From 02eed0c903e14a33c95b4abded0c66d193678d70 Mon Sep 17 00:00:00 2001
From: Juha <juha@lazarus-ide.org>
Date: Mon, 4 Oct 2021 11:28:13 +0300
Subject: [PATCH] LCL: A new angle bracket option for TreeViewExpandSignType.
 Issue #39361, patch by Alexey T.

---
 lcl/comctrls.pp          | 12 +++++++----
 lcl/include/treeview.inc | 45 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/lcl/comctrls.pp b/lcl/comctrls.pp
index f19044156e..5fec4451eb 100644
--- a/lcl/comctrls.pp
+++ b/lcl/comctrls.pp
@@ -3318,10 +3318,11 @@ const
 
 type
   TTreeViewExpandSignType = (
-    tvestTheme,      // use themed sign
-    tvestPlusMinus,  // use +/- sign
-    tvestArrow,      // use blank arrow
-    tvestArrowFill   // use filled arrow
+    tvestTheme,       // use themed sign
+    tvestPlusMinus,   // use +/- sign
+    tvestArrow,       // use blank arrow
+    tvestArrowFill,   // use filled arrow
+    tvestAngleBracket // use > symbol
   );
 
   TTreeViewInsertMarkType = (
@@ -3340,6 +3341,7 @@ type
     FEditingItem: TTreeNode;
     FExpandSignType: TTreeViewExpandSignType;
     FExpandSignSize: integer;
+    FExpandSignWidth: integer;
     FThemeExpandSignSize: integer;
     FDefItemHeight: integer;
     FDefItemSpace: Integer;
@@ -3494,6 +3496,7 @@ type
     function AllowMultiSelectWithCtrl(AState: TShiftState): Boolean;
     function AllowMultiSelectWithShift(AState: TShiftState): Boolean;
     procedure SetExpandSignSize(const AExpandSignSize: integer);
+    procedure SetExpandSignWidth(const AValue: integer);
   protected
     FChangeTimer: TTimer;
     FEditor: TEdit;
@@ -3701,6 +3704,7 @@ type
     property DropTarget: TTreeNode read GetDropTarget write SetDropTarget;
     property ExpandSignColor: TColor read FExpandSignColor write FExpandSignColor default clWindowFrame;
     property ExpandSignSize: integer read GetExpandSignSize write SetExpandSignSize stored ExpandSignSizeIsStored;
+    property ExpandSignWidth: integer read FExpandSignWidth write SetExpandSignWidth default 2;
     property ExpandSignType: TTreeViewExpandSignType
       read FExpandSignType write SetExpandSignType default tvestTheme;
     property Images: TCustomImageList read FImages write SetImages;
diff --git a/lcl/include/treeview.inc b/lcl/include/treeview.inc
index de40fbbbcc..dfd6beadab 100644
--- a/lcl/include/treeview.inc
+++ b/lcl/include/treeview.inc
@@ -3277,6 +3277,7 @@ begin
   FDefItemSpace := ScaleY(2, 96);
   FExpandSignType := tvestTheme;
   FExpandSignSize := -1;
+  FExpandSignWidth := 2;
   Details := ThemeServices.GetElementDetails(ttGlyphOpened);
   FThemeExpandSignSize := ThemeServices.GetDetailSize(Details).cx;
   FTreeNodes := CreateNodes;
@@ -4697,6 +4698,13 @@ begin
   Invalidate;
 end;
 
+procedure TCustomTreeView.SetExpandSignWidth(const AValue: integer);
+begin
+  if FExpandSignWidth = AValue then Exit;
+  FExpandSignWidth := AValue;
+  Invalidate;
+end;
+
 function TCustomTreeView.IsEditing: Boolean;
 begin
   Result:=tvsIsEditing in FStates;
@@ -5175,6 +5183,43 @@ var
             Brush.Color := PrevColor;
           end;
         end;
+      tvestAngleBracket:
+        begin
+          // draw an arrow. down for collapse and right for expand
+          R := Rect(ALeft, ATop, ARight+1, ABottom+1); //+1 for simmetry of arrow
+          if CollapseSign then
+          begin
+            // draw an arrow down
+            Points[0] := Point(R.Left, MidY - cShiftHorzArrow);
+            Points[1] := Point(R.Right - 1, MidY - cShiftHorzArrow);
+            Points[2] := Point(MidX, R.Bottom - 1 - cShiftHorzArrow);
+          end else
+          begin
+            // draw an arrow right
+            Points[0] := Point(MidX - 2, ATop);
+            Points[1] := Point(MidX - 2, R.Bottom - 1);
+            Points[2] := Point(R.Right - 3, MidY);
+          end;
+
+          for SmallIndent := 1 to FExpandSignWidth do
+          begin
+            Line(Points[2], Points[0]);
+            Line(Points[2], Points[1]);
+
+            if CollapseSign then
+            begin
+              Dec(Points[0].Y);
+              Dec(Points[1].Y);
+              Dec(Points[2].Y);
+            end
+            else
+            begin
+              Dec(Points[0].X);
+              Dec(Points[1].X);
+              Dec(Points[2].X);
+            end;
+          end;
+        end;
       end;
     end;
   end;