{
* UHistoryMenus.pas
*
* Custom popup menu components that display menu items for recent view items in
* the history. Separate menu classes deal with "forward" and "back" menus.
*
* $Rev$
* $Date$
*
* ***** BEGIN LICENSE BLOCK *****
*
* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
* the specific language governing rights and limitations under the License.
*
* The Original Code is UHistoryMenus.pas
*
* The Initial Developer of the Original Code is Peter Johnson
* (http://www.delphidabbler.com/).
*
* Portions created by the Initial Developer are Copyright (C) 2005-2009 Peter
* Johnson. All Rights Reserved.
*
* Contributor(s)
* NONE
*
* ***** END LICENSE BLOCK *****
}
unit UHistoryMenus;
interface
uses
// Delphi
Classes, Menus,
// Project
UHistory, UView, UViewItemAction;
type
{
THistoryMenu:
Abstract base class for popup menu components that display menu items for
recent view items in the history.
}
THistoryMenu = class abstract(TPopupMenu)
strict private
var
fHistory: THistory; // Reference to menu's history list
fAction: TViewItemAction; // Action triggered when menu items clicked
const
cMaxHistoryMenuItems = 10; // max items displayed in a history menu
strict protected
procedure PopulateMenu;
{Builds menu with a menu item for each view item in history.
}
procedure MenuItemClick(Sender: TObject);
{Handles OnClick events for all menu items by triggering view item action
for view item associated with menu item.
@param Sender [in] Menu item that was clicked.
}
procedure GetViewItemList(const List: TViewItemList); virtual; abstract;
{Returns list of view items to be displayed in menu, subject to maximum
menu size limit. Descendant classes overrride this method to get
appropriate view items.
@param List [in] Receives view item list.
}
procedure DoPopup(Sender: TObject); override;
{Populates menu with required items just before it is displayed.
@param Sender [in] Not used.
}
property History: THistory read fHistory;
{Reference to history list associated with menu}
public
constructor Create(AOwner: TComponent; const History: THistory;
const Action: TViewItemAction); reintroduce;
{Class constructor. Sets up menu for a history list.
@param AOwner [in[ Component that owns this menu.
@param History [in] Reference to history list that stores view items
displayed in this menu.
@param Action [in] Action triggered when a menu item is selected.
}
end;
{
TBackHistoryMenu:
Popup menu component that displays menu items for recent view items in the
"back" history - i.e. view items that preceed the currently selected history
item.
}
TBackHistoryMenu = class sealed(THistoryMenu)
strict protected
procedure GetViewItemList(const List: TViewItemList); override;
{Gets list of view items in "back" history.
@param List [in] Receives relevant view items.
}
end;
{
TForwardHistoryMenu:
Popup menu component that displays menu items for recent view items in the
"forward" history - i.e. view items that follow the currently selected
history item.
}
TForwardHistoryMenu = class sealed(THistoryMenu)
strict protected
procedure GetViewItemList(const List: TViewItemList); override;
{Gets list of view items in "forward" history.
@param List [in] Receives relevant view items.
}
end;
implementation
uses
// Delphi
SysUtils,
// Project
UExceptions;
type
{
THistoryMenuItem:
Menu item class that extends TMenuItem by adding a property that references
a TViewItem object.
}
THistoryMenuItem = class sealed(TMenuItem)
strict private
fViewItem: TViewItem;
{View item associated with menu item}
procedure SetViewItem(const Value: TViewItem);
{Write accessor for ViewItem property. Sets menu item Caption property
to represent view item.
@param Value [in] View item associated with menu.
}
public
property ViewItem: TViewItem
read fViewItem write SetViewItem;
{View item associated with this menu item. Setting this property also
stores a description in menu item Caption}
end;
{ THistoryMenu }
constructor THistoryMenu.Create(AOwner: TComponent;
const History: THistory; const Action: TViewItemAction);
{Class constructor. Sets up menu for a history list.
@param AOwner [in[ Component that owns this menu.
@param History [in] Reference to history list that stores view items
displayed in this menu.
@param Action [in] Action triggered when a menu item is selected.
}
begin
Assert(Assigned(History), ClassName + '.Create: History is nil');
Assert(Assigned(Action), ClassName + '.Create: Action is nil');
inherited Create(AOwner);
// Record history list and action
fHistory := History;
fAction := Action;
end;
procedure THistoryMenu.DoPopup(Sender: TObject);
{Populates menu with required items just before it is displayed.
@param Sender [in] Not used.
}
begin
PopulateMenu;
inherited; // triggers menu's OnPopup event
end;
procedure THistoryMenu.MenuItemClick(Sender: TObject);
{Handles OnClick events for all menu items by triggering view item action for
view item associated with menu item.
@param Sender [in] Menu item that was clicked.
}
begin
fAction.ViewItem := (Sender as THistoryMenuItem).ViewItem;
fAction.Execute;
end;
procedure THistoryMenu.PopulateMenu;
{Builds menu with a menu item for each view item in history.
}
var
ViewList: TViewItemList; // list of view items in required section of history
MI: THistoryMenuItem; // a menu item instance
Idx: Integer; // loops thru ViewList
begin
// Remove any existing menu items (this frees them)
Items.Clear;
// Get a list of view items to be displayed in menu
ViewList := TViewItemList.Create;
try
GetViewItemList(ViewList);
// Loop thru view items, up to maximum that can be displayed
for Idx := 0 to Pred(ViewList.Count) do
begin
if Idx = cMaxHistoryMenuItems then
Break;
// Create menu item
MI := THistoryMenuItem.Create(Self); // use custom menu item class
MI.ViewItem := ViewList[Idx]; // record view item (also sets Caption)
MI.OnClick := MenuItemClick; // every item uses same OnClick handler
MI.Default := (Idx = 0); // first menu item is default
// Add item to menu
Items.Add(MI);
end;
finally
FreeAndNil(ViewList);
end;
end;
{ TBackHistoryMenu }
procedure TBackHistoryMenu.GetViewItemList(const List: TViewItemList);
{Gets list of view items in "back" history.
@param List [in] Receives relevant view items.
}
begin
History.BackList(List);
end;
{ TForwardHistoryMenu }
procedure TForwardHistoryMenu.GetViewItemList(const List: TViewItemList);
{Gets list of view items in "forward" history.
@param List [in] Receives relevant view items.
}
begin
History.ForwardList(List);
end;
{ THistoryMenuItem }
procedure THistoryMenuItem.SetViewItem(const Value: TViewItem);
{Write accessor for ViewItem property. Sets menu item Caption property to
represent view item.
@param Value [in] View item associated with menu.
}
resourcestring
// Menu caption templates
sRoutineDesc = 'Routine: %s';
sCategoryDesc = 'Category: %s';
sSnipKindDesc = 'Snippets type: %s';
sAlphabetDesc = 'Alphabetic section: %s';
const
cBadViewItem = '%s.SetViewItem: unknown view item kind';
begin
// Record view item
fViewItem := Value;
// Set menu item caption to describe view item
case fViewItem.Kind of
vkWelcome:
Caption := ViewItem.Description;
vkRoutine:
Caption := Format(sRoutineDesc, [ViewItem.Description]);
vkCategory:
Caption := Format(sCategoryDesc, [ViewItem.Description]);
vkSnipKind:
Caption := Format(sSnipKindDesc, [ViewItem.Description]);
vkAlphabet:
Caption := Format(sAlphabetDesc, [ViewItem.Description]);
else
raise EBug.CreateFmt(cBadViewItem, [cBadViewItem]);
end;
end;
end.
