delphi - NSIS 插件 "nsScreenshot"在 Windows NT 6.x 中无法工作

Question

我添加了比原始插件晚3年发布的代码，但它仍然返回错误...

代码很简单，恕我直言......但我仍然很可能错过某些方面......

查看这段代码:

{
        nsScreenshot NSIS Plugin
        (c) 2003: Leon Zandman (leon@wirwar.com)

        Re-compiled by: Linards Liepins (linards.liepins@gmail.com)
        Code by: http://www.delphitricks.com/source-code/forms/make_a_desktop_screenshot.html
        (e) 2012.
}
library nsScreenshot;

uses
  nsis in './nsis.pas',
  Windows,
  Jpeg,
  graphics,
  types,
  SysUtils;

const
  USER32 = 'user32.dll';

type
  HWND = type LongWord;
  {$EXTERNALSYM HWND}
  HDC = type LongWord;
  {$EXTERNALSYM HDC}
  BOOL = LongBool;
  {$EXTERNALSYM BOOL}

{$EXTERNALSYM GetDesktopWindow}
function GetDesktopWindow: HWND; stdcall; external USER32 name 'GetDesktopWindow';
{$EXTERNALSYM GetWindowDC}
function GetWindowDC(hWnd: HWND): HDC; stdcall; external USER32 name 'GetWindowDC';
{$EXTERNALSYM GetWindowRect}
function GetWindowRect(hWnd: HWND; var lpRect: TRect): BOOL; stdcall; external USER32 name 'GetWindowRect';
{$EXTERNALSYM ReleaseDC}
function ReleaseDC(hWnd: HWND; hDC: HDC): Integer; stdcall; external user32 name 'ReleaseDC';

function GetScreenshot(Filename: string; Hwnd: HWND; var Width: integer; var Height: integer): boolean; forward;
function ScreenShot(Bild: TBitMap; hWnd: HWND): boolean; forward;


function Grab_FullScreen(hwndParent: HWND; string_size: integer; variables: PChar; stacktop: pointer):integer; cdecl;
var
  buf: array[0..1024] of char;
  W,H: integer;
begin
  Result := 0;
  // set up global variables
  Init(hwndParent,string_size,variables,stacktop);

  // Get filename to save to
  PopString;//(@buf);

  // Get a full-screen screenshot
  if GetScreenShot(buf,GetDesktopWindow,W,H) then begin
    // Everything went just fine...

    // Push image dimensions onto stack
    PushString(PChar(IntToStr(H)));
    PushString(PChar(IntToStr(W)));

    // Push result onto stack
    PushString(PChar('ok'));
    Result := 1;
  end else begin
    // Something went wrong...
    PushString(PChar('error'));
  end;
end;

function Grab(hwndParent: HWND; string_size: integer; variables: PChar; stacktop: pointer):integer; cdecl;
var
  buf: array[0..1024] of char;
  grabWnd: HWND;
  Filename: string;
  W,H: integer;
begin
  Result := 0;
  // set up global variables
  Init(hwndParent,string_size,variables,stacktop);

  try
    // Get filename to save to
    PopString;//(@buwf);
    Filename := buf;

    // Get window handle of window to grab
    PopString;//(@buf);
    grabWnd := StrToInt(buf);
  except
    PushString(PChar('error'));
    exit;
  end;

  // Get screenshot of parent windows (NSIS)
  if GetScreenShot(Filename,grabWnd,W,H) then begin
    // Everything went just fine...

    // Push image dimensions onto stack
    PushString(PChar(IntToStr(H)));
    PushString(PChar(IntToStr(W)));

    // Push result onto stack
    PushString(PChar('ok'));
    Result := 1;
  end else begin
    // Something went wrong...
    PushString(PChar('error'));
  end;
end;

function GetScreenshot(Filename: string; Hwnd: HWND; var Width: integer; var Height: integer): boolean;
var
  bmp: TBitmap;
begin
  Result := false;

  // Get screenshot
  bmp := TBitmap.Create;
  try
    try
      if ScreenShot(bmp,Hwnd) then begin
        Width  := bmp.Width;
        Height := bmp.Height;
        bmp.SaveToFile(Filename);
        Result := true;
      end;
    except
      // Catch exception and do nothing (function return value remains 'false')
    end;
  finally
    bmp.Free;
  end;
end;

function ScreenShot(Bild: TBitMap; hWnd: HWND): boolean;
var
  c: TCanvas;
  r, t: TRect;
  h: THandle;
begin
  Result := false;

  c := TCanvas.Create;
  c.Handle := GetWindowDC(GetDesktopWindow);

  h := hWnd;
  if h <> 0 then begin
    GetWindowRect(h, t);
    try
      r := Rect(0, 0, t.Right - t.Left, t.Bottom - t.Top);
      Bild.Width  := t.Right - t.Left;
      Bild.Height := t.Bottom - t.Top;
      Bild.Canvas.CopyRect(r, c, t);
    finally
      ReleaseDC(0, c.Handle);
      c.Free;
    end;
    Result := true;
  end;
end;

function GetScreenToFile(FileName: string; Quality: Word; Percent: Word): boolean;
var
  Bmp: TBitmap;
  Jpg: TJpegImage;
begin
  Bmp := TBitmap.Create;
  Jpg := TJpegImage.Create;
  try
    Bmp.Width := GetDeviceCaps(GetDc(0), 8) * Percent div 100;
    Bmp.Height := GetDeviceCaps(GetDc(0), 10) * Percent div 100;
    SetStretchBltMode(Bmp.Canvas.Handle, HALFTONE);
    StretchBlt(Bmp.Canvas.Handle, 0, 0, Bmp.Width, Bmp.Height, GetDc(0), 0, 0, GetDeviceCaps(GetDc(0), 8), GetDeviceCaps(GetDc(0), 10), SRCCOPY);
    Jpg.Assign(Bmp);
    Jpg.CompressionQuality := Quality;
    Jpg.SaveToFile(FileName);
  finally
    Jpg.free;
    Bmp.free;
  end;
end;

function ScreenToFile(hwndParent: HWND; string_size: integer; variables: PChar; stacktop: pointer):integer; cdecl;
var
  buf: array[0..1024] of char;
  grabWnd: HWND;
  Filename: string;
  W,H: integer;
begin
  Result := 0;
  Init(hwndParent,string_size,variables,stacktop);
  try
    PopString;
    Filename := buf;
    PopString;
    grabWnd := StrToInt(buf);
  except
    PushString(PChar('error'));
    exit;
  end;
  if GetScreenToFile(Filename,W,H) then
  begin
    PushString(PChar('ok'));
    Result := 1;
  end else
  begin
    PushString(PChar('error'));
  end;
end;

  //ScreenToFile('SHOT.JPG', 50, 70);

exports Grab_FullScreen,
        Grab,
        ScreenToFile;

begin
end.

搜索ScreenToFile。

感谢您的任何意见。该插件对于安装程序文档生成自动化至关重要。

Answer 1

1。 NSIS插件核心单元问题:

1.1。关于错误字符串:

从您自己的回答帖子中可以看出您正在使用 ANSI 版本的 NSIS。由于您在 Delphi XE 中编译的库代码中使用了 string、Char 和 PChar 映射到 Unicode 字符串，因此您可以在 NSIS 设置应用程序和您的库之间传递错误的数据。

1.2。对核心插件单元的另一种看法:

我检查了您稍微修改过的插件核心单元 NSIS.pas并且存在一些问题，导致您的插件无法正常工作。然而，正如我看到这个单元时，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:

因为您目前只使用了 your code 中原始核心单元的 3 个函数。我已经简化了仅使用这些类的类(以及一个额外的用于显示消息框的类)。这是修改后的插件核心单元的代码。我不是数据操作专家，所以也许下面的代码可以简化，但它至少可以在我测试过的 Delphi XE2 和 Delphi 2009 中运行。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。修改后的插件核心单元的用法:

正如您所看到的，声明了 NullsoftInstaller 全局变量，它允许您使用我包装了您之前使用过的函数的类。通过初始化和终结部分简化了此变量中对象实例的使用，在加载库时创建此对象实例并将其分配给此变量，并在释放库时释放该对象实例。

因此，您在代码中唯一需要做的就是使用这个 NullsoftInstaller 全局变量，如下所示:

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

这是我尝试的屏幕截图程序，代码中的TakeScreenshot。它需要一个额外的参数 DropShadow，当启用 Aero 合成时，该参数应该截取包括窗口阴影的屏幕截图。然而，除了将假窗口放置在捕获的窗口后面之外，我找不到一种以不同的方式执行此操作的方法。它有一个很大的弱点:有时会发生捕获完成后假窗口未完全显示的情况，因此它会截取捕获窗口周围的当前桌面的屏幕截图，而不是后面的白色假窗口(尚未显示)。因此，将 DropShadow 设置为 True 现在还处于实验阶段。

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，由于上述 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, 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, 0, 0, R.Right - R.Left, R.Bottom - R.Top,
          DeviceContext, R.Left, R.Top, 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, 0, R.Right - R.Left, 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, 0, 0, R.Right - R.Left, R.Bottom - R.Top,
          DeviceContext, 0, 0, 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, ParamSize, 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.