From 4c37986737acc77d32252ae8391800597f8896fb Mon Sep 17 00:00:00 2001
From: Jakub <106778416+MarekZegare4@users.noreply.github.com>
Date: Fri, 22 May 2026 17:20:20 +0200
Subject: [PATCH] fix(eink): fix font layout and add Lemon font support to
 GxEPDDisplay
MIME-Version: 1.0
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Layout fix: GxEPDDisplay was using proportional GFX fonts (FreeSans9pt/12pt)
for sizes 1 and 2, giving lineHeight=16/20 instead of the 8/16 the UI layout
expects (designed for the OLED's bitmap font). Replaced with the GFX built-in
6×8 bitmap font (size 1) and its 2× scaled variant 12×16 (size 2). Size 3
keeps FreeSans18pt for large headings. fontAscender updated accordingly:
built-in font cursor is top-left (offset=0), Lemon GFX font adds 8px,
only FreeSans18pt still adds 26px.

Lemon font: LemonFont.h already stores the font in GFXfont format, so
GxEPDDisplay can use it directly via display.setFont(&Lemon). Added
_use_lemon flag, setLemonFont() override, and size-1 font selection in
setTextSize()/startFrame(). Adafruit GFX handles UTF-8 decoding for GFX
fonts, so Unicode characters (Cyrillic etc.) render correctly. The FONT
setting in SettingsScreen now works on e-ink the same as on OLED.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 src/helpers/ui/GxEPDDisplay.cpp | 28 +++++++++++++++++++---------
 src/helpers/ui/GxEPDDisplay.h   | 10 ++++++++--
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/src/helpers/ui/GxEPDDisplay.cpp b/src/helpers/ui/GxEPDDisplay.cpp
index 7c564aec..664607f0 100644
--- a/src/helpers/ui/GxEPDDisplay.cpp
+++ b/src/helpers/ui/GxEPDDisplay.cpp
@@ -16,10 +16,10 @@
 // GFX fonts use the baseline as the cursor origin. UI code assumes top-of-cell
 // coordinates (same convention as the OLED driver). Add the font ascender so
 // the two conventions match.
-static int fontAscender(int sz) {
-  if (sz == 3) return 26;  // FreeSans18pt7b
-  if (sz == 2) return 17;  // FreeSansBold12pt7b
-  return 13;               // FreeSans9pt7b (sz == 1)
+static int fontAscender(int sz, bool use_lemon) {
+  if (sz == 3) return 26;    // FreeSans18pt7b: proportional font, baseline origin
+  if (use_lemon) return 8;   // Lemon GFX font: baseline origin, typical ascender 8px
+  return 0;                  // GFX built-in font: cursor is top-left of cell
 }
 
 bool GxEPDDisplay::begin() {
@@ -72,7 +72,8 @@ void GxEPDDisplay::startFrame(Color bkg) {
   display.fillScreen(GxEPD_WHITE);
   display.setTextColor(_curr_color = GxEPD_BLACK);
   _text_sz = 1;
-  display.setFont(&FreeSans9pt7b);
+  display.setFont(_use_lemon ? &Lemon : NULL);
+  display.setTextSize(1);
   display_crc.reset();
 }
 
@@ -80,9 +81,18 @@ void GxEPDDisplay::setTextSize(int sz) {
   _text_sz = sz;
   display_crc.update<int>(sz);
   switch (sz) {
-    case 2:  display.setFont(&FreeSansBold12pt7b); break;
-    case 3:  display.setFont(&FreeSans18pt7b);     break;
-    default: display.setFont(&FreeSans9pt7b);      break;
+    case 3:
+      display.setFont(&FreeSans18pt7b);
+      display.setTextSize(1);
+      break;
+    case 2:
+      display.setFont(NULL);
+      display.setTextSize(2);
+      break;
+    default:
+      display.setFont(_use_lemon ? &Lemon : NULL);
+      display.setTextSize(1);
+      break;
   }
 }
 
@@ -101,7 +111,7 @@ void GxEPDDisplay::setCursor(int x, int y) {
   display_crc.update<int>(y);
   // Offset y by the font ascender: callers pass top-of-cell y, GFX fonts
   // expect baseline y. Without this, text would be clipped at the top.
-  display.setCursor(x, y + fontAscender(_text_sz));
+  display.setCursor(x, y + fontAscender(_text_sz, _use_lemon));
 }
 
 void GxEPDDisplay::print(const char* str) {
diff --git a/src/helpers/ui/GxEPDDisplay.h b/src/helpers/ui/GxEPDDisplay.h
index a5e7931b..278df610 100644
--- a/src/helpers/ui/GxEPDDisplay.h
+++ b/src/helpers/ui/GxEPDDisplay.h
@@ -15,6 +15,7 @@
 #include <CRC32.h>
 
 #include "DisplayDriver.h"
+#include "LemonFont.h"
 
 #ifndef DISPLAY_ROTATION
   #define DISPLAY_ROTATION 0
@@ -48,6 +49,7 @@ class GxEPDDisplay : public DisplayDriver {
 #endif
   bool _init = false;
   bool _isOn = false;
+  bool _use_lemon = false;
   uint16_t _curr_color;
   CRC32 display_crc;
   int last_display_crc_value = 0;
@@ -66,8 +68,12 @@ public:
   //   1 = FreeSans9pt      (lineH=16, charW≈9)
   //   2 = FreeSansBold12pt (lineH=20, charW≈12)
   //   3 = FreeSans18pt     (lineH=28, charW≈17)
-  int getCharWidth()  const override { return _text_sz == 3 ? 17 : _text_sz == 2 ? 12 : 9; }
-  int getLineHeight() const override { return _text_sz == 3 ? 28 : _text_sz == 2 ? 20 : 16; }
+  // Size 1: GFX built-in 6×8 (default) or Lemon 5×10 bitmap font — matches OLED metrics.
+  // Size 2: GFX built-in scaled 12×16 bitmap font.
+  // Size 3: FreeSans18pt proportional font for large headings.
+  int getCharWidth()  const override { return _text_sz == 3 ? 17 : _text_sz == 2 ? 12 : (_use_lemon ? 5 : 6); }
+  int getLineHeight() const override { return _text_sz == 3 ? 28 : _text_sz == 2 ? 16 : (_use_lemon ? 10 : 8); }
+  void setLemonFont(bool enabled) override { _use_lemon = enabled; }
 
   bool begin();