unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
  System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs,
  Vcl.StdCtrls, hyieutils, iexBitmaps, hyiedefs, iesettings, ieview,
  imageenview, Vcl.ExtCtrls;

type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;
    ImageEnView1: TImageEnView;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{Note: Screen.Width and Screen.Height produce incorrect results when using Screen.Width
 and Screen.Height to set the dimensions of a bitmap for screen capture on high resolution
 monitor similar to that on a Microsoft Surface Pro 3.  Both GetDeviceCaps and Monitor return
 the correct screen dimensions on a Surface 3 Pro and on Desktop monitors while Screen.Height and
 Screen.Width does not.  I attempted to use WMI to achieve the same result but this failed
 to function in my tests.  Subsequently it was determined that both GetDeviceCaps as well as
 Monitor returns the correct values.  Tested on Windows 10 on a Desktop PC and Desktop Monitor
 as well as with a Surface Pro 3 Tablet with Windows 10. Compiled with Delphi 10 Seattle. }

procedure ScreenShot(ActiveWindow: bool; DestBitmap: TBitmap);
{ Capture the desktop using GetDeviceCaps rather than Screen.Width and Screen.Height }
var
  iWidth: integer;
  iHeight: integer;
  DC: HDC;
  hWin: Cardinal;
  iRect: TRect;
begin
  if ActiveWindow then
  begin
    hWin := GetForegroundWindow;
    DC := GetWindowDC(hWin);
    GetWindowRect(hWin, iRect);
    iWidth := iRect.Right - iRect.Left;
    iHeight := iRect.Bottom - iRect.Top;
  end
  else
  begin
    hWin := GetDesktopWindow;
    DC := GetDC(hWin);
    iWidth := GetDeviceCaps(DC, HORZRES);
    iHeight := GetDeviceCaps(DC, VERTRES);
  end;
  try
    DestBitmap.Width := iWidth;
    DestBitmap.Height := iHeight;
    BitBlt(DestBitmap.Canvas.Handle, 0, 0, DestBitmap.Width, DestBitmap.Height,
      DC, 0, 0, SRCCOPY);
  finally
    ReleaseDC(hWin, DC);
  end;
end;

procedure ScreenShot2(ActiveWindow: bool; DestBitmap: TBitmap);
{ Capture the desktop using Monitor rather than Screen.Width and Screen.Height }
var
  iWidth: integer;
  iHeight: integer;
  DC: HDC;
  hWin: Cardinal;
  iRect: TRect;
begin
  if ActiveWindow then
  begin
    hWin := GetForegroundWindow;
    DC := GetWindowDC(hWin);
    GetWindowRect(hWin, iRect);
    iWidth := iRect.Right - iRect.Left;
    iHeight := iRect.Bottom - iRect.Top;
  end
  else
  begin
    hWin := GetDesktopWindow;
    DC := GetDC(hWin);
    iWidth := Form1.Monitor.Width;
    iHeight := Form1.Monitor.Height;
  end;
  try
    DestBitmap.Width := iWidth;
    DestBitmap.Height := iHeight;
    BitBlt(DestBitmap.Canvas.Handle, 0, 0, DestBitmap.Width, DestBitmap.Height,
      DC, 0, 0, SRCCOPY);
  finally
    ReleaseDC(hWin, DC);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
{ Capture an image of the Desktop screen on high res monitors by using
  GetDeviceCaps to set the bitmap dimensions. Tested on a Surface Pro 3.}
begin
  WindowState := wsMinimized;
  Sleep(250);
  ImageEnView1.Bitmap.PixelFormat := pf24bit;
  ScreenShot(False, ImageEnView1.Bitmap);
  ImageEnView1.Update;
  WindowState := wsNormal;
end;

procedure TForm1.Button2Click(Sender: TObject);
{ Capture an image of the Desktop screen on high res monitors by using
  Monitor to set the bitmap dimensions. Tested on a Surface Pro 3.}
begin
  WindowState := wsMinimized;
  Sleep(250);
  ImageEnView1.Bitmap.PixelFormat := pf24bit;
  ScreenShot2(False, ImageEnView1.Bitmap);
  ImageEnView1.Update;
  WindowState := wsNormal;
end;

end.