The DEVMODE structure is used for the environment and the initialization data (which are the same). By convention, all drivers place the device name in the first 32 bytes of DEVMODE as a null-terminated string. All the other data is device dependent.
For Windows 3.x, a new convention has been adopted that defines an additional number of members. These members enable the application to perform device-independent manipulations of the device environment.
When Enable is called, the device driver should first check the lpInitData parameter to see if the application has supplied valid initialization data. If it is valid, then the driver should use that environment to initialize the GDIINFO and PDEVICE structures and not use or modify the default environment information.
If the environment cannot be found or if the data obtained is invalid or intended for another device, the device driver should extract user settings from the WIN.INI file, by using the profile string functions, such as GetProfileInt.
However, the driver should contain useful defaults for all strings, so that it can create a valid environment even if the WIN.INI file is empty.
The driver should use the device name string at the beginning of the DEV-MODE structure to determine whether or not the environment obtained from
GetEnvironment is correct.
A driver may also maintain additional information in its DEVMODE structure to determine validity if the device name matches one the driver supports.
The printer driver can set or delete the environment by using the Set-Environment function (GDI.132). It can retrieve the current environment using the GetEnvironment function (GDI.133).
The driver should always set up the default environment if it is not present, except when the driver is initialized with a non-default environment (that is, the lpInitData parameter to Enable points to application-supplied data).
The dmYResolution and dmTTOption members in the DEVMODE structure are new for Windows 3.1. The DEVMODE structure returned by the ExtDeviceMode function contains one or both of these members if the dmField member includes the following values:
DM_YRESOLUTION 0x0002000L
DM_TTOPTION 0x0004000L
The dmYResolution member specifies the vertical resolution of the printer in dots per inch. In this case, the dmPrintQuality member specifies the horizontal resolution in dots per inch. If the DM_YRESOLUTION bit is not set in dmFields, dmYResolution is not used and dmPrintQuality retains the original meaning.
The dmTTOption member specifies how TrueType fonts should be printed. The member can be set to one of the following values.
| Value | Meaning |
| DMTT_BITMAP (1) | Prints TrueType fonts as graphics. |
| DMTT_DOWNLOAD (2) | Downloads TrueType fonts as soft fonts. |
| DMTT_SUBDEV (3) | Substitutes device fonts for TrueType. |
Note:
Before calling the the CreateDC or CreateIC functions, an application should call the DeviceCapabilities function with the DC_TRUETYPE index to retrieve the driver's TrueType capabilities. The application can use the value returned by the driver to set the dmTTOption member to the appropriate value.
The default action is to download TrueType as soft fonts for Hewlett-Packard printers that use PCL; substitute device fonts for TrueType for PostScript printers; and to print TrueType fonts as graphics for dot-matrix printers.