关于UltraVNC中抓图部分 ( 积分: 200 )

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目前对于屏幕的抓取方式，有2种：
1、利用HookAPI的方式。利用BitBlt来进行图像的抓取。
2、利用镜像Driver的方式，直接中硬件成获取图像。

UltraVNC中就实现了上面的二种方式。我想了解一下如何硬件层获取图像。但是在分析了UltraVNC的Code以后，还是没有能够明白它到底是如何实现的。希望强人能够帮忙解决一下。

希望大家经来讨论一下
 
目前对于屏幕的抓取方式，有2种：
1、利用HookAPI的方式。利用BitBlt来进行图像的抓取。
2、利用镜像Driver的方式，直接中硬件成获取图像。

UltraVNC中就实现了上面的二种方式。我想了解一下如何硬件层获取图像。但是在分析了UltraVNC的Code以后，还是没有能够明白它到底是如何实现的。希望强人能够帮忙解决一下。

希望大家经来讨论一下
 
可能我的问题说的不是很明白。其实，我想知道如何实现通过驱动来抓取图片的。
我已经将驱动部分转化为Delphi的代码了。如果你对这个有兴趣的话，请联系我。

QQ:31317107
 
unit UVideoDriver;

interface
uses windows,Registry,SysUtils;

Const
DriverName = 'Winvnc video hook driver';

ENUM_CURRENT_SETTINGS = DWORD(-1) ; // Cardinal(-1)
ENUM_REGISTRY_SETTINGS = DWORD(-2) ;


Map1 = 1030;
UNMap1 = 1031;
CursorEN = 1060;
CursorDIS = 1061;
TestDriver2 = 1060;
TestMapped2 = 1061;

MaxChangesBuf =2000;
Clip_Limit =50;
Ignore = 0;

FromScreen = 1;
FromDIB = 2;
ToScreen = 3;

ScreenScreen = 11;
BLIT = 12;
SolidFill = 13;
Blend = 14;
Trans = 15;
PLG = 17;
TextOut = 18;

BMF_1BPP = 1;
BMF_4BPP = 2;
BMF_8BPP = 3;
BMF_16BPP = 4;
BMF_24BPP = 5;
BMF_32BPP = 6;
BMF_4RLE = 7;
BMF_8RLE = 8;
BMF_JPEG = 9;
BMF_PNG = 10;

NoCache = 1;
OldCache = 2;
NewCache = 3;

SIOCTL_TYPE = 40000;
METHOD_BUFFERED = 0;
METHOD_IN_DIRECT = 1;
METHOD_OUT_DIRECT = 2;
METHOD_NEITHER = 3;

FILE_ANY_ACCESS = 0;
FILE_READ_ACCESS = 1;
FILE_WRITE_ACCESS = 2;

IOCTL_SIOCTL_METHOD_IN_DIRECT = ( ((SIOCTL_TYPE) shl 16) or (($900) shl 2) or (METHOD_IN_DIRECT) or ((FILE_ANY_ACCESS) shl 14) );
IOCTL_SIOCTL_METHOD_OUT_DIRECT= ( ((SIOCTL_TYPE) shl 16) or (($901) shl 2) or (METHOD_OUT_DIRECT) or ((FILE_ANY_ACCESS) shl 14) );
IOCTL_SIOCTL_METHOD_BUFFERED = ( ((SIOCTL_TYPE) shl 16) or (($902) shl 2) or (METHOD_BUFFERED) or ((FILE_ANY_ACCESS) shl 14) );
IOCTL_SIOCTL_METHOD_NEITHER = ( ((SIOCTL_TYPE) shl 16) or (($902) shl 2) or (METHOD_NEITHER) or ((FILE_ANY_ACCESS) shl 14) );

type
PChangesRecord = ^TChangesRecord;
TChangesRecord = record
ScreenType:ULONG; //screen_to_screen, blit, newcache,oldcache
Rect:TRECT;
Point:TPOINT;
end;

PChangesBuf = ^TChangesBuf;
TChangesBuf =record
Counter:ULong;
PointRect:array[0..MaxChangesBuf] of TChangesRecord;
end;

PGetChangesBuf = ^TGetChangesBuf;
TGetChangesBuf = record
Buffer :PChangesBuf;
UserBufferBegin:Pointer;
UserBufferEnd:Pointer;
end;

TEnumDisplayDevices = function (Unused: Pointer; iDevNum: DWORD;
var lpDisplayDevice: TDisplayDevice; dwFlags: DWORD): Boolean;stdcall;

TChangeDisplaySettingsExA = function (lpszDeviceName: PAnsiChar; var lpDevMode: TDeviceModeA;
wnd: HWND; dwFlags: DWORD; lParam: Pointer): Longint;stdcall;

TVNCVideoDriver = class(TObject)
private
FBlocked: Boolean;
FDriverSucces: Boolean;
FFirst: Boolean;
FResolution: Boolean;
FFileHandle: THandle;
FGDC: HDC;
FOutGetChangesBuf: TGetChangesBuf;
FOldaantal: Cardinal;
procedure RestoreReg(RegValue:Integer);
protected
public
// Make the desktop thread & window proc friends
property Oldaantal:Cardinal read FOldaantal write FOldaantal;
property GDC:HDC read FGDC write FGDC;
property DriverSucces: Boolean read FDriverSucces write FDriverSucces;
property Blocked: Boolean read FBlocked write FBlocked;
property OutGetChangesBuf: TGetChangesBuf read FOutGetChangesBuf write FOutGetChangesBuf;
property First:Boolean read FFirst write FFirst;
Property Resolution:Boolean read FResolution write FResolution;
constructor Create;
destructor Destroy; virtual;
function ActivateVideoDriver(Auto: Boolean;X,Y,W,H: Integer):Boolean;
procedure DesActivateVideoDriver;
procedure StartMirroring;
procedure StopMirroring;
function ExistMirrorDriver:Boolean;
function HardWareCursor:Boolean;
function NoHardWareCursor:Boolean;
function CreateCommunicationBuffer(ScreenSize: Integer):TGetChangesBuf;
function RemoveCommunicationBuffer:TGetChangesBuf;
function IsMirrorDriverActive:Boolean;
function GetDllProductVersion(var VBuffer:string;DllName:string;Size:Integer):Boolean;
procedure UpDateCommunicationBuffer;
function GetDCMirror:HDC;
function Tempres:Boolean;
end;


implementation

{ TVNCVideoDriver }

function TVNCVideoDriver.ActivateVideoDriver(Auto: Boolean; X, Y, W,
H: Integer): Boolean;
var
DMPosition:Integer;
HDeskInput,HDeskCurrent:HDESK;
j:Integer;
pd:TEnumDisplayDevices;
pcdse:TChangeDisplaySettingsExA;
DeviceName:string;
TmpDevMode:TDeviceMode;
bChange:Boolean;
Moudle: THandle;
DisplayDevice:TDisplayDevice;
DeviceNum:Integer;
RBool:Boolean;
hKeyProfileMirror,hKeyDevice:HKEY;
CursorPos:TPoint;
FarProc:TFarProc;
begin
Result:=False;
//#define DM_POSITION 0x00000020L
DMPosition := 32; //确认中
First := True;

//FillMemory(@TmpDevMode, SizeOf(DEVMODE), 0);
TmpDevMode.dmSize := SizeOf(DEVMODE);
TmpDevMode.dmDriverExtra :=0;

bChange := EnumDisplaySettings(nil,0,TmpDevMode);
TmpDevMode.dmFields := DM_BITSPERPEL or DM_PELSWIDTH or DM_PELSHEIGHT or DM_POSITION or DM_DISPLAYFLAGS ;


Moudle := LoadLibrary('USER32');
FarProc:=GetProcAddress(Moudle, 'EnumDisplayDevicesA');
if FarProc=nil then exit;
pd := TEnumDisplayDevices(FarProc);
FarProc:=GetProcAddress(Moudle, 'ChangeDisplaySettingsExA');
pcdse := TChangeDisplaySettingsExA(FarProc);
FreeLibrary(Moudle);

if FarProc<>nil then
begin
ZeroMemory(@DisplayDevice,SizeOf(DisplayDevice));
DisplayDevice.cb:=SizeOf(DisplayDevice);
DeviceName:='';
DeviceNum :=0;
TmpDevMode.dmDeviceName[0] := #0;
RBool:=pd(nil,DeviceNum,DisplayDevice,0);
while RBool do
begin
if (CompareStr(DisplayDevice.DeviceString,DriverName) = 0) then Break;
Inc(DeviceNum);
RBool:=pd(nil,DeviceNum,DisplayDevice,0);
end;
if not RBool then exit;

RestoreReg(1);
StrCopy(Pchar(TmpDevMode.dmDeviceName[0]), Pchar('vncdrv'));
DeviceName:='vncdrv';
hDeskCurrent := GetThreadDesktop(GetCurrentThreadId());
if hDeskCurrent<>0 then
begin
hDeskInput := OpenInputDesktop(0, FALSE, MAXIMUM_ALLOWED);
if hDeskInput<>0 then
SetThreadDesktop(hDeskInput)
else
Windows.Beep(1000,500);
end;
end;
if (Moudle>0) then FreeLibrary(Moudle);
Sleep(500);
Result:=TRUE;
end;

constructor TVNCVideoDriver.Create;
begin
DriverSucces:=False;
Blocked:=False;
First:=True;
Resolution:=False;
end;

function TVNCVideoDriver.CreateCommunicationBuffer(
ScreenSize: Integer): TGetChangesBuf;
begin
First := True;
if FFileHandle<>0 then CloseHandle(FFileHandle);
FFileHandle :=CreateFile('//./VncIoctl',GENERIC_READ or GENERIC_WRITE,0,Nil,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,0);
if FFileHandle = INVALID_HANDLE_VALUE then
begin
DriverSucces := False;
Exit;
end;
UpDateCommunicationBuffer;
Result:=OutGetChangesbuf;
end;

procedure TVNCVideoDriver.DesActivateVideoDriver;
var
hDeskInput,hDeskCurrent:HDESK;
pd:TEnumDisplayDevices;
pcdse:TChangeDisplaySettingsExA;
i:Integer;
DeviceMode:TDeviceMode;
Moudle: THandle;
FarProc:TFarProc;
DisplayDevice:TDisplayDevice;
DeviceName:string;
DeviceNum:Integer;
RBool:Boolean;
begin
First := True;
{
FillMemory(DeviceMode, sizeof(DEVMODE), 0);
TmpDevMode.dmSize := sizeof(DEVMODE);
TmpDevMode.dmDriverExtra := 0;
}
EnumDisplaySettings(nil,ENUM_CURRENT_SETTINGS,DeviceMode);
DeviceMode.dmFields := DM_BITSPERPEL or DM_PELSWIDTH or DM_PELSHEIGHT;
Moudle := LoadLibrary('USER32');
pd := TEnumDisplayDevices(GetProcAddress( Moudle, 'EnumDisplayDevicesA'));
pcdse := TChangeDisplaySettingsExA(GetProcAddress( Moudle, 'ChangeDisplaySettingsExA'));
if Moudle<>0 then
begin
//ZeroMemory(@DisplayDevice,SizeOf(DisplayDevice));
DisplayDevice.cb:=SizeOf(TDisplayDevice);
DeviceName:='';
DeviceMode.dmDeviceName[0] := #0;
DeviceNum:=0;
RBool := pd(nil,DeviceNum, DisplayDevice,0);
while RBool do
begin
if (CompareStr(Pchar(DisplayDevice.DeviceName[0]),DriverName) = 0) then Break;
Inc(DeviceNum);
end;

if not RBool then exit;
RestoreReg(0);

StrCopy(Pchar(DeviceMode.dmDeviceName[0]), Pchar('vncdrv'));
DeviceName := 'vncdrv';

// save the current desktop
hDeskCurrent := GetThreadDesktop(GetCurrentThreadId());
if hdeskCurrent<>0 then
begin
hDeskInput := OpenInputDesktop(0, FALSE, MAXIMUM_ALLOWED);
if hdeskInput<>0 then
SetThreadDesktop(hDeskInput)
else
Windows.Beep(1000,500);
end;

Blocked:=False;
if not Resolution then
begin
pcdse(Pchar(DeviceName),DeviceMode,0,CDS_UPDATEREGISTRY,nil);
pcdse(Pchar(DeviceName),DeviceMode,0,0,nil);
end;
Blocked:=false;
if Moudle>0 then FreeLibrary(Moudle);
// reset desktop
SetThreadDesktop(hDeskCurrent);
// close the input desktop
CloseDesktop(hDeskInput);

RestoreReg(0);


end;

end;

destructor TVNCVideoDriver.Destroy;
begin
FDriverSucces:=False;
if (FFileHandle<>0) then
CloseHandle(FFileHandle);
StopMirroring;
if IsMirrorDriverActive then
DesActivateVideoDriver;
end;

function TVNCVideoDriver.ExistMirrorDriver: Boolean;
var
pd:TEnumDisplayDevices;
DeviceMode:TDeviceMode;
Module:THandle;
DisplayDevice:TDisplayDevice;
DeviceNum:Integer;
RBool:Boolean;
FarProc:TFarProc;
begin
EnumDisplaySettings(nil,ENUM_CURRENT_SETTINGS,DeviceMode);
DeviceMode.dmFields := DM_BITSPERPEL or DM_PELSWIDTH or DM_PELSHEIGHT;
Module := LoadLibrary('USER32');
if Module<>0 then
begin
FarProc:=GetProcAddress( Module, 'EnumDisplayDevicesA');
if FarProc=nil then exit;
pd := TEnumDisplayDevices(FarProc);
//ZeroMemory(@DisplayDevice,SizeOf(DisplayDevice));
DisplayDevice.cb:=SizeOf(DisplayDevice);
DeviceMode.dmDeviceName[0] := #0;
DeviceNum:=0;
Result := pd(nil,DeviceNum, DisplayDevice,0);
while RBool do
begin
if (CompareStr(DisplayDevice.DeviceString,DriverName) = 0) then Break;
Inc(DeviceNum);
Result := pd(nil,DeviceNum, DisplayDevice,0);
end;
if Module<>0 then FreeLibrary(Module);
end;
end;

function TVNCVideoDriver.GetDCMirror: HDC;
var
RootDC:HDC;
pd:TEnumDisplayDevices;
ISFoundDriver:Boolean;
DeviceMode:TDeviceMode;
DisplayDevice:TDisplayDevice;
Module:THandle;
RBool:Boolean;
DeviceNum:Integer;
begin
RootDC:=0;
EnumDisplaySettings(nil,ENUM_CURRENT_SETTINGS,DeviceMode);
DeviceMode.dmFields := DM_BITSPERPEL or DM_PELSWIDTH or DM_PELSHEIGHT;
Module:=LoadLibrary('USER32');
if Module<>0 then
begin
pd := TEnumDisplayDevices(GetProcAddress( Module, 'EnumDisplayDevicesA'));
//ZeroMemory(@DisplayDevice,SizeOf(DisplayDevice));
DisplayDevice.cb:=SizeOf(TDisplayDevice);
DeviceMode.dmDeviceName[0] := #0;
DeviceNum := 0;
ISFoundDriver:=False;
RBool:=pd(nil,DeviceNum,DisplayDevice,0);
while RBool do
begin
if (CompareStr(DisplayDevice.DeviceString,DriverName) = 0) then
begin
ISFoundDriver:=True;
Break;
end;
Inc(DeviceNum);
RBool:=pd(nil,DeviceNum,DisplayDevice,0);
end;
if (ISFoundDriver) then
begin
RootDC := CreateDC('DISPLAY',Pchar(DeviceMode.dmDeviceName[0]),nil,nil);
end;
end;
if Module<>0 then FreeLibrary(Module);
Result:=RootDC;
end;

function TVNCVideoDriver.GetDllProductVersion(var VBuffer:string;DllName:string;
Size: Integer): Boolean;
var
VersionInfo:string;
FileName:string;
lpVerBuffer:Pointer;
VerBufferSize:DWORD;
rBuffer:DWORD;
sVersion:DWORD;
RVersion,RValue:Boolean;
InfoSize, Wnd: DWORD;
begin
Result:=False;
if (not ((DLLName<>'') and (VBuffer<>''))) then exit;
//GetModuleFileName(0,Pchar(FileName), sizeof(FileName));
// FYI only
InfoSize := GetFileVersionInfoSize(Pchar(DLLName), Wnd);
if InfoSize=0 then exit;
SetLength(VersionInfo,InfoSize);
GetFileVersionInfo(Pchar(DLLName),Wnd,InfoSize,Pchar(VersionInfo));
RValue:=VerQueryValue(Pchar(VersionInfo),Pchar('/StringFileInfo/040904b0/ProductVersion'),lpVerBuffer,VerBufferSize);
if not RValue then
begin
RValue := VerQueryValue(Pchar(VersionInfo),Pchar('/StringFileInfo/000004b0/ProductVersion'),lpVerBuffer,VerBufferSize);
end;
if RValue then
begin
VBuffer:=strpas(lpVerBuffer);
Result:=True;
end
else
VBuffer:='';
end;

function TVNCVideoDriver.HardWareCursor: Boolean;
var
RInt:Integer;
begin
GDC := GetDC(0);
RInt:= ExtEscape(GDC, Cursoren, 0, nil, 0, nil);
ReleaseDC(0,GDC);
if RInt>0 then
Result := True
else
Result := False;
end;

function TVNCVideoDriver.IsMirrorDriverActive: Boolean;
var
pd:TEnumDisplayDevices;
DeviceMode:TDeviceMode;
DisplayDevice:TDisplayDevice;
Module:THandle;
RBool:Boolean;
DeviceNum:Integer;
begin
Result:=False;
EnumDisplaySettings(nil,ENUM_CURRENT_SETTINGS,DeviceMode);
DeviceMode.dmFields := DM_BITSPERPEL or DM_PELSWIDTH or DM_PELSHEIGHT;
Module:=LoadLibrary('USER32');
if Module<>0 then
begin
pd := TEnumDisplayDevices(GetProcAddress( Module, 'EnumDisplayDevicesA'));
//ZeroMemory(@DisplayDevice,SizeOf(DisplayDevice));
DisplayDevice.cb:=SizeOf(DisplayDevice);
DeviceMode.dmDeviceName[0] := #0;
DeviceNum := 0;
RBool := pd(nil,DeviceNum, DisplayDevice,0);
while RBool do
begin
if (CompareStr(DisplayDevice.DeviceString,DriverName) = 0) then Break;
Inc(DeviceNum);
RBool := pd(nil,DeviceNum, DisplayDevice,0);
end;
if (DisplayDevice.StateFlags<>0) then
Result:=True;
end;
if Module<>0 then FreeLibrary(Module);
end;

function TVNCVideoDriver.NoHardWareCursor: Boolean;
var
RInt:Integer;
begin
GDC:=GetDC(0);
RInt:=ExtEscape(GDC, CursorDIS, 0, nil, 0, nil);
ReleaseDC(0,GDC);
if RInt>0 then
Result := True
else
Result := False;
end;

function TVNCVideoDriver.RemoveCommunicationBuffer: TGetChangesBuf;
begin
if FFileHandle<>0 then CloseHandle(FFileHandle);
//OutGetChangesBuf.Buffer:=Nil;
//OutGetChangesBuf.UserBufferBegin:=Nil;
//OutGetChangesBuf.UserBufferEnd:=Nil;
Result := OutGetChangesBuf;
end;

procedure TVNCVideoDriver.RestoreReg(RegValue: Integer);
var
Registry:TRegistry;
begin
Registry := TRegistry.Create;
try
Registry.RootKey := HKEY_LOCAL_MACHINE;
Registry.OpenKey('SYSTEM/CurrentControlSet/Hardware Profiles/Current/System/CurrentControlSet/Services/vncdrv/DEVICE0', True);
Registry.WriteInteger('Attach.ToDesktop',RegValue);
finally
Registry.Free;
end;
end;

procedure TVNCVideoDriver.StartMirroring;
begin
First:=True;
Oldaantal:=1;
GDC := GetDC(0);
DriverSucces:=False;
if ExtEscape(GDC, Map1, 0, nil, 0, nil)>0 then DriverSucces := True;
HardWareCursor;
ReleaseDC(0,GDC);
// We need also to check if the communication service is activer
if FFileHandle=0 then
begin
FFileHandle := CreateFile('//./VncIoctl',
GENERIC_READ or GENERIC_WRITE,
0,
nil,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
0
);
if ( FFileHandle = INVALID_HANDLE_VALUE ) then
DriverSucces := False
else
begin
CloseHandle(FFileHandle);
FFileHandle := 0;
end;
end;
end;

procedure TVNCVideoDriver.StopMirroring;
begin
DriverSucces := False;
GDC := GetDC(0);
ExtEscape(GDC, UnMap1, 0, nil, 0, nil);
ReleaseDC(0, gdc);
First := True;
end;


function TVNCVideoDriver.Tempres: Boolean;
var
pd:TEnumDisplayDevices;
Module:THandle;
i:DWORD;
CurW,CurH,CurP,RegW,RegH,RegP:Integer;
DisplayDevice:TDisplayDevice;
DeviceMode:TDeviceMode;
RBool:Boolean;
DeviceName:string;
DeviceNum:Integer;
begin
Module:=LoadLibrary('USER32');
pd := TEnumDisplayDevices(GetProcAddress( Module, 'EnumDisplayDevicesA'));

//ZeroMemory(@DisplayDevice,SizeOf(DisplayDevice));
DisplayDevice.cb:=SizeOf(TDisplayDevice);
DeviceNum:=0;
RBool:=pd(nil,DeviceNum,DisplayDevice,0);
while RBool do
begin
if (DisplayDevice.StateFlags<>0) then
begin
EnumDisplaySettings(Pchar(DisplayDevice.DeviceName[0]), ENUM_CURRENT_SETTINGS, DeviceMode);
Break;
end;
Inc(DeviceNum);
RBool:=pd(nil,DeviceNum,DisplayDevice,0);
end;
DeviceName:= Pchar(DisplayDevice.DeviceName[0]);
EnumDisplaySettings(Pchar(DeviceName),ENUM_CURRENT_SETTINGS,DeviceMode);
curw:=DeviceMode.dmPelsWidth;
curh:=DeviceMode.dmPelsHeight;
curp:=DeviceMode.dmBitsPerPel;
EnumDisplaySettings(Pchar(DeviceName),ENUM_REGISTRY_SETTINGS,DeviceMode);
regw:=DeviceMode.dmPelsWidth;
regh:=DeviceMode.dmPelsHeight;
regp:=DeviceMode.dmBitsPerPel;
if (curw=regw) and (curh=regh) and (curp=regp) then
Result:= False
else
Result:= True;
end;


procedure TVNCVideoDriver.UpDateCommunicationBuffer;
var
bRc:Boolean;
BytesReturned:Cardinal;
InGetChangesbuf: TGetChangesBuf;
begin
bRc := False;
BytesReturned := 0;
InGetChangesBuf.Buffer := nil;
InGetChangesBuf.UserBufferBegin := nil;
InGetChangesBuf.UserBufferEnd := nil;
bRc := DeviceIoControl ( FFileHandle,
DWORD(IOCTL_SIOCTL_METHOD_BUFFERED),
@InGetChangesbuf,
sizeof(TGetChangesBuf),
@OutGetChangesbuf,
sizeof(TGetChangesBuf),
BytesReturned,
nil
);
end;




end.
 
VNC的代码中调用的部分： http://www.qznu.cn/winvncsc.rar

http://s19.yousendit.com/d.aspx?id=0IXNMBPFD1RWE1ZBHQP90552W4
 
希望有人在看了VNC的代码后，给出在Delphi中通过驱动镜像抓图的程序。THX
 
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