将笛卡尔坐标转换为图片框坐标c＃

Question

The question I have is more of mathematics! I have some pair of values that reperesent points of a curve that I want to draw on a picturebox using fromImage(Bitmap). My picture box is sized at 500x500. I also know that the top-left corner has point of (0,0) and bottom right corner has points of (500,500). Obviously the origin should be (250,250). Now I am wondering how can I convert my own values to this format?

A sample points that I have are like:

Voltage: -0.175         Current: -9.930625E-06
Voltage: -0.171875      Current: -9.53375E-06
Voltage: -0.16875       Current: -9.136875E-06
Voltage: -0.16875       Current: -8.74E-06
Voltage: -0.165625      Current: -8.343125E-06
Voltage: -0.1625        Current: -7.94625E-06
Voltage: -0.1625        Current: -7.549375E-06
Voltage: -0.159375      Current: -7.152188E-06
Voltage: -0.15625       Current: -6.755312E-06

You see there are Voltage values which should be on X axis and Current on Y axis. I know that to make them a bit better I have to multiply them in a bigger number and also maybe multiply by an inverse or something. but I still cant figure out how to represent them on my picturebox. These points are usually start from 3rd quadrant and end up in first quadrant. Please assist!

Just to add that my X axis min and max are -2V and +2V and for Y Axis I would have -10uA to +10uA (that is 10*10^-6)

EDIT

What I am trying to do is have a curve like these, so those points I have are used in Graphics.DrawCurve:

UPDATE This is how my code looks like:

            g.DrawLine(penAxis, 250, 0, 250, 500); // Y AXIS 
        g.DrawLine(penAxis, 0, 250, 500, 250); // X AXIS          

        PointF[] p = new PointF[pinData.GetLength(0)];   //pinData is AboutBoxForm double[,] array

        for (int i = 0; i < pinData.GetLength(0); i++)
        {
            p[i] = new PointF(250 * ((1 + (float)pinData[i, 0]) / 2), 250 * ((1 + (float)pinData[i, 1] )/ 10));  
        }

        Pen pengraph = new Pen(pinColor, 2.0F);
        g.DrawCurve(pengraph, p);

PROGRESS UPDATE

ok now using the code below my curve looks like:

            g.DrawLine(penAxis, 250, 0, 250, 500); // Y AXIS 
        g.DrawLine(penAxis, 0, 250, 500, 250); // X AXIS          

        PointF[] p = new PointF[pinData.GetLength(0)];   //pinData is AboutBoxForm double[,] array

        for (int i = 0; i < pinData.GetLength(0); i++)
        {
            p[i] = new PointF(250 * (1 - ((float)pinData[i, 1] *100000) / 10), 250 * (1 + (((float)pinData[i, 0]))/ 2));  
        }

        Pen pengraph = new Pen(pinColor, 2.0F);
        g.DrawCurve(pengraph, p);

I think now the problem is scaling it. SOLVED I had to multiply by 10^6 but I did with ^5 no it is ok!!! Thanks all.

Answer 1

If you want scaling to fit screen multiply each voltage and current value by 50 .

All your points lie in third quadrant ; you can choose origin (0, 0) on your screen and make all your negative x-axis points positive, ie flip along y-axis .

If you don't want scaling, keep multiplication factor unity.

Answer 2

To use the entire range of the picture box, with (V,C) = (0, 0) being mapped to the centre, you can use the transformations:

X = 250 * (1 + Voltage/2)
Y = 250 * (1 - Current/10)

Do note that this will make Current increase upward on the Y axis. If you want the reverse, use (1 + Current/10) in the second transformation.