How to use DEVMODE

I received a question about how to use DEVMODE. Below is some sample code that retrieves the screen’s current width/height screen resolution and rotates it for a few seconds if supported by your machine (mostly on Tablet PCs)


The user’s question continues:


The printer properties you can control start with DM_ORIENTATION and go through DM_DITHERTYPE.  Each constant represents the bit in DM_FIELDS for that property, but there's a gap in the sequence between DM_SCALE and DM_COPIES.  Why aren't the bits for 32, 64 and 128 used?



There is no rule saying that all values in a bitfield must be used. An API can define bit 1 to mean A, bit 4 to mean B, but bits 2 and 3 do not have to be defined.  Also, APIs evolve as the OS version changes to support newer hardware/software. However, the #define’s below show that 32, 64 and 128 are used for DM_POSITION, DM_NUP, DM_DISPLAYORIENTATION



DEVMODE is defined in C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\wingdi.h

It’s a little bit complex with some #ifdefs and macros. WINVER is 0x0501 for Windows XP


typedef struct _devicemodeA {

    BYTE   dmDeviceName[CCHDEVICENAME];

    WORD dmSpecVersion;

    WORD dmDriverVersion;

    WORD dmSize;

    WORD dmDriverExtra;

    DWORD dmFields;

    union {

      /* printer only fields */

      struct {

        short dmOrientation;

        short dmPaperSize;

        short dmPaperLength;

        short dmPaperWidth;

        short dmScale;

        short dmCopies;

        short dmDefaultSource;

        short dmPrintQuality;


      /* display only fields */

      struct {

        POINTL dmPosition;

        DWORD  dmDisplayOrientation;

        DWORD  dmDisplayFixedOutput;



    short dmColor;

    short dmDuplex;

    short dmYResolution;

    short dmTTOption;

    short dmCollate;

    BYTE   dmFormName[CCHFORMNAME];

    WORD   dmLogPixels;

    DWORD  dmBitsPerPel;

    DWORD  dmPelsWidth;

    DWORD  dmPelsHeight;

    union {

        DWORD  dmDisplayFlags;

        DWORD  dmNup;


    DWORD  dmDisplayFrequency;

#if(WINVER >= 0x0400)

    DWORD  dmICMMethod;

    DWORD  dmICMIntent;

    DWORD  dmMediaType;

    DWORD  dmDitherType;

    DWORD  dmReserved1;

    DWORD  dmReserved2;

#if (WINVER >= 0x0500) || (_WIN32_WINNT >= 0x0400)

    DWORD  dmPanningWidth;

    DWORD  dmPanningHeight;


#endif /* WINVER >= 0x0400 */




From that same file:


/* field selection bits */

#define DM_ORIENTATION          0x00000001L

#define DM_PAPERSIZE            0x00000002L

#define DM_PAPERLENGTH          0x00000004L

#define DM_PAPERWIDTH           0x00000008L

#define DM_SCALE                0x00000010L

#if(WINVER >= 0x0500)

#define DM_POSITION             0x00000020L

#define DM_NUP                  0x00000040L

#endif /* WINVER >= 0x0500 */

#if(WINVER >= 0x0501)

#define DM_DISPLAYORIENTATION   0x00000080L

#endif /* WINVER >= 0x0501 */

#define DM_COPIES               0x00000100L

#define DM_DEFAULTSOURCE        0x00000200L

#define DM_PRINTQUALITY         0x00000400L

#define DM_COLOR                0x00000800L

#define DM_DUPLEX               0x00001000L

#define DM_YRESOLUTION          0x00002000L

#define DM_TTOPTION             0x00004000L

#define DM_COLLATE              0x00008000L

#define DM_FORMNAME             0x00010000L

#define DM_LOGPIXELS            0x00020000L

#define DM_BITSPERPEL           0x00040000L

#define DM_PELSWIDTH            0x00080000L

#define DM_PELSHEIGHT           0x00100000L

#define DM_DISPLAYFLAGS         0x00200000L

#define DM_DISPLAYFREQUENCY     0x00400000L

#if(WINVER >= 0x0400)

#define DM_ICMMETHOD            0x00800000L

#define DM_ICMINTENT            0x01000000L

#define DM_MEDIATYPE            0x02000000L

#define DM_DITHERTYPE           0x04000000L

#define DM_PANNINGWIDTH         0x08000000L

#define DM_PANNINGHEIGHT        0x10000000L

#endif /* WINVER >= 0x0400 */

#if(WINVER >= 0x0501)

#define DM_DISPLAYFIXEDOUTPUT   0x20000000L

#endif /* WINVER >= 0x0501 */




Here’s the VFP code to change the screen orientation. Check out the uses of BINTOC and CTOBIN  (see also Tools->Task Pane->Solution Samples->New in VFP9->BINTOC Binary Conversion and Floating Point calculations: comparing with zero). The string offsets are offsets into the DEVMODE structure. They are easy to figure out in a debugger, especially with the macros, unions and nested structures. Just put &(*(DEVMODE *)0).dmDisplayOrientation in the watch window and 0x00000034 (52 base 10) is displayed. (That says interpret the address at 0 as a DEVMODE structure and give the address of the dmDisplayOrientation member.) The SUBSTR function is 1 based, so the SUBSTR offset of dmDisplayOrientation is 53.





#define ENUM_CURRENT_SETTINGS       0xffffffff

#define ENUM_REGISTRY_SETTINGS      0xfffffffe

#define DMDO_DEFAULT    0

#define DMDO_90         1

#define DMDO_180        2

#define DMDO_270        3

#define DM_DISPLAYORIENTATION   0x00000080









PROCEDURE SetDisplay(nOrientation as Integer)



      DECLARE integer EnumDisplaySettings IN WIN32API integer,integer,string @

      DECLARE integer ChangeDisplaySettings IN WIN32API string @, integer


      IF EnumDisplaySettings(0,ENUM_CURRENT_SETTINGS,@cDevmode)=0






      ?"Screen dimensions are ",nWidth,"X",nHeight






            nDisplay = CTOBIN(SUBSTR(cDevmode,53,4),"4sr")

            ?"Current DisplayOrientation=",nDisplay

            IF nOrientation != nDisplay   && if different


                  DO CASE

                  CASE INLIST(nOrientation,DMDO_DEFAULT,DMDO_180)

                        fSwap = !fLandscape     && if it wasn't lasndscape, we need to swap x,y pixels

                  CASE INLIST(nOrientation,DMDO_90,DMDO_270)

                        fSwap = fLandscape


                  IF fSwap








                  n= ChangeDisplaySettings(@cDevmode,0)

                  IF n=0







            ?"Can't get Display Orientation"





Comments (8)
  1. Barbara Peisch says:

    Thanks for answering my question. I hadn’t thought about those bits being used for some other purpose than printer properties. (Just focused too narrowly on printing at the moment.) Thanks too for pointing out BINTOC and CTOBIN. I had been using other UDFs to do that were much more cumbersome.

    See you in Phoenix!


  2. Hank Fay says:

    Very interesting, thanks.

    Hmm… looks like a great tool addition to VFP to increase interoperability: feed the class method a struct definition as a text string, get back an object that has the offsets built-in for getting/setting values given an initial address.

  3. Barbara Peisch says:

    Hank, I’ve been working on something sort of like this. I have a class that accepts the constants (or value) for the property you want to change and the setting and returns the modified DEVMODE structure to you. Right now it only works for the printer properties. And I need to switch it to using the BINTOC and CTOBIN functions, but you can download a version of this now from The file is

  4. akajai says:

    Input devmode is always NULL in DrvDocumentPropertySheet

  5. nestor says:

    i need to know how to get the amounth of copies of acopies of a report in order to save in a file this is done in Oracle.                                                                                                                                                                                          

  6. nestle28 says:

    I need to get the dm_copies from the file devmode,  how may I get it?

  7. it should be:

    #define DMDO_270        4 // not 3

    check the microsoft include files…

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