fix(desktop): enable trackpad pinch-zoom in PDF viewer on Windows

WebView2 ships with IsPinchZoomEnabled=true, which intercepts trackpad pinches as a compositor-level "Page Scale" zoom in a post-render step and never dispatches the synthetic ctrl+wheel event the PDF viewer's useWheelZoom hook relies on. Chrome/Firefox fire that event so pinch-zoom works there but not in the Tauri desktop app. Add the --disable-pinch WebView2 browser arg so Chromium reverts to its standard ctrl+wheel dispatch, which the existing zoom handler consumes. Applied in both the main window (tauri.conf.json) and spawned windows (window.rs) since WebView2 requires byte-for-byte identical browser args to share one user-data folder.
2026-06-01 16:00:46 +01:00
2 changed files with 8 additions and 3 deletions
@@ -47,9 +47,14 @@ fn build_window(app: &AppHandle, label: &str, url: &str) -> Result<WebviewWindow
    // nothing more. We mirror that string byte-for-byte so windows share one data
    // dir (and thus IndexedDB / localStorage / cookies). macOS (WKWebView) and
    // Linux (WebKitGTK) don't have this constraint, so the arg is Windows-only.
+    //
+    // `--disable-pinch` turns off WebView2's built-in "Page Scale" pinch zoom,
+    // which otherwise intercepts trackpad pinches as a post-render compositor step
+    // and never dispatches the synthetic ctrl+wheel event the PDF viewer relies on
+    // for zoom. Must stay byte-for-byte in sync with tauri.conf.json.
    #[cfg(target_os = "windows")]
-    let builder =
-        builder.additional_browser_args("--enable-features=CertVerifierBuiltinFeature");
+    let builder = builder
+        .additional_browser_args("--enable-features=CertVerifierBuiltinFeature --disable-pinch");

    builder.build().map_err(|e| e.to_string())
 }
@@ -17,7 +17,7 @@
        "height": 800,
        "resizable": true,
        "fullscreen": false,
-        "additionalBrowserArgs": "--enable-features=CertVerifierBuiltinFeature"
+        "additionalBrowserArgs": "--enable-features=CertVerifierBuiltinFeature --disable-pinch"
      }
    ]
  },