immich improvements

README.md

@@ -34,7 +34,7 @@ slide [-t rotation_seconds] [-T transition_seconds] [-h/--overlay-color overlay_
 * `aspect(default=a)`: the required aspect ratio of the picture to display. Valid values are 'a' (all), 'l' (landscape) and 'p' (portrait)
 * `background_opacity(default=150)`: opacity of the background filling image between 0 (black background) and 255
 * `blur_radius(default=20)`: blur radius of the background filling image
-* `-v` or `--verbose`: Verbose debug output when running, plus a thumbnail of the original image in the bottom left of the screen
+* `-v` or `--verbose`: Verbose debug output when running
 * `--stretch`: When in aspect mode 'l','p' or 'm' crop the image rather than leaving a blurred background. For example, in landscape mode this will make images as wide as the screen and crop the top and bottom to fit.
 * `-h` or `--overlay-color` the color of the overlay text, in the form of 3 or 6 digits hex rgb string prefixed by `#`, for example `#00FF00` or `#0F0` for color 🟢
 * `-O` is used to create a overlay string.
@@ -69,6 +69,7 @@ The file format is:
    "rotationSeconds" : 300,
    "opacity" : 200,
    "debug" : false,
+   "debugThumbnail" : false,
    "scheduler" : [
       {
          "exclusive" : true,
@@ -117,6 +118,7 @@ Supported keys and values in the JSON configuration are:
 * `opacity` : the same as the command line `-o` argument
 * `blur` : the same as the command line `-b` argument
 * `debug` : set to true to enable verbose output from the program
+* `debugThumbnail` : set to true to draw a small thumbnail of the source image in the bottom left
 * `mqtt` : MQTT playback control (see below)
 * `immich` : connect to an Immich server instead of a local path (see below)
 * `scheduler` : this entry is an array of possible path values and associated settings. This key lets you manage display times/settings for a collection of paths. In the example above the top entry shows ONLY files from a Redit feed between 2 and 4pm, ONLY files from the `show_peak_times` folder from 8am to 10am and then 4pm to 7pm. At all other times it alternates displaying files in the `always_show_1` and `always_show_2` folder.
@@ -167,7 +169,7 @@ Immich control topic (`immichTopic`):
 
 ### Immich configuration (lightweight + low power)
 
-Immich uses an API key and a `/api` base path. This integration requests the asset search endpoint and downloads the configured image size into a local cache before displaying them. That keeps bandwidth and power usage low while still letting `slide` do its normal scaling and transitions. If you have RAW/HEIC images, set `size` to `preview`/`thumbnail` or use `extensions` to limit results to JPEG/PNG; `slide` will also fall back to `preview` if a `fullsize` download isn't readable.
+Immich uses an API key and a `/api` base path. This integration requests the asset search endpoint and downloads the configured image size into a local cache before displaying them. That keeps bandwidth and power usage low while still letting `slide` do its normal scaling and transitions. If you have RAW/HEIC images, set `size` to `preview`/`thumbnail` or use `extensions` to limit results to JPEG/PNG; `slide` will also fall back to `preview` if a `fullsize` download isn't readable. Immich metadata (EXIF original time / created time) is stored alongside cached assets so `<exifdatetime>` continues to work even if the cached image doesn't contain EXIF data.
 
 #### Getting an Immich API key
 
@@ -192,6 +194,7 @@ Example (single source):
     "pageSize": 200,
     "maxAssets": 1000,
     "refreshSeconds": 300,
+    "skipRetrySeconds": 3600,
     "cachePath": "~/.cache/slide/immich",
     "cacheMaxMB": 512,
     "includeArchived": false
@@ -228,6 +231,7 @@ Immich settings:
 * `pageSize`: assets fetched per page.
 * `maxAssets`: cap on total assets fetched (0 means no cap).
 * `refreshSeconds`: refresh interval for reloading Immich assets (0 disables).
+* `skipRetrySeconds`: retry interval for assets marked unsupported (0 disables retry).
 * `cachePath`: local cache directory for downloaded images.
 * `cacheMaxMB`: maximum cache size in MB (0 disables cleanup).
 * `includeArchived`: include archived assets in search results.
@@ -266,6 +270,10 @@ See the `Configuration File` section for details of each setting.
 * libexif
 * libmosquitto-dev
 
+## Home Assistant
+
+See `doc/homeassistant.md` for a ready-to-use MQTT dashboard and scripts.
+
 Ubuntu/Raspbian:
 
 ```

doc/homeassistant.md

@@ -0,0 +1,273 @@
+# Home Assistant MQTT Dashboard for slide
+
+This guide adds a Home Assistant dashboard to control `slide` via MQTT (play/pause/next, plus Immich filters).
+
+Default MQTT topics used by `slide`:
+
+- Control: `slide/control`
+- Immich control: `slide/immich`
+
+If you changed topics in your `slide` config, update the YAML below to match.
+
+---
+
+## 1) Helpers
+
+Add these helpers in `configuration.yaml` (or your helpers include file):
+
+```yaml
+input_text:
+  slide_album_id:
+    name: Slide Album ID
+  slide_person_id:
+    name: Slide Person ID
+  slide_user_id:
+    name: Slide User ID
+  slide_extensions:
+    name: Slide Extensions (csv)
+    initial: "jpg,jpeg,png"
+  slide_refresh_seconds:
+    name: Slide Refresh Seconds
+    initial: "300"
+
+input_select:
+  slide_size:
+    name: Slide Size
+    options:
+      - fullsize
+      - preview
+      - thumbnail
+      - original
+    initial: fullsize
+  slide_order:
+    name: Slide Order
+    options:
+      - desc
+      - asc
+    initial: desc
+```
+
+---
+
+## 2) Scripts
+
+Add these scripts in `scripts.yaml`:
+
+```yaml
+slide_mqtt_play:
+  alias: Slide Play
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/control
+        payload: "play"
+
+slide_mqtt_pause:
+  alias: Slide Pause
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/control
+        payload: "pause"
+
+slide_mqtt_next:
+  alias: Slide Next Image
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/control
+        payload: "next"
+
+slide_mqtt_next_folder:
+  alias: Slide Next Folder
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/control
+        payload: "next-folder"
+
+slide_mqtt_restart:
+  alias: Slide Restart
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/control
+        payload: "restart"
+
+slide_mqtt_reset_filters:
+  alias: Slide Reset Filters
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/immich
+        payload: "reset"
+
+slide_mqtt_set_album:
+  alias: Slide Set Album
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/immich
+        payload_template: "album:{{ states('input_text.slide_album_id') }}"
+
+slide_mqtt_set_person:
+  alias: Slide Set Person
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/immich
+        payload_template: "person:{{ states('input_text.slide_person_id') }}"
+
+slide_mqtt_set_user:
+  alias: Slide Set User
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/immich
+        payload_template: "user:{{ states('input_text.slide_user_id') }}"
+
+slide_mqtt_set_extensions:
+  alias: Slide Set Extensions
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/immich
+        payload_template: "extensions:{{ states('input_text.slide_extensions') }}"
+
+slide_mqtt_set_refresh:
+  alias: Slide Set Refresh Seconds
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/immich
+        payload_template: "refreshSeconds:{{ states('input_text.slide_refresh_seconds') }}"
+
+slide_mqtt_set_size:
+  alias: Slide Set Size
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/immich
+        payload_template: "size:{{ states('input_select.slide_size') }}"
+
+slide_mqtt_set_order:
+  alias: Slide Set Order
+  sequence:
+    - service: mqtt.publish
+      data:
+        topic: slide/immich
+        payload_template: "order:{{ states('input_select.slide_order') }}"
+```
+
+---
+
+## 3) Lovelace Dashboard
+
+Add this view in `ui-lovelace.yaml` (or a raw YAML dashboard):
+
+```yaml
+title: Slide
+views:
+  - title: Slide Control
+    path: slide
+    icon: mdi:image-frame
+    cards:
+      - type: grid
+        columns: 3
+        cards:
+          - type: button
+            name: Play
+            icon: mdi:play
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_play
+          - type: button
+            name: Pause
+            icon: mdi:pause
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_pause
+          - type: button
+            name: Next
+            icon: mdi:skip-next
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_next
+          - type: button
+            name: Next Folder
+            icon: mdi:folder-arrow-right
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_next_folder
+          - type: button
+            name: Restart
+            icon: mdi:restart
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_restart
+          - type: button
+            name: Reset Filters
+            icon: mdi:filter-remove
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_reset_filters
+
+      - type: entities
+        title: Immich Filters
+        entities:
+          - entity: input_text.slide_album_id
+          - entity: input_text.slide_person_id
+          - entity: input_text.slide_user_id
+          - entity: input_text.slide_extensions
+          - entity: input_text.slide_refresh_seconds
+          - entity: input_select.slide_size
+          - entity: input_select.slide_order
+
+      - type: grid
+        columns: 3
+        cards:
+          - type: button
+            name: Set Album
+            icon: mdi:album
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_set_album
+          - type: button
+            name: Set Person
+            icon: mdi:account
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_set_person
+          - type: button
+            name: Set User
+            icon: mdi:account-cog
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_set_user
+          - type: button
+            name: Set Extensions
+            icon: mdi:file-image
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_set_extensions
+          - type: button
+            name: Set Refresh
+            icon: mdi:clock-sync
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_set_refresh
+          - type: button
+            name: Set Size/Order
+            icon: mdi:image-size-select-large
+            tap_action:
+              action: call-service
+              service: script.slide_mqtt_set_size
+```
+
+---
+
+## Notes
+
+- If you changed the MQTT topics in `slide`’s config, update all `topic:` entries to match.
+- `extensions` filters by file extension (e.g., `jpg,jpeg,png`) to avoid RAW/HEIC if your display environment can’t decode them.
+- `refreshSeconds` controls how often `slide` refreshes the Immich asset list.

src/appconfig.cpp

@@ -139,6 +139,8 @@ ImmichConfig ParseImmichConfigObject(QJsonObject immichJson) {
   SetJSONInt(config.maxAssets, immichJson, "maxAssets");
   SetJSONInt(config.refreshSeconds, immichJson, "refreshSeconds");
   SetJSONInt(config.refreshSeconds, immichJson, "refreshIntervalSeconds");
+  SetJSONInt(config.skipRetrySeconds, immichJson, "skipRetrySeconds");
+  SetJSONInt(config.skipRetrySeconds, immichJson, "skipRetryIntervalSeconds");
   SetJSONInt(config.cacheMaxMB, immichJson, "cacheMaxMB");
   SetJSONBool(config.includeArchived, immichJson, "includeArchived");
 
@@ -404,6 +406,7 @@ AppConfig loadAppConfiguration(const AppConfig &commandLineConfig) {
   SetJSONBool(baseShuffle, jsonDoc, "shuffle");
   SetJSONBool(baseSorted, jsonDoc, "sorted");
   SetJSONBool(loadedConfig.debugMode, jsonDoc, "debug");
+  SetJSONBool(loadedConfig.debugThumbnail, jsonDoc, "debugThumbnail");
 
   std::string overlayString = ParseJSONString(jsonDoc, "overlay");
   if(!overlayString.empty())

src/appconfig.h

@@ -19,6 +19,7 @@ struct ImmichConfig {
   int pageSize = 200;
   int maxAssets = 1000;
   int refreshSeconds = 300;
+  int skipRetrySeconds = 3600;
   std::string cachePath = "";
   int cacheMaxMB = 512;
   bool includeArchived = false;
@@ -62,6 +63,8 @@ struct ImmichConfig {
     }
     if (refreshSeconds != b.refreshSeconds)
       return false;
+    if (skipRetrySeconds != b.skipRetrySeconds)
+      return false;
     return true;
   }
 
@@ -163,6 +166,7 @@ struct AppConfig : public Config {
     MqttConfig mqtt;
 
     bool debugMode = false;
+    bool debugThumbnail = false;
 
     static const std::string valid_aspects; 
   public:

src/immichclient.cpp

@@ -14,11 +14,42 @@
 #include <QSaveFile>
 #include <QTimer>
 #include <QUrlQuery>
+#include <QDateTime>
 #include <QFileInfo>
 
 namespace {
 const int kMetadataTimeoutMs = 15000;
 const int kAssetTimeoutMs = 30000;
+QString ReadJsonString(const QJsonObject &obj, const char *key)
+{
+  auto value = obj.value(key);
+  if (!value.isString())
+    return "";
+  return value.toString();
+}
+
+QString ExtractAssetDateTime(const QJsonObject &item)
+{
+  QJsonObject exifInfo = item.value("exifInfo").toObject();
+  const char *exifKeys[] = {"dateTimeOriginal", "dateTimeDigitized", "dateTime", "createDate"};
+  for (const auto *key : exifKeys)
+  {
+    QString value = ReadJsonString(exifInfo, key);
+    if (!value.isEmpty())
+      return value;
+  }
+
+  const char *fallbackKeys[] = {"localDateTime", "fileCreatedAt", "createdAt", "fileModifiedAt", "updatedAt"};
+  for (const auto *key : fallbackKeys)
+  {
+    QString value = ReadJsonString(item, key);
+    if (!value.isEmpty())
+      return value;
+  }
+
+  return "";
+}
+
 QString DetectImageExtension(const QByteArray &data)
 {
   QBuffer buffer;
@@ -202,6 +233,7 @@ QVector<ImmichAsset> ImmichClient::fetchAssetsBySearch()
       ImmichAsset asset;
       asset.id = id;
       asset.originalFileName = item["originalFileName"].toString();
+      asset.exifDateTime = ExtractAssetDateTime(item);
       if (!extensionAllowed(asset.originalFileName))
       {
         Log("Immich skip by extension: ", asset.originalFileName.toStdString());
@@ -269,6 +301,7 @@ QVector<ImmichAsset> ImmichClient::fetchAssetsByUser()
       ImmichAsset asset;
       asset.id = id;
       asset.originalFileName = item["originalFileName"].toString();
+      asset.exifDateTime = ExtractAssetDateTime(item);
       if (!extensionAllowed(asset.originalFileName))
       {
         Log("Immich skip by extension: ", asset.originalFileName.toStdString());
@@ -349,6 +382,7 @@ ImmichAssetCache::ImmichAssetCache(const ImmichConfig &config)
   cacheDirPath = resolveCachePath(rawPath);
   if (config.cacheMaxMB > 0)
     cacheMaxBytes = static_cast<qint64>(config.cacheMaxMB) * 1024 * 1024;
+  skipRetrySeconds = config.skipRetrySeconds;
 }
 
 QString ImmichAssetCache::resolveCachePath(const QString &rawPath) const
@@ -446,8 +480,25 @@ QString ImmichAssetCache::getCachedPath(const QString &assetId, const QString &a
   {
     if (existing.endsWith(".skip"))
     {
-      Log("Immich skip marker: ", assetId.toStdString());
+      if (skipRetrySeconds > 0)
-      return "";
+      {
+        QFileInfo info(existing);
+        if (info.exists() && info.lastModified().secsTo(QDateTime::currentDateTime()) >= skipRetrySeconds)
+        {
+          Log("Immich skip expired, retrying: ", assetId.toStdString());
+          QFile::remove(existing);
+        }
+        else
+        {
+          Log("Immich skip marker: ", assetId.toStdString());
+          return "";
+        }
+      }
+      else
+      {
+        Log("Immich skip marker: ", assetId.toStdString());
+        return "";
+      }
     }
     QFileInfo info(existing);
     if (info.size() <= 0)

src/immichclient.h

@@ -14,6 +14,7 @@
 struct ImmichAsset {
   QString id;
   QString originalFileName;
+  QString exifDateTime;
 };
 
 class ImmichClient {
@@ -55,6 +56,7 @@ class ImmichAssetCache {
     qint64 cacheMaxBytes = 0;
     bool cacheSizeKnown = false;
     qint64 cacheSizeBytes = 0;
+    int skipRetrySeconds = 0;
 };
 
 #endif // IMMICHCLIENT_H

src/immichpathtraverser.cpp

@@ -1,6 +1,9 @@
 #include "immichpathtraverser.h"
 #include "logger.h"
 #include <QDateTime>
+#include <QFile>
+#include <QFileInfo>
+#include <QSaveFile>
 
 ImmichPathTraverser::ImmichPathTraverser(const ImmichConfig &configIn)
   : PathTraverser(""),
@@ -17,6 +20,7 @@ void ImmichPathTraverser::loadAssets()
 {
   assetIds.clear();
   assetNames.clear();
+  assetDateTimes.clear();
   QVector<ImmichAsset> assets = client.fetchAssets();
   for (const auto &asset : assets)
   {
@@ -24,6 +28,8 @@ void ImmichPathTraverser::loadAssets()
       continue;
     assetIds.append(asset.id);
     assetNames.insert(asset.id, asset.originalFileName);
+    if (!asset.exifDateTime.isEmpty())
+      assetDateTimes.insert(asset.id, asset.exifDateTime);
   }
   Log("Immich assets loaded: ", assetIds.size());
   lastRefresh = QDateTime::currentDateTime();
@@ -44,6 +50,12 @@ const std::string ImmichPathTraverser::getImagePath(const std::string image) con
   QString assetId = QString::fromStdString(image);
   QString name = assetNames.value(assetId);
   QString path = cache.getCachedPath(assetId, name, client);
+  if (!path.isEmpty())
+  {
+    QString dateTime = assetDateTimes.value(assetId);
+    if (!dateTime.isEmpty())
+      writeExifSidecar(path, dateTime);
+  }
   return path.toStdString();
 }
 
@@ -66,3 +78,29 @@ bool ImmichPathTraverser::shouldReloadImages() const
 {
   return refreshDue();
 }
+
+void ImmichPathTraverser::writeExifSidecar(const QString &imagePath, const QString &dateTime) const
+{
+  if (imagePath.isEmpty() || dateTime.isEmpty())
+    return;
+
+  QString sidecarPath = imagePath + ".exif";
+  QFileInfo info(sidecarPath);
+  if (info.exists())
+  {
+    QFile existing(sidecarPath);
+    if (existing.open(QIODevice::ReadOnly | QIODevice::Text))
+    {
+      QString current = QString::fromUtf8(existing.readAll()).trimmed();
+      existing.close();
+      if (current == dateTime.trimmed())
+        return;
+    }
+  }
+
+  QSaveFile file(sidecarPath);
+  if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
+    return;
+  file.write(dateTime.trimmed().toUtf8());
+  file.commit();
+}

src/immichpathtraverser.h

@@ -19,6 +19,7 @@ class ImmichPathTraverser : public PathTraverser
 
   private:
     void loadAssets();
+    void writeExifSidecar(const QString &imagePath, const QString &dateTime) const;
     bool refreshDue() const;
 
     ImmichConfig config;
@@ -26,6 +27,7 @@ class ImmichPathTraverser : public PathTraverser
     mutable ImmichAssetCache cache;
     QStringList assetIds;
     QHash<QString, QString> assetNames;
+    QHash<QString, QString> assetDateTimes;
     QDateTime lastRefresh;
 };
 

src/main.cpp

@@ -156,6 +156,7 @@ void ConfigureWindowFromSettings(MainWindow &w, const AppConfig &appConfig)
     std::unique_ptr<Overlay> o = std::unique_ptr<Overlay>(new Overlay(appConfig.overlay));
     w.setOverlay(o);
   }
+  w.setDebugThumbnail(appConfig.debugThumbnail);
   w.setBaseOptions(appConfig.baseDisplayOptions);
 }
 
@@ -370,6 +371,11 @@ static bool ApplyImmichPayload(ImmichConfig &config, const QString &payload)
       config.refreshSeconds = (int)obj["refreshSeconds"].toDouble();
       changed = true;
     }
+    if (obj.contains("skipRetrySeconds") && obj["skipRetrySeconds"].isDouble())
+    {
+      config.skipRetrySeconds = (int)obj["skipRetrySeconds"].toDouble();
+      changed = true;
+    }
     if (obj.contains("includeArchived"))
     {
       if (obj["includeArchived"].isBool())
@@ -543,6 +549,16 @@ static bool ApplyImmichPayload(ImmichConfig &config, const QString &payload)
       return true;
     }
   }
+  if (key == "skipretryseconds")
+  {
+    bool ok = false;
+    int parsed = value.toInt(&ok);
+    if (ok)
+    {
+      config.skipRetrySeconds = parsed;
+      return true;
+    }
+  }
 
   return false;
 }

src/mainwindow.cpp

@@ -164,6 +164,11 @@ void MainWindow::setImage(const ImageDetails &imageDetails)
     updateImage();
 }
 
+void MainWindow::setDebugThumbnail(bool enabled)
+{
+    debugThumbnail = enabled;
+}
+
 void MainWindow::updateImage()
 {
     checkWindowSize();
@@ -205,7 +210,7 @@ void MainWindow::updateImage()
       drawText(background, overlay->getMarginTopRight(), overlay->getFontsizeTopRight(), overlay->getRenderedTopRight(currentImage.filename).c_str(), Qt::AlignTop|Qt::AlignRight);
       drawText(background, overlay->getMarginBottomLeft(), overlay->getFontsizeBottomLeft(), overlay->getRenderedBottomLeft(currentImage.filename).c_str(), Qt::AlignBottom|Qt::AlignLeft);
       drawText(background, overlay->getMarginBottomRight(), overlay->getFontsizeBottomRight(), overlay->getRenderedBottomRight(currentImage.filename).c_str(), Qt::AlignBottom|Qt::AlignRight);
-      if (ShouldLog())
+      if (debugThumbnail)
       {
         // draw a thumbnail version of the source image in the bottom left, to check for cropping issues
         QPainter pt(&background);

src/mainwindow.h

@@ -34,6 +34,7 @@ public:
     const ImageDisplayOptions &getBaseOptions();
     void setImageSwitcher(ImageSwitcher *switcherIn);
     void setOverlayHexRGB(QString overlayHexRGB);
+    void setDebugThumbnail(bool enabled);
 public slots:
     void checkWindowSize();
 private:
@@ -47,6 +48,7 @@ private:
     QSize lastScreenSize = {0,0};
     QString overlayHexRGB = "#FFFF";
     unsigned int transitionSeconds = 1;
+    bool debugThumbnail = false;
 
     std::unique_ptr<Overlay> overlay;
     ImageSwitcher *switcher = nullptr;

src/overlay.cpp

@@ -8,6 +8,7 @@
 #include <QLocale>
 #include <QTime>
 #include <QFileInfo>
+#include <QFile>
 #include <QStringList>
 #include <QRegExp>
 #include <iostream>
@@ -162,9 +163,47 @@ QString Overlay::getExifDate(std::string filename) {
       dateTime = exif_entry_get_value(exifEntry, buf, sizeof(buf));
     }
     exif_data_free(exifData);
-    QString exifDateFormat = "yyyy:MM:dd hh:mm:ss";
-    QDateTime exifDateTime = QDateTime::fromString(dateTime, exifDateFormat);
-    return QLocale::system().toString(exifDateTime);
   }
-  return dateTime;
+  QString formatted = formatExifDateString(dateTime);
+  if (!formatted.isEmpty())
+    return formatted;
+
+  QString sidecar = readSidecarExifDate(QString::fromStdString(filename));
+  if (!sidecar.isEmpty())
+    return formatExifDateString(sidecar);
+
+  return "";
+}
+
+QString Overlay::readSidecarExifDate(const QString &filePath)
+{
+  QString sidecarPath = filePath + ".exif";
+  QFile file(sidecarPath);
+  if (!file.exists())
+    return "";
+  if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
+    return "";
+  QString contents = QString::fromUtf8(file.readAll()).trimmed();
+  file.close();
+  return contents;
+}
+
+QString Overlay::formatExifDateString(const QString &raw)
+{
+  QString trimmed = raw.trimmed();
+  if (trimmed.isEmpty())
+    return "";
+
+  QDateTime parsed = QDateTime::fromString(trimmed, Qt::ISODate);
+  if (!parsed.isValid())
+    parsed = QDateTime::fromString(trimmed, Qt::ISODateWithMs);
+  if (!parsed.isValid())
+    parsed = QDateTime::fromString(trimmed, "yyyy:MM:dd hh:mm:ss");
+  if (!parsed.isValid())
+    parsed = QDateTime::fromString(trimmed, "yyyy-MM-dd hh:mm:ss");
+
+  if (parsed.isValid())
+    return QLocale::system().toString(parsed);
+
+  return trimmed;
 }

src/overlay.h

@@ -59,5 +59,7 @@ class Overlay
     QString getBasename(std::string filename);
     void parseInput();
     std::string renderString(QString overlayTemplate, std::string filename);
+    QString readSidecarExifDate(const QString &filePath);
+    QString formatExifDateString(const QString &raw);
 };
 #endif