew-${style}.ttf"
+  local viet_path="../builtinFonts/source/Ubuntu/Ubuntu-Vietnamese-${style}.ttf"
+  local output_path="../builtinFonts/${font_name}.h"
+  python fontconvert.py $font_name $size $font_path $hebrew_path $viet_path \
+    --additional-intervals 0x05D0,0x05EA $extra_flags > $output_path
+  echo "Generated $output_path"
+}
+
 for size in ${UI_FONT_SIZES[@]}; do
   for style in ${UI_FONT_STYLES[@]}; do
-    font_name="ubuntu_${size}_$(echo $style | tr '[:upper:]' '[:lower:]')"
-    font_path="../builtinFonts/source/Ubuntu/Ubuntu-${style}.ttf"
-    hebrew_path="../builtinFonts/source/NotoSansHebrew/NotoSansHebrew-${style}.ttf"
-    # Ubuntu lacks the Latin Extended Additional block (U+1EA0-U+1EF9) used for
-    # Vietnamese tone marks. Append a Vietnamese-only Ubuntu cut so those glyphs
-    # are filled from it while every glyph Ubuntu already has stays unchanged
-    # (fontstack is ordered by descending priority).
-    viet_path="../builtinFonts/source/Ubuntu/Ubuntu-Vietnamese-${style}.ttf"
-    output_path="../builtinFonts/${font_name}.h"
-    python fontconvert.py $font_name $size $font_path $hebrew_path $viet_path \
-      --additional-intervals 0x05D0,0x05EA > $output_path
-    echo "Generated $output_path"
+    generate_ui_font $size $style ""
+  done
+done
+
+for size in ${UI_FONT_SIZES_LARGE[@]}; do
+  for style in ${UI_FONT_STYLES[@]}; do
+    generate_ui_font $size $style "--2bit --compress"
   done
 done
 

src/fontIds.h

@@ -11,6 +11,7 @@
 #define NOTOSANS_18_FONT_ID (37077304)
 #define UI_10_FONT_ID (22918846)
 #define UI_12_FONT_ID (1635686837)
+#define UI_14_FONT_ID (1899049399)
 #define SMALL_FONT_ID (674098198)
 
 // Font ID 0 is reserved as the "not found" sentinel.
@@ -25,4 +26,5 @@ static_assert(NOTOSANS_16_FONT_ID != 0, "Font ID collision with sentinel");
 static_assert(NOTOSANS_18_FONT_ID != 0, "Font ID collision with sentinel");
 static_assert(UI_10_FONT_ID != 0, "Font ID collision with sentinel");
 static_assert(UI_12_FONT_ID != 0, "Font ID collision with sentinel");
+static_assert(UI_14_FONT_ID != 0, "Font ID collision with sentinel");
 static_assert(SMALL_FONT_ID != 0, "Font ID collision with sentinel");

src/main.cpp

@@ -110,6 +110,12 @@ EpdFont ui12RegularFont(&ubuntu_12_regular);
 EpdFont ui12BoldFont(&ubuntu_12_bold);
 EpdFontFamily ui12FontFamily(&ui12RegularFont, &ui12BoldFont);
 
+// 14pt UI cut (2-bit) for the enlarged chrome the uiScale remap lands on for
+// touch boards. Same Hebrew + Vietnamese coverage as the 10/12pt cuts.
+EpdFont ui14RegularFont(&ubuntu_14_regular);
+EpdFont ui14BoldFont(&ubuntu_14_bold);
+EpdFontFamily ui14FontFamily(&ui14RegularFont, &ui14BoldFont);
+
 // measurement of power button press duration calibration value
 unsigned long t1 = 0;
 unsigned long t2 = 0;
@@ -297,21 +303,22 @@ void setupDisplayAndFonts(bool seamless = false) {
 #endif  // OMIT_FONTS
   renderer.insertFont(UI_10_FONT_ID, ui10FontFamily);
   renderer.insertFont(UI_12_FONT_ID, ui12FontFamily);
+  renderer.insertFont(UI_14_FONT_ID, ui14FontFamily);
   renderer.insertFont(SMALL_FONT_ID, smallFontFamily);
 
-  // UI chrome font scaling on touch/high-density boards: Ubuntu UI is only built at
-  // 10/12pt, so remap the UI fonts up the Noto Sans ladder with uiScale. SMALL is
-  // deliberately not remapped — it's compact secondary text (status bar, subtitles,
-  // battery %) that stays small. Reader body fonts aren't remapped either.
+  // UI chrome font scaling on touch/high-density boards: substitute a larger Ubuntu
+  // UI cut for each scaled UI font id at lookup time so menus/settings grow to finger
+  // size. We stay on the Ubuntu ladder (not Noto Sans) because the UI font carries
+  // Hebrew + Vietnamese glyphs that the Noto Sans reader fonts don't — remapping onto
+  // Noto Sans would drop those scripts from the UI. SMALL is deliberately not remapped
+  // — it's compact secondary text (status bar, subtitles, battery %) that stays small.
+  // Reader body fonts aren't remapped either.
   if (const float s = UITheme::uiScale(); s > 1.05f) {
-    auto nearestNotoSans = [](float pt) -> int {
+    auto nearestUbuntu = [](float pt) -> int {
       const struct {
         float pt;
         int id;
-      } sizes[] = {{12, NOTOSANS_12_FONT_ID},
-                   {14, NOTOSANS_14_FONT_ID},
-                   {16, NOTOSANS_16_FONT_ID},
-                   {18, NOTOSANS_18_FONT_ID}};
+      } sizes[] = {{10, UI_10_FONT_ID}, {12, UI_12_FONT_ID}, {14, UI_14_FONT_ID}};
       int best = sizes[0].id;
       float bestDiff = 1e9f;
       for (const auto& z : sizes) {
@@ -324,7 +331,7 @@ void setupDisplayAndFonts(bool seamless = false) {
       return best;
     };
     const int from[2] = {UI_10_FONT_ID, UI_12_FONT_ID};
-    const int to[2] = {nearestNotoSans(10 * s), nearestNotoSans(12 * s)};
+    const int to[2] = {nearestUbuntu(10 * s), nearestUbuntu(12 * s)};
     renderer.setUiFontRemap(from, to, 2);
   }