Show inline image previews for binary files

Add inline image preview support for binary image files in diffs and the file viewer. Frontend: new CSS rules for diff/viewer image panels and macOS window radius, JS templates to render base64 image previews and wire previewMime/previewBase64 into rendering flow, plus applyPlatformChrome to set platform-specific chrome. Backend (Tauri): add base64 and ico deps and expose image preview data (mime + base64) on GitFileDiff and LocalRepoFile; implement mime detection, size-limited preview generation (5MB), .ico → PNG extraction, and integration into get_file_diff and local_repo_file to return previews when available. Also updates icon asset.

frontend/css/components.css

@@ -4,10 +4,13 @@
   width: 100%;
   height: 100%;
   overflow: hidden;
-  border-radius: var(--radius-window);
   background: var(--bg-app);
 }
 
+#app[data-platform="macos"] {
+  border-radius: var(--radius-window);
+}
+
 .layout {
   display: grid;
   grid-template-rows: 48px 1fr;
@@ -998,6 +1001,67 @@
 .diff-line-hunk { color: var(--accent); background: var(--accent-subtle); }
 .diff-line-meta { color: var(--text-muted); background: rgba(156, 166, 181, 0.06); }
 
+.diff-binary-image-panel {
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
+  min-height: 200px;
+  padding: 12px;
+}
+
+.diff-image-preview-frame {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  min-height: 120px;
+  padding: 12px;
+  border-radius: var(--radius-md);
+  background: rgba(0, 0, 0, 0.12);
+}
+
+.diff-image-preview {
+  min-width: 96px;
+  min-height: 96px;
+  max-width: 100%;
+  max-height: min(70vh, 720px);
+  object-fit: contain;
+  border-radius: var(--radius-md);
+}
+
+.diff-binary-caption {
+  margin: 0;
+  padding: 12px;
+  font-family: ui-monospace, "Cascadia Code", "Fira Code", "Consolas", monospace;
+  font-size: 11px;
+  line-height: 1.5;
+  color: var(--text-muted);
+  white-space: pre-wrap;
+  word-break: break-word;
+  border: 1px solid var(--border);
+  border-radius: var(--radius-md);
+  background: rgba(0, 0, 0, 0.15);
+}
+
+.viewer-image-preview-wrap {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  min-height: 160px;
+  padding: 16px;
+  border: 1px solid var(--border);
+  border-radius: var(--radius-lg);
+  background: var(--bg-code);
+}
+
+.viewer-image-preview {
+  min-width: 96px;
+  min-height: 96px;
+  max-width: 100%;
+  max-height: min(75vh, 800px);
+  object-fit: contain;
+  border-radius: var(--radius-md);
+}
+
 /* ── Workflow empty state ─────────────────────────────────────────────────── */
 
 .workflow-empty-state {

frontend/js/app.js

@@ -130,6 +130,10 @@ function currentPlatform() {
   return "linux";
 }
 
+function applyPlatformChrome() {
+  appRoot.dataset.platform = currentPlatform();
+}
+
 function currentTauriWindow() {
   const tauriWindow = window.__TAURI__?.window;
   if (tauriWindow?.getCurrentWindow) {
@@ -443,6 +447,18 @@ function groupedChangedFiles(files = []) {
   return order.map((status) => ({ status, files: groups.get(status) })).filter((group) => group.files.length);
 }
 
+function diffBinaryImagePreviewTemplate(diffResult) {
+  const mime = escapeHtml(diffResult.previewMime || "");
+  const b64 = diffResult.previewBase64 || "";
+  const caption = diffResult.diff ? escapeHtml(diffResult.diff) : "";
+  return `<div class="diff-preview diff-binary-image-panel">
+    <div class="diff-image-preview-frame">
+      <img class="diff-image-preview" alt="" decoding="async" src="data:${mime};base64,${b64}" />
+    </div>
+    ${caption ? `<pre class="diff-binary-caption">${caption}</pre>` : ""}
+  </div>`;
+}
+
 function diffTemplate(diffResult) {
   if (!diffResult) {
     return workflowEmptyStateTemplate({
@@ -452,6 +468,9 @@ function diffTemplate(diffResult) {
       actions: false,
     });
   }
+  if (diffResult.previewBase64 && diffResult.previewMime) {
+    return diffBinaryImagePreviewTemplate(diffResult);
+  }
   if (diffResult.isBinary) {
     return workflowEmptyStateTemplate({
       title: "Binary file",
@@ -928,6 +947,11 @@ function filePreviewTemplate(file) {
       <span class="muted">${escapeHtml(meta)}</span>
     </div>`;
 
+  if (file.previewBase64 && file.previewMime) {
+    const mime = escapeHtml(file.previewMime);
+    const b64 = file.previewBase64;
+    return `${header}<div class="viewer-image-preview-wrap"><img class="viewer-image-preview" alt="" decoding="async" src="data:${mime};base64,${b64}" /></div>`;
+  }
   if (file.tooLarge) {
     return header + `<div class="empty-state viewer-empty"><div>File too large to preview</div><div class="muted">Preview is limited to ${formatBytes(maxPreviewBytes)}.</div></div>`;
   }
@@ -1993,6 +2017,8 @@ async function openViewerFile(path) {
         content: file.content || "",
         isBinary: file.isBinary,
         tooLarge: file.tooLarge,
+        previewMime: file.previewMime,
+        previewBase64: file.previewBase64,
       };
     }
   } catch (error) {
@@ -2670,11 +2696,13 @@ function bindDashboardEvents() {
 
 function render() {
   applyTheme();
+  applyPlatformChrome();
   dashboardView();
 }
 
 window.addEventListener("DOMContentLoaded", async () => {
   applyTheme();
+  applyPlatformChrome();
   await loadRepositories();
   if (getState().selectedRepoPath) {
     await refreshRepoData();

src-tauri/Cargo.lock

@@ -1292,6 +1292,8 @@ dependencies = [
 name = "gitpub-desktop"
 version = "0.1.0"
 dependencies = [
+ "base64 0.22.1",
+ "ico",
  "reqwest 0.12.28",
  "serde",
  "serde_json",

src-tauri/Cargo.toml

@@ -22,6 +22,8 @@ tauri = { version = "2", features = ["macos-private-api"] }
 tauri-plugin-opener = "2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+base64 = "0.22"
+ico = "0.5"
 reqwest = { version = "0.12", default-features = false, features = ["blocking", "json", "rustls-tls"] }
 tauri-plugin-dialog = "2.7.1"
 

src-tauri/src/lib.rs

@@ -1,9 +1,11 @@
+use base64::{engine::general_purpose::STANDARD, Engine as _};
 use reqwest::blocking::Client;
 use reqwest::header::{ACCEPT, AUTHORIZATION};
 use serde::Serialize;
 use std::collections::HashSet;
 use std::env;
 use std::fs;
+use std::io::Cursor;
 use std::path::Path;
 use std::path::PathBuf;
 use std::process::Command;
@@ -49,6 +51,8 @@ struct LocalRepoFile {
     content: Option<String>,
     is_binary: bool,
     too_large: bool,
+    preview_mime: Option<String>,
+    preview_base64: Option<String>,
 }
 
 #[derive(Serialize)]
@@ -101,6 +105,8 @@ struct GitFileDiff {
     is_binary: bool,
     is_deleted: bool,
     is_untracked: bool,
+    preview_mime: Option<String>,
+    preview_base64: Option<String>,
 }
 
 #[derive(Serialize)]
@@ -620,6 +626,109 @@ fn is_binary_file(path: &Path) -> bool {
         .unwrap_or(false)
 }
 
+/// Max decoded image size embedded into the UI as a data URL (base64 expands payload).
+const MAX_IMAGE_PREVIEW_BYTES: u64 = 5 * 1024 * 1024;
+
+fn repository_relative_image_mime(path: &str) -> Option<&'static str> {
+    let lower = path.to_lowercase();
+    let ext = Path::new(&lower).extension()?.to_str()?;
+    match ext {
+        "png" => Some("image/png"),
+        "jpg" | "jpeg" => Some("image/jpeg"),
+        "gif" => Some("image/gif"),
+        "webp" => Some("image/webp"),
+        "bmp" | "dib" => Some("image/bmp"),
+        "ico" => Some("image/x-icon"),
+        "avif" => Some("image/avif"),
+        "tif" | "tiff" => Some("image/tiff"),
+        "heic" | "heif" => Some("image/heif"),
+        "svg" => Some("image/svg+xml"),
+        _ => None,
+    }
+}
+
+fn ico_preview_as_png(bytes: &[u8]) -> Option<(String, String)> {
+    let icon_dir = ico::IconDir::read(Cursor::new(bytes)).ok()?;
+    let best_entry = icon_dir
+        .entries()
+        .iter()
+        .max_by_key(|entry| (entry.width() * entry.height(), entry.bits_per_pixel()))?;
+    let image = best_entry.decode().ok()?;
+    let mut png = Vec::new();
+    image.write_png(&mut png).ok()?;
+    Some(("image/png".to_string(), STANDARD.encode(png)))
+}
+
+fn image_preview_pair(path: &str, bytes: &[u8]) -> (Option<String>, Option<String>) {
+    let Some(mime) = repository_relative_image_mime(path) else {
+        return (None, None);
+    };
+    if bytes.len() as u64 > MAX_IMAGE_PREVIEW_BYTES {
+        return (None, None);
+    }
+    if Path::new(path)
+        .extension()
+        .and_then(|ext| ext.to_str())
+        .is_some_and(|ext| ext.eq_ignore_ascii_case("ico"))
+    {
+        if let Some((mime, encoded_png)) = ico_preview_as_png(bytes) {
+            return (Some(mime), Some(encoded_png));
+        }
+    }
+    (Some(mime.to_string()), Some(STANDARD.encode(bytes)))
+}
+
+fn diff_image_preview(
+    repo_path: &str,
+    git_path: Option<String>,
+    file_path: &str,
+    is_deleted: bool,
+) -> (Option<String>, Option<String>) {
+    if repository_relative_image_mime(file_path).is_none() {
+        return (None, None);
+    }
+
+    if is_deleted {
+        let spec = format!("HEAD:{file_path}");
+        let size_bytes = match run_git_output(
+            repo_path,
+            git_path.clone(),
+            vec!["cat-file".to_string(), "-s".to_string(), spec.clone()],
+        ) {
+            Ok(buf) => buf,
+            Err(_) => return (None, None),
+        };
+        let size_str = String::from_utf8_lossy(&size_bytes);
+        let Ok(size) = size_str.trim().parse::<u64>() else {
+            return (None, None);
+        };
+        if size > MAX_IMAGE_PREVIEW_BYTES {
+            return (None, None);
+        }
+        let bytes = match run_git_output(
+            repo_path,
+            git_path,
+            vec!["show".to_string(), "--no-ext-diff".to_string(), spec],
+        ) {
+            Ok(b) => b,
+            Err(_) => return (None, None),
+        };
+        return image_preview_pair(file_path, &bytes);
+    }
+
+    let absolute = PathBuf::from(repo_path).join(file_path);
+    let Ok(meta) = fs::metadata(&absolute) else {
+        return (None, None);
+    };
+    if meta.len() > MAX_IMAGE_PREVIEW_BYTES {
+        return (None, None);
+    }
+    let Ok(bytes) = fs::read(&absolute) else {
+        return (None, None);
+    };
+    image_preview_pair(file_path, &bytes)
+}
+
 fn normalize_repo_path(path: &str) -> Result<String, String> {
     let trimmed = path.trim().trim_matches('/');
     if trimmed.contains('\\') || trimmed.contains('\0') {
@@ -1087,6 +1196,8 @@ fn get_file_diff(
     if is_untracked {
         let absolute_path = PathBuf::from(&repo_path).join(&file_path);
         if is_binary_file(&absolute_path) {
+            let bytes = fs::read(&absolute_path).unwrap_or_default();
+            let (preview_mime, preview_base64) = image_preview_pair(&file_path, &bytes);
             return Ok(GitFileDiff {
                 path: file_path,
                 diff: "Binary file. Diff preview is not available for untracked binary files."
@@ -1094,6 +1205,8 @@ fn get_file_diff(
                 is_binary: true,
                 is_deleted: false,
                 is_untracked: true,
+                preview_mime,
+                preview_base64,
             });
         }
         let content = fs::read_to_string(&absolute_path)
@@ -1113,12 +1226,14 @@ fn get_file_diff(
             is_binary: false,
             is_deleted: false,
             is_untracked: true,
+            preview_mime: None,
+            preview_base64: None,
         });
     }
 
     let output = run_git_command(
         Some(&repo_path),
-        git_path,
+        git_path.clone(),
         vec![
             "diff".to_string(),
             "--no-ext-diff".to_string(),
@@ -1131,6 +1246,8 @@ fn get_file_diff(
         diff = output.stderr;
     }
     let is_binary = diff.contains("Binary files") || diff.contains("GIT binary patch");
+    let (preview_mime, preview_base64) =
+        diff_image_preview(repo_path.trim(), git_path, &file_path, is_deleted);
     Ok(GitFileDiff {
         path: file_path,
         diff: if diff.is_empty() {
@@ -1141,6 +1258,8 @@ fn get_file_diff(
         is_binary,
         is_deleted,
         is_untracked: false,
+        preview_mime,
+        preview_base64,
     })
 }
 
@@ -1741,33 +1860,56 @@ fn local_repo_file(
         .map_err(|_| "Unable to determine file size.".to_string())?;
 
     if size > MAX_TEXT_PREVIEW_BYTES {
+        if size <= MAX_IMAGE_PREVIEW_BYTES && repository_relative_image_mime(&path).is_some() {
+            let raw = run_git_output(
+                repo_path.trim(),
+                git_path,
+                vec!["show".to_string(), "--no-ext-diff".to_string(), spec.clone()],
+            )?;
+            let (preview_mime, preview_base64) = image_preview_pair(&path, &raw);
+            return Ok(LocalRepoFile {
+                path,
+                size,
+                content: None,
+                is_binary: preview_base64.is_none(),
+                too_large: preview_base64.is_none(),
+                preview_mime,
+                preview_base64,
+            });
+        }
         return Ok(LocalRepoFile {
             path,
             size,
             content: None,
             is_binary: false,
             too_large: true,
+            preview_mime: None,
+            preview_base64: None,
         });
     }
 
-    let content = run_git_output(
+    let raw = run_git_output(
         repo_path.trim(),
         git_path,
         vec!["show".to_string(), "--no-ext-diff".to_string(), spec],
     )?;
-    let is_binary = content.contains(&0);
+    let (preview_mime, preview_base64) = image_preview_pair(&path, &raw);
-    let content = if is_binary {
+    let has_null = raw.contains(&0);
+    let content = if has_null {
         None
     } else {
-        String::from_utf8(content).ok()
+        String::from_utf8(raw).ok()
     };
+    let is_binary = content.is_none();
 
     Ok(LocalRepoFile {
         path,
         size,
-        is_binary: content.is_none(),
+        is_binary,
         too_large: false,
         content,
+        preview_mime,
+        preview_base64,
     })
 }