XY plots with color squares -- i.e. shmoo plots

[Uwe]

What's the best way to represent XY plots with color squares, as typified by "shmoo plots"?

There are plot and paint device coordinates - how are your squares related to these coordinate systems ?

Uwe

[alketi]

There are plot and paint device coordinates - how are your squares related to these coordinate systems ?

So, in the attached image the relationship would be:
PLOT COORDINATES
x=10
y=2.5

DATA COORDINATES
x=0
y=0

The squares could be just a simple 2D array of color, as in:

QColor shmoo[10][10];
shmoo [0][0] = QColor("red");

But, they could also be represented in another way, if that's easier.

My requirements are
1. Create a plot that looks like the attached
2. Allow the user to click on a specific square and, in plot coordinates, re-measure that point. So, in the example below, clicking anywhere inside the lower-left point would tell me to re-measure Freq(x)=10MHz, Voltage(y)=2.5V.

What is the best way to draw color squares in Qwt that accomplishes these two goals?

Thank you for your guidance Uwe.

image5224074054341222068.jpg

[Uwe]

The squares could be just a simple 2D array of color, ...

This can be done with a QwtPlotSpectrogram.

QwtMatrixRasterData in NearestNeighbur mode is close to what you want to do - see the rasterview example.

Allow the user to click on a specific square and, in plot coordinates, re-measure that point.

Using QwtPlotPicker you have the plot coordinates of each click.

Uwe