[PATCH v3 3/6] shell32/autocomplete: Implement PageDown and PageUp for the auto-suggest listbox

[Gabriel Ivăncescu]

Signed-off-by: Gabriel Ivăncescu <gabrielopcode at gmail.com>
---

It's meant to be the same as on Windows; these keys always go to the visible
bottom or top of the list, unless the selection is already there in which
case they scroll by one page.

However, when wrapping around, they go through txtbackup just like the
arrow keys. The logic for the arrow keys has not been changed.

PageDown/PageUp also do work with ACO_UPDOWNKEYDROPSLIST on Windows (they
show the listbox).

 dlls/shell32/autocomplete.c | 93 ++++++++++++++++++++++++++++++---------------
 1 file changed, 63 insertions(+), 30 deletions(-)

diff --git a/dlls/shell32/autocomplete.c b/dlls/shell32/autocomplete.c
index 621c5fd..5cf63fe 100644
--- a/dlls/shell32/autocomplete.c
+++ b/dlls/shell32/autocomplete.c
@@ -134,6 +134,66 @@ static size_t format_quick_complete(WCHAR *dst, const WCHAR *qc, const WCHAR *st
     return dst - base;
 }
 
+static LRESULT change_selection(IAutoCompleteImpl *ac, HWND hwnd, UINT key)
+{
+    INT count = SendMessageW(ac->hwndListBox, LB_GETCOUNT, 0, 0);
+    INT sel = SendMessageW(ac->hwndListBox, LB_GETCURSEL, 0, 0);
+    if (key == VK_PRIOR || key == VK_NEXT)
+    {
+        if (sel < 0)
+            sel = (key == VK_PRIOR) ? count - 1 : 0;
+        else
+        {
+            INT base = SendMessageW(ac->hwndListBox, LB_GETTOPINDEX, 0, 0);
+            INT pgsz = SendMessageW(ac->hwndListBox, LB_GETLISTBOXINFO, 0, 0);
+            pgsz = max(pgsz - 1, 1);
+            if (key == VK_PRIOR)
+            {
+                if (sel == 0)
+                    sel = -1;
+                else
+                {
+                    if (sel == base) base -= min(base, pgsz);
+                    sel = base;
+                }
+            }
+            else
+            {
+                if (sel == count - 1)
+                    sel = -1;
+                else
+                {
+                    base += pgsz;
+                    if (sel >= base) base += pgsz;
+                    sel = min(base, count - 1);
+                }
+            }
+        }
+    }
+    else if (key == VK_UP)
+        sel = ((sel - 1) < -1) ? count - 1 : sel - 1;
+    else
+        sel = ((sel + 1) >= count) ? -1 : sel + 1;
+
+    SendMessageW(ac->hwndListBox, LB_SETCURSEL, sel, 0);
+    if (sel >= 0)
+    {
+        WCHAR *msg;
+        UINT len = SendMessageW(ac->hwndListBox, LB_GETTEXTLEN, sel, 0);
+        if (!(msg = heap_alloc((len + 1) * sizeof(WCHAR))))
+            return 0;
+        len = SendMessageW(ac->hwndListBox, LB_GETTEXT, sel, (LPARAM)msg);
+        set_text_and_selection(ac, hwnd, msg, len, len);
+        heap_free(msg);
+    }
+    else
+    {
+        UINT len = strlenW(ac->txtbackup);
+        set_text_and_selection(ac, hwnd, ac->txtbackup, len, len);
+    }
+    return 0;
+}
+
 static void autoappend_str(IAutoCompleteImpl *ac, WCHAR *text, UINT len, WCHAR *str, HWND hwnd)
 {
     DWORD sel_start;
@@ -287,6 +347,8 @@ static LRESULT ACEditSubclassProc_KeyDown(IAutoCompleteImpl *ac, HWND hwnd, UINT
             break;
         case VK_UP:
         case VK_DOWN:
+        case VK_PRIOR:
+        case VK_NEXT:
             /* Two cases here:
                - if the listbox is not visible and ACO_UPDOWNKEYDROPSLIST is
                  set, display it with all the entries, without selecting any
@@ -304,36 +366,7 @@ static LRESULT ACEditSubclassProc_KeyDown(IAutoCompleteImpl *ac, HWND hwnd, UINT
                 }
             }
             else
-            {
-                INT count, sel;
-                count = SendMessageW(ac->hwndListBox, LB_GETCOUNT, 0, 0);
-
-                /* Change the selection */
-                sel = SendMessageW(ac->hwndListBox, LB_GETCURSEL, 0, 0);
-                if (wParam == VK_UP)
-                    sel = ((sel - 1) < -1) ? count - 1 : sel - 1;
-                else
-                    sel = ((sel + 1) >= count) ? -1 : sel + 1;
-                SendMessageW(ac->hwndListBox, LB_SETCURSEL, sel, 0);
-                if (sel >= 0)
-                {
-                    WCHAR *msg;
-                    UINT len;
-
-                    len = SendMessageW(ac->hwndListBox, LB_GETTEXTLEN, sel, 0);
-                    if (!(msg = heap_alloc((len + 1) * sizeof(WCHAR))))
-                        return 0;
-                    len = SendMessageW(ac->hwndListBox, LB_GETTEXT, sel, (LPARAM)msg);
-                    set_text_and_selection(ac, hwnd, msg, len, len);
-                    heap_free(msg);
-                }
-                else
-                {
-                    UINT len = strlenW(ac->txtbackup);
-                    set_text_and_selection(ac, hwnd, ac->txtbackup, len, len);
-                }
-                return 0;
-            }
+                return change_selection(ac, hwnd, wParam);
             break;
         case VK_DELETE:
         {
-- 
1.9.1