Make Preferences dialogue remember last tab used

Add new Preferences "meta" section to store name of tab that was
displayed when dialogue box was last closed.
Preferences dialogue now uses that preference to make the last tab
current when it is opened.

Author: delphidabbler

Src/FmPreferencesDlg.pas

@@ -39,6 +39,7 @@   TPreferencesDlg = class(TGenericOKDlg, INoPublicConstruct)
     ///  <summary>Handles event triggered when list box is clicked or changed
     ///  via keyboard.</summary>
     procedure lbPagesClick(Sender: TObject);
+    procedure FormDestroy(Sender: TObject);
   strict private
     class var
       ///  <summary>List of registered page frames</summary>
@@ -76,6 +77,9 @@   TPreferencesDlg = class(TGenericOKDlg, INoPublicConstruct)
     ///  <remarks>Stores state of tab being closed and restores state of tab
     ///  being opened.</remarks>
     procedure SelectTab(TS: TTabSheet);
+    ///  <summary>Returns index of tab selected when dialogue box was last
+    ///  closed or -1 if no tab recorded or tab doesn't exist.</summary>
+    function GetLastTabIdx: Integer;
   strict protected
     ///  <summary>Gets the help A-link keyword to be used when help button
     ///  clicked.</summary>
@@ -170,7 +174,8 @@ implementation
 
 uses
   // Project
-  IntfCommon;
+  IntfCommon,
+  UStrUtils;
 
 
 {$R *.dfm}
@@ -292,14 +297,36 @@ class function TPreferencesDlg.Execute(AOwner: TComponent;
   Result := Execute(AOwner, [FrameClass], UpdateUI);
 end;
 
+procedure TPreferencesDlg.FormDestroy(Sender: TObject);
+begin
+  // Save current tab
+  if Assigned(pcMain.ActivePage) then
+    Preferences.LastTab := MapTabSheetToPage(pcMain.ActivePage).DisplayName;
+  inherited;
+end;
+
+function TPreferencesDlg.GetLastTabIdx: Integer;
+var
+  TabName: string;
+  ListIdx: Integer;
+begin
+  TabName := Preferences.LastTab;
+  if TabName = '' then
+    Exit(-1);
+  for ListIdx := 0 to Pred(lbPages.Count) do
+    if StrSameText(TabName, lbPages.Items[ListIdx]) then
+      Exit(ListIdx);
+  Result := -1;
+end;
+
 function TPreferencesDlg.GetSelectedPage: TPrefsBaseFrame;
 begin
   Result := MapTabSheetToPage(pcMain.ActivePage);
 end;
 
 procedure TPreferencesDlg.InitForm;
 var
-  TabIdx: Integer;  // loops thru tabs in page control
+  TabIdx: Integer;      // loops thru tabs in page control
 begin
   inherited;
   // Take local copy of global preferences. This local copy will be updated as
@@ -309,8 +336,10 @@ procedure TPreferencesDlg.InitForm;
   // Display and initialise required pages
   for TabIdx := 0 to Pred(pcMain.PageCount) do
     MapTabSheetToPage(TabIdx).LoadPrefs(fLocalPrefs);
-  // Select first TabSheet
-  fCurrentPageIdx := 0;
+  // Select last use tab sheet (or 1st if last not known)
+  fCurrentPageIdx := GetLastTabIdx;
+  if fCurrentPageIdx < 0 then
+    fCurrentPageIdx := 0;
   pcMain.ActivePageIndex := fCurrentPageIdx;
   lbPages.ItemIndex := fCurrentPageIdx;
 end;

Src/UPreferences.pas

@@ -37,6 +37,23 @@ interface
   IPreferences = interface(IInterface)
     ['{381B9A92-B528-47E1-AC04-90E1FFFDADA7}']
 
+    ///  <summary>Gets last tab displayed by Preferences dialogue box when it
+    ///  was last closed, or empty string if the tab is not known.
+    ///  </summary>
+    ///  <remarks>This is meta data about the dialogue box itself, not about
+    ///  user preferences.</remarks>
+    function GetLastTab: string;
+    ///  <summary>Sets last tab displayed by Preferences dialogue box when it
+    ///  was last closed.</summary>
+    ///  <remarks>This is meta data about the dialogue box itself, not about
+    ///  user preferences.</remarks>
+    procedure SetLastTab(const Value: string);
+    ///  <summary>Last tab displayed by Preferences dialogue box when it was
+    ///  last closed, or empty string if the tab is not known.</summary>
+    ///  <remarks>This is meta data about the dialogue box itself, not about
+    ///  user preferences.</remarks>
+    property LastTab: string read GetLastTab write SetLastTab;
+
     ///  <summary>Gets style of commenting used to describe snippets in
     ///  generated code.</summary>
     function GetSourceCommentStyle: TCommentStyle;
@@ -283,6 +300,7 @@   TPreferences = class(TInterfacedObject,
   )
   strict protected
     var
+      fLastTab: string;
       ///  <summary>Default file extension / type used when writing code
       ///  snippets  file.</summary>
       fSourceDefaultFileType: TSourceFileType;
@@ -344,6 +362,24 @@   TPreferences = class(TInterfacedObject,
     ///  <summary>Destroys object instance.</summary>
     destructor Destroy; override;
 
+    ///  <summary>Gets last tab displayed by Preferences dialogue box when it
+    ///  was last closed, or empty string if the tab is not known.
+    ///  </summary>
+    ///  <remarks>
+    ///  <para>This is meta data about the dialogue box itself, not about
+    ///  user preferences.</para>
+    ///  <para>Method of IPreferences.</para>
+    ///  </remarks>
+    function GetLastTab: string;
+    ///  <summary>Sets last tab displayed by Preferences dialogue box when it
+    ///  was last closed.</summary>
+    ///  <remarks>
+    ///  <para>This is meta data about the dialogue box itself, not about user
+    ///  preferences.</para>
+    ///  <para>Method of IPreferences.</para>
+    ///  </remarks>
+    procedure SetLastTab(const Value: string);
+
     ///  <summary>Gets style of commenting used to describe snippets in
     ///  generated code.</summary>
     ///  <remarks>Method of IPreferences.</remarks>
@@ -608,6 +644,7 @@ procedure TPreferences.Assign(const Src: IInterface);
   if not Supports(Src, IPreferences, SrcPref) then
     raise EBug.Create(ClassName + '.Assign: Src is wrong type');
   // Copy the data
+  Self.fLastTab := SrcPref.LastTab;
   Self.fSourceDefaultFileType := SrcPref.SourceDefaultFileType;
   Self.fSourceCommentStyle := SrcPref.SourceCommentStyle;
   Self.fTruncateSourceComments := SrcPref.TruncateSourceComments;
@@ -671,6 +708,11 @@ function TPreferences.GetHiliteAttrs: IHiliteAttrs;
   Result := fHiliteAttrs;
 end;
 
+function TPreferences.GetLastTab: string;
+begin
+  Result := fLastTab;
+end;
+
 function TPreferences.GetMeasurementUnits: TMeasurementUnits;
 begin
   Result := fMeasurementUnits;
@@ -768,6 +810,11 @@ procedure TPreferences.SetHiliteAttrs(const Attrs: IHiliteAttrs);
   (fHiliteAttrs as IAssignable).Assign(Attrs);
 end;
 
+procedure TPreferences.SetLastTab(const Value: string);
+begin
+  fLastTab := Value;
+end;
+
 procedure TPreferences.SetMeasurementUnits(const Value: TMeasurementUnits);
 begin
   fMeasurementUnits := Value;
@@ -854,6 +901,7 @@ function TPreferencesPersist.Clone: IInterface;
   Result := TPreferences.Create;
   // Copy properties to it
   NewPref := Result as IPreferences;
+  NewPref.LastTab := Self.fLastTab;
   NewPref.SourceDefaultFileType := Self.fSourceDefaultFileType;
   NewPref.SourceCommentStyle := Self.fSourceCommentStyle;
   NewPref.TruncateSourceComments := Self.fTruncateSourceComments;
@@ -886,6 +934,10 @@ constructor TPreferencesPersist.Create;
 begin
   inherited Create;
 
+  // Read meta data section (no sub-section name)
+  Storage := Settings.ReadSection(ssPreferences);
+  fLastTab := Storage.GetString('LastTab');
+
   // Read general section
   Storage := Settings.ReadSection(ssPreferences, cGeneral);
   fMeasurementUnits := TMeasurementUnits(
@@ -969,6 +1021,11 @@ destructor TPreferencesPersist.Destroy;
 var
   Storage: ISettingsSection;  // object used to access persistent storage
 begin
+  // Wreite meta section (no sub-section name)
+  Storage := Settings.EmptySection(ssPreferences);
+  Storage.SetString('LastTab', fLastTab);
+  Storage.Save;
+
   // Write general section
   Storage := Settings.EmptySection(ssPreferences, cGeneral);
   Storage.SetInteger('Units', Ord(fMeasurementUnits));