How to make plot from file WinAPI

Question

We have txt file with numbers:

60 0

120 4

180 20

60 -28

180 28

30 -28

30 28

30 -28

60 0

I need a plot with first column in horizontal coordinate line and the second column in vertical coordinate line like on this picture. But now I have smth like this

std::ifstream omega_file("test.txt");

MoveToEx(hdc, 0, 0, NULL); // start point
double T_new = 0;
while (!omega_file.eof())
{
    omega_file >> T >> Omega;

    T_new = T_new + T;

    LineTo(hdc, T_new / 60 * horizontal_step_grid, - Omega * vertical_step_grid);
    MoveToEx(hdc, T_new / 60 * horizontal_step_grid, - Omega * vertical_step_grid, NULL);
}

To begin with, your usage of `while (!omega_file.eof())` is [wrong](http://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-considered-wrong). — MikeCAT, Jul 17 '22 at 09:10

score 1 · Accepted Answer · answered Jul 17 '22 at 09:30

You will need to draw two lines (horizontal, then vertical) instead of one per one coordinate.

Also note that LineTo() sets the current position, so MoveToEx() to the same coordinate is redundant.

Try this:

std::ifstream omega_file("test.txt");

MoveToEx(hdc, 0, 0, NULL); // start point
int currentY = 0;
double T_new = 0;
while (omega_file >> T >> Omega)
{

    T_new = T_new + T;

    int x = T_new / 60 * horizontal_step_grid;
    int nextY = - Omega * vertical_step_grid;
    LineTo(hdc, x, currentY);
    LineTo(hdc, x, nextY);
    currentY = nextY;
}

but i understood that now there is a problem with scale. Blue - program plot, red - plot which should be. One horizontal step is 30 seconds (for example, if in first column there is 60, it should be two steps) https://ibb.co/PFf6jC9 — , Jul 17 '22 at 16:24

How to make plot from file WinAPI

1 Answers1