Route prepared file targets through platform services

src/app.h

@@ -181,12 +181,9 @@ public:
     bool clipboard_set_text(const std::string& s);
     void pick_image(std::function<void(std::string path)> callback);
     void pick_file(std::vector<std::string> types, std::function<void(std::string path)> callback);
-#if __IOS__ || __WEB__
     void pick_file_save(const std::string& type, const std::string& default_name,
         std::function<void(std::string path)> writer, std::function<void(const std::string& path, bool saved)> callback);
-#else
     void pick_file_save(std::vector<std::string> types, std::function<void(std::string path)> callback);
-#endif
     void pick_dir(std::function<void(std::string path)> callback);
     void display_file(std::string path);
     void share_file(std::string path);

src/app_events.cpp

@@ -152,35 +152,34 @@ void App::pick_file(std::vector<std::string> types, std::function<void (std::str
     active_platform_services().pick_file(std::move(types), std::move(callback));
 }
 
-#if __IOS__
 void App::pick_file_save(const std::string& type, const std::string& default_name,
     std::function<void(std::string)> writer, std::function<void(const std::string& path, bool saved)> callback)
 {
     redraw = true;
-    std::string ext = "." + type;
-    std::string path = tmp_path + "/" + default_name + ext;
-    std::thread([=]{
-        writer(path);
-        save_prepared_file(path, default_name + ext, callback);
-    }).detach();
+    const auto target = active_platform_services().prepare_writable_file(type, default_name, data_path, tmp_path);
+    if (target.path.empty())
+    {
+        callback({}, false);
+        return;
+    }
+
+    LOG("App::pick_file_save %s", target.path.c_str());
+    auto write_and_save = [=] {
+        writer(target.path);
+        save_prepared_file(target.path, target.suggested_name, callback);
+    };
+
+    if (target.write_on_background_thread)
+        std::thread(write_and_save).detach();
+    else
+        write_and_save();
 }
-#elif __WEB__
-void App::pick_file_save(const std::string& type, const std::string& default_name,
-    std::function<void(std::string)> writer, std::function<void(const std::string& path, bool saved)> callback)
-{
-    redraw = true;
-    auto path = data_path + "/" + default_name + "." + type;
-    LOG("App::pick_file_save %s", path.c_str());
-    writer(path);
-    save_prepared_file(path, default_name + "." + type, std::move(callback));
-}
-#else
+
 void App::pick_file_save(std::vector<std::string> types, std::function<void(std::string)> callback)
 {
     redraw = true;
     active_platform_services().pick_save_file(std::move(types), std::move(callback));
 }
-#endif
 
 void App::pick_dir(std::function<void(std::string path)> callback)
 {

src/platform_api/platform_services.h

@@ -10,6 +10,12 @@ namespace pp::platform {
 using PickedPathCallback = std::function<void(std::string path)>;
 using PreparedFileCallback = std::function<void(std::string path, bool saved)>;
 
+struct PreparedFileTarget {
+    std::string path;
+    std::string suggested_name;
+    bool write_on_background_thread = false;
+};
+
 struct PlatformStoragePaths {
     std::string data_path;
     std::string work_path;
@@ -57,6 +63,11 @@ public:
     virtual void pick_file(std::vector<std::string> file_types, PickedPathCallback callback) = 0;
     virtual void pick_save_file(std::vector<std::string> file_types, PickedPathCallback callback) = 0;
     virtual void pick_directory(PickedPathCallback callback) = 0;
+    [[nodiscard]] virtual PreparedFileTarget prepare_writable_file(
+        std::string_view type,
+        std::string_view default_name,
+        std::string_view data_path,
+        std::string_view temporary_path) = 0;
     virtual void save_prepared_file(
         std::string_view path,
         std::string_view suggested_name,

src/platform_legacy/legacy_platform_services.cpp

@@ -431,6 +431,34 @@ public:
 #endif
     }
 
+    [[nodiscard]] pp::platform::PreparedFileTarget prepare_writable_file(
+        std::string_view type,
+        std::string_view default_name,
+        std::string_view data_path,
+        std::string_view temporary_path) override
+    {
+        const std::string name = std::string(default_name) + "." + std::string(type);
+#ifdef __IOS__
+        (void)data_path;
+        return {
+            std::string(temporary_path) + "/" + name,
+            name,
+            true,
+        };
+#elif __WEB__
+        (void)temporary_path;
+        return {
+            std::string(data_path) + "/" + name,
+            name,
+            false,
+        };
+#else
+        (void)data_path;
+        (void)temporary_path;
+        return {};
+#endif
+    }
+
     void display_file(std::string_view path) override
     {
         const std::string value(path);

src/platform_windows/windows_platform_services.cpp

@@ -448,6 +448,19 @@ public:
         invoke_selected_path(path, callback);
     }
 
+    [[nodiscard]] pp::platform::PreparedFileTarget prepare_writable_file(
+        std::string_view type,
+        std::string_view default_name,
+        std::string_view data_path,
+        std::string_view temporary_path) override
+    {
+        (void)type;
+        (void)default_name;
+        (void)data_path;
+        (void)temporary_path;
+        return {};
+    }
+
     void save_prepared_file(
         std::string_view path,
         std::string_view suggested_name,