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CDC::SetMapMode
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──Microsoft Foundation Classes──────────────────────────────────────────────
int SetMapMode( int nMapMode );
Parameter Description
<nMapMode> Specifies the new mapping mode. It can be any one of the
following values:
Value Meaning
MM_ANISOTROPIC Logical units are mapped to arbitrary units
with arbitrarily scaled axes. The
◄SetWindowExt► and ◄SetViewportExt► member
functions of class CDC must be used to
specify the desired units, orientation, and
scaling.
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. The SetWindowExt and
SetViewportExt member functions of class
CDC must be used to specify the desired
units and the orientation of the axes. GDI
makes adjustments as necessary to ensure
that the x and y units remain the same
size.
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). Positive x is to the right; positive
y is up.
Remarks
Sets the mapping mode. The mapping mode defines the unit of measure used
to transform logical units into device units, and also defines the
orientation of the device's x- and y-axes. GDI uses the mapping mode to
convert logical coordinates into the appropriate device coordinates. 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 that need to draw in physically
meaningful units (such as inches or millimeters). The MM_ISOTROPIC mode
ensures a 1:1 aspect ratio, which is useful when it is important to
preserve the exact shape of an image. The MM_ANISOTROPIC mode allows the
x- and y-coordinates to be adjusted independently.
Return Value
The previous mapping mode.
See Also
◄CDC::SetViewportExt►, ◄CDC::SetWindowExt►, ◄::SetMapMode►
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