delphi – NSIS插件“nsScreenshot”在Windows NT 6.x中不起作用

1.1.关于错误的字符串：

从您自己的回答中发现您正在使用ANSI版本的NSIS.由于您在Delphi XE中编译的库代码中使用了字符串,Char和PChar映射到Unicode字符串,因此您在NSIS安装应用程序和库错误数据之间传递.

1.2.关于核心插件单元的另一种观点：

我已经检查了你的略有修改的插件核心单元NSIS.pas,并且存在一些问题,这会阻止你的插件正常工作.但是,正如我所看到的那样,我首先想到的是将独立的过程和函数包装到一个类中.这就是我所做的.

1.3. NSIS.pas v2.0：

由于您目前在your code中仅使用了原始核心单元中的3个功能,因此我简化了仅使用这些功能的类(以及一个用于显示消息框的额外功能).所以这是修改后的插件核心单元的代码.我不是数据操作方面的专家,所以也许可以简化以下代码,但它至少在Delphi XE2和Delphi 2009中有效,我在那里测试过它.这是代码：

unit NSIS;

interface

uses
  Windows,CommCtrl,SysUtils;

type
  PParamStack = ^TParamStack;
  TParamStack = record
    Next: PParamStack;
    Value: PAnsiChar;
  end;
  TNullsoftInstaller = class
  private
    FParent: HWND;
    FParamSize: Integer;
    FParameters: PAnsiChar;
    FStackTop: ^PParamStack;
  public
    procedure Initialize(Parent: HWND; ParamSize: Integer; Parameters: PAnsiChar;
      StackTop: Pointer);
    procedure PushString(const Value: string = '');
    function PopString: string;
    function MessageDialog(const Text,Caption: string; Buttons: UINT): Integer;
  end;

var
  NullsoftInstaller: TNullsoftInstaller;

implementation

procedure TNullsoftInstaller.Initialize(Parent: HWND; ParamSize: Integer;
  Parameters: PAnsiChar; StackTop: Pointer);
begin
  FParent := Parent;
  FParamSize := ParamSize;
  FParameters := Parameters;
  FStackTop := StackTop;
end;

procedure TNullsoftInstaller.PushString(const Value: string = '');
var
  CurrParam: PParamStack;
begin
  if Assigned(FStackTop) then
  begin
    CurrParam := PParamStack(GlobalAlloc(GPTR,SizeOf(TParamStack) + FParamSize));
    StrLCopy(@CurrParam.Value,PAnsiChar(AnsiString(Value)),FParamSize);
    CurrParam.Next := FStackTop^;
    FStackTop^ := CurrParam;
  end;
end;

function TNullsoftInstaller.PopString: string;
var
  CurrParam: PParamStack;
begin
  Result := '';
  if Assigned(FStackTop) then
  begin
    CurrParam := FStackTop^;
    Result := String(PAnsiChar(@CurrParam.Value));
    FStackTop^ := CurrParam.Next;
    GlobalFree(HGLOBAL(CurrParam));
  end;
end;

function TNullsoftInstaller.MessageDialog(const Text,Caption: string;
  Buttons: UINT): Integer;
begin
  Result := MessageBox(FParent,PChar(Text),PChar(Caption),Buttons);
end;

initialization
  NullsoftInstaller := TNullsoftInstaller.Create;
finalization
  if Assigned(NullsoftInstaller) then
    NullsoftInstaller.Free;

end.

1.4.使用修改后的插件核心单元：

正如您所看到的,声明了NullsoftInstaller全局变量,它允许您使用我之前已经使用过的函数的类.使用此变量中的对象实例可以简化初始化和终结部分,其中创建此对象实例并在库被加载时分配给此变量,并在释放库时释放.

所以你需要在代码中做的唯一事情就是像这样使用这个NullsoftInstaller全局变量：

uses
  NSIS;

function ScreenToFile(Parent: HWND; ParamSize: Integer; Parameters: PAnsiChar;
  StackTop: Pointer): Integer; cdecl;
var
  InputString: string;
begin
  Result := 0;

  // this is not necessary,if you keep the NullsoftInstaller object instance 
  // alive (and there's even no reason to free it,since this will be done in 
  // the finalization section when the library is unloaded),so the following
  // statement has no meaning when you won't free the NullsoftInstaller
  if not Assigned(NullsoftInstaller) then
    NullsoftInstaller := TNullsoftInstaller.Create;

  // this has the same meaning as the Init procedure in the original core unit
  NullsoftInstaller.Initialize(Parent,ParamSize,Parameters,StackTop);
  // this is the same as in the original,except that returns a native string
  InputString := NullsoftInstaller.PopString;
  NullsoftInstaller.MessageDialog(InputString,'PopString Result',0);
  // and finally the PushString method,this is also the same as original and
  // as well as the PopString supports native string for your Delphi version
  NullsoftInstaller.PushString('ok');
end;

2. Aero合成窗口的屏幕截图

这是我尝试的截图程序,代码中的TakeScreenshot.它需要一个额外的参数DropShadow,它应该在启用Aero组合时拍摄包括窗口投影的屏幕截图.然而,我找不到一种方法如何以不同的方式做到这一点,而不是在被捕获的窗口后面放置假窗口.它有一个很大的弱点;有时会发生捕获完成后假窗口没有完全显示的情况,因此它会捕获当前桌面的屏幕截图,而不是后面的白色虚假窗口(尚未显示).因此,将DropShadow设置为True现在正处于试验阶段.

当DropShadow为False(没有投影的屏幕截图)时,它可以正常工作.我的猜测是,由于上面描述的Unicode Delphi与ANSI NSIS问题,您传递了错误的参数.

library nsScreenshot;

uses
  Windows,SysUtils,Types,Graphics,DwmApi,Forms,JPEG,NSIS;

procedure CalcCloseCrop(Bitmap: TBitmap; const BackColor: TColor;
  out CropRect: TRect);
var
  X: Integer;
  Y: Integer;
  Color: TColor;
  Pixel: PRGBTriple;
  RowClean: Boolean;
  LastClean: Boolean;
begin
  LastClean := False;
  CropRect := Rect(Bitmap.Width,Bitmap.Height,0);
  for Y := 0 to Bitmap.Height-1 do
  begin
    RowClean := True;
    Pixel := Bitmap.ScanLine[Y];
    for X := 0 to Bitmap.Width - 1 do
    begin
      Color := RGB(Pixel.rgbtRed,Pixel.rgbtGreen,Pixel.rgbtBlue);
      if Color <> BackColor then
      begin
        RowClean := False;
        if X < CropRect.Left then
          CropRect.Left := X;
        if X + 1 > CropRect.Right then
          CropRect.Right := X + 1;
      end;
      Inc(Pixel);
    end;
    if not RowClean then
    begin
      if not LastClean then
      begin
        LastClean := True;
        CropRect.Top := Y;
      end;
      if Y + 1 > CropRect.Bottom then
        CropRect.Bottom := Y + 1;
    end;
  end;
  with CropRect do
  begin
    if (Right < Left) or (Right = Left) or (Bottom < Top) or 
      (Bottom = Top) then
    begin
      if Left = Bitmap.Width then
        Left := 0;
      if Top = Bitmap.Height then
        Top := 0;
      if Right = 0 then
        Right := Bitmap.Width;
      if Bottom = 0 then
        Bottom := Bitmap.Height;
    end;
  end;
end;

procedure TakeScreenshot(WindowHandle: HWND; const FileName: string;
  DropShadow: Boolean);
var
  R: TRect;
  Form: TForm;
  Bitmap: TBitmap;
  Target: TBitmap;
  DeviceContext: HDC;
  DesktopHandle: HWND;
  ExtendedFrame: Boolean;
const
  CAPTUREBLT = $40000000;
begin
  ExtendedFrame := False;
  if DwmCompositionEnabled then
  begin
    DwmGetWindowAttribute(WindowHandle,DWMWA_EXTENDED_FRAME_BOUNDS,@R,SizeOf(TRect));
    if DropShadow then
    begin
      ExtendedFrame := True;
      R.Left := R.Left - 30;
      R.Top := R.Top - 30;
      R.Right := R.Right + 30;
      R.Bottom := R.Bottom + 30;
    end;
  end
  else
    GetWindowRect(WindowHandle,R);

  SetForegroundWindow(WindowHandle);
  Bitmap := TBitmap.Create;
  try
    Bitmap.PixelFormat := pf24bit;
    Bitmap.SetSize(R.Right - R.Left,R.Bottom - R.Top);
    if ExtendedFrame then
    begin
      DesktopHandle := GetDesktopWindow;
      DeviceContext := GetDC(GetDesktopWindow);
      Form := TForm.Create(nil);
      try
        Form.Color := clWhite;
        Form.BorderStyle := bsNone;
        Form.AlphaBlend := True;
        Form.AlphaBlendValue := 0;
        ShowWindow(Form.Handle,SW_SHOWNOACTIVATE);
        SetWindowPos(Form.Handle,WindowHandle,R.Left,R.Top,R.Right - R.Left,R.Bottom - R.Top,SWP_NOACTIVATE);
        Form.AlphaBlendValue := 255;
        BitBlt(Bitmap.Canvas.Handle,DeviceContext,SRCCOPY or CAPTUREBLT);
      finally
        Form.Free;
        ReleaseDC(DesktopHandle,DeviceContext);
      end;
      Target := TBitmap.Create;
      try
        CalcCloseCrop(Bitmap,clWhite,R);
        Target.SetSize(R.Right - R.Left,R.Bottom - R.Top);
        Target.Canvas.CopyRect(Rect(0,R.Bottom - R.Top),Bitmap.Canvas,R);
        Target.SaveToFile(FileName);
      finally
        Target.Free;
      end;
    end
    else
    begin
      DeviceContext := GetWindowDC(WindowHandle);
      try
        BitBlt(Bitmap.Canvas.Handle,SRCCOPY or CAPTUREBLT);
      finally
        ReleaseDC(WindowHandle,DeviceContext);
      end;
      Bitmap.SaveToFile(FileName);
    end;
  finally
    Bitmap.Free;
  end;
end;

function ScreenToFile(Parent: HWND; ParamSize: Integer; Params: PAnsiChar;
  StackTop: Pointer): Integer; cdecl;
var
  I: Integer;
  FileName: string;
  DropShadow: Boolean;
  Parameters: array[0..1] of string;
begin
  Result := 0;
  if not Assigned(NullsoftInstaller) then
    NullsoftInstaller := TNullsoftInstaller.Create;

  NullsoftInstaller.Initialize(Parent,Params,StackTop);

  for I := 0 to High(Parameters) do
    Parameters[I] := NullsoftInstaller.PopString;
  FileName := Parameters[1];
  if not DirectoryExists(ExtractFilePath(FileName)) or
    not TryStrToBool(Parameters[0],DropShadow) then
  begin
    NullsoftInstaller.PushString('error');
    NullsoftInstaller.PushString('Invalid parameters!');
    Exit;
  end;

  try
    TakeScreenshot(Parent,FileName,DropShadow);
    NullsoftInstaller.PushString('ok');
    Result := 1;
  except
    on E: Exception do
    begin
      NullsoftInstaller.PushString('error');
      NullsoftInstaller.PushString(E.Message);
      NullsoftInstaller.MessageDialog(E.Message,'Error',0);
    end;
  end;
end;

exports
  ScreenToFile;

begin

end.