Drawing a grid for plotting a graph - C# Discussion Boards

Re: Using C++ Code in C# Project/Solution?

BobJanova13-Jul-11 0:11

BobJanova

13-Jul-11 0:11

Thanks for the information ... not something I need right now but it might be useful one day!

Re: Using C++ Code in C# Project/Solution?

Shameel13-Jul-11 2:21

Shameel

13-Jul-11 2:21

you're welcome.

Re: Using C++ Code in C# Project/Solution?

Manfred Rudolf Bihy13-Jul-11 0:40

Manfred Rudolf Bihy

13-Jul-11 0:40

Thanks for the information! 5+ Thumbs Up | :thumbsup:

Re: Using C++ Code in C# Project/Solution?

Shameel13-Jul-11 2:21

Shameel

13-Jul-11 2:21

you're welcome.

Re: Using C++ Code in C# Project/Solution?

jschell13-Jul-11 9:16

jschell

13-Jul-11 9:16

overloaded Name wrote:
I am just experimenting on how to use both C++ and C# at the same time.

Why?

There are many, many more things in the languages, APIs, and in computing in general that are going to be far, far more useful in terms of spending ones time on it.

Re: Using C++ Code in C# Project/Solution?

AmbiguousName14-Jul-11 23:57

AmbiguousName

14-Jul-11 23:57

Reusability. If a task is done in one language, lets say I want to print a report (just example) then why do I havae to re write that code in other language. Why can not I use the existing code which is doing the job perfectly?

Re: Using C++ Code in C# Project/Solution?

Morton song19-Jul-11 17:37

Morton song

19-Jul-11 17:37

Yeah,I am very interesting,for me,i use C++ for major developing and C# just for some special programs.

Drawing a grid for plotting a graph

Praveen Raghuvanshi12-Jul-11 19:23

Praveen Raghuvanshi

12-Jul-11 19:23

Hi,

I am plotting a graph between frequency on x-axis and gain on y-axis.
X-axis(frequency) needs to vary logarithmically and y-axis(gain) needs to vary linearly.

The first step was to create the axis and put numbers on the lines.
As the default origin is at the Left Top corner of the client area, I moved the origin to the center of the client area and inverted the y-axis, so that whatever drawing takes place it should be as per the new origin and looks more realistic.

I tried to create few lines along with string to number them. Lines are drawn properly, however the string also got inverted.

Here is the code, I tried to use. It can be used in any winform application.

private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;
            g.TranslateTransform(this.ClientSize.Width / 2, this.ClientSize.Height / 2);
            g.ScaleTransform(1, -1);


            Point A = new Point(0, 0);
            Point B = new Point(120, 80);
            Point C = new Point(120, -80);

            g.DrawLine(Pens.Red, A, B);
            g.DrawLine(Pens.Green, A, C);

            g.DrawLine(Pens.Purple, 0, 0, -50, 70);
            //g.ResetTransform();
            g.DrawString("3", new Font("Arial", 16), new SolidBrush(Color.Purple), B); 
        }

Question 1: How can we draw string after inverting the y-axis?
Question 2: How can we make vertical lines that should vary logarithmically?

Any idea/solution is welcome.

Praveen Raghuvanshi
Software Developer

Re: Drawing a grid for plotting a graph

lukeer12-Jul-11 21:03

lukeer

12-Jul-11 21:03

Leave the graphics object untranslated and untransformed. Do the y-axis inversion and scaling in separate code instead. That way, you have full control over what is drawn where.

A good idea would be to encapsulate all of that conversion processing so that you can call it using just "normal" values.

Ciao,

luker

Re: Drawing a grid for plotting a graph

Praveen Raghuvanshi12-Jul-11 22:41

Praveen Raghuvanshi

12-Jul-11 22:41

Thanks Lukeer!!!

I tried your suggestion, missed somewhere.

Appreciate if you can help me draw three lines with numbering on them according to the order of drawing them.

I wish to have origin in the center of the window and all points should be given according to that. Y-axis should be positive in the upward direction and negative in the downward direction.

Thanks,

Praveen Raghuvanshi
Software Developer

Re: Drawing a grid for plotting a graph [modified]

lukeer13-Jul-11 0:38

lukeer

13-Jul-11 0:38

Here is a quick proposal with horrible readablility:

private PointF Transform(PointF logicalPoint)
{
    float logicalXMin = -100;
    float logicalXMax = 100;
    float logicalYMin = -100;
    float logicalYMax = 100;

    float canvasXMin = this.ClientRectangle.Left;
    float canvasXMax = this.ClientRectangle.Right;
    float canvasYMin = this.ClientRectangle.Top;
    float canvasYMax = this.ClientRectangle.Bottom;

    float canvasX = ((((float)(Math.Log(logicalPoint.X, 10))) - logicalXMin) / (logicalXMax - logicalXMin) * (canvasXMax - canvasXMin)) + canvasXMin;
    float canvasY = ((-logicalPoint.Y - logicalYMin ) / (logicalYMax - logicalYMin) * (canvasYMax - canvasYMin)) + canvasYMin;

    return (new PointF(canvasX, canvasY));
}

You use a control as canvas. You have to transform logical co-ordinates into canvas co-ordinates. Therefore you look at your logical value in relation to logical maximum and minimum. Then apply the same relation to canvas minimum and maximum.
Since canvas Y-axis is inverted, you have to use negative logical Y value to compensate.

As mathematics dictates, you can't use negative X values here.
Draw grid lines using logical co-ordinates. They should get processed just as any data point.

for( int power = 0, power < 4, power++)
{
    g.DrawLine( gridPen, Math.Pow(1, power), logicalYMin, Math.Pow(1, power), logicalYMax);
    g.DrawLine( gridPen, Math.Pow(2, power), logicalYMin, Math.Pow(2, power), logicalYMax);
    g.DrawLine( gridPen, Math.Pow(5, power), logicalYMin, Math.Pow(5, power), logicalYMax);
}

Horizontal grid lines should be even easier.

for( int i = logicalYMin; i <= logicalYMax; i += 10)
{
    g.DrawLine( gridPen, logicalXMin, i, logicalXMax, i);
}

Ciao,

luker

modified on Wednesday, July 13, 2011 7:17 AM

Re: Drawing a grid for plotting a graph

Praveen Raghuvanshi13-Jul-11 22:31

Praveen Raghuvanshi

13-Jul-11 22:31

Thanks, I will give a shot.

Praveen Raghuvanshi
Software Developer

Re: Drawing a grid for plotting a graph

BobJanova12-Jul-11 22:52

BobJanova

12-Jul-11 22:52

As Lukeer says, you should calculate the canvas position from chart coordinates yourself. Using translate and scale seems clever but as you've discovered it causes text to be drawn upside down as well.

When I draw a log chart I still place gridlines linearly but label them logarithmically (e.g. 0.5, 1, 2, 4, or 1, 10, 100, 1000). I find the 'log graphpaper' approach to be fussy and generally not helpful. But if you want to do that then it is easy enough to calculate the appropriate chart coordinate Y values (log y at sensible Y values such as 1, 2, 5 each power of 10), and then you can transform those like all the other things for drawing.

XMLTextReader - Find Max Depth

Kevin Marois12-Jul-11 7:30

Kevin Marois

12-Jul-11 7:30

XMLTextReader has a depth property that returns the depth of the current node. Anyone know a way to determine the maximum depth? I guess I could read through the file first, but that doesn't seem very efficient.

Everything makes sense in someone's mind

Re: XMLTextReader - Find Max Depth

Heath Stewart12-Jul-11 12:27

Heath Stewart

12-Jul-11 12:27

Until you read through the file, the XML reader wouldn't know anyway (even if, as another example, you used an XPathNavigator to search only leaf nodes). But a better question is why you need to find depth? Because to do so may be considered inefficient, maybe first you should determine if you really need to.

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Re: XMLTextReader - Find Max Depth

BobJanova13-Jul-11 0:48

BobJanova

13-Jul-11 0:48

XML doesn't include structure metadata in a header or anything, so to find the maximum depth you would have to read the whole document and check every node.

Vertical Alignment in RichTextbox

Blubbo12-Jul-11 7:28

Blubbo

12-Jul-11 7:28

I googled and found none... according to MSDN, in framework 4, there is vertical alighment property available (see [RichTextBox Property]). Not sure how I can get that implemented.

Pls 'F1'!

Re: Vertical Alignment in RichTextbox [modified]

Carmelo La Monica12-Jul-11 7:55

Carmelo La Monica

12-Jul-11 7:55

Hello Blubbo,

property of vertical alignment of text on RichTextBox control is not available,

Bye

Carmelo La Monica

modified on Tuesday, July 12, 2011 3:06 PM

Re: Vertical Alignment in RichTextbox

Blubbo12-Jul-11 8:00

Blubbo

12-Jul-11 8:00

Oh, the link I provided was for the cellphone (something like that).... so is there a such way to do that anyway?

Re: Vertical Alignment in RichTextbox

Carmelo La Monica12-Jul-11 8:14

Carmelo La Monica

12-Jul-11 8:14

Hello blubb,

the link you posted refers to if you use WPF, what technology you're using?

Bye

Carmelo La Monica

Re: Vertical Alignment in RichTextbox

Blubbo12-Jul-11 8:16

Blubbo

12-Jul-11 8:16

Visual Studio c# for windows (not WPF)

SQL DataGridView

Falterfire12-Jul-11 6:02

Falterfire

12-Jul-11 6:02

Okay, so I'm thinking my problem here probably involves completely misunderstanding the use of a DataGridView, but here goes:

I'm currently working on learning how to use SQL with C#/.NET using VS2010. I created a DataGridView that's linked to my data table. Adding rows to the DataGridView while the program was running did not actually save the changes to the database, so I created a separate piece using SqlConnection & SqlCommand. This successfully added the rows to the database, but did not update the DataGridView.

So I suppose there are two questions here: How do I save the changes to a DataGridView to the bound data table? and How do I have the DataGridView reload table data?

Re: SQL DataGridView

Dan Mos12-Jul-11 8:35

Dan Mos

12-Jul-11 8:35

While this most definitely doesn't answer your question, here goes:

Don't use DataGridViews to enter/introduce/edit data. Use dedicated windows/forms.
You're life gets a whole lot easier.
The reasons are plenty: more control(like data validation), easier to debug, the app looks nicer...

I only use DataGridViews for displaying data(if that).
Smile | :)

All the best,

Dan

Re: SQL DataGridView

Falterfire12-Jul-11 8:58

Falterfire

12-Jul-11 8:58

Good to know. Given that I'm at this point just trying to figure out how to use SQL in C#, it's good to know which pieces to avoid. So yes, that answer was useful, even if it didn't actually answer my specific question.

Re: SQL DataGridView

PIEBALDconsult12-Jul-11 17:42

PIEBALDconsult

12-Jul-11 17:42

The updating is usually handled by a DataAdapter.Update -- but as has been said, you won't have a very impressive app.

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.