为什么在新桌面执行 MagSetImageScalingCallback 函数会失败？
Why MagSetImageScalingCallback function fails when is executed in new desktop?
我正在尝试获取创建的新桌面的屏幕截图（CreateDesktop api + executing explorer.exe to new desktop) using Magnification api like showed in this tutorial. I ported with success the C++ code from tutorial to Delphi and both examples (C++ and Delphi) works fine when executed from Win Vista ~ Win 10 and with Aero Theme 已启用。
这个问题的问题是因为如果我创建一个新桌面（克隆原始桌面）并执行这个屏幕截图示例，MagSetImageScalingCallback 失败。
有人知道 MagSetImageScalingCallback 的可能解决方案也适用于创建的新桌面吗？
在此先感谢您的帮助。
type
TForm1 = class(TForm)
CAPTURE: TButton;
SaveFileDialog1: TSaveDialog;
procedure FormCreate(Sender: TObject);
procedure CAPTUREClick(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
uses
Magnification;
{$R *.dfm}
function HostWndProc(hWindow: HWND; Msg: UINT; wParam: wParam; lParam: lParam)
: LRESULT; stdcall;
begin
Result := DefWindowProc(hWindow, Msg, wParam, lParam);
end;
var
MyBMP: TBitmap;
abitmap: HBitmap;
desktoprect: TRect;
hWndMag: HWND;
CallbackDone: Boolean = False;
function MagImageScalingCallback(HWND: HWND; srcdata: Pointer;
srcheader: MAGIMAGEHEADER; destdata: Pointer; destheader: MAGIMAGEHEADER;
unclipped: TRect; clipped: TRect; dirty: HRGN): BOOL; stdcall;
var
lpbmih: TBitmapInfoHeader;
lpbmi: TBitmapInfo;
aDC: HDC;
begin
aDC := GetWindowDC(HWND);
Fillchar(lpbmih, sizeof(lpbmih), 0);
lpbmih.biSize := sizeof(lpbmih);
// (-) Otherwise the image is upside down.
lpbmih.biHeight := -srcheader.height { -GetDeviceCaps(aDC, VERTRES) };
lpbmih.biWidth := srcheader.width { GetDeviceCaps(aDC, HORZRES) };
lpbmih.biSizeImage := srcheader.cbSize;
lpbmih.biPlanes := 1;
lpbmih.biBitCount := 32;
lpbmih.biCompression := BI_RGB;
Fillchar(lpbmi, sizeof(lpbmi), 0);
lpbmi.bmiHeader.biSize := sizeof(lpbmi.bmiHeader);
// (-) Otherwise the image is upside down.
lpbmi.bmiHeader.biHeight := -srcheader.height { -GetDeviceCaps(aDC, VERTRES) };
lpbmi.bmiHeader.biWidth := srcheader.width { GetDeviceCaps(aDC, HORZRES) };
lpbmi.bmiHeader.biSizeImage := srcheader.cbSize;
lpbmi.bmiHeader.biPlanes := 1;
lpbmi.bmiHeader.biBitCount := 32;
lpbmi.bmiHeader.biCompression := BI_RGB;
MyBMP := TBitmap.Create;
abitmap := 0;
try
abitmap := CreateDIBitmap(aDC, lpbmih, CBM_INIT, srcdata, lpbmi,
DIB_RGB_COLORS);
MyBMP.handle := abitmap;
MyBMP.PixelFormat := pf32bit;
CallbackDone := True;
finally
DeleteDC(aDC);
end;
Result := True;
end;
procedure TForm1.CAPTUREClick(Sender: TObject);
var
filterList: THWNDArray;
sourceRect: TRect;
begin
filterList[0] := Form1.handle;
If (MagSetWindowFilterList(hWndMag, MW_FILTERMODE_EXCLUDE, 1,
@filterList[0])) Then
begin
sourceRect.left := 0;
sourceRect.top := 0;
sourceRect.right := desktoprect.width;
sourceRect.bottom := desktoprect.height;
CallbackDone := False;
If (MagSetWindowSource(hWndMag, sourceRect)) Then
Screen.Cursor := crHourGlass;
repeat
until CallbackDone;
Screen.Cursor := crDefault;
SaveFileDialog1.Title := 'Save Image File';
SaveFileDialog1.Filter :=
'JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif|Png Image|*.png';
SaveFileDialog1.DefaultExt := 'bmp';
SaveFileDialog1.FilterIndex := 2;
SaveFileDialog1.InitialDir := GetCurrentDir;
if SaveFileDialog1.Execute then
begin
MyBMP.SaveToFile(SaveFileDialog1.FileName);
MessageDlg('File saved: ' + SaveFileDialog1.FileName, mtInformation,
[mbOK], 0);
end
else
MessageDlg('Save file was cancelled', mtWarning, [mbOK], 0);
DeleteObject(abitmap);
MyBMP.Free;
end;
end;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
if (MagUninitialize) then
MessageDlg('Magnification api finished!', mtInformation, [mbOK], 0);
end;
procedure TForm1.FormCreate(Sender: TObject);
const
HOST_CLASSNAME = 'MagnifierHost';
var
wc: TWndClass;
hWndHost, desktop: HWND;
begin
hWndHost := 0;
wc.lpszClassName := HOST_CLASSNAME;
wc.lpfnWndProc := @HostWndProc;
wc.Style := 0;
wc.hInstance := 0;
wc.hIcon := 0;
wc.hCursor := 0;
wc.hbrBackground := 0;
wc.lpszMenuName := nil;
wc.cbClsExtra := 0;
wc.cbWndExtra := 0;
desktop := GetDesktopWindow;
GetWindowRect(desktop, desktoprect);
if (Winapi.Windows.RegisterClass(wc) <> 0) then
hWndHost := CreateWindowEx(WS_EX_TOPMOST Or WS_EX_LAYERED Or
WS_EX_TRANSPARENT, HOST_CLASSNAME, 'Host Window',
WS_POPUP Or WS_CLIPCHILDREN, 0, 0, desktoprect.width, desktoprect.height,
0, 0, hInstance, nil);
if (hWndHost <> 0) then
begin
SetWindowPos(hWndHost, 0, 0, 0, desktoprect.width, desktoprect.height,
SWP_HIDEWINDOW);
SetLayeredWindowAttributes(hWndHost, 0, 255, LWA_ALPHA);
end;
If (MagInitialize) Then
hWndMag := CreateWindowEx(0, WC_MAGNIFIER, 'MagnifierWindow',
WS_CHILD Or MS_SHOWMAGNIFIEDCURSOR Or WS_VISIBLE, 0, 0, desktoprect.width,
desktoprect.height, hWndHost, 0, 0, nil);
If (hWndMag = 0) Then
ShowMessage(SysErrorMessage(GetLastError));
if (MagSetImageScalingCallback(hWndMag, MagImageScalingCallback)) then
ShowMessage('MagSetImageScalingCallback registred!');
ShowMessage(SysErrorMessage(GetLastError));
left := (GetSystemMetrics(SM_CXSCREEN) - width) div 2;
top := (GetSystemMetrics(SM_CYSCREEN) - height) div 2;
end;
end.
Magnification.pas
unit Magnification;
{$ALIGN ON}
{$MINENUMSIZE 4}
interface
uses
Windows;
const
// Magnifier Class Name
WC_MAGNIFIERA: AnsiString = 'Magnifier';
WC_MAGNIFIERW: WideString = 'Magnifier';
WC_MAGNIFIER = 'Magnifier';
// Magnifier Window Styles
MS_SHOWMAGNIFIEDCURSOR = [=11=]01;
MS_CLIPAROUNDCURSOR = [=11=]02;
MS_INVERTCOLORS = [=11=]04;
// Filter Modes
MW_FILTERMODE_EXCLUDE = 0;
MW_FILTERMODE_INCLUDE = 1;
type
tagMAGTRANSFORM = record
v: array[1..3, 1..3] of Single;
end;
MAGTRANSFORM = tagMAGTRANSFORM;
TMagTransform = tagMAGTRANSFORM;
PMagTransform = ^TMagTransform;
tagMAGIMAGEHEADER = record
width: UINT;
height: UINT;
format: TGUID;
stride: UINT;
offset: UINT;
cbSize: UINT;
end;
MAGIMAGEHEADER = tagMAGIMAGEHEADER;
TMagImageHeader = tagMAGIMAGEHEADER;
PMagImageHeader = ^TMagImageHeader;
tagMAGCOLOREFFECT = record
transform: array[1..5, 1..5] of Single;
end;
MAGCOLOREFFECT = tagMAGCOLOREFFECT;
TMagColorEffect = tagMAGCOLOREFFECT;
PMagColorEffect = ^TMagColorEffect;
TMagImageScalingCallback = function (hwnd: HWND; srcdata: Pointer;
srcheader: MAGIMAGEHEADER; destdata: Pointer; destheader: MAGIMAGEHEADER;
unclipped: TRect; clipped: TRect; dirty: HRGN): BOOL; stdcall;
THWNDArray = array[0..0] of HWND;
PHWNDArray = ^THWNDArray;
// Public Functions
function MagInitialize(): BOOL; stdcall;
function MagUninitialize(): BOOL; stdcall;
function MagSetWindowSource(hwnd: HWND; rect: TRect): BOOL; stdcall;
function MagGetWindowSource(hwnd: HWND; var Rect: TRect): BOOL; stdcall;
function MagSetWindowTransform(hwnd: HWND; var Transform: TMagTransform): BOOL; stdcall;
function MagGetWindowTransform(hwnd: HWND; var Transform: TMagTransform): BOOL; stdcall;
function MagSetWindowFilterList(hwnd: HWND; dwFilterMode: DWORD;
count: Integer; pHWND: PHWNDArray): BOOL; stdcall;
function MagGetWindowFilterList(hwnd: HWND; var dwFilterMode: DWORD;
count: Integer; pHWND: PHWNDArray): Integer; stdcall;
function MagSetImageScalingCallback(hwnd: HWND;
MagImageScalingCallback: TMagImageScalingCallback): BOOL; stdcall;
// MagImageScalingCallback WINAPI MagGetImageScalingCallback(HWND hwnd );
function MagSetColorEffect(hwnd: HWND; var Effect: TMagColorEffect): BOOL; stdcall;
function MagGetColorEffect(hwnd: HWND; var Effect: TMagColorEffect): BOOL; stdcall;
implementation
const
MagnificationDll = 'Magnification.dll';
function MagInitialize; external MagnificationDll name 'MagInitialize';
function MagUninitialize; external MagnificationDll name 'MagUninitialize';
function MagSetWindowSource; external MagnificationDll name 'MagSetWindowSource';
function MagGetWindowSource; external MagnificationDll name 'MagGetWindowSource';
function MagSetWindowTransform; external MagnificationDll name 'MagSetWindowTransform';
function MagGetWindowTransform; external MagnificationDll name 'MagGetWindowTransform';
function MagSetWindowFilterList; external MagnificationDll name 'MagSetWindowFilterList';
function MagGetWindowFilterList; external MagnificationDll name 'MagGetWindowFilterList';
function MagSetImageScalingCallback; external MagnificationDll name 'MagSetImageScalingCallback';
function MagSetColorEffect; external MagnificationDll name 'MagSetColorEffect';
function MagGetColorEffect; external MagnificationDll name 'MagGetColorEffect';
end.
版本：
GetLastError() returns 50 - ERROR_NOT_SUPPORTED - The request is not supported.
但这适用于原始桌面，我不明白。
已解决！
这适用于 Win 8/8.1 和 10，所有 x86 和 x64。
不适用于 Windows 版本 < 8
我正在尝试获取创建的新桌面的屏幕截图（CreateDesktop api + executing explorer.exe to new desktop) using Magnification api like showed in this tutorial. I ported with success the C++ code from tutorial to Delphi and both examples (C++ and Delphi) works fine when executed from Win Vista ~ Win 10 and with Aero Theme 已启用。
这个问题的问题是因为如果我创建一个新桌面（克隆原始桌面）并执行这个屏幕截图示例，MagSetImageScalingCallback 失败。
有人知道 MagSetImageScalingCallback 的可能解决方案也适用于创建的新桌面吗？
在此先感谢您的帮助。
type
TForm1 = class(TForm)
CAPTURE: TButton;
SaveFileDialog1: TSaveDialog;
procedure FormCreate(Sender: TObject);
procedure CAPTUREClick(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
uses
Magnification;
{$R *.dfm}
function HostWndProc(hWindow: HWND; Msg: UINT; wParam: wParam; lParam: lParam)
: LRESULT; stdcall;
begin
Result := DefWindowProc(hWindow, Msg, wParam, lParam);
end;
var
MyBMP: TBitmap;
abitmap: HBitmap;
desktoprect: TRect;
hWndMag: HWND;
CallbackDone: Boolean = False;
function MagImageScalingCallback(HWND: HWND; srcdata: Pointer;
srcheader: MAGIMAGEHEADER; destdata: Pointer; destheader: MAGIMAGEHEADER;
unclipped: TRect; clipped: TRect; dirty: HRGN): BOOL; stdcall;
var
lpbmih: TBitmapInfoHeader;
lpbmi: TBitmapInfo;
aDC: HDC;
begin
aDC := GetWindowDC(HWND);
Fillchar(lpbmih, sizeof(lpbmih), 0);
lpbmih.biSize := sizeof(lpbmih);
// (-) Otherwise the image is upside down.
lpbmih.biHeight := -srcheader.height { -GetDeviceCaps(aDC, VERTRES) };
lpbmih.biWidth := srcheader.width { GetDeviceCaps(aDC, HORZRES) };
lpbmih.biSizeImage := srcheader.cbSize;
lpbmih.biPlanes := 1;
lpbmih.biBitCount := 32;
lpbmih.biCompression := BI_RGB;
Fillchar(lpbmi, sizeof(lpbmi), 0);
lpbmi.bmiHeader.biSize := sizeof(lpbmi.bmiHeader);
// (-) Otherwise the image is upside down.
lpbmi.bmiHeader.biHeight := -srcheader.height { -GetDeviceCaps(aDC, VERTRES) };
lpbmi.bmiHeader.biWidth := srcheader.width { GetDeviceCaps(aDC, HORZRES) };
lpbmi.bmiHeader.biSizeImage := srcheader.cbSize;
lpbmi.bmiHeader.biPlanes := 1;
lpbmi.bmiHeader.biBitCount := 32;
lpbmi.bmiHeader.biCompression := BI_RGB;
MyBMP := TBitmap.Create;
abitmap := 0;
try
abitmap := CreateDIBitmap(aDC, lpbmih, CBM_INIT, srcdata, lpbmi,
DIB_RGB_COLORS);
MyBMP.handle := abitmap;
MyBMP.PixelFormat := pf32bit;
CallbackDone := True;
finally
DeleteDC(aDC);
end;
Result := True;
end;
procedure TForm1.CAPTUREClick(Sender: TObject);
var
filterList: THWNDArray;
sourceRect: TRect;
begin
filterList[0] := Form1.handle;
If (MagSetWindowFilterList(hWndMag, MW_FILTERMODE_EXCLUDE, 1,
@filterList[0])) Then
begin
sourceRect.left := 0;
sourceRect.top := 0;
sourceRect.right := desktoprect.width;
sourceRect.bottom := desktoprect.height;
CallbackDone := False;
If (MagSetWindowSource(hWndMag, sourceRect)) Then
Screen.Cursor := crHourGlass;
repeat
until CallbackDone;
Screen.Cursor := crDefault;
SaveFileDialog1.Title := 'Save Image File';
SaveFileDialog1.Filter :=
'JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif|Png Image|*.png';
SaveFileDialog1.DefaultExt := 'bmp';
SaveFileDialog1.FilterIndex := 2;
SaveFileDialog1.InitialDir := GetCurrentDir;
if SaveFileDialog1.Execute then
begin
MyBMP.SaveToFile(SaveFileDialog1.FileName);
MessageDlg('File saved: ' + SaveFileDialog1.FileName, mtInformation,
[mbOK], 0);
end
else
MessageDlg('Save file was cancelled', mtWarning, [mbOK], 0);
DeleteObject(abitmap);
MyBMP.Free;
end;
end;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
if (MagUninitialize) then
MessageDlg('Magnification api finished!', mtInformation, [mbOK], 0);
end;
procedure TForm1.FormCreate(Sender: TObject);
const
HOST_CLASSNAME = 'MagnifierHost';
var
wc: TWndClass;
hWndHost, desktop: HWND;
begin
hWndHost := 0;
wc.lpszClassName := HOST_CLASSNAME;
wc.lpfnWndProc := @HostWndProc;
wc.Style := 0;
wc.hInstance := 0;
wc.hIcon := 0;
wc.hCursor := 0;
wc.hbrBackground := 0;
wc.lpszMenuName := nil;
wc.cbClsExtra := 0;
wc.cbWndExtra := 0;
desktop := GetDesktopWindow;
GetWindowRect(desktop, desktoprect);
if (Winapi.Windows.RegisterClass(wc) <> 0) then
hWndHost := CreateWindowEx(WS_EX_TOPMOST Or WS_EX_LAYERED Or
WS_EX_TRANSPARENT, HOST_CLASSNAME, 'Host Window',
WS_POPUP Or WS_CLIPCHILDREN, 0, 0, desktoprect.width, desktoprect.height,
0, 0, hInstance, nil);
if (hWndHost <> 0) then
begin
SetWindowPos(hWndHost, 0, 0, 0, desktoprect.width, desktoprect.height,
SWP_HIDEWINDOW);
SetLayeredWindowAttributes(hWndHost, 0, 255, LWA_ALPHA);
end;
If (MagInitialize) Then
hWndMag := CreateWindowEx(0, WC_MAGNIFIER, 'MagnifierWindow',
WS_CHILD Or MS_SHOWMAGNIFIEDCURSOR Or WS_VISIBLE, 0, 0, desktoprect.width,
desktoprect.height, hWndHost, 0, 0, nil);
If (hWndMag = 0) Then
ShowMessage(SysErrorMessage(GetLastError));
if (MagSetImageScalingCallback(hWndMag, MagImageScalingCallback)) then
ShowMessage('MagSetImageScalingCallback registred!');
ShowMessage(SysErrorMessage(GetLastError));
left := (GetSystemMetrics(SM_CXSCREEN) - width) div 2;
top := (GetSystemMetrics(SM_CYSCREEN) - height) div 2;
end;
end.
Magnification.pas
unit Magnification;
{$ALIGN ON}
{$MINENUMSIZE 4}
interface
uses
Windows;
const
// Magnifier Class Name
WC_MAGNIFIERA: AnsiString = 'Magnifier';
WC_MAGNIFIERW: WideString = 'Magnifier';
WC_MAGNIFIER = 'Magnifier';
// Magnifier Window Styles
MS_SHOWMAGNIFIEDCURSOR = [=11=]01;
MS_CLIPAROUNDCURSOR = [=11=]02;
MS_INVERTCOLORS = [=11=]04;
// Filter Modes
MW_FILTERMODE_EXCLUDE = 0;
MW_FILTERMODE_INCLUDE = 1;
type
tagMAGTRANSFORM = record
v: array[1..3, 1..3] of Single;
end;
MAGTRANSFORM = tagMAGTRANSFORM;
TMagTransform = tagMAGTRANSFORM;
PMagTransform = ^TMagTransform;
tagMAGIMAGEHEADER = record
width: UINT;
height: UINT;
format: TGUID;
stride: UINT;
offset: UINT;
cbSize: UINT;
end;
MAGIMAGEHEADER = tagMAGIMAGEHEADER;
TMagImageHeader = tagMAGIMAGEHEADER;
PMagImageHeader = ^TMagImageHeader;
tagMAGCOLOREFFECT = record
transform: array[1..5, 1..5] of Single;
end;
MAGCOLOREFFECT = tagMAGCOLOREFFECT;
TMagColorEffect = tagMAGCOLOREFFECT;
PMagColorEffect = ^TMagColorEffect;
TMagImageScalingCallback = function (hwnd: HWND; srcdata: Pointer;
srcheader: MAGIMAGEHEADER; destdata: Pointer; destheader: MAGIMAGEHEADER;
unclipped: TRect; clipped: TRect; dirty: HRGN): BOOL; stdcall;
THWNDArray = array[0..0] of HWND;
PHWNDArray = ^THWNDArray;
// Public Functions
function MagInitialize(): BOOL; stdcall;
function MagUninitialize(): BOOL; stdcall;
function MagSetWindowSource(hwnd: HWND; rect: TRect): BOOL; stdcall;
function MagGetWindowSource(hwnd: HWND; var Rect: TRect): BOOL; stdcall;
function MagSetWindowTransform(hwnd: HWND; var Transform: TMagTransform): BOOL; stdcall;
function MagGetWindowTransform(hwnd: HWND; var Transform: TMagTransform): BOOL; stdcall;
function MagSetWindowFilterList(hwnd: HWND; dwFilterMode: DWORD;
count: Integer; pHWND: PHWNDArray): BOOL; stdcall;
function MagGetWindowFilterList(hwnd: HWND; var dwFilterMode: DWORD;
count: Integer; pHWND: PHWNDArray): Integer; stdcall;
function MagSetImageScalingCallback(hwnd: HWND;
MagImageScalingCallback: TMagImageScalingCallback): BOOL; stdcall;
// MagImageScalingCallback WINAPI MagGetImageScalingCallback(HWND hwnd );
function MagSetColorEffect(hwnd: HWND; var Effect: TMagColorEffect): BOOL; stdcall;
function MagGetColorEffect(hwnd: HWND; var Effect: TMagColorEffect): BOOL; stdcall;
implementation
const
MagnificationDll = 'Magnification.dll';
function MagInitialize; external MagnificationDll name 'MagInitialize';
function MagUninitialize; external MagnificationDll name 'MagUninitialize';
function MagSetWindowSource; external MagnificationDll name 'MagSetWindowSource';
function MagGetWindowSource; external MagnificationDll name 'MagGetWindowSource';
function MagSetWindowTransform; external MagnificationDll name 'MagSetWindowTransform';
function MagGetWindowTransform; external MagnificationDll name 'MagGetWindowTransform';
function MagSetWindowFilterList; external MagnificationDll name 'MagSetWindowFilterList';
function MagGetWindowFilterList; external MagnificationDll name 'MagGetWindowFilterList';
function MagSetImageScalingCallback; external MagnificationDll name 'MagSetImageScalingCallback';
function MagSetColorEffect; external MagnificationDll name 'MagSetColorEffect';
function MagGetColorEffect; external MagnificationDll name 'MagGetColorEffect';
end.
版本：
GetLastError()returns 50 - ERROR_NOT_SUPPORTED - The request is not supported.
但这适用于原始桌面，我不明白。
已解决！
这适用于 Win 8/8.1 和 10，所有 x86 和 x64。
不适用于 Windows 版本 < 8