On 21/06/18 11:51, Massimiliano Maini wrote:
I'd need to do something like this: https://imgur.com/MLAEuadI have a set of (x,y,z) data points and want to plot them on a usual 2d plot ( x and y values), but with the line color depending on the z values (colormap).How can this be achieved in Qt ?
I'm not sure if I understood correctly; the graph in the picture isn't using a third independent variable for the color of each point, rather it's just using the y (in other words: the color of each point in the line is just a function of its y coordinate.)
Anyhow, short of using a complete graphing solution, you can easily generate a vertical gradient using QLinearGradient (with the number of stops you need), and the curve as a QPainterPath. Then you have a couple of easy options:
1) set the curve as a clip path on a QPainter, and fill a rectangle with the gradient (=> only the path will be filled), or
2) create a transparent QImage of suitable size, draw the path in some solid color, and draw a rectangle filled with the gradient over the path using some composition mode, e.g. SourceIn. Then draw the image on your chart.
HTH, -- Giuseppe D'Angelo | [email protected] | Senior Software Engineer KDAB (France) S.A.S., a KDAB Group company Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com KDAB - The Qt, C++ and OpenGL Experts
smime.p7s
Description: S/MIME Cryptographic Signature
_______________________________________________ Interest mailing list [email protected] http://lists.qt-project.org/mailman/listinfo/interest
