Add a PC renderer for the themed pages; fix overlapping layouts

tools/render_pages.py compiles the page code natively with g++ against
ESPHome's own display and font code and the font bitmaps of the last
`esphome compile`, and draws pages to PNG at chosen moments with sample
data (normal, empty, alert, busy), as a contact sheet, or as one example
per page in docs/images/pages (now shown in the README).

Fixes found with it: Cyber HUD zone names ran into the temperatures,
the breach header label hit the tag and the column marker the matrix
label; KonoSuba subtitle, guild weather icon, cabbage text and all-day
deadline, and hills through the party; Steins;Gate D-mail recipient, the
microwave display, the gadget card value and world line labels; LCARS
room rows, readout bars and data cascade, warp core readouts, and the
captain's log weather wording.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

@@ -37,3 +37,6 @@ esphome/*-local.yaml
 
 # Python bytecode (ESPHome component)
 __pycache__/
+
+# tools/render_pages.py build folder and renders
+.render/

README.md

@@ -95,7 +95,7 @@ src/test_images/        test sketch: cycles through 12 test images (env esp32dev
 esphome/                el512-panel.yaml (Home Assistant display), el512-smoke.yaml
 home_assistant/packages/  el512_panel.yaml: helper sensors for the ESPHome pages
 tools/                  import_still_alive.py, konosuba_sprites.py, steins_sprites.py,
-                        trek_sprites.py
+                        trek_sprites.py, render_pages.py (+ render/: PC renderer)
 test/                   unit tests (placeholder)
 docs/                   datasheet and notes
 ```
@@ -198,6 +198,11 @@ endorsed by Valve.
 
 ## Cyberpunk pages
 
+| | |
+|---|---|
+| ![Cyber HUD](docs/images/pages/cyber_hud.png) | ![Cyber Breach](docs/images/pages/cyber_breach.png) |
+| ![Cyber Scan](docs/images/pages/cyber_scan.png) | ![Cyber Split](docs/images/pages/cyber_split.png) |
+
 Four animated ESPHome pages in a Cyberpunk look, drawn by
 [components/el512/cyberpunk.cpp](components/el512/cyberpunk.cpp) with Orbitron, Rajdhani
 and Share Tech Mono (Google Fonts). All of them take part in the rotation:
@@ -224,6 +229,11 @@ with or endorsed by CD PROJEKT RED.
 
 ## KonoSuba pages
 
+| | |
+|---|---|
+| ![KonoSuba Explosion](docs/images/pages/ks_explosion.png) | ![KonoSuba Guild](docs/images/pages/ks_guild.png) |
+| ![KonoSuba Card](docs/images/pages/ks_card.png) | ![KonoSuba Battle](docs/images/pages/ks_battle.png) |
+
 Four animated pages around the KonoSuba party, drawn by
 [components/el512/konosuba.cpp](components/el512/konosuba.cpp) with Cinzel, Nunito,
 Press Start 2P, Noto Sans JP and Dela Gothic One (Google Fonts), all in the rotation:
@@ -256,6 +266,11 @@ affiliated with or endorsed by them.
 
 ## Steins;Gate pages
 
+| | |
+|---|---|
+| ![Divergence Meter](docs/images/pages/sg_meter.png) | ![D-Mail](docs/images/pages/sg_dmail.png) |
+| ![Gadget Lab](docs/images/pages/sg_lab.png) | ![World Lines](docs/images/pages/sg_world.png) |
+
 Four animated pages from the Future Gadget Lab, drawn by
 [components/el512/steins.cpp](components/el512/steins.cpp) with Nixie One, Special
 Elite and Noto Sans JP (plus fonts shared with the other themed pages), all in the
@@ -282,6 +297,11 @@ from the series is used. Steins;Gate is © MAGES. and its other rights holders;
 
 ## Star Trek pages
 
+| | |
+|---|---|
+| ![LCARS Status](docs/images/pages/st_lcars.png) | ![Duty Roster](docs/images/pages/st_roster.png) |
+| ![Warp Core](docs/images/pages/st_warp.png) | ![Captain's Log](docs/images/pages/st_log.png) |
+
 Four animated pages aboard a Lower Decks-era ship, drawn by
 [components/el512/trek.cpp](components/el512/trek.cpp) with Antonio (standing in for
 the LCARS typeface), all in the rotation:
@@ -309,6 +329,27 @@ These pages are fan art: the pixel art, layouts and texts are original, and no m
 from the series is used. Star Trek and Star Trek: Lower Decks are trademarks of CBS
 Studios Inc.; this project is not affiliated with or endorsed by them.
 
+## Rendering pages on the PC
+
+[tools/render_pages.py](tools/render_pages.py) draws the themed pages to PNG without
+the panel, to check layouts before flashing and to make the images above. It compiles
+the page code natively with g++ against ESPHome's own display and font code (from the
+installed `esphome` package) and the exact font bitmaps of the last `esphome compile`,
+so text sizes and positions match the device. Pages are drawn at chosen moments after
+they were shown, with sample data:
+
+```bash
+esphome compile esphome/el512-panel-local.yaml        # once, and after font changes
+python tools/render_pages.py                          # all pages -> .render/out
+python tools/render_pages.py --page st_lcars --at 0,2000 --scenario alert
+python tools/render_pages.py --scenario busy --sheet  # long names, high values
+python tools/render_pages.py --scenario empty         # no data yet
+python tools/render_pages.py --examples               # docs/images/pages/*.png
+```
+
+It needs a C++20 g++ (MinGW-w64 works on Windows) and Pillow. The host stand-in for
+the display and the sample data are in [tools/render/](tools/render/).
+
 ## Using the driver
 
 ```cpp

components/el512/cyberpunk.cpp

@@ -404,9 +404,10 @@ void netrunner_hud(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime
   cut_frame(it, 254, 150, 258, 86);
   tag(it, f.mono, 254, 150, 14, "ZONES");
   for (int i = 0; i < 4; i++) {
-    const int x = 264 + (i % 2) * 124, y = 192 + (i / 2) * 34;
+    // Name on top, temperature below it.
-    it.print(x, y, f.label, TextAlign::BASELINE_LEFT, el512::fit(f.label, d.rooms[i].name, 62).c_str());
+    const int x = 264 + (i % 2) * 124, y = 164 + (i / 2) * 36;
-    it.print(x + 116, y, f.value, TextAlign::BASELINE_RIGHT, temp_text(d.rooms[i].value).c_str());
+    it.print(x, y + 11, f.mono, TextAlign::BASELINE_LEFT, el512::fit(f.mono, upper(d.rooms[i].name), 114).c_str());
+    it.print(x, y + 33, f.value, TextAlign::BASELINE_LEFT, temp_text(d.rooms[i].value).c_str());
   }
 
   // Bottom: ticker.
@@ -432,7 +433,7 @@ void breach_protocol(EL512Display &it, const Fonts &f) {
 
   // Header and timer.
   tag(it, f.title, 0, 0, 24, "BREACH PROTOCOL");
-  it.print(420, 18, f.label, TextAlign::BASELINE_RIGHT, "BREACH TIME REMAINING");
+  it.print(420, 18, f.label, TextAlign::BASELINE_RIGHT, "TIME REMAINING");
   cut_frame(it, 428, 0, 84, 26, 6);
   const bool low = v.remain < 10.0f && (t / 250) % 2;
   if (!low)
@@ -441,8 +442,8 @@ void breach_protocol(EL512Display &it, const Fonts &f) {
 
   // Code matrix.
   cut_frame(it, 0, 40, 296, 216);
-  it.print(10, 54, f.mono, TextAlign::BASELINE_LEFT, "CODE MATRIX");
+  it.print(10, 52, f.mono, TextAlign::BASELINE_LEFT, "CODE MATRIX");
-  draw_matrix(it, {10, 62, 46, 31, f.code}, p, v);
+  draw_matrix(it, {10, 64, 46, 31, f.code}, p, v);
 
   // Buffer.
   it.print(304, 54, f.mono, TextAlign::BASELINE_LEFT, "BUFFER");

components/el512/el512_pages.h

@@ -96,6 +96,12 @@ inline std::string upper(std::string s) {
   return s;
 }
 
+inline std::string lower(std::string s) {
+  for (auto &c : s)
+    c = (char) tolower((unsigned char) c);
+  return s;
+}
+
 inline int text_width(display::Display &it, display::BaseFont *font, const char *text) {
   int x, y, w, h;
   it.get_text_bounds(0, 0, text, font, display::TextAlign::TOP_LEFT, &x, &y, &w, &h);

components/el512/konosuba.cpp

@@ -215,7 +215,7 @@ void explosion(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime now)
   // Title and clock (hidden while the sky is on fire).
   if (!blasting) {
     it.print(8, 4, f.jp_big, TextAlign::TOP_LEFT, "爆裂魔法");
-    it.print(10, 52, f.pixel, TextAlign::TOP_LEFT, "EXPLOSION MAGIC");
+    it.print(10, 56, f.pixel, TextAlign::TOP_LEFT, "EXPLOSION MAGIC");
     if (now.is_valid())
       it.strftime(504, 6, f.pixel_l, TextAlign::TOP_RIGHT, "%H:%M", now);
   }
@@ -372,7 +372,7 @@ void guild_board(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime no
     if (quests.size() == 3)
       break;
     const std::string day = field(e, 0), time = field(e, 1);
-    quests.push_back({field(e, 2), upper(day) + " " + (time.empty() ? "ALL DAY" : time), true, day == today});
+    quests.push_back({field(e, 2), upper(day) + (time.empty() ? "" : " " + time), true, day == today});
   }
   static const char *const STANDING[][2] = {{"Exterminate five giant toads", "BEFORE DUSK"},
                                             {"Escort a merchant cart to the next town", "THIS WEEK"},
@@ -412,13 +412,13 @@ void guild_board(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime no
   // Hazard notice (weather) and the cabbage bounty (solar).
   note(it, 386, 48, 116, 94);
   it.print(444, 60, f.pixel, TextAlign::TOP_CENTER, "HAZARD");
-  it.print(416, 102, f.weather, TextAlign::CENTER, weather_icon(d.weather));
+  it.print(416, 98, f.weather, TextAlign::CENTER, weather_icon(d.weather));
   it.print(492, 94, f.text, TextAlign::BASELINE_RIGHT, std::isnan(d.temp) ? "--" : str("%.0f°", d.temp).c_str());
-  it.print(444, 128, f.pixel, TextAlign::TOP_CENTER, fit(f.pixel, upper(weather_text(d.weather)), 100).c_str());
+  it.print(444, 131, f.pixel, TextAlign::TOP_CENTER, fit(f.pixel, upper(weather_text(d.weather)), 100).c_str());
 
   note(it, 386, 150, 116, 94);
   it.print(444, 162, f.pixel, TextAlign::TOP_CENTER, "BOUNTY");
-  it.print(444, 176, f.text, TextAlign::TOP_CENTER, "Cabbage harvest");
+  it.print(444, 176, f.text, TextAlign::TOP_CENTER, "Cabbage crop");
   it.print(444, 198, f.text, TextAlign::TOP_CENTER,
            std::isnan(d.solar_today) ? "--" : str("%.1f kWh", d.solar_today / 1000.0f).c_str());
   it.printf(444, 222, f.pixel, TextAlign::TOP_CENTER, "NOW %s", upper(watts_text(d.solar)).c_str());
@@ -535,8 +535,8 @@ void party_battle(EL512Display &it, const Fonts &f, const HomeData &d) {
   // Scenery.
   it.print(8, 6, f.jp, TextAlign::TOP_LEFT, "戦闘");
   it.printf(56, 12, f.pixel, TextAlign::TOP_LEFT, "ROUND %u", (unsigned) (round + 1));
-  arc(it, 110, GROUND + 70, 110, -52, 52);
+  // A hill between the party and the toad, clear of both.
-  arc(it, 300, GROUND + 90, 120, -40, 40);
+  arc(it, 270, GROUND + 50, 80, -46, 46);
   it.horizontal_line(0, GROUND, W);
   for (int i = 0; i < 18; i++) {
     const int x = (int) (hash(i, 21) % W);

components/el512/steins.cpp

@@ -223,7 +223,7 @@ void d_mail(EL512Display &it, const Fonts &f, const HomeData &d) {
   for (int b = 0; b < 4; b++)
     it.filled_rectangle(146 + b * 6, 26 - b * 2 - 2, 4, b * 2 + 2, COLOR_OFF);
   if (c < SEND) {
-    it.print(35, 34, f.pixel, TextAlign::TOP_LEFT, "TO: ME, 1 WEEK AGO");
+    it.print(35, 34, f.pixel, TextAlign::TOP_LEFT, "TO: ME, -1 WEEK");
     it.horizontal_line(34, 45, 138);
     std::string body = c < TYPE_AT ? "" : typed(msg, c - TYPE_AT, CPS);
     if ((t / 300) % 2)
@@ -267,7 +267,11 @@ void d_mail(EL512Display &it, const Fonts &f, const HomeData &d) {
           it.draw_pixel_at(x, y, COLOR_ON);
     it.printf(MX + 209, MY + 23, f.mono, TextAlign::CENTER, "0:%02u", (unsigned) ((ZAP + 300 - c) / 1000));
   } else {
-    it.print(MX + 209, MY + 23, f.mono, TextAlign::CENTER, upper(watts_text(d.house)).c_str());
+    // The microwave's little display: "850W" or "12.0kW".
+    const std::string lcd = std::isnan(d.house) ? "--"
+                            : d.house >= 1000  ? str("%.1fkW", d.house / 1000.0f)
+                                               : str("%.0fW", d.house);
+    it.print(MX + 209, MY + 23, f.mono, TextAlign::CENTER, lcd.c_str());
   }
   // Turntable with a banana on it.
   for (int a = 0; a < 360; a += 15) {
@@ -374,17 +378,19 @@ void gadget_lab(EL512Display &it, const Fonts &f, const HomeData &d) {
   // Detail card for the selected gadget.
   const Gadget &g = gadgets[sel];
   const uint32_t since = t % STEP;
-  it.rectangle(340, 38, 170, 128);
+  // Number, name, value, then the description.
-  it.rectangle(342, 40, 166, 124);
+  it.rectangle(340, 38, 170, 140);
-  it.printf(350, 46, f.title, TextAlign::TOP_LEFT, "NO.%s", g.no.c_str());
+  it.rectangle(342, 40, 166, 136);
-  it.print(502, 46, f.title, TextAlign::TOP_RIGHT, g.value.c_str());
+  it.printf(350, 44, f.title, TextAlign::TOP_LEFT, "NO.%s", g.no.c_str());
-  int y = 74;
+  int y = 68;
   for (const auto &l : wrap(it, f.mono, g.name, 150, 2)) {
     it.print(350, y, f.mono, TextAlign::TOP_LEFT, l.c_str());
     y += 15;
   }
-  it.horizontal_line(350, y + 2, 150);
+  it.print(350, y + 2, f.title, TextAlign::TOP_LEFT, g.value.c_str());
-  y += 8;
+  y += 26;
+  it.horizontal_line(350, y, 150);
+  y += 5;
   for (const auto &l : wrap(it, f.mono, typed(g.desc, since, 40), 150, 3)) {
     it.print(350, y, f.mono, TextAlign::TOP_LEFT, l.c_str());
     y += 15;
@@ -429,7 +435,7 @@ void world_lines(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime no
   }
   for (int h = 0; h <= 24; h += 6) {
     it.vertical_line(xmap(h), PY1, 4);
-    it.printf(xmap(h), PY1 + 8, f.pixel, TextAlign::TOP_CENTER, "%02d:00", h % 24);
+    it.printf(xmap(h), PY1 + 8, f.pixel, h == 24 ? TextAlign::TOP_RIGHT : TextAlign::TOP_CENTER, "%02d:00", h);
   }
 
   // Attractor fields.
@@ -441,14 +447,15 @@ void world_lines(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime no
   const int phase = (int) (t / 80);
   for (const auto &fl : fields) {
     const int y = ymap(fl.div);
-    if (fl.div == 1.048596f) {
+    // Labels on the left, where the chart stays empty until sunrise: Beta's
+    // above its line, the others below theirs (Steins Gate and Beta are only a
+    // few pixels apart).
+    if (fl.div == 1.048596f)
       it.horizontal_line(PX0 + 1, y, PX1 - PX0);
-      it.print(PX1, y - 3, f.pixel, TextAlign::BOTTOM_RIGHT, fl.name);
+    else
-    } else {
       dashed_hline(it, PX0 + 1, y, PX1 - PX0, 4, 4, phase);
-      it.print(PX1, fl.div > 1.1f ? y - 3 : y + 3, f.pixel, fl.div > 1.1f ? TextAlign::BOTTOM_RIGHT : TextAlign::TOP_RIGHT,
+    const bool above = fl.div > 1.1f;
-               fl.name);
+    it.print(PX0 + 6, above ? y - 3 : y + 3, f.pixel, above ? TextAlign::BOTTOM_LEFT : TextAlign::TOP_LEFT, fl.name);
-    }
   }
 
   // Today's world line, drawn in over the first 1.5 s.
@@ -472,7 +479,7 @@ void world_lines(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime no
     points++;
   }
   if (points == 0 && (t / 600) % 2)
-    it.print((PX0 + PX1) / 2, (PY0 + PY1) / 2 + 30, f.mono, TextAlign::CENTER, "COLLECTING WORLD LINE DATA...");
+    it.print((PX0 + PX1) / 2 - 40, PY1 - 10, f.mono, TextAlign::CENTER, "COLLECTING WORLD LINE DATA...");
 
   // Where we are now, and the futures branching off it.
   if (now.is_valid() && t >= 1500) {

components/el512/trek.cpp

@@ -173,16 +173,16 @@ void lcars_status(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime n
   for (int i = 0; i < 3; i++) {
     const int y = 48 + i * 24;
     block(it, f.small, 84, y, 66, 18, rows[i].name);
-    readout(it, 156, y + 4, 90, 10, rows[i].w / 5000.0f);
+    readout(it, 156, y + 4, 80, 10, rows[i].w / 5000.0f);
     it.print(298, y + 18, f.small, TextAlign::BOTTOM_RIGHT, kw(rows[i].w).c_str());
   }
 
   // Environmental.
   it.print(84, 128, f.small, TextAlign::TOP_LEFT, "ENVIRONMENTAL  DECKS 1-4");
   for (int i = 0; i < 4; i++) {
-    const int x = 84 + (i % 2) * 110, y = 150 + (i / 2) * 40;
+    const int x = 84 + (i % 2) * 110, y = 148 + (i / 2) * 44;
     it.print(x, y, f.small, TextAlign::TOP_LEFT, fit(f.small, upper(d.rooms[i].name), 104).c_str());
-    it.print(x, y + 16, f.medium, TextAlign::TOP_LEFT, deg(d.rooms[i].value).c_str());
+    it.print(x, y + 14, f.medium, TextAlign::TOP_LEFT, deg(d.rooms[i].value).c_str());
   }
 
   // Clock, sensors, fabrication bay.
@@ -200,7 +200,7 @@ void lcars_status(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime n
   for (int col = 0; col < 2; col++) {
     for (int row = 0; row < 9; row++) {
       const uint32_t r = hash(col * 31 + row, (t / 180) + row * 3);
-      const int x = 446 + col * 32, y = 96 + row * 12;
+      const int x = 456 + col * 30, y = 96 + row * 12;
       if (r % 5 == 0)
         continue;
       it.printf(x, y, f.pixel, TextAlign::TOP_LEFT, "%03u", (unsigned) (r % 1000));
@@ -325,8 +325,8 @@ void warp_core(EL512Display &it, const Fonts &f, const HomeData &d) {
   for (int i = 0; i < 3; i++) {
     const int y = 36 + i * 44;
     it.print(0, y, f.small, TextAlign::TOP_LEFT, rows[i].name);
-    it.print(204, y, f.small, TextAlign::TOP_RIGHT, rows[i].value.c_str());
+    it.print(196, y, f.small, TextAlign::TOP_RIGHT, rows[i].value.c_str());
-    readout(it, 0, y + 22, 200, 10, rows[i].frac);
+    readout(it, 0, y + 22, 196, 10, rows[i].frac);
   }
   it.print(0, 172, f.small, TextAlign::TOP_LEFT, "MATTER / ANTIMATTER  1:1");
   it.print(0, 192, f.small, TextAlign::TOP_LEFT, "DILITHIUM MATRIX  STABLE");
@@ -409,7 +409,7 @@ void captains_log(EL512Display &it, const Fonts &f, const HomeData &d, ESPTime n
   std::string entry = "We are holding position at home.";
   if (!std::isnan(d.temp))
     entry += str(" Outside it is %.0f degrees", d.temp) +
-             (d.weather.empty() ? std::string(".") : " and " + weather_text(d.weather) + ".");
+             (d.weather.empty() ? std::string(".") : " and " + lower(weather_text(d.weather)) + ".");
   if (!std::isnan(d.solar))
     entry += " The solar collectors deliver " + watts(d.solar) +
              (std::isnan(d.house) ? std::string(".") : " while the replicators draw " + watts(d.house) + ".");

tools/render/el512_display.h

@@ -0,0 +1,104 @@
+// Host stand-in for components/el512/el512_display.h, used by
+// tools/render_pages.py to draw the themed pages on a PC: the same drawing
+// surface (ESPHome's Display, 512 x 256, 1 bpp) and the same buffer effects,
+// without the panel, DMA or ESPHome components.
+#pragma once
+
+#include <algorithm>
+#include <cstdint>
+#include <cstring>
+
+#include "cyberpunk.h"
+#include "el512_helpers.h"
+#include "esphome/components/display/display.h"
+#include "esphome/core/hal.h"
+#include "konosuba.h"
+#include "steins.h"
+#include "trek.h"
+
+namespace esphome::el512 {
+
+class EL512Display : public display::Display {
+ public:
+  static constexpr int WIDTH = 512, HEIGHT = 256, ROW = WIDTH / 8;
+
+  uint8_t fb[ROW * HEIGHT]{};  // row-major, MSB = leftmost pixel (also PBM P4 order)
+  uint32_t shown_at{0};        // millis() when the page was "shown"
+
+  void update() override {}
+  display::DisplayType get_display_type() override { return display::DisplayType::DISPLAY_TYPE_BINARY; }
+
+  void fill(Color color) override {
+    if (this->get_clipping().is_set()) {
+      Display::fill(color);
+      return;
+    }
+    memset(this->fb, color.is_on() ? 0xFF : 0x00, sizeof(this->fb));
+  }
+  void draw_pixel_at(int x, int y, Color color) override {
+    if (!this->get_clipping().inside(x, y))
+      return;
+    this->set(x, y, color.is_on());
+  }
+
+  uint32_t page_age_ms() { return millis() - this->shown_at; }
+  uint32_t page_shown_at() const { return this->shown_at; }
+
+  // Same effects as the device (el512_display.cpp).
+  void shift_rows(int y, int height, int dx) {
+    dx %= WIDTH;
+    if (dx < 0)
+      dx += WIDTH;
+    if (dx == 0)
+      return;
+    uint8_t src[ROW];
+    for (int r = std::max(y, 0); r < std::min(y + height, HEIGHT); r++) {
+      uint8_t *row = this->fb + r * ROW;
+      memcpy(src, row, ROW);
+      memset(row, 0, ROW);
+      for (int x = 0; x < WIDTH; x++) {
+        const int s = (x - dx + WIDTH) % WIDTH;
+        if (src[s >> 3] & (0x80 >> (s & 7)))
+          row[x >> 3] |= 0x80 >> (x & 7);
+      }
+    }
+  }
+  void invert_rect(int x, int y, int width, int height) {
+    for (int py = y; py < y + height; py++)
+      for (int px = x; px < x + width; px++)
+        if (px >= 0 && py >= 0 && px < WIDTH && py < HEIGHT)
+          this->set(px, py, !this->get(px, py));
+  }
+  void dither_mask(int level) {
+    if (level >= 16)
+      return;
+    static const uint8_t BAYER[4][4] = {{0, 8, 2, 10}, {12, 4, 14, 6}, {3, 11, 1, 9}, {15, 7, 13, 5}};
+    uint8_t masks[4];
+    for (int r = 0; r < 4; r++) {
+      masks[r] = 0;
+      for (int x = 0; x < 8; x++)
+        if (BAYER[r][x & 3] < level)
+          masks[r] |= 0x80 >> x;
+    }
+    for (int y = 0; y < HEIGHT; y++)
+      for (int i = 0; i < ROW; i++)
+        this->fb[y * ROW + i] &= masks[y & 3];
+  }
+
+  bool get(int x, int y) const { return this->fb[y * ROW + (x >> 3)] & (0x80 >> (x & 7)); }
+  void set(int x, int y, bool on) {
+    if (x < 0 || y < 0 || x >= WIDTH || y >= HEIGHT)
+      return;
+    uint8_t &b = this->fb[y * ROW + (x >> 3)];
+    if (on)
+      b |= 0x80 >> (x & 7);
+    else
+      b &= ~(0x80 >> (x & 7));
+  }
+
+ protected:
+  int get_width_internal() override { return WIDTH; }
+  int get_height_internal() override { return HEIGHT; }
+};
+
+}  // namespace esphome::el512

tools/render/host_stubs.cpp

@@ -0,0 +1,29 @@
+// The parts of ESPHome's core that the display code links against but the
+// renderer never uses: there is no component lifecycle, polling, MAC or RNG on
+// the PC side.
+#include <cstring>
+
+#include "esphome/core/component.h"
+#include "esphome/core/helpers.h"
+
+namespace esphome {
+
+void Component::setup() {}
+void Component::loop() {}
+void Component::dump_config() {}
+float Component::get_setup_priority() const { return 0.0f; }
+bool Component::can_proceed() { return true; }
+void Component::call_setup() {}
+
+PollingComponent::PollingComponent(uint32_t update_interval) : update_interval_(update_interval) {}
+void PollingComponent::call_setup() {}
+uint32_t PollingComponent::get_update_interval() const { return this->update_interval_; }
+void PollingComponent::stop_poller() {}
+
+bool random_bytes(uint8_t *data, size_t len) {
+  memset(data, 0x5A, len);
+  return true;
+}
+void get_mac_address_raw(uint8_t *mac) { memset(mac, 0, 6); }
+
+}  // namespace esphome

tools/render/render_main.cpp

@@ -0,0 +1,157 @@
+// Renders the themed ESPHome pages on a PC with ESPHome's own display and
+// font code and the fonts of the last `esphome compile`. Built and run by
+// tools/render_pages.py; see there for usage.
+//
+//   render list                                  page names and default moments
+//   render <out_dir> <scenario> <page>:<ms> ...  one PBM per page and moment
+//
+// Scenarios: normal, empty (no data), alert (3D printer paused), busy (long
+// names, high values, export).
+#include <cstdio>
+#include <functional>
+#include <string>
+#include <vector>
+
+#include "el512_display.h"
+#include "fonts.h"
+
+using namespace esphome;
+using namespace esphome::el512;
+
+static uint32_t g_millis = 0;
+namespace esphome {
+uint32_t millis() { return g_millis; }
+uint64_t millis_64() { return g_millis; }
+uint32_t micros() { return g_millis * 1000; }
+void delay(uint32_t) {}
+void delayMicroseconds(uint32_t) {}
+}  // namespace esphome
+
+// Monday 2026-10-19 14:37:25 (UTC, so renders don't depend on the PC's zone).
+static ESPTime sample_time() { return ESPTime::from_epoch_utc(1792420645); }
+
+static HomeData sample(const std::string &scenario) {
+  HomeData d;
+  if (scenario == "empty")
+    return d;
+  d.weather = "partlycloudy";
+  d.temp = 12.4f;
+  d.humidity = 81;
+  d.wind = 14;
+  d.solar = 3420;
+  d.solar_today = 9800;
+  d.house = 1240;
+  d.grid = -2180;
+  d.agenda = "Mon 19|16:00|Dentist appointment;Tue 20||Holiday;Wed 21|09:30|Team meeting about the roadmap;"
+             "Thu 22|19:00|Dinner at Stans & Paul";
+  d.message = "";
+  d.printer = scenario == "alert" ? "paused" : "printing";
+  d.rooms[0] = {"Woonkamer", 21.3f};
+  d.rooms[1] = {"Voorkamer", 19.8f};
+  d.rooms[2] = {"Patrick", 20.5f};
+  d.rooms[3] = {"Badkamer", 22.1f};
+  if (scenario == "busy") {
+    d.weather = "lightning-rainy";
+    d.temp = -12.6f;
+    d.solar = 12450;
+    d.solar_today = 48700;
+    d.house = 11980;
+    d.grid = 8520;
+    d.humidity = 100;
+    d.wind = 104;
+    d.message = "Remember to take the bins out tonight before 22:00!";
+    d.agenda = "Mon 19|16:00|Very long appointment title that keeps going and going to test wrapping;"
+               "Tue 20||Holiday;Wed 21|09:30|Quarterly planning session with the entire department;"
+               "Thu 22|19:00|Dinner";
+    d.rooms[0] = {"Vloerverwarming", 23.9f};
+    d.rooms[1] = {"Stans & Paul", 18.2f};
+  }
+  // Today's solar curve up to now (14:37), for the world line chart.
+  for (int s = 7 * 4; s <= 14 * 4 + 2; s++) {
+    const float h = s / 4.0f;
+    d.solar_slots[s] = std::max(0.0f, 4200.0f * std::sin((h - 7.0f) / 12.0f * 3.14159f));
+  }
+  return d;
+}
+
+struct Page {
+  const char *name;
+  std::vector<uint32_t> moments;  // ms after the page was shown; the first is its example
+  std::function<void(EL512Display &, const HomeData &, ESPTime)> draw;
+};
+
+static std::vector<Page> pages() {
+  const cyber::Fonts cp{f_cp_title, f_cp_label, f_cp_value, f_cp_huge, f_cp_mono, f_cp_code};
+  const konosuba::Fonts ks{f_ks_title, f_ks_big, f_ks_text, f_ks_pixel, f_ks_pixel_l, f_ks_jp, f_ks_jp_big, icons_l};
+  const steins::Fonts sg{f_sg_nixie, f_sg_title, f_cp_mono, f_cp_code, f_ks_pixel, f_sg_jp};
+  const trek::Fonts st{f_st_small, f_st_medium, f_st_large, f_ks_text, f_ks_pixel};
+  return {
+      {"cyber_hud", {2000}, [=](auto &it, auto &d, auto now) { cyber::netrunner_hud(it, cp, d, now); }},
+      {"cyber_breach", {4500, 9000}, [=](auto &it, auto &, auto) { cyber::breach_protocol(it, cp); }},
+      {"cyber_scan", {7000, 2500}, [=](auto &it, auto &d, auto now) { cyber::optics_scan(it, cp, d, now); }},
+      {"cyber_split", {4500}, [=](auto &it, auto &d, auto now) { cyber::split_hud(it, cp, d, now); }},
+      {"ks_explosion", {6900, 800, 5200, 10500, 15000},
+       [=](auto &it, auto &d, auto now) { konosuba::explosion(it, ks, d, now); }},
+      {"ks_guild", {3000}, [=](auto &it, auto &d, auto now) { konosuba::guild_board(it, ks, d, now); }},
+      {"ks_card", {2000}, [=](auto &it, auto &d, auto now) { konosuba::adventurer_card(it, ks, d, now); }},
+      {"ks_battle", {2500, 10500, 18300, 20000}, [=](auto &it, auto &d, auto) { konosuba::party_battle(it, ks, d); }},
+      {"sg_meter", {3000, 11000}, [=](auto &it, auto &, auto now) { steins::divergence_meter(it, sg, now); }},
+      {"sg_dmail", {8000, 3000, 13500}, [=](auto &it, auto &d, auto) { steins::d_mail(it, sg, d); }},
+      {"sg_lab", {1500}, [=](auto &it, auto &d, auto) { steins::gadget_lab(it, sg, d); }},
+      {"sg_world", {3000}, [=](auto &it, auto &d, auto now) { steins::world_lines(it, sg, d, now); }},
+      {"st_lcars", {2000}, [=](auto &it, auto &d, auto now) { trek::lcars_status(it, st, d, now); }},
+      {"st_roster", {1500}, [=](auto &it, auto &d, auto now) { trek::duty_roster(it, st, d, now); }},
+      {"st_warp", {2000}, [=](auto &it, auto &d, auto) { trek::warp_core(it, st, d); }},
+      {"st_log", {14000, 6000}, [=](auto &it, auto &d, auto now) { trek::captains_log(it, st, d, now); }},
+  };
+}
+
+int main(int argc, char **argv) {
+  const auto all = pages();
+  if (argc >= 2 && std::string(argv[1]) == "list") {
+    for (const auto &p : all) {
+      printf("%s", p.name);
+      for (size_t i = 0; i < p.moments.size(); i++)
+        printf("%c%u", i ? ',' : ' ', (unsigned) p.moments[i]);
+      printf("\n");
+    }
+    return 0;
+  }
+  if (argc < 4) {
+    fprintf(stderr, "usage: render list | render <out_dir> <scenario> <page>:<ms> ...\n");
+    return 2;
+  }
+  const std::string out = argv[1];
+  const HomeData data = sample(argv[2]);
+  for (int a = 3; a < argc; a++) {
+    const std::string arg = argv[a];
+    const size_t colon = arg.find(':');
+    const std::string name = arg.substr(0, colon);
+    const uint32_t at = colon == std::string::npos ? 0 : (uint32_t) std::stoul(arg.substr(colon + 1));
+    const Page *page = nullptr;
+    for (const auto &p : all)
+      if (name == p.name)
+        page = &p;
+    if (page == nullptr) {
+      fprintf(stderr, "unknown page %s\n", name.c_str());
+      return 1;
+    }
+    EL512Display it;
+    it.shown_at = 1000000;
+    g_millis = it.shown_at + at;
+    // Like the device: start from a clear buffer, then the page draws.
+    it.fill(display::COLOR_OFF);
+    page->draw(it, data, sample_time());
+    const std::string path = out + "/" + name + "_" + std::to_string(at) + ".pbm";
+    FILE *f = fopen(path.c_str(), "wb");
+    if (f == nullptr) {
+      fprintf(stderr, "cannot write %s\n", path.c_str());
+      return 1;
+    }
+    fprintf(f, "P4\n%d %d\n", EL512Display::WIDTH, EL512Display::HEIGHT);
+    fwrite(it.fb, 1, sizeof(it.fb), f);
+    fclose(f);
+    printf("%s\n", path.c_str());
+  }
+  return 0;
+}

tools/render_pages.py

@@ -0,0 +1,241 @@
+#!/usr/bin/env python3
+"""Render the themed ESPHome pages to PNG on this PC, for checking layouts
+without flashing and for example images.
+
+Compiles the page code (components/el512/cyberpunk, konosuba, steins, trek)
+natively with g++ against ESPHome's own display and font code (from the
+installed esphome package) and the exact font bitmaps of the last
+`esphome compile` (its generated main.cpp), then draws each page at given
+moments after it was shown. Run `esphome compile esphome/el512-panel-local.yaml`
+first, and again after changing fonts in the YAML.
+
+    python tools/render_pages.py                          # all pages, default moments
+    python tools/render_pages.py --page ks_explosion --at 0,6900,15000
+    python tools/render_pages.py --scenario busy          # also: normal, empty, alert
+    python tools/render_pages.py --sheet                  # plus one contact sheet
+    python tools/render_pages.py --list                   # page names and moments
+    python tools/render_pages.py --examples               # docs/images/pages/<page>.png
+
+Output goes to .render/out (git-ignored) unless --out says otherwise. Needs a
+g++ with C++20 (MinGW-w64 on Windows works) and Pillow.
+"""
+
+import argparse
+import re
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+WORK = ROOT / ".render"
+PAGE_SOURCES = ["cyberpunk", "konosuba", "steins", "trek"]
+PAGE_HEADERS = ["el512_pages.h", "el512_helpers.h", "konosuba_sprites.h", "steins_sprites.h", "trek_sprites.h"]
+ESPHOME_PARTS = ["core", "components/display", "components/font", "components/host", "components/time",
+                 "components/lvgl", "components/graph"]
+ESPHOME_SOURCES = ["components/display/display.cpp", "components/display/rect.cpp",
+                   "components/font/font.cpp", "core/time.cpp", "core/color.cpp", "core/helpers.cpp"]
+# ESPHome's headers include "defines.h" from their own folder; on the host only
+# the display and font code is wanted.
+HOST_DEFINES = "#pragma once\n#define USE_HOST\n#define USE_DISPLAY\n#define USE_FONT\n#define ESPHOME_LOG_LEVEL 0\n"
+COMPAT = """#pragma once
+// MinGW lacks strcasestr, which ESPHome's helpers use.
+#ifdef __cplusplus
+#include <cctype>
+#include <cstring>
+inline char *strcasestr(const char *h, const char *n) {
+  const size_t len = strlen(n);
+  for (; *h; h++)
+    if (strncasecmp(h, n, len) == 0)
+      return (char *) h;
+  return len == 0 ? (char *) h : nullptr;
+}
+#endif
+"""
+AMBER = (255, 170, 30)
+BACKGROUND = (20, 12, 0)
+
+
+def run(cmd, **kw):
+    r = subprocess.run(cmd, capture_output=True, text=True, **kw)
+    if r.returncode != 0:
+        sys.stderr.write(r.stdout + r.stderr)
+        raise SystemExit(f"failed: {' '.join(str(c) for c in cmd[:3])} ...")
+    return r.stdout
+
+
+def write_if_changed(path, text):
+    if not path.exists() or path.read_text(encoding="utf-8") != text:
+        path.write_text(text, encoding="utf-8")
+
+
+def stage_esphome(stage):
+    """Copy the needed part of the installed ESPHome sources, with host defines."""
+    import esphome
+
+    src = Path(esphome.__file__).parent
+    marker = stage / "esphome" / ".version"
+    version = getattr(__import__("esphome.const", fromlist=["__version__"]), "__version__", "?")
+    if marker.exists() and marker.read_text() == version:
+        return version
+    shutil.rmtree(stage / "esphome", ignore_errors=True)
+    for part in ESPHOME_PARTS:
+        dst = stage / "esphome" / part
+        dst.mkdir(parents=True, exist_ok=True)
+        for f in (src / part).iterdir():
+            if f.suffix in (".h", ".cpp", ".c"):
+                shutil.copy2(f, dst / f.name)
+    (stage / "esphome" / "core" / "defines.h").write_text(HOST_DEFINES)
+    shutil.rmtree(stage / "obj", ignore_errors=True)  # rebuild ESPHome objects
+    marker.write_text(version)
+    return version
+
+
+def extract_fonts(main_cpp, stage):
+    """Turn the fonts of ESPHome's generated main.cpp into fonts.cpp / fonts.h."""
+    text = main_cpp.read_text(encoding="utf-8")
+    cpp = ['#include "fonts.h"', "", "using esphome::font::Font;", "using esphome::font::Glyph;", ""]
+    hdr = ["#pragma once", '#include "esphome/components/font/font.h"', ""]
+    for name, glyphs, args in re.findall(r"new\((\w+)\) font::Font\((\w+), ([^;]*)\);", text):
+        gdef = re.search(rf"static const font::Glyph {glyphs}\[\] = (\{{.*?\}});\n", text)
+        if gdef is None:
+            raise SystemExit(f"glyphs of {name} not found in {main_cpp}")
+        for data in sorted(set(re.findall(r"\((uint8_t_id\w*) \+", gdef.group(1)))):
+            ddef = re.search(rf"static constexpr uint8_t {data}\[\] PROGMEM = (\{{.*?\}});\n", text)
+            cpp.append(f"static constexpr uint8_t {data}[] = {ddef.group(1)};")
+        cpp.append(f"static const Glyph {glyphs}[] = {gdef.group(1)};")
+        cpp.append(f"Font *const {name} = new Font({glyphs}, {args});")
+        cpp.append("")
+        hdr.append(f"extern esphome::font::Font *const {name};")
+    if len(hdr) == 3:
+        raise SystemExit(f"no fonts found in {main_cpp}")
+    write_if_changed(stage / "fonts.cpp", "\n".join(cpp) + "\n")
+    write_if_changed(stage / "fonts.h", "\n".join(hdr) + "\n")
+
+
+def stage_pages(stage):
+    """Page sources, with the host EL512Display in place of the panel's."""
+    pages = stage / "el512"
+    pages.mkdir(parents=True, exist_ok=True)
+    comp = ROOT / "components" / "el512"
+    for name in PAGE_HEADERS + [f"{p}.h" for p in PAGE_SOURCES] + [f"{p}.cpp" for p in PAGE_SOURCES]:
+        write_if_changed(pages / name, (comp / name).read_text(encoding="utf-8"))
+    here = Path(__file__).resolve().parent / "render"
+    write_if_changed(pages / "el512_display.h", (here / "el512_display.h").read_text(encoding="utf-8"))
+    for name in ("render_main.cpp", "host_stubs.cpp"):
+        write_if_changed(stage / name, (here / name).read_text(encoding="utf-8"))
+    write_if_changed(stage / "compat.h", COMPAT)
+
+
+def build(stage, cxx):
+    obj = stage / "obj"
+    obj.mkdir(exist_ok=True)
+    flags = ["-std=gnu++20", "-O1", "-include", str(stage / "compat.h"), "-I", str(stage), "-I", str(stage / "el512")]
+    objects = []
+    # ESPHome's own sources: compiled once per ESPHome version.
+    for src in ESPHOME_SOURCES:
+        o = obj / (src.replace("/", "_") + ".o")
+        if not o.exists():
+            run([cxx, *flags, "-w", "-c", str(stage / "esphome" / src), "-o", str(o)])
+        objects.append(o)
+    # Ours: rebuilt when they change.
+    for src in [stage / "fonts.cpp", stage / "render_main.cpp", stage / "host_stubs.cpp"] + [stage / "el512" / f"{p}.cpp" for p in PAGE_SOURCES]:
+        o = obj / (src.stem + ".o")
+        deps = [src] + list((stage / "el512").glob("*.h")) + [stage / "fonts.h"]
+        if not o.exists() or any(d.stat().st_mtime > o.stat().st_mtime for d in deps):
+            warn = ["-w"] if src.stem == "fonts" else ["-Wall"]
+            out = run([cxx, *flags, *warn, "-c", str(src), "-o", str(o)])
+            sys.stdout.write(out)
+        objects.append(o)
+    exe = stage / ("render.exe" if sys.platform == "win32" else "render")
+    if not exe.exists() or any(o.stat().st_mtime > exe.stat().st_mtime for o in objects):
+        run([cxx, *[str(o) for o in objects], "-o", str(exe), "-static"])
+    return exe
+
+
+def to_png(pbm, png, scale):
+    from PIL import Image
+
+    # PBM stores lit pixels as 1, which Pillow reads as black: invert for the mask.
+    lit = Image.open(pbm).convert("L").point(lambda v: 255 - v)
+    img = Image.new("RGB", lit.size, BACKGROUND)
+    img.paste(AMBER, mask=lit)
+    if scale != 1:
+        img = img.resize((img.width * scale, img.height * scale), Image.NEAREST)
+    img.save(png)
+    pbm.unlink()
+
+
+def contact_sheet(pngs, path, cols=2):
+    from PIL import Image, ImageDraw
+
+    imgs = [Image.open(p) for p in pngs]
+    w, h = imgs[0].size
+    label = 18
+    sheet = Image.new("RGB", (cols * (w + 8) + 8, ((len(imgs) + cols - 1) // cols) * (h + label + 8) + 8), (0, 0, 0))
+    draw = ImageDraw.Draw(sheet)
+    for i, (p, im) in enumerate(zip(pngs, imgs)):
+        x, y = 8 + (i % cols) * (w + 8), 8 + (i // cols) * (h + label + 8)
+        draw.text((x, y), p.stem, fill=(180, 120, 20))
+        sheet.paste(im, (x, y + label))
+    sheet.save(path)
+
+
+def main():
+    ap = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
+    ap.add_argument("--page", action="append", help="page name (repeatable; default: all)")
+    ap.add_argument("--at", help="moments in ms after the page was shown, e.g. 0,2000 (default: per page)")
+    ap.add_argument("--scenario", default="normal", choices=["normal", "empty", "alert", "busy"])
+    ap.add_argument("--out", type=Path, default=WORK / "out")
+    ap.add_argument("--scale", type=int, default=2)
+    ap.add_argument("--sheet", action="store_true", help="also write sheet.png with all renders")
+    ap.add_argument("--list", action="store_true", help="list pages and their default moments")
+    ap.add_argument("--examples", action="store_true",
+                    help="one image per page (its first moment) as docs/images/pages/<page>.png")
+    ap.add_argument("--build-dir", type=Path, default=ROOT / "esphome/.esphome/build/el512-panel",
+                    help="ESPHome build folder with src/main.cpp")
+    ap.add_argument("--cxx", default=shutil.which("g++") or "g++")
+    args = ap.parse_args()
+
+    main_cpp = args.build_dir / "src" / "main.cpp"
+    if not main_cpp.exists():
+        raise SystemExit(f"{main_cpp} not found: run `esphome compile esphome/el512-panel-local.yaml` first")
+    WORK.mkdir(exist_ok=True)
+    stage_esphome(WORK)
+    extract_fonts(main_cpp, WORK)
+    stage_pages(WORK)
+    exe = build(WORK, args.cxx)
+
+    listing = {}
+    for line in run([str(exe), "list"]).splitlines():
+        name, _, moments = line.partition(" ")
+        listing[name] = [int(m) for m in moments.split(",") if m]
+    if args.list:
+        for name, moments in listing.items():
+            print(f"{name:14} {', '.join(map(str, moments))}")
+        return
+    if args.examples:
+        args.out, args.at = ROOT / "docs/images/pages", None
+        listing = {n: m[:1] for n, m in listing.items()}
+    names = args.page or list(listing)
+    for n in names:
+        if n not in listing:
+            raise SystemExit(f"unknown page {n}; pages: {', '.join(listing)}")
+    jobs = [f"{n}:{m}" for n in names
+            for m in ([int(x) for x in args.at.split(",")] if args.at else listing[n])]
+    args.out.mkdir(parents=True, exist_ok=True)
+    pngs = []
+    for pbm in run([str(exe), str(args.out), args.scenario, *jobs]).splitlines():
+        pbm = Path(pbm)
+        stem = pbm.stem.rsplit("_", 1)[0] if args.examples else pbm.stem
+        png = pbm.with_name(f"{stem}{'' if args.scenario == 'normal' else '_' + args.scenario}.png")
+        to_png(pbm, png, args.scale)
+        pngs.append(png)
+    if args.sheet and pngs:
+        contact_sheet(pngs, args.out / f"sheet_{args.scenario}.png")
+        pngs.append(args.out / f"sheet_{args.scenario}.png")
+    print(f"{len(pngs)} image(s) in {args.out}")
+
+
+if __name__ == "__main__":
+    main()