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Multiple display
How can I detect if windows is using multiple display's and
get the information (resolution pixel depth etc).
get the information (resolution pixel depth etc).
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See TScreen type. At run time use Screen variable to retreive screen parameters.
I think it's a new feature for Win98 to work with several screens. Documentation should be available in the MSDN or some new versoin of WIN32S.HLP.
I think it's a new feature for Win98 to work with several screens. Documentation should be available in the MSDN or some new versoin of WIN32S.HLP.
The EnumDisplayMonitors function enumerates the display monitors that intersect a region formed by the intersection of a specified clipping rectangle
and the visible region of a device context. EnumDisplayMonitors calls an application-defined MonitorEnumProc callback function once for each display
monitor that intersects the region.
BOOL EnumDisplayMonitors (
HDC hdc, // handle to a display device context
LPCRECT lprcClip, // specifies a clipping rectangle
MONITORENUMPROC lpfnEnum, // pointer to a callback function
LPARAM dwData // data passed to the callback function
);
Parameters
hdc
Handle to a display device context that defines the visible region of interest.
If this parameter is NULL, the hdcMonitor parameter passed to the MonitorEnumProc calls will be NULL, and the visible region of interest is the
virtual screen that encompasses all the displays on the desktop.
lprcClip
Pointer to a RECT structure that specifies a clipping rectangle. The region of interest is the intersection of the clipping rectangle with the visible
region specified by hdc.
If hdc is non-NULL, the coordinates of the clipping rectangle are relative to the origin of the hdc. If hdc is NULL, the coordinates are virtual screen
coordinates.
This parameter can be NULL if you don't want to clip the region specified by hdc.
lpfnEnum
Pointer to a MonitorEnumProc application-defined callback function.
dwData
Application-defined data that EnumDisplayMonitors passes directly to the MonitorEnumProc function.
Return Values
If the function succeeds, the return value is nonzero
If the function fails, the return value is zero.
Windows NT: To get extended error information, call GetLastError. .
Remarks
There are two key reasons to call the EnumDisplayMonitors function:
You want to draw optimally into a device context that spans several display monitors, and the monitors have different color formats.
You want to obtain a handle and position rectangle for one or more display monitors.
To determine whether all the display monitors in a system share the same color format, call GetSystemMetrics(SM_SAMEDI
You do not need to use the EnumDisplayMonitors function when a window spans display monitors that have different color formats. You can continue to
paint under the assumption that the entire screen has the color properties of the primary monitor. Your windows will look fine. EnumDisplayMonitors just
lets you make them look better.
Setting the hdc parameter to NULL lets you use the EnumDisplayMonitors function to obtain a handle and position rectangle for one or more display
monitors. The following table shows how the four combinations of NULL and non-NULL hdc and lprcClip values affect the behavior of the
EnumDisplayMonitors function:
hdc
lprcRect
EnumDisplayMonitors Behavior
NULL
NULL
Enumerates all display monitors.
The callback function receives a NULL
HDC.
NULL
non-NULL
Enumerates all display monitors that
intersect the clipping rectangle. Use
virtual screen coordinates for the
clipping rectangle.
The callback function receives a NULL
HDC.
non-NULL
NULL
Enumerates all display monitors that
intersect the visible region of the device
context.
The callback function receives a handle
to a DC for the specific display monitor.
non-NULL
non-NULL
Enumerates all display monitors that
intersect the visible region of the device
context and the clipping rectangle. Use
device context coordinates for the
clipping rectangle.
The callback function receives a handle
to a DC for the specific display monitor.
Examples
To paint in response to a WM_PAINT message, using the capabilities of each monitor, you can use code like this in a window procedure:
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
EnumDisplayMonitors(hdc, NULL, MyPaintEnumProc, 0);
EndPaint(hwnd, &ps);
To paint the top half of a window using the capabilities of each monitor, you can use code like this:
GetClientRect(hwnd, &rc);
rc.bottom = (rc.bottom - rc.top) / 2;
hdc = GetDC(hwnd);
EnumDisplayMonitors(hdc, &rc, MyPaintEnumProc, 0);
ReleaseDC(hwnd, hdc);
To paint the entire virtual screen optimally for each display monitor, you can use code like this:
hdc = GetDC(NULL);
EnumDisplayMonitors(hdc, NULL, MyPaintScreenEnumProc, 0);
ReleaseDC(NULL, hdc);
To get information about all of the display monitors, you can use code like this:
EnumDisplayMonitors(NULL, NULL, MyInfoEnumProc, 0);
QuickInfo
Windows NT: Requires version 5.0 or later.
Windows: Requires Windows 98.
and the visible region of a device context. EnumDisplayMonitors calls an application-defined MonitorEnumProc callback function once for each display
monitor that intersects the region.
BOOL EnumDisplayMonitors (
HDC hdc, // handle to a display device context
LPCRECT lprcClip, // specifies a clipping rectangle
MONITORENUMPROC lpfnEnum, // pointer to a callback function
LPARAM dwData // data passed to the callback function
);
Parameters
hdc
Handle to a display device context that defines the visible region of interest.
If this parameter is NULL, the hdcMonitor parameter passed to the MonitorEnumProc calls will be NULL, and the visible region of interest is the
virtual screen that encompasses all the displays on the desktop.
lprcClip
Pointer to a RECT structure that specifies a clipping rectangle. The region of interest is the intersection of the clipping rectangle with the visible
region specified by hdc.
If hdc is non-NULL, the coordinates of the clipping rectangle are relative to the origin of the hdc. If hdc is NULL, the coordinates are virtual screen
coordinates.
This parameter can be NULL if you don't want to clip the region specified by hdc.
lpfnEnum
Pointer to a MonitorEnumProc application-defined callback function.
dwData
Application-defined data that EnumDisplayMonitors passes directly to the MonitorEnumProc function.
Return Values
If the function succeeds, the return value is nonzero
If the function fails, the return value is zero.
Windows NT: To get extended error information, call GetLastError. .
Remarks
There are two key reasons to call the EnumDisplayMonitors function:
You want to draw optimally into a device context that spans several display monitors, and the monitors have different color formats.
You want to obtain a handle and position rectangle for one or more display monitors.
To determine whether all the display monitors in a system share the same color format, call GetSystemMetrics(SM_SAMEDI
You do not need to use the EnumDisplayMonitors function when a window spans display monitors that have different color formats. You can continue to
paint under the assumption that the entire screen has the color properties of the primary monitor. Your windows will look fine. EnumDisplayMonitors just
lets you make them look better.
Setting the hdc parameter to NULL lets you use the EnumDisplayMonitors function to obtain a handle and position rectangle for one or more display
monitors. The following table shows how the four combinations of NULL and non-NULL hdc and lprcClip values affect the behavior of the
EnumDisplayMonitors function:
hdc
lprcRect
EnumDisplayMonitors Behavior
NULL
NULL
Enumerates all display monitors.
The callback function receives a NULL
HDC.
NULL
non-NULL
Enumerates all display monitors that
intersect the clipping rectangle. Use
virtual screen coordinates for the
clipping rectangle.
The callback function receives a NULL
HDC.
non-NULL
NULL
Enumerates all display monitors that
intersect the visible region of the device
context.
The callback function receives a handle
to a DC for the specific display monitor.
non-NULL
non-NULL
Enumerates all display monitors that
intersect the visible region of the device
context and the clipping rectangle. Use
device context coordinates for the
clipping rectangle.
The callback function receives a handle
to a DC for the specific display monitor.
Examples
To paint in response to a WM_PAINT message, using the capabilities of each monitor, you can use code like this in a window procedure:
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
EnumDisplayMonitors(hdc, NULL, MyPaintEnumProc, 0);
EndPaint(hwnd, &ps);
To paint the top half of a window using the capabilities of each monitor, you can use code like this:
GetClientRect(hwnd, &rc);
rc.bottom = (rc.bottom - rc.top) / 2;
hdc = GetDC(hwnd);
EnumDisplayMonitors(hdc, &rc, MyPaintEnumProc, 0);
ReleaseDC(hwnd, hdc);
To paint the entire virtual screen optimally for each display monitor, you can use code like this:
hdc = GetDC(NULL);
EnumDisplayMonitors(hdc, NULL, MyPaintScreenEnumProc, 0);
ReleaseDC(NULL, hdc);
To get information about all of the display monitors, you can use code like this:
EnumDisplayMonitors(NULL, NULL, MyInfoEnumProc, 0);
QuickInfo
Windows NT: Requires version 5.0 or later.
Windows: Requires Windows 98.
The GetMonitorInfo function lets you obtain information about a display monitor.
BOOL GetMonitorInfo(
HMONITOR hMonitor, // handle to display monitor
LPMONITORINFO lpmi // pointer to display monitor information
);
Parameters
hmonitor
Handle to the display monitor of interest.
lpmi
Pointer to a MONITORINFO structure or a MONITORINFOEX structure. The function stores information about the specified display monitor
in this structure.
You must set the cbSize member of the structure to sizeof(MONITORINFO) or sizeof(MONITORINFOEX) before calling the GetMonitorInfo
function. Doing so lets the function determine the type of structure you are passing to it.
The MONITORINFOEX structure is a superset of the MONITORINFO structure. It has one additional member: a string member, to contain a
name for the display monitor. Most applications have no use for a display monitor name, and so can save some bytes by using a MONITORINFO
structure.
Return Values
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero.
Windows NT: To get extended error information, call GetLastError. .
QuickInfo
Windows NT: Requires version 5.0 or later.
Windows: Requires Windows 98.
BOOL GetMonitorInfo(
HMONITOR hMonitor, // handle to display monitor
LPMONITORINFO lpmi // pointer to display monitor information
);
Parameters
hmonitor
Handle to the display monitor of interest.
lpmi
Pointer to a MONITORINFO structure or a MONITORINFOEX structure. The function stores information about the specified display monitor
in this structure.
You must set the cbSize member of the structure to sizeof(MONITORINFO) or sizeof(MONITORINFOEX) before calling the GetMonitorInfo
function. Doing so lets the function determine the type of structure you are passing to it.
The MONITORINFOEX structure is a superset of the MONITORINFO structure. It has one additional member: a string member, to contain a
name for the display monitor. Most applications have no use for a display monitor name, and so can save some bytes by using a MONITORINFO
structure.
Return Values
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero.
Windows NT: To get extended error information, call GetLastError. .
QuickInfo
Windows NT: Requires version 5.0 or later.
Windows: Requires Windows 98.
This helps a lot. But I am still stuck. How do I know on which
display my active form is. I need to change the size according to this.
display my active form is. I need to change the size according to this.
Hi, these will help I guess:
The MonitorFromWindow function obtains a handle to the display monitor that has the largest area of intersection with the bounding rectangle of a specified window.
HMONITOR MonitorFromWindow(
HWND hwnd, // handle to a window
DWORD dwFlags // flags if no monitor intersects the window
);
Parameters
hwnd
Handle to the window of interest.
dwFlags
A set of flags that determine the function's return value if the window does not intersect any display monitor.
This parameter can be one of the following values.
Value
Meaning
MONITOR_DEFAULTTONEAREST
Return a handle to the display monitor that is nearest to the window.
MONITOR_DEFAULTTONULL
Return NULL.
MONITOR_DEFAULTTOPRIMARY
Return a handle to the primary display monitor.
Return Values
If the window intersects one or more display monitor rectangles, the return value is an HMONITOR handle to the display monitor that has the largest area of intersection with
the window.
If the window does not intersect a display monitor, the return value depends on the value of dwFlags.
Remarks
If the window is currently minimized, MonitorFromWindow uses the rectangle of the window before it was minimized.
The MonitorFromWindow function obtains a handle to the display monitor that has the largest area of intersection with the bounding rectangle of a specified window.
HMONITOR MonitorFromWindow(
HWND hwnd, // handle to a window
DWORD dwFlags // flags if no monitor intersects the window
);
Parameters
hwnd
Handle to the window of interest.
dwFlags
A set of flags that determine the function's return value if the window does not intersect any display monitor.
This parameter can be one of the following values.
Value
Meaning
MONITOR_DEFAULTTONEAREST
Return a handle to the display monitor that is nearest to the window.
MONITOR_DEFAULTTONULL
Return NULL.
MONITOR_DEFAULTTOPRIMARY
Return a handle to the primary display monitor.
Return Values
If the window intersects one or more display monitor rectangles, the return value is an HMONITOR handle to the display monitor that has the largest area of intersection with
the window.
If the window does not intersect a display monitor, the return value depends on the value of dwFlags.
Remarks
If the window is currently minimized, MonitorFromWindow uses the rectangle of the window before it was minimized.
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HMONITOR MonitorFromPoint(
POINT pt, // a specified point
DWORD dwFlags // flags if no monitor contains specified point
);
Parameters
pt
A POINT structure that specifies the point of interest.
dwFlags
A set of flags that determine the function's return value if the point is not contained within any display monitor.
This parameter can be one of the following values.
Value
Meaning
MONITOR_DEFAULTTONEAREST
Return a handle to the display monitor that is nearest to the point.
MONITOR_DEFAULTTONULL
Return NULL.
MONITOR_DEFAULTTOPRIMARY
Return a handle to the primary display monitor.
Return Values
If the point is contained by a display monitor, the return value is an HMONITOR handle to that display monitor.
If the point is not contained by a display monitor, the return value depends on the value of dwFlags.
__________________________
The MonitorFromRect function obtains a handle to the display monitor that has the largest area of intersection with a specified rectangle.
HMONITOR MonitorFromRect(
LPCRECT lprc, // pointer to a RECT structure
DWORD dwFlags // flags if no monitor intersects the rectangle
);
Parameters
lprc
Pointer to a RECT structure that specifies the rectangle of interest.
dwFlags
A set of flags that determine the function's return value if the rectangle does not intersect any display monitor.
This parameter can be one of the following values.
Value
Meaning
MONITOR_DEFAULTTONEAREST
Return a handle to the display monitor that is nearest to the rectangle.
MONITOR_DEFAULTTONULL
Return NULL.
MONITOR_DEFAULTTOPRIMARY
Return a handle to the primary display monitor.
Return Values
If the rectangle intersects one or more display monitor rectangles, the return value is an HMONITOR handle to the display monitor that has the largest area of intersection with
the rectangle.
If the rectangle does not intersect a display monitor, the return value depends on the value of dwFlags.
__________________________
Good luck!
--Matvey