feat: Take screenshots (#759)

## Summary

* **What is the goal of this PR?** Implements a take-screenshot feature
* **What changes are included?**

- Quick press Power button and Down button at the same time to take a
screenshot
- Screenshots are saved in `screenshots` folder

## Additional Context

- Currently it does not use the device orientation.

---

Example screenshots:


![screenshot-6771.bmp](https://github.com/user-attachments/files/25157071/screenshot-6771.bmp)

[screenshot-6771.bmp](https://github.com/user-attachments/files/25157071/screenshot-6771.bmp)


![screenshot-14158.bmp](https://github.com/user-attachments/files/25157073/screenshot-14158.bmp)

[screenshot-14158.bmp](https://github.com/user-attachments/files/25157073/screenshot-14158.bmp)


### AI Usage

Did you use AI tools to help write this code? _** YES

---------

Co-authored-by: Eliz Kilic <elizk@google.com>
Co-authored-by: Xuan Son Nguyen <son@huggingface.co>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Arthur Tazhitdinov <lisnake@gmail.com>

lib/GfxRenderer/Bitmap.h

@@ -6,6 +6,38 @@
 
 #include "BitmapHelpers.h"
 
+#pragma pack(push, 1)
+struct BmpHeader {
+  struct {
+    uint16_t bfType;
+    uint32_t bfSize;
+    uint16_t bfReserved1;
+    uint16_t bfReserved2;
+    uint32_t bfOffBits;
+  } fileHeader;
+  struct {
+    uint32_t biSize;
+    int32_t biWidth;
+    int32_t biHeight;
+    uint16_t biPlanes;
+    uint16_t biBitCount;
+    uint32_t biCompression;
+    uint32_t biSizeImage;
+    int32_t biXPelsPerMeter;
+    int32_t biYPelsPerMeter;
+    uint32_t biClrUsed;
+    uint32_t biClrImportant;
+  } infoHeader;
+  struct RgbQuad {
+    uint8_t rgbBlue;
+    uint8_t rgbGreen;
+    uint8_t rgbRed;
+    uint8_t rgbReserved;
+  };
+  RgbQuad colors[2];
+};
+#pragma pack(pop)
+
 enum class BmpReaderError : uint8_t {
   Ok = 0,
   FileInvalid,

lib/GfxRenderer/BitmapHelpers.cpp

@@ -1,6 +1,9 @@
 #include "BitmapHelpers.h"
 
 #include <cstdint>
+#include <cstring>  // Added for memset
+
+#include "Bitmap.h"
 
 // Brightness/Contrast adjustments:
 constexpr bool USE_BRIGHTNESS = false;       // true: apply brightness/gamma adjustments
@@ -104,3 +107,44 @@ uint8_t quantize1bit(int gray, int x, int y) {
   const int adjustedThreshold = 128 + ((threshold - 128) / 2);  // Range: 64-192
   return (gray >= adjustedThreshold) ? 1 : 0;
 }
+
+void createBmpHeader(BmpHeader* bmpHeader, int width, int height) {
+  if (!bmpHeader) return;
+
+  // Zero out the memory to ensure no garbage data if called on uninitialized stack memory
+  std::memset(bmpHeader, 0, sizeof(BmpHeader));
+
+  uint32_t rowSize = (width + 31) / 32 * 4;
+  uint32_t imageSize = rowSize * height;
+  uint32_t fileSize = sizeof(BmpHeader) + imageSize;
+
+  bmpHeader->fileHeader.bfType = 0x4D42;
+  bmpHeader->fileHeader.bfSize = fileSize;
+  bmpHeader->fileHeader.bfReserved1 = 0;
+  bmpHeader->fileHeader.bfReserved2 = 0;
+  bmpHeader->fileHeader.bfOffBits = sizeof(BmpHeader);
+
+  bmpHeader->infoHeader.biSize = sizeof(bmpHeader->infoHeader);
+  bmpHeader->infoHeader.biWidth = width;
+  bmpHeader->infoHeader.biHeight = height;
+  bmpHeader->infoHeader.biPlanes = 1;
+  bmpHeader->infoHeader.biBitCount = 1;
+  bmpHeader->infoHeader.biCompression = 0;
+  bmpHeader->infoHeader.biSizeImage = imageSize;
+  bmpHeader->infoHeader.biXPelsPerMeter = 0;
+  bmpHeader->infoHeader.biYPelsPerMeter = 0;
+  bmpHeader->infoHeader.biClrUsed = 0;
+  bmpHeader->infoHeader.biClrImportant = 0;
+
+  // Color 0 (black)
+  bmpHeader->colors[0].rgbBlue = 0;
+  bmpHeader->colors[0].rgbGreen = 0;
+  bmpHeader->colors[0].rgbRed = 0;
+  bmpHeader->colors[0].rgbReserved = 0;
+
+  // Color 1 (white)
+  bmpHeader->colors[1].rgbBlue = 255;
+  bmpHeader->colors[1].rgbGreen = 255;
+  bmpHeader->colors[1].rgbRed = 255;
+  bmpHeader->colors[1].rgbReserved = 0;
+}

lib/GfxRenderer/BitmapHelpers.h

@@ -1,13 +1,19 @@
 #pragma once
 
+#include <cstdint>
 #include <cstring>
 
+struct BmpHeader;
+
 // Helper functions
 uint8_t quantize(int gray, int x, int y);
 uint8_t quantizeSimple(int gray);
 uint8_t quantize1bit(int gray, int x, int y);
 int adjustPixel(int gray);
 
+// Populates a 1-bit BMP header in the provided memory.
+void createBmpHeader(BmpHeader* bmpHeader, int width, int height);
+
 // 1-bit Atkinson dithering - better quality than noise dithering for thumbnails
 // Error distribution pattern (same as 2-bit but quantizes to 2 levels):
 //     X  1/8 1/8

lib/I18n/I18nKeys.h

@@ -355,6 +355,7 @@ enum class StrId : uint16_t {
   STR_BOOK_S_STYLE,
   STR_EMBEDDED_STYLE,
   STR_OPDS_SERVER_URL,
+  STR_SCREENSHOT_BUTTON,
   // Sentinel - must be last
   _COUNT
 };

lib/I18n/translations/czech.yaml

@@ -317,3 +317,4 @@ STR_UPLOAD: "Nahrát"
 STR_BOOK_S_STYLE: "Styl knihy"
 STR_EMBEDDED_STYLE: "Vložený styl"
 STR_OPDS_SERVER_URL: "URL serveru OPDS"
+STR_SCREENSHOT_BUTTON: "Udělat snímek obrazovky"

lib/I18n/translations/english.yaml

@@ -317,3 +317,4 @@ STR_UPLOAD: "Upload"
 STR_BOOK_S_STYLE: "Book's Style"
 STR_EMBEDDED_STYLE: "Embedded Style"
 STR_OPDS_SERVER_URL: "OPDS Server URL"
+STR_SCREENSHOT_BUTTON: "Take screenshot"

lib/I18n/translations/french.yaml

@@ -317,3 +317,4 @@ STR_UPLOAD: "Envoi"
 STR_BOOK_S_STYLE: "Style du livre"
 STR_EMBEDDED_STYLE: "Style intégré"
 STR_OPDS_SERVER_URL: "URL du serveur OPDS"
+STR_SCREENSHOT_BUTTON: "Prendre une capture d'écran"

lib/I18n/translations/german.yaml

@@ -317,3 +317,4 @@ STR_UPLOAD: "Hochladen"
 STR_BOOK_S_STYLE: "Buch-Stil"
 STR_EMBEDDED_STYLE: "Eingebetteter Stil"
 STR_OPDS_SERVER_URL: "OPDS-Server-URL"
+STR_SCREENSHOT_BUTTON: "Screenshot aufnehmen"

lib/I18n/translations/portuguese.yaml

@@ -317,3 +317,4 @@ STR_UPLOAD: "Enviar"
 STR_BOOK_S_STYLE: "Estilo do livro"
 STR_EMBEDDED_STYLE: "Estilo embutido"
 STR_OPDS_SERVER_URL: "URL do servidor OPDS"
+STR_SCREENSHOT_BUTTON: "Capturar tela"

lib/I18n/translations/russian.yaml

@@ -317,3 +317,4 @@ STR_UPLOAD: "Отправить"
 STR_BOOK_S_STYLE: "Стиль книги"
 STR_EMBEDDED_STYLE: "Встроенный стиль"
 STR_OPDS_SERVER_URL: "URL OPDS сервера"
+STR_SCREENSHOT_BUTTON: "Сделать снимок экрана"

lib/I18n/translations/spanish.yaml

@@ -317,3 +317,4 @@ STR_UPLOAD: "Subir"
 STR_BOOK_S_STYLE: "Estilo del libro"
 STR_EMBEDDED_STYLE: "Estilo integrado"
 STR_OPDS_SERVER_URL: "URL del servidor OPDS"
+STR_SCREENSHOT_BUTTON: "Tomar captura de pantalla"

lib/I18n/translations/swedish.yaml

@@ -317,3 +317,4 @@ STR_UPLOAD: "Uppladdning"
 STR_BOOK_S_STYLE: "Bokstil"
 STR_EMBEDDED_STYLE: "Inbäddad stil"
 STR_OPDS_SERVER_URL: "OPDS-serveradress"
+STR_SCREENSHOT_BUTTON: "Ta en skärmdump"