From 78448991ca0c89a607290ef751edaeddb58ad1dc Mon Sep 17 00:00:00 2001
From: eikek <eike.kettner@posteo.de>
Date: Mon, 28 Feb 2022 11:20:17 +0100
Subject: [PATCH] Use iframe for cross-browser pdf view (pdfjs)

Since some browsers (safari and some mobile ones) don't update their
ui when the src attribute of an embed element changes, an iframe is
used now. But only for the "cross browser" variant.

Fixes: #1210
---
 .../elm/Comp/ItemDetail/SingleAttachment.elm  |  8 ++---
 .../webapp/src/main/elm/Data/UiSettings.elm   | 32 +++++++++++++++++--
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/modules/webapp/src/main/elm/Comp/ItemDetail/SingleAttachment.elm b/modules/webapp/src/main/elm/Comp/ItemDetail/SingleAttachment.elm
index e6690153..fdec3702 100644
--- a/modules/webapp/src/main/elm/Comp/ItemDetail/SingleAttachment.elm
+++ b/modules/webapp/src/main/elm/Comp/ItemDetail/SingleAttachment.elm
@@ -85,12 +85,12 @@ view texts flags settings model pos attach =
                 , style "max-height" "calc(100vh - 140px)"
                 , style "min-height" "500px"
                 ]
-                [ embed
-                    [ src <| Data.UiSettings.pdfUrl settings flags fileUrl
-                    , class "absolute h-full w-full top-0 left-0 mx-0 py-0"
+                [ Data.UiSettings.pdfView settings
+                    flags
+                    fileUrl
+                    [ class "absolute h-full w-full top-0 left-0 mx-0 py-0"
                     , id "ds-pdf-view-iframe"
                     ]
-                    []
                 ]
         ]
 
diff --git a/modules/webapp/src/main/elm/Data/UiSettings.elm b/modules/webapp/src/main/elm/Data/UiSettings.elm
index 4e8c8194..34446a3b 100644
--- a/modules/webapp/src/main/elm/Data/UiSettings.elm
+++ b/modules/webapp/src/main/elm/Data/UiSettings.elm
@@ -24,6 +24,7 @@ module Data.UiSettings exposing
     , merge
     , mergeDefaults
     , pdfUrl
+    , pdfView
     , storedUiSettingsDecoder
     , storedUiSettingsEncode
     , tagColor
@@ -41,8 +42,8 @@ import Data.ItemTemplate exposing (ItemTemplate)
 import Data.Pdf exposing (PdfMode)
 import Data.UiTheme exposing (UiTheme)
 import Dict exposing (Dict)
-import Html exposing (Attribute)
-import Html.Attributes as HA
+import Html exposing (Attribute, Html, embed, iframe)
+import Html.Attributes as HA exposing (src)
 import Json.Decode as Decode
 import Json.Decode.Pipeline as P
 import Json.Encode as Encode
@@ -426,6 +427,33 @@ pdfUrl settings flags originalUrl =
             Data.Pdf.serverUrl originalUrl
 
 
+pdfView : UiSettings -> Flags -> String -> List (Attribute msg) -> Html msg
+pdfView settings flags originalUrl attrs =
+    let
+        url =
+            pdfUrl settings flags originalUrl
+
+        native =
+            embed (src url :: attrs) []
+
+        fallback =
+            iframe (src url :: attrs) []
+    in
+    case settings.pdfMode of
+        Data.Pdf.Detect ->
+            if flags.pdfSupported then
+                native
+
+            else
+                fallback
+
+        Data.Pdf.Native ->
+            native
+
+        Data.Pdf.Server ->
+            fallback
+
+
 getUiLanguage : Flags -> UiSettings -> UiLanguage -> UiLanguage
 getUiLanguage flags settings default =
     case flags.account of