QwtPlotGrid, precise grid and backgroundimage

[Momergil]

Hello!

In my software where I need to plot a QwtPlot showing medical, ECG-like curves, I need a grid that simulate a graph paper with precision - because I will add a print possibility that when the printing will be done, the result in the paper will have to be in precise scale so it can be measured with ruler or caliper rule by a doctor.

Essentially what I'm doing is to copy the following graph (that was done using OpenGL) to Qwt code:

Curvas - 2.jpg

Question: is that possible?


Thanks,

Momergil

[FelixB]

Hi,

a QwtPlotGrid paints the lines at the ticks of the corresponding axis. Give it a try, it should be precise enough.

Felix

[Momergil]

Hi,

a QwtPlotGrid paints the lines at the ticks of the corresponding axis. Give it a try, it should be precise enough.

Felix

Well, i'm already using QwtPlotGrid, but it's being quite hard to find exactly the "coordinates" to plot the graph paper. So if there is a better solution, I'ld be glad to test it.


Momergil

[FelixB]

could you explan that a bit more? I don't understand what you mean "find exactly the coordinates to plot the graph paper".

Felix

[Spitfire]

I'm guessing he wants the grid on the plot to align exacly with the grid on the paper he later prints on.

[engy oun]

hellow every body ,i need help from you to read file .ecg and plot it by using qwt ,
i need this in the nearest time because this help me in my project

---

Added after 43 minutes:

i need help ,how i plot data coming from file.ecg ?

[d_stranz]

What is this, you and Ahmed Ali all have the same homework assignment?

First, NO ONE HERE knows what an "ecg" file is, as has been explained over and over to Ahmed. If it is a binary file, and you do not know the format, no one else here will either. "ecg" is simply a file extension, it could contain almost any format imaginable.

Once you have read the file into one or more arrays of (x, y) pairs, then it is extremely simple to plot this using Qwt. Simply look at the Qwt examples and substitute your x,y data for the x,y data in the example.

And don't hijack someone's thread to ask a new question. Start a new thread.

---

Added after 5 minutes:

I'm guessing he wants the grid on the plot to align exacly with the grid on the paper he later prints on.

That would be nearly impossible, I think. Even if he did get it right for one printer, another printer might behave completely differently, or even the same printer with a different output setting (like fit to page vs. no scaling). And if I remember correctly, Qwt will layout the width of the y-axis depending on the precision of the numbers on the ticks, so if the ticks change, the layout changes, too.