SetMapMode
The SetMapMode
function sets the mapping mode of the specified device context. The mapping
mode defines the unit of measure used to transform page-space units into
device-space units, and also defines the orientation of the device s x and y
axes.
int SetMapMode(
|
HDC hdc, |
// handle of device
context |
|
int fnMapMode |
// new mapping mode
|
|
); |
|
Parameters
hdc
Identifies
the device context.
fnMapMode
Specifies the
new mapping mode. It can be any one of the following values:
|
Value |
Description |
|
MM_ANISOTROPIC |
Logical
units are mapped to arbitrary units with arbitrarily scaled axes. Use the SetWindowExtEx and SetViewportExtEx functions to specify the
units, orientation, and scaling that you want. |
|
MM_HIENGLISH |
Each
logical unit is mapped to 0.001 inch. Positive x is to the right; positive y
is up. |
|
MM_HIMETRIC |
Each
logical unit is mapped to 0.01 millimeter. Positive x is to the right;
positive y is up. |
|
MM_ISOTROPIC |
Logical
units are mapped to arbitrary units with equally scaled axes; that is, one unit
along the x-axis is equal to one unit along the y-axis. Use the SetWindowExtEx
and SetViewportExtEx functions to specify the units and the
orientation of the axes that you want. Graphics device interface (GDI) makes
adjustments as necessary to ensure the x and y units remain the same size
(for example, if you set the window extent, the viewport will be adjusted to
keep the units isotropic). |
|
MM_LOENGLISH |
Each
logical unit is mapped to 0.01 inch. Positive x is to the right; positive y
is up. |
|
MM_LOMETRIC |
Each
logical unit is mapped to 0.1 millimeter. Positive x is to the right;
positive y is up. |
|
MM_TEXT |
Each
logical unit is mapped to one device pixel. Positive x is to the right;
positive y is down. |
|
MM_TWIPS |
Each
logical unit is mapped to one twentieth of a printer s point (1/1440 inch,
also called a twip ). Positive x is to the right; positive y is up. |
Return Values
If the
function succeeds, the return value identifies the previous mapping mode.
If the
function fails, the return value is zero.
Remarks
The MM_TEXT
mode allows applications to work in device pixels, whose size varies from
device to device.
The
MM_HIENGLISH, MM_HIMETRIC, MM_LOENGLISH, MM_LOMETRIC, and MM_TWIPS modes are
useful for applications drawing in physically meaningful units (such as inches
or millimeters).
The
MM_ISOTROPIC mode ensures a 1:1 aspect ratio.
The
MM_ANISOTROPIC mode allows the x-coordinates and y-coordinates to be adjusted
independently.
See Also