1.415 cuts off miters at angles less than 90 degrees, and converts them to bevels.| #define SETMITERLIMIT 23 |
| short Control(lpDevice, SETMITERLIMIT, lpInData, lpOutData) | |||
| LPPDEVICE lpDevice; | |||
| LPWORD lpInData; | |||
| LPWORD lpOutData; |
The SETMITERLIMIT escape tells the driver how an application wants to clip off miter-type line joins when they become too long. It sets the current miter-limit parameter in the graphics state to a number greater than or equal to one.
lpDevice
Points to a PDEVICE structure specifying the destination device.
lpInData
Points to a 16-bit variable that specifies the miter-limit value. If this parameter is NULL, the escape does not change the miter-limit value.
lpOutData
Points to a 16-bit variable that receives the previous or current miter-limit value (if the lpInData parameter is NULL). If this parameter is NULL, the escape does not return to the previous limit.
The return value is TRUE if the escape is successful. Otherwise, it is FALSE.
The miter limit controls the stroke operator's treatment of corners when miter joins have been specified. For more information about miter joins, see the SETLINEJOIN escape.
When path segments connect at a sharp angle, a miter join results in a spike that extends well beyond the connection point. The purpose of the miter limit is to cut off such spikes when they become too long.
At any given corner, the miter length is the distance from the point at which the inner edges of the strokes intersect to the point at which the outside edges of the strokes intersect (that is, the diagonal length of the miter). This distance increases as the angle between the segments decreases. If the ratio of the miter length to the line width exceeds the miter-limit parameter, the corner is treated with a bevel join instead of a miter join.
The ratio of miter length to line width is directly related to the angle alpha between the segments by the formula:
miter-length / line-width = 1 / sin(alpha/2)
The following are examples of miter-limit values:
1.415 cuts off miters at angles less than 90 degrees, and converts them to bevels.
2.0 cuts off miters at angles less than 60 degrees.
10.0 cuts off miters at angles less than 11 degrees.
The default value of the miter limit is 10. Setting the miter limit to 1 cuts off miters at all angles so that bevels are always produced even when miters are specified.