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# QLineF Class Reference
[com.trolltech.qt.gui module]

The `QLineF` class provides a two-dimensional vector using floating point precision. More...

## Detailed Description

The `QLineF` class provides a two-dimensional vector using floating point precision.

A `QLineF` describes a finite length line (or line segment) on a two-dimensional surface. `QLineF` defines the start and end points of the line using floating point accuracy for coordinates. Use the `toLine` function to retrieve an integer based copy of this line.

The positions of the line's start and end points can be retrieved using the `p1`, `x1`, `y1`, `p2`, `x2`, and `y2` functions. The `dx` and `dy` functions return the horizontal and vertical components of the line, respectively.

The line's length can be retrieved using the `length` function, and altered using the `setLength` function. Use the `isNull` function to determine whether the `QLineF` represents a valid line or a null line.

The intersect() function determines the `IntersectType` for this line and a given line, while the `angle` function returns the angle between the lines. In addition, the `unitVector` function returns a line that has the same starting point as this line, but with a length of only 1, while the `normalVector` function returns a line that is perpendicular to this line with the same starting point and length.

Finally, the line can be translated a given offset using the `translate` function, and can be traversed using the `pointAt` function.

See also `QLine`, `QPolygonF`, and `QRectF`.