Share image Stage 2: native save/share + settings background picker

Rust export_image(filename,base64,action) + read_file_base64(path) (registered).
Kotlin exportimg: branch — base64-decode, then SAF-save the PNG (CreateDocument
image/png) or share it via FileProvider + ACTION_SEND chooser. Settings gets a
'Фон для картинки' row: pick a photo (pickLocalFile image/*), read it as base64,
downscale to <=1080 and store as a data URL in localStorage for the 'С фото'
variant. Rust compiles in tauri dev; native paths need an APK rebuild to test.

docs/session-logs/2026-09-14_share-image.md

@@ -19,9 +19,21 @@ base64 (Rust). Canvas в WebView доступен.
   `invoke("export_image")` (нативной команды пока нет — на десктопе тост-ошибка, это ок).
 - Кнопка `#sd-share` «Похвастаться» в детали трека. CSS `.share-modal` (шахматка под прозрачность).
 
+## Сделано — Стадия 2 (нативный вывод + подложка)
+- Rust `export_image(filename, base64, action)` (пишет base64 + команду `exportimg:` в мост) и
+  `read_file_base64(path)` (для чтения выбранного фото); зарегистрированы.
+- Kotlin: ветка `exportimg:` — Base64-декод; `save` → `saveImageLauncher` (CreateDocument
+  image/png, байты), `share` → запись в `cacheDir/shared`, FileProvider URI, `ACTION_SEND`
+  image/png через чузер.
+- Настройки: строка «Фон для картинки» (Выбрать/Сброс): `pickLocalFile("image/*")` →
+  `read_file_base64` → даунскейл ≤1080 → `localStorage.baldav_share_bg` (jpeg 0.85).
+
 ## Проверка
-- Синтаксис main.js OK. Рендер модалки на десктопе (Xvfb) — следующий шаг.
+- Стадия 1 рендер — ПРОВЕРЕНО на десктопе (Xvfb): модалка рисует форму трека + Distance/Time/
+  Speed + ↑набор/ккал/дата, прозрачный PNG (шахматка), переключатель/кнопки. Скрин.
+- lib.rs пересобрался в `tauri dev` без ошибок (команды компилируются/регистрируются).
+- Нативный save/share/чтение фото и Kotlin — ТОЛЬКО на теле после `./build.sh android -d -i`.
 
 ## Дальше
-- Стадия 2: Rust `export_image`/`read_file_base64`, Kotlin `exportimg:` (SAF-сейв PNG +
-  ACTION_SEND), выбор подложки в настройках; пересборка APK; тест на теле.
+- Пересборка APK и тест на теле: «Поделиться» (чузер), «Сохранить» (SAF), выбор подложки →
+  вариант «С фото». По явной просьбе.

frontend/js/main.js

@@ -6542,6 +6542,16 @@ async function renderSettings(container) {
           </div>
           <button class="btn-secondary" id="s-import-tiles" style="padding:6px 12px;font-size:13px;">Файл</button>
         </div>
+        <div class="settings-item">
+          <div class="settings-item-left">
+            <div class="settings-item-title">Фон для картинки «Похвастаться»</div>
+            <div class="settings-item-desc">Фото-подложка под форму трека и статы</div>
+          </div>
+          <div style="display:flex;gap:6px">
+            <button class="btn-secondary" id="s-share-bg" style="padding:6px 12px;font-size:13px;">Выбрать</button>
+            <button class="btn-secondary" id="s-share-bg-clear" style="padding:6px 12px;font-size:13px;color:#cf6679">Сброс</button>
+          </div>
+        </div>
         <div class="settings-item">
           <div class="settings-item-left">
             <div class="settings-item-title">Очистить продукты без магазина</div>
@@ -6913,6 +6923,40 @@ async function renderSettings(container) {
     }
   };
 
+  // Share-image background: pick a photo, downscale, store as a data URL in localStorage.
+  let sbgBtn = container.querySelector("#s-share-bg");
+  if (sbgBtn) sbgBtn.onclick = async () => {
+    let prev = sbgBtn.textContent, path;
+    if (/Android/i.test(navigator.userAgent)) {
+      sbgBtn.disabled = true; sbgBtn.textContent = "Выбор...";
+      try { path = await pickLocalFile("image/*"); } catch (e) { showToast("Ошибка выбора: " + (e.message || e)); }
+      sbgBtn.disabled = false; sbgBtn.textContent = prev;
+    } else {
+      path = await appPrompt("Путь к фото-подложке:", "");
+    }
+    if (!path) return;
+    sbgBtn.disabled = true; sbgBtn.textContent = "Загрузка...";
+    try {
+      let b64 = await window.__TAURI__.core.invoke("read_file_base64", { path });
+      let mime = /\.png$/i.test(path) ? "image/png" : "image/jpeg";
+      await new Promise((res, rej) => {
+        let img = new Image();
+        img.onload = () => {
+          let s = Math.min(1, 1080 / img.width);
+          let c = document.createElement("canvas"); c.width = Math.round(img.width * s); c.height = Math.round(img.height * s);
+          c.getContext("2d").drawImage(img, 0, 0, c.width, c.height);
+          try { localStorage.setItem("baldav_share_bg", c.toDataURL("image/jpeg", 0.85)); res(); } catch (e) { rej(e); }
+        };
+        img.onerror = () => rej(new Error("не удалось прочитать изображение"));
+        img.src = "data:" + mime + ";base64," + b64;
+      });
+      showToast("Подложка сохранена");
+    } catch (e) { showToast("Подложка: " + (e.message || e)); }
+    sbgBtn.disabled = false; sbgBtn.textContent = prev;
+  };
+  let sbgClear = container.querySelector("#s-share-bg-clear");
+  if (sbgClear) sbgClear.onclick = () => { localStorage.removeItem("baldav_share_bg"); showToast("Подложка сброшена"); };
+
   // Download tiles from router — the list comes from the router's directory
   // listing, so a newly uploaded .db shows up without rebuilding the app.
   container.querySelector("#s-download-tiles").onclick = async () => {

src-tauri/gen/android/app/src/main/java/dev/baldav/app/MainActivity.kt

@@ -24,6 +24,7 @@ import javax.net.ssl.HttpsURLConnection
 class MainActivity : TauriActivity() {
   private var commandObserver: FileObserver? = null
   private var pendingSaveContent: String? = null
+  private var pendingImageBytes: ByteArray? = null
   private var backWebView: WebView? = null
 
   // Disable WryActivity's generated back handler: its mWebView.goBack() does NOT
@@ -66,6 +67,33 @@ class MainActivity : TauriActivity() {
     pendingSaveContent = null
   }
 
+  // SAF "create document" for the share PNG (bytes, image/png mime).
+  private val saveImageLauncher = registerForActivityResult(
+    ActivityResultContracts.CreateDocument("image/png")
+  ) { uri: Uri? ->
+    if (uri != null && pendingImageBytes != null) {
+      try { contentResolver.openOutputStream(uri)?.use { it.write(pendingImageBytes!!) } }
+      catch (e: Exception) { Log.e("BalDav", "Failed to save image", e) }
+    }
+    pendingImageBytes = null
+  }
+
+  // Share a PNG via the system chooser (write to cache, FileProvider content:// URI, ACTION_SEND).
+  private fun shareImage(bytes: ByteArray, filename: String) {
+    try {
+      val dir = File(cacheDir, "shared"); dir.mkdirs()
+      val f = File(dir, if (filename.isBlank()) "baldav.png" else filename)
+      f.writeBytes(bytes)
+      val uri = androidx.core.content.FileProvider.getUriForFile(this, "$packageName.fileprovider", f)
+      val send = Intent(Intent.ACTION_SEND).apply {
+        type = "image/png"
+        putExtra(Intent.EXTRA_STREAM, uri)
+        addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+      }
+      startActivity(Intent.createChooser(send, "Поделиться").addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION))
+    } catch (e: Exception) { Log.e("BalDav", "share image failed", e) }
+  }
+
   // SAF "open document" picker. A content:// URI has no filesystem path, so the
   // picked file is copied into the app dir and its path is written to
   // open_file_result.txt, which the JS side polls via the Rust get_picked_file.
@@ -472,6 +500,21 @@ class MainActivity : TauriActivity() {
         Log.d("BalDav", "Opening file picker for mime=$mime")
         openFileLauncher.launch(arrayOf(mime))
       }
+      cmd.startsWith("exportimg:") -> {
+        // exportimg:<save|share>:<filename> — decode export_image.b64, then SAF-save or share.
+        val rest = cmd.substringAfter("exportimg:")
+        val action = rest.substringBefore(":")
+        val filename = rest.substringAfter(":")
+        val b64File = File(appDataDir, "export_image.b64")
+        if (b64File.exists()) {
+          val bytes = try { android.util.Base64.decode(b64File.readText().trim(), android.util.Base64.DEFAULT) } catch (e: Exception) { null }
+          b64File.delete()
+          if (bytes != null) {
+            if (action == "save") { pendingImageBytes = bytes; saveImageLauncher.launch(filename) }
+            else shareImage(bytes, filename)
+          }
+        }
+      }
     }
   }
 

src-tauri/src/lib.rs

@@ -533,6 +533,30 @@ fn save_file(app: tauri::AppHandle, filename: String, content: String) -> Result
     Ok("save_requested".to_string())
 }
 
+// Export a PNG (base64) via the file bridge → Kotlin decodes + SAF-saves ("save") or shares it
+// via a chooser ("share"). Mirrors save_file but carries binary as base64.
+#[tauri::command]
+fn export_image(app: tauri::AppHandle, filename: String, base64: String, action: String) -> Result<String, String> {
+    let data_dir = app.path().app_data_dir().map_err(|e| e.to_string())?;
+    std::fs::create_dir_all(&data_dir).ok();
+    let root = data_dir.parent().and_then(|p| p.parent()).map(|p| p.to_path_buf());
+    let write_both = |name: &str, content: &str| {
+        let _ = std::fs::write(data_dir.join(name), content);
+        if let Some(r) = &root { let _ = std::fs::write(r.join(name), content); }
+    };
+    write_both("export_image.b64", &base64);
+    write_both("gps_command.txt", &format!("exportimg:{}:{}", action, filename));
+    Ok("export_requested".to_string())
+}
+
+// Read any file and return its bytes base64-encoded (for loading a picked image into the WebView).
+#[tauri::command]
+fn read_file_base64(path: String) -> Result<String, String> {
+    use base64::Engine;
+    let bytes = std::fs::read(&path).map_err(|e| e.to_string())?;
+    Ok(base64::engine::general_purpose::STANDARD.encode(&bytes))
+}
+
 // Read tiles from a SQLite file in batches for import into IndexedDB
 #[tauri::command]
 fn import_tiles(path: String, offset: u32, batch_size: u32) -> Result<String, String> {
@@ -997,7 +1021,7 @@ pub fn run() {
                 .add_migrations("sqlite:baldav.db", migrations)
                 .build(),
         )
-        .invoke_handler(tauri::generate_handler![get_safe_insets, import_seed_products, import_tiles, download_file, get_points_filename, delete_points_file, gps_set_session_id, list_points_files, read_points_file, pick_file_open, get_picked_file, debug_native_paths, rebuild_roads, get_road_points, get_app_info, gps_service_command, gps_service_read_points, brouter_route, brouter_download_tile, brouter_download_status, brouter_list_tiles, save_file, get_update_info, http_request, chzn_http, ble::ble_scan, ble::ble_scan_results, ble::ble_connect, ble::ble_disconnect, ble::ble_get_hr, ble::ble_is_connected, ble::ble_check_bluetooth, ble::ble_save_device, ble::ble_clear_hr])
+        .invoke_handler(tauri::generate_handler![get_safe_insets, import_seed_products, import_tiles, download_file, get_points_filename, delete_points_file, gps_set_session_id, list_points_files, read_points_file, pick_file_open, get_picked_file, debug_native_paths, rebuild_roads, get_road_points, get_app_info, gps_service_command, gps_service_read_points, brouter_route, brouter_download_tile, brouter_download_status, brouter_list_tiles, save_file, export_image, read_file_base64, get_update_info, http_request, chzn_http, ble::ble_scan, ble::ble_scan_results, ble::ble_connect, ble::ble_disconnect, ble::ble_get_hr, ble::ble_is_connected, ble::ble_check_bluetooth, ble::ble_save_device, ble::ble_clear_hr])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");
 }