QTransform

QTransform is a class in the Qt framework that encapsulates a 3x3 matrix to perform 2D geometric transformations. It is primarily used to represent and apply affine transformations in two dimensions, including translation, rotation, scaling, and shearing. The transform can be combined with other transforms to build complex coordinate mappings.

A QTransform stores its transformation as a matrix and provides a range of operations to modify or combine transforms. It can be constructed as an identity transform or initialized with specific matrix components. Transforms can be composed by multiplying two QTransform objects, producing a new transform that applies one after the other. The class also supports inversion, allowing the calculation of an inverse transform for reversing a mapping, provided the transform is invertible.

Mapping capabilities are a core feature. QTransform can map numerous geometric primitives, such as points, rectangles, and polygons, from one coordinate space to another. The map functions are used to transform coordinates quickly and efficiently. In practice, QTransform is frequently used to adjust coordinate spaces in rendering pipelines.

In Qt applications, QTransform is commonly applied through painting operations. It can be set as the current transformation for a QPainter, affecting how shapes, images, and text are drawn. This makes it a fundamental tool for implementing view transforms, camera effects, or any scenario that requires consistent 2D coordinate manipulation.

Overall, QTransform provides a concise, flexible way to represent and compose 2D transformations within the Qt ecosystem, supporting efficient coordinate mapping and integration with the rendering pipeline.