![]() ![]() While it is easy to determine the necessary values of these parameters for a non-rotated rectangle, it is an entirely different matter when we are dealing with more complex polygons. All of them require parameters, which define the arc center and size, starting angle and the arc length. The entire process can be illustrated in the figure below.Ĭlass QPainter has some overloaded methods named drawArc, which can draw circular arcs. How could we do that with a polygon, a planar shape bounded by a group of straight line segments? If we have a polygon drawn with a pencil on a piece of paper, my first idea would be to use an eraser and delete a small part of the lines at each corner and then connect the remaining segment ends with a circular arc. But if we need a little more complex shape, we have to implement it ourselves. It has a method called drawRoundedRect, which, just as the name suggests, draws a rectangle with rounded corners. For example, Qt framework has a class QPainter, which is used to draw on all classes derived from QPaintDevice, including widgets, pixmaps, and images. But what happens, when we have to generate a shape with rounded corners on the fly, and we cannot preload it? Some programming libraries offer limited capabilities for creating predefined shapes with rounded corners, but usually, they cannot be used in more complicated cases. ![]() The visual elements of user interfaces are created by designers, and the programmer only has to put them in the right places.
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