From 4dc4c993dec1d8285ef0e7167e8cc01574a2d8be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dariusz=20Komosi=C5=84ski?= <darek.komosinski@gmail.com>
Date: Wed, 9 Feb 2022 14:41:07 +0100
Subject: [PATCH] Merge pull request #7569 from
 MarchingCube/win32-filepicker-no-exceptions

Avoid using COM exceptions for dialog control flow.
---
 .../Avalonia.Win32/SystemDialogImpl.cs        | 31 +++++++++++++------
 src/Windows/Avalonia.Win32/Win32Com/win32.idl |  2 +-
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/src/Windows/Avalonia.Win32/SystemDialogImpl.cs b/src/Windows/Avalonia.Win32/SystemDialogImpl.cs
index 29844368db6..fa53bf57fed 100644
--- a/src/Windows/Avalonia.Win32/SystemDialogImpl.cs
+++ b/src/Windows/Avalonia.Win32/SystemDialogImpl.cs
@@ -79,7 +79,16 @@ internal class SystemDialogImpl : ISystemDialogImpl
                         }
                     }
 
-                    frm.Show(hWnd);
+                    var showResult = frm.Show(hWnd);
+
+                    if ((uint)showResult == (uint)UnmanagedMethods.HRESULT.E_CANCELLED)
+                    {
+                        return result;
+                    } 
+                    else if ((uint)showResult != (uint)UnmanagedMethods.HRESULT.S_OK)
+                    {
+                        throw new Win32Exception(showResult);
+                    }
 
                     if (openDialog?.AllowMultiple == true)
                     {
@@ -108,10 +117,6 @@ internal class SystemDialogImpl : ISystemDialogImpl
                 }
                 catch (COMException ex)
                 {
-                    if ((uint)ex.HResult == (uint)UnmanagedMethods.HRESULT.E_CANCELLED)
-                    {
-                        return result;
-                    }
                     throw new Win32Exception(ex.HResult);
                 }
             })!;
@@ -151,7 +156,17 @@ internal class SystemDialogImpl : ISystemDialogImpl
                         }
                     }
 
-                    frm.Show(hWnd);
+                    var showResult = frm.Show(hWnd);
+
+                    if ((uint)showResult == (uint)UnmanagedMethods.HRESULT.E_CANCELLED)
+                    {
+                        return result;
+                    }
+                    else if ((uint)showResult != (uint)UnmanagedMethods.HRESULT.S_OK)
+                    {
+                        throw new Win32Exception(showResult);
+                    }
+
                     if (frm.Result is not null)
                     {
                         result = GetAbsoluteFilePath(frm.Result);
@@ -161,10 +176,6 @@ internal class SystemDialogImpl : ISystemDialogImpl
                 }
                 catch (COMException ex)
                 {
-                    if ((uint)ex.HResult == (uint)UnmanagedMethods.HRESULT.E_CANCELLED)
-                    {
-                        return result;
-                    }
                     throw new Win32Exception(ex.HResult);
                 }
             });
diff --git a/src/Windows/Avalonia.Win32/Win32Com/win32.idl b/src/Windows/Avalonia.Win32/Win32Com/win32.idl
index 904ac41ff24..54e9aa583f2 100644
--- a/src/Windows/Avalonia.Win32/Win32Com/win32.idl
+++ b/src/Windows/Avalonia.Win32/Win32Com/win32.idl
@@ -112,7 +112,7 @@ interface IShellItemArray : IUnknown
 interface IModalWindow : IUnknown
 {
     [local]
-    HRESULT Show(
+    int Show(
         [in, unique] HWND hwndOwner);
 }