问题
I have an TActionManager, and a TActionMainMenuBar, and I know how to add an TActionClientItem for each MRU file to the main menu bar. But do I have to create a separate action for each MRU file in the list? Or is there a way to create just one action, and somehow pass a tag or something to the action's OnExecute event based on which MRU file was clicked?
Delphi's help says: "For more information about MRU lists, sample code, and methods for finding actions in lists, see FindItemByAction and FindItemByCaption in the online Help." But I can't find anything in those subjects that is helpful, and certainly not sample code. I'd really like to avoid using a 3rd party component to get this done.
回答1:
You'll have a separate TAction
for each menu item anyway so that they can have distinct Caption
values. But you don't have to have separate OnExecute
event handlers. The event handler will receive a reference to the action in its Sender
parameter. Use the sender's Tag
property to refer to a list where your file names are kept. (Don't use the Caption
property to discover which file to open; that restricts you from doing nice things like adding accelerators or abbreviating unwieldy paths.)
That's what the documentation assumes you'd do, too. FindItemByAction
returns the first item that the given action is attached to. If you attach a single action to all your MRU menu items, then you won't be able to use that function to tell you which menu was selected. On the other hand, the menu item wouldn't hold any more information than the associated action would, so I see no reason to look for the menu item anyway. Just use the information from the action directly.
回答2:
I use code as follows, but you may need to knock it around some. The only thing very obviously missing is IAbbreviatedFileName
which essentially wraps up the Windows API function PathCompactPath
. You'll want some way to abbreviate very long file names and that's my preferred choice. Sorry for such a huge dump of code, but somebody may find something of use within!
type
TFileAwareMenuItem = class(TMenuItem)
private
FFileName: string;
public
property FileName: string read FFileName write FFilename;
end;
TMRU = class
private
FParent: array of TMenuItem;
FMenuItemStart: array of TMenuItem;
FMenuItemFinish: array of TMenuItem;
FMenuCount: Integer;
FRegistryKey: string;
FOwner: TCustomForm;
FMRUFileNames: TStringList;
FAction: TAction;
function GetCount: Integer;
function GetItem(Index: Integer): string;
procedure SetAction(Value: TAction);
procedure Read;
procedure Write;
procedure UpdateMenu;
public
constructor Create(const RegistrySubKey: string; const Owner: TCustomForm);
destructor Destroy; override;
procedure RegisterBoundingMenuItems(Start, Finish: TMenuItem);
procedure Add(const FileName: string);
procedure Delete(ItemNum: Integer);
property Count: Integer read GetCount;
property Action: TAction read FAction write SetAction;
property Items[Index: Integer]: string read GetItem; default;
end;
const
MRUSize=9;
AppRegistryKey='??put your apps registry key here??';
var
Registry: TRegistry;
constructor TMRU.Create(const RegistrySubKey: string; const Owner: TCustomForm);
begin
inherited Create;
FRegistryKey := Format('%s\%s', [AppRegistryKey, RegistrySubKey]);
FOwner := Owner;
FMRUFileNames := TStringList.Create;
Read;
end;
destructor TMRU.Destroy;
begin
Write;
FreeAndNil(FMRUFileNames);
inherited;
end;
procedure TMRU.RegisterBoundingMenuItems(Start, Finish: TMenuItem);
begin
inc(FMenuCount);
SetLength(FParent, FMenuCount);
SetLength(FMenuItemStart, FMenuCount);
SetLength(FMenuItemFinish, FMenuCount);
FMenuItemStart[FMenuCount-1] := Start;
FMenuItemFinish[FMenuCount-1] := Finish;
Assert(Start.Parent=Finish.Parent);
FParent[FMenuCount-1] := Start.Parent;
UpdateMenu;
end;
procedure TMRU.UpdateMenu;
var
Intf: IAbbreviatedFileName;
i, j: Integer;
FileName: string;
NewMenuItem: TFileAwareMenuItem;
begin
Intf := FOwner as IAbbreviatedFileName;
for i := 0 to FMenuCount-1 do begin
j := FMenuItemStart[i].MenuIndex+1;
while j<FMenuItemFinish[i].MenuIndex do begin
FParent[i][j].Free;
end;
for j := 0 to Count-1 do begin
NewMenuItem := TFileAwareMenuItem.Create(FMenuItemStart[i].Owner);
NewMenuItem.Action := Action;
NewMenuItem.FileName := FMRUFileNames[j];
FileName := ReplaceString(Intf.AbbreviatedFileName(NewMenuItem.FileName, False), '&', '&&');
NewMenuItem.Caption := Format('&%d. %s', [j+1, FileName]);
FParent[i].Insert(FMenuItemFinish[i].MenuIndex, NewMenuItem);
end;
FMenuItemStart[i].Visible := (Count>0) and (FMenuItemStart[i].MenuIndex>0);
FMenuItemFinish[i].Visible := (FMenuItemFinish[i].MenuIndex<FParent[i].Count-1);
end;
end;
procedure TMRU.Read;
var
i: Integer;
s: string;
begin
if Registry.OpenKey(HKEY_CURRENT_USER, FRegistryKey) then begin
FMRUFileNames.Clear;
for i := 0 to MRUSize-1 do begin
s := Registry.ReadString(IntToStr(i+1), '');
if s<>'' then begin
FMRUFileNames.Add(s);
end;
end;
UpdateMenu;
Registry.CloseKey;
end;
end;
procedure TMRU.Write;
var
i: Integer;
ValueName: string;
begin
if Registry.OpenKey(HKEY_CURRENT_USER, FRegistryKey, KEY_ALL_ACCESS, True) then begin
Registry.WriteInteger('Size', MRUSize);
for i := 0 to MRUSize-1 do begin
ValueName := IntToStr(i+1);
if i<Count then begin
Registry.WriteString(ValueName, FMRUFileNames.Strings[i]);
end else begin
if Registry.ValueExists(ValueName) then begin
Registry.DeleteValue(ValueName);
end;
end;
end;
Registry.CloseKey;
end;
end;
function TMRU.GetCount: Integer;
begin
Result := Min(FMRUFileNames.Count, MRUSize);
end;
function TMRU.GetItem(Index: Integer): string;
begin
Result := FMRUFileNames[Index];
end;
procedure TMRU.SetAction(Value: TAction);
begin
if Value<>FAction then begin
FAction := Value;
UpdateMenu;
end;
end;
procedure TMRU.Add(const FileName: string);
var
i, Index: Integer;
begin
Index := -1;
for i := 0 to FMRUFileNames.Count-1 do begin
if FileNamesEqual(FileName, FMRUFileNames[i]) then begin
Index := i;
break;
end;
end;
if Index<>-1 then begin
FMRUFileNames.Move(Index, 0);
end else begin
FMRUFileNames.Insert(0, FileName);
if FMRUFileNames.Count>MRUSize then begin
FMRUFileNames.Delete(FMRUFileNames.Count-1);
end;
end;
UpdateMenu;
Write;
end;
procedure TMRU.Delete(ItemNum: Integer);
begin
FMRUFileNames.Delete(ItemNum);
UpdateMenu;
end;
initialization
Registry := TRegistry.Create;
if not Registry.KeyExists(AppRegistryKey) then begin
Registry.CreateKey(AppRegistryKey);
end;
finalization
FreeAndNil(Registry);
来源:https://stackoverflow.com/questions/4605664/how-can-i-create-a-most-recently-used-file-list-in-delphi-2009