可以改变！MM_HIMETRIC Each logical unit is converted to 0.01 millimeter. Positive x is to the right; positive y is up. MM_ISOTROPIC Logical units are converted to arbitrary units with equally scaled axes; that is, 1 unit along the x-axis is equal to 1 unit along the y-axis. Use the SetWindowExt and SetViewportExt member functions 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 converted to 0.01 inch. Positive x is to the right; positive y is up. MM_LOMETRIC Each logical unit is converted to 0.1 millimeter. Positive x is to the right; positive y is up. MM_TEXT Each logical unit is converted to 1 device pixel. Positive x is to the right; positive y is down. MM_TWIPS Each logical unit is converted to 1/20 of a point. (Because a point is 1/72 inch, a twip is 1/1440 inch.) Positive x is to the right; positive y is up.
int SetMapMode( HDC hdc, // handle to device context int fnMapMode // new mapping mode ); 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. 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. Graphics device interface (GDI) makes adjustments as necessary to ensure the x and y units remain the same size (When the window extent is set, 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.
MM_HIENGLISH MM_HIMETRIC MM_LOENGLISH MM_LOMETRIC MM_TWIPS x轴向右，y轴向上MM_TEXT x轴向右，y轴向下
MM_ISOTROPIC Logical units are converted to arbitrary units with equally scaled axes; that is, 1 unit along the x-axis is equal to 1 unit along the y-axis. Use the SetWindowExt and SetViewportExt member functions 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 converted to 0.01 inch. Positive x is to the right; positive y is up.
MM_LOMETRIC Each logical unit is converted to 0.1 millimeter. Positive x is to the right; positive y is up.
MM_TEXT Each logical unit is converted to 1 device pixel. Positive x is to the right; positive y is down.
MM_TWIPS Each logical unit is converted to 1/20 of a point. (Because a point is 1/72 inch, a twip is 1/1440 inch.) Positive x is to the right; positive y is up.
HDC hdc, // handle to device context
int fnMapMode // new mapping mode
);
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.
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. Graphics device interface (GDI) makes adjustments as necessary to ensure the x and y units remain the same size (When the window extent is set, 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.