From 3935699262f15faeee9dccb74a926a1600fecf81 Mon Sep 17 00:00:00 2001
From: Marc Durdin <marc@durdin.net>
Date: Mon, 19 Oct 2020 16:31:08 +1100
Subject: [PATCH 1/2] fix(windows): tweak scrolling in keyboard menu

Fixes #3694.

The keyboard menu would sometimes scroll too far, which could be
confusing for the end user. This fix stops the scroll once the last
item is in view; it also tweaks the down arrow key handler to ensure
that the current item is correctly scrolled into view.
---
 windows/src/engine/keyman/UfrmKeymanMenu.pas | 45 +++++++++++---------
 1 file changed, 26 insertions(+), 19 deletions(-)

diff --git a/windows/src/engine/keyman/UfrmKeymanMenu.pas b/windows/src/engine/keyman/UfrmKeymanMenu.pas
index 28bcecddc7..1548f32e0f 100644
--- a/windows/src/engine/keyman/UfrmKeymanMenu.pas
+++ b/windows/src/engine/keyman/UfrmKeymanMenu.pas
@@ -362,11 +362,12 @@ end;
 procedure TfrmKeymanMenu.PopupEx(mnu: TPopupMenu; X, Y: Integer; IconRect: TRect);   // I3990
 var
   kmi: TKeymanMenuItem;
-  i, ItemWidth, ItemHeight: Integer;
+  i, ItemWidth, ItemHeight, TempItemHeight: Integer;
   v: Integer;
 begin
   Fmnu := mnu;
 
+  MaxScrollPosition := 0;
   MaxKeyboardWidth := 0;
   MaxItemWidth := 0;
   TotalKeyboardHeight := 0;
@@ -411,7 +412,6 @@ begin
           MaxKeyboardWidth := ItemWidth;
 
         Inc(TotalKeyboardHeight, ItemHeight);
-        Inc(MaxScrollPosition);
       end
       else
       begin
@@ -426,16 +426,34 @@ begin
     end;
   end;
 
-  Dec(MaxScrollPosition); // Don't allow scroll off the end of the list
-
   //
   // Do we need scrollable keyboard list? Only if it's greater than 75% of screen height
   //
 
-  ScrollableView := TotalKeyboardHeight > (Screen.Height * 3 div 4);
+  ScrollableView := TotalKeyboardHeight > (Screen.Height * 1 div 5);
   if ScrollableView then
   begin
-    TotalKeyboardHeight := Screen.Height * 3 div 4;
+    TotalKeyboardHeight := Screen.Height * 1 div 5;
+
+    // Calculate the maximum scroll
+    TempItemHeight := 0;
+    for i := Fmnu.Items.Count - 1 downto 0 do
+    begin
+      if Fmnu.Items[i] is TKeymanMenuItem then
+      begin
+        kmi := Fmnu.Items[i] as TKeymanMenuItem;
+        kmi.OnMeasureItem(kmi, Canvas, ItemWidth, ItemHeight);
+        if (kmi.CMIItemType = _mitKeyboardsList) then
+        begin
+          Inc(TempItemHeight, ItemHeight);
+          if TempItemHeight > TotalKeyboardHeight - ScrollBoxHeight*2 then
+          begin
+            MaxScrollPosition := i + 1;
+            Break;
+          end;
+        end;
+      end;
+    end;
   end;
 
   if not FIsKeyboardMenu then
@@ -726,18 +744,6 @@ begin
   if not Assigned(Fmnu) or not Assigned(Fmnu.Items) then Exit;  // I2884
 
   case Key of
-    {VK_NEXT:
-      begin
-        Key := 0;
-        if ScrollableView and (ScrollPosition < MaxScrollPosition) then
-          Inc(ScrollPosition);
-      end;
-    VK_PRIOR:
-      begin
-        Key := 0;
-        if ScrollableView and (ScrollPosition > 0) then
-          Dec(ScrollPosition);
-      end;}
     VK_UP:
       begin
         Key := 0;
@@ -819,7 +825,8 @@ begin
     if FSelectedItemIndex < ScrollPosition then
       ScrollPosition := FSelectedItemIndex
     else
-      while FItemRects[FSelectedItemIndex].Top + FItemOffsets[FSelectedItemIndex] < 0 do
+      while (FItemRects[FSelectedItemIndex].Top + FItemOffsets[FSelectedItemIndex] < 0) or
+        (FItemRects[FSelectedItemIndex].Bottom + FItemOffsets[FSelectedItemIndex] > ScrollRects[1].Top) do
       begin
         Inc(ScrollPosition);
         RecalculateScrollPositions;

From 929e32601ce9266c04564efa5632c7a195ab5beb Mon Sep 17 00:00:00 2001
From: Marc Durdin <marc@durdin.net>
Date: Mon, 19 Oct 2020 16:33:59 +1100
Subject: [PATCH 2/2] chore(windows): remove debug code

---
 windows/src/engine/keyman/UfrmKeymanMenu.pas | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/windows/src/engine/keyman/UfrmKeymanMenu.pas b/windows/src/engine/keyman/UfrmKeymanMenu.pas
index 1548f32e0f..10c54a1628 100644
--- a/windows/src/engine/keyman/UfrmKeymanMenu.pas
+++ b/windows/src/engine/keyman/UfrmKeymanMenu.pas
@@ -430,10 +430,10 @@ begin
   // Do we need scrollable keyboard list? Only if it's greater than 75% of screen height
   //
 
-  ScrollableView := TotalKeyboardHeight > (Screen.Height * 1 div 5);
+  ScrollableView := TotalKeyboardHeight > (Screen.Height * 3 div 4);
   if ScrollableView then
   begin
-    TotalKeyboardHeight := Screen.Height * 1 div 5;
+    TotalKeyboardHeight := Screen.Height * 3 div 4;
 
     // Calculate the maximum scroll
     TempItemHeight := 0;