From e1d784ff8a75b5d9153ba9b9667f41c500dec71e Mon Sep 17 00:00:00 2001
From: lazarus-bart <lazarus-bart@8e941d3f-bd1b-0410-a28a-d453659cc2b4>
Date: Sat, 4 Jan 2020 17:19:07 +0000
Subject: [PATCH] Sudoku: restrict user input in grid.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7228 8e941d3f-bd1b-0410-a28a-d453659cc2b4
---
 applications/sudoku/sudokumain.lfm |  1 +
 applications/sudoku/sudokumain.pas | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/applications/sudoku/sudokumain.lfm b/applications/sudoku/sudokumain.lfm
index 6de0ea146..b0a36bc6f 100644
--- a/applications/sudoku/sudokumain.lfm
+++ b/applications/sudoku/sudokumain.lfm
@@ -27,6 +27,7 @@ object Form1: TForm1
     ScrollBars = ssNone
     TabOrder = 2
     OnPrepareCanvas = SGridPrepareCanvas
+    OnSelectEditor = SGridSelectEditor
     OnSetEditText = SGridSetEditText
   end
   object ButtonFill: TButton
diff --git a/applications/sudoku/sudokumain.pas b/applications/sudoku/sudokumain.pas
index 188dd6fba..39212b6ef 100644
--- a/applications/sudoku/sudokumain.pas
+++ b/applications/sudoku/sudokumain.pas
@@ -43,9 +43,12 @@ type
     SGrid: TStringGrid;
     procedure ButtonFillClick(Sender: TObject);
     procedure ButtonSolveClick(Sender: TObject);
+    procedure EditorKeyPress(Sender: TObject; var Key: char);
     procedure FormActivate(Sender: TObject);
     procedure SGridPrepareCanvas(sender: TObject; aCol, aRow: Integer;
       {%H-}aState: TGridDrawState);
+    procedure SGridSelectEditor(Sender: TObject; {%H-}aCol, {%H-}aRow: Integer;
+      var Editor: TWinControl);
     procedure SGridSetEditText(Sender: TObject; ACol, ARow: Integer;
       const Value: string);
   private
@@ -84,6 +87,19 @@ begin
   ShowSolution;
 end;
 
+procedure TForm1.EditorKeyPress(Sender: TObject; var Key: char);
+var
+  Ed: TStringCellEditor;
+begin
+  if (Sender is TStringCellEditor) then
+  begin
+    Ed := TStringCellEditor(Sender);
+    Ed.SelectAll; //Key will now overwrite selection, in effect allowing to enter only 1 key
+    if not (Key in [#8, '1'..'9']) then Key := #0;
+  end;
+end;
+
+
 procedure TForm1.FormActivate(Sender: TObject);
 begin
   Self.OnActivate := nil;
@@ -92,6 +108,7 @@ begin
   ClientWidth := 2 * SGrid.Left + SGrid.Width;
 end;
 
+
 procedure TForm1.SGridPrepareCanvas(sender: TObject; aCol, aRow: Integer;
   aState: TGridDrawState);
 var
@@ -116,6 +133,18 @@ begin
     (Sender as TStringGrid).Canvas.Brush.Color := $00EEEEEE;
 end;
 
+procedure TForm1.SGridSelectEditor(Sender: TObject; aCol, aRow: Integer;
+  var Editor: TWinControl);
+var
+  Ed: TStringCellEditor;
+begin
+  if Editor is TStringCellEditor then
+  begin
+    Ed := TStringCellEditor(Editor);
+    Ed.OnKeyPress := @EditorKeyPress;
+  end;
+end;
+
 procedure TForm1.SGridSetEditText(Sender: TObject; ACol, ARow: Integer;
   const Value: string);
 begin
@@ -153,6 +182,7 @@ begin
     ShowMessage(Format('Unable to completely solve sudoku (tried %d steps).',[Steps]));
 end;
 
+
 procedure TForm1.ShowSolution;
 var
   Col, Row: Integer;