Show EXIF data for JPEG/TIFF images (#9153)

When selecting an JPEG or TIFF image, we will show its EXIF contents in
the selection panel

<img width="341" alt="Screenshot 2025-02-27 at 11 15 46"
src="https://github.com/user-attachments/assets/23840ec6-e653-490a-a5de-8d7ec7df2d8d"
/>

Author: emilk

Cargo.lock

@@ -6037,6 +6037,7 @@ dependencies = [
  "re_ui",
  "re_video",
  "re_viewer_context",
+ "rexif",
  "unindent",
 ]
 
@@ -7644,6 +7645,12 @@ dependencies = [
  "usvg",
 ]
 
+[[package]]
+name = "rexif"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "be932047c168919c8d5af065b16fa7d4bd24835ffa256bf0cf1ff463f91c15df"
+
 [[package]]
 name = "rfd"
 version = "0.15.0"

Cargo.toml

@@ -258,6 +258,7 @@ quote = "1.0"
 rand = { version = "0.8", default-features = false }
 rand_distr = { version = "0.4", default-features = false }
 rayon = "1.7"
+rexif = "0.7.5"
 rfd = { version = "0.15", default-features = false, features = [
   "async-std",
   "xdg-portal",

crates/viewer/re_data_ui/Cargo.toml

@@ -46,4 +46,5 @@ egui.workspace = true
 image.workspace = true
 itertools.workspace = true
 nohash-hasher.workspace = true
+rexif.workspace = true
 unindent.workspace = true

crates/viewer/re_data_ui/src/blob.rs

@@ -1,5 +1,13 @@
-use re_types::components::{Blob, MediaType, VideoTimestamp};
-use re_ui::{list_item::PropertyContent, UiExt};
+use std::sync::Arc;
+
+use re_types::{
+    components::{Blob, MediaType, VideoTimestamp},
+    RowId,
+};
+use re_ui::{
+    list_item::{self, PropertyContent},
+    UiExt,
+};
 use re_viewer_context::UiLayout;
 
 use crate::{
@@ -108,6 +116,10 @@ pub fn blob_preview_and_save_ui(
     let mut video_result_for_frame_preview = None;
 
     if let Some(blob_row_id) = blob_row_id {
+        if !ui_layout.is_single_line() && ui_layout != UiLayout::Tooltip {
+            exif_ui(ui, blob_row_id, blob);
+        }
+
         // Try to treat it as an image:
         image = ctx
             .store_context
@@ -197,3 +209,40 @@ pub fn blob_preview_and_save_ui(
         }
     }
 }
+
+/// Show EXIF data about the given blob (image), if possible.
+fn exif_ui(ui: &mut egui::Ui, blob_row_id: RowId, blob: &re_types::datatypes::Blob) {
+    let exif_result = ui.ctx().memory_mut(|mem| {
+        // Cache EXIF parsing to avoid re-parsing every frame.
+        // The parsing is really fast, so this is not really needed.
+        let key = blob_row_id;
+        let cache = mem
+            .caches
+            .cache::<egui::cache::FramePublisher<RowId, Arc<rexif::ExifResult>>>();
+        cache.get(&key).cloned().unwrap_or_else(|| {
+            re_tracing::profile_scope!("exif-parse");
+            let (result, _warnings) = rexif::parse_buffer_quiet(blob);
+            let result = Arc::new(result);
+            cache.set(key, result.clone());
+            result
+        })
+    });
+
+    if let Ok(exif) = &*exif_result {
+        ui.list_item_collapsible_noninteractive_label("EXIF", false, |ui| {
+            list_item::list_item_scope(ui, "exif", |ui| {
+                for entry in &exif.entries {
+                    let tag_string = if entry.tag == rexif::ExifTag::UnknownToMe {
+                        "<Unknown tag>".to_owned()
+                    } else {
+                        entry.tag.to_string()
+                    };
+                    ui.list_item_flat_noninteractive(
+                        list_item::PropertyContent::new(tag_string)
+                            .value_text(entry.value_more_readable.to_string()),
+                    );
+                }
+            });
+        });
+    }
+}