檢測窗口外殼變化

Question

我對使用C Builder的知識非常有限，你能給我一個例子或者指向我，教程展示如何在Delphi中使用FindNextChangeNotification，或者如果可能的話，如何在Delphi中使用C組件？

Answer 1

ReadDirectoryChanges似乎是我正在尋找的功能。這裏是我嘗試使用mghie的代碼Why does ReadDirectoryChangesW omit events?

我的目標是監視你將在Unit1中看到的目錄/路徑或文件。我只想要一個簡單的showmessage對話框，以便在檢測到位置更改時彈出。我無法找到我應該通過我的通知程序或功能的地方。 Unit2只保存了mghie中未改變的代碼。當我編譯這個項目並在目錄中做一個簡單的改變時，什麼都不會發生。我正確使用ReadDirectoryChanges？

這裏是1單元：

unit Unit1; 

interface 

uses 
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
    Dialogs, Unit2; 

type 
    TForm1 = class(TForm) 
    Button1: TButton; 
    Button2: TButton; 
    procedure FormCreate(Sender: TObject); 
    procedure FormDestroy(Sender: TObject); 
    procedure Button1Click(Sender: TObject); 
    private 
    { Private declarations } 
    public 
    { Public declarations } 
    end; 

var 
    Form1: TForm1; 
    fthread:TWatcherthread; 

implementation 

{$R *.dfm} 

procedure TForm1.Button1Click(Sender: TObject); 
begin 
//start directory or file watch here 
end; 

procedure TForm1.FormCreate(Sender: TObject); 
begin 
    fThread := TWatcherThread.Create('C:\Users\abe\Desktop\statcious\mitsu\Demo\abc.txt'); 

end; 

procedure TForm1.FormDestroy(Sender: TObject); 
begin 
    if fThread <> nil then begin 
    TWatcherThread(fThread).Shutdown; 
    fThread.Free; 
    end; 
end; 

end. 

這裏是UNIT2：

unit Unit2; 

interface 

uses 
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
    Dialogs; 

type 
    TWatcherThread = class(TThread) 
    private 
    fChangeHandle: THandle; 
    fDirHandle: THandle; 
    fShutdownHandle: THandle; 
    protected 
    procedure Execute; override; 
    public 
    constructor Create(ADirectoryToWatch: string); 
    destructor Destroy; override; 

    procedure Shutdown; 

    end; 

type 
    TForm2 = class(TForm) 
    private 
    { Private declarations } 
    public 
    { Public declarations } 
    end; 

var 
    Form2: TForm2; 

implementation 

{$R *.dfm} 

constructor TWatcherThread.Create(ADirectoryToWatch: string); 
const 
    FILE_LIST_DIRECTORY = 1; 
begin 
    inherited Create(TRUE); 
    fChangeHandle := CreateEvent(nil, FALSE, FALSE, nil); 
    fDirHandle := CreateFile(PChar(ADirectoryToWatch), 
    FILE_LIST_DIRECTORY or GENERIC_READ, 
    FILE_SHARE_READ or FILE_SHARE_WRITE or FILE_SHARE_DELETE, 
    nil, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS or FILE_FLAG_OVERLAPPED, 0); 
    fShutdownHandle := CreateEvent(nil, FALSE, FALSE, nil); 
    Resume; 
end; 

destructor TWatcherThread.Destroy; 
begin 
    if fDirHandle <> INVALID_HANDLE_VALUE then 
    CloseHandle(fDirHandle); 
    if fChangeHandle <> 0 then 
    CloseHandle(fChangeHandle); 
    if fShutdownHandle <> 0 then 
    CloseHandle(fShutdownHandle); 
    inherited Destroy; 
end; 

procedure TWatcherThread.Execute; 
type 
    PFileNotifyInformation = ^TFileNotifyInformation; 
    TFileNotifyInformation = record 
    NextEntryOffset: DWORD; 
    Action: DWORD; 
    FileNameLength: DWORD; 
    FileName: WideChar; 
    end; 
const 
    BufferLength = 65536; 
var 
    Filter, BytesRead: DWORD; 
    InfoPointer: PFileNotifyInformation; 
    Offset, NextOffset: DWORD; 
    Buffer: array[0..BufferLength - 1] of byte; 
    Overlap: TOverlapped; 
    Events: array[0..1] of THandle; 
    WaitResult: DWORD; 
    FileName, s: string; 
begin 
    if fDirHandle <> INVALID_HANDLE_VALUE then begin 
    Filter := FILE_NOTIFY_CHANGE_FILE_NAME or FILE_NOTIFY_CHANGE_DIR_NAME 
     or FILE_NOTIFY_CHANGE_SIZE or FILE_NOTIFY_CHANGE_LAST_WRITE; 

    FillChar(Overlap, SizeOf(TOverlapped), 0); 
    Overlap.hEvent := fChangeHandle; 

    Events[0] := fChangeHandle; 
    Events[1] := fShutdownHandle; 

    while not Terminated do begin 
     if ReadDirectoryChangesW (fDirHandle, @Buffer[0], BufferLength, TRUE, 
     Filter, @BytesRead, @Overlap, nil) 
     then begin 
     WaitResult := WaitForMultipleObjects(2, @Events[0], FALSE, INFINITE); 
     if WaitResult = WAIT_OBJECT_0 then begin 
      InfoPointer := @Buffer[0]; 
      Offset := 0; 
      repeat 
      NextOffset := InfoPointer.NextEntryOffset; 
      FileName := WideCharLenToString(@InfoPointer.FileName, 
       InfoPointer.FileNameLength); 
      SetLength(FileName, StrLen(PChar(FileName))); 
      s := Format('[%d] Action: %.8xh, File: "%s"', 
       [Offset, InfoPointer.Action, FileName]); 
      OutputDebugString(PChar(s)); 
      PByte(InfoPointer) := PByte(DWORD(InfoPointer) + NextOffset); 
      Offset := Offset + NextOffset; 
      until NextOffset = 0; 
     end; 
     end; 
    end; 
    end; 
end; 

procedure TWatcherThread.Shutdown; 
begin 
    Terminate; 
    if fShutdownHandle <> 0 then 
    SetEvent(fShutdownHandle); 
end; 

end. 

Answer 2

一個選項是使用TJvChangeNotify組件，JVCL支持Delphi和C++ Builder。

另一種選擇是使用SHChangeNotifyRegister函數。 看到這個鏈接Monitoring System Shell Changes using Delphi

再見。