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create cartesian coordinate system c# windows forms drawing

I created simple form and now I want to draw single objects (rectangle, circle, lines..) in relative coordinates.
Main problem for me here is to create 2D cartesian coordinate system in middle of the form.Is it possible and how to do it??
Main question is how to efficiently transform absolute coordinates to relative? How to create my own system so I get results in numbers (negative, positive depending on quadrant) and not in pixel?
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Currently I made MouseMove event to display current location of mouse with Cursor.Position.X, Cursor.Position.Y and display it in label. Displayed coordinates are pixels, how to change that? I've read something about converting with PointToClient method but I don't really understand it.
I am tied to windows forms becouse I already made a program in win forms and now I just want to add this feature to it.
Thanks

What you're most likely looking for are Graphics.TranslateTransform and Graphics.ScaleTransform.
private void Transform(PaintEventArgs e)
{
e.Graphics.ScaleTransform(width, height);
e.Graphics.TranslateTransform(xOffset, yOffset);
}
You'll also need to make sure that whatever drawing method you're using has an overload for either PointF structures or Singles.
Of course, you could also just handle all of this on your end. Scaling your input/output coordinates by the width and height of the form and then translating by half of that will give you the same results.
Edit- To add some clarity, Windows always expects your coordinates to be in pixel form. You can use the above transformations to do your work at a different scale and then transform into the form that Windows expects.
Setting the translation should be straightforward. If you want the middle of the form, you simply want to translate by half the width and half the height. How you choose to scale your coordinates is going to depend on the range that you need to work in (ie, -1.0 to 1.0, -0.5 to 0.5, etc.).

Move System.Drawing.Rectangle to a different area on Screen

I am creating a screen capture & crop utility using answer posted here
The code draws a rectangle (System.Drawing.Rectangle) on the screen and saves a cropped image.
I need to make this rectangle movable to a different area on the screen without changing the size.
How can I achieve this?
What did not work for me?
I tried this codeproject article, works very good to move controls on the screen.
For this code to work correctly I would need to draw rectangle on a container control.
Which container can be used to wrapping?
Being a succesful web developer I used to think that I can write for WinForms also... I was wrong :-( Some help would be much appreciated!

In C# Windows Forms to change the location of a rectangle you do the following
rect.Location = new Location(x,y);
Where x and y are the coordinates (relative to the window's origin) that you want to move it to.
Here's a link to The MSDN Page on System.Drawing.Rectangle

How to zoom into a specific area of a DirectShow window?

I'm trying to zoom into the area of the DirectShow window between Marker A and Marker B(It's a RangeBar) which represent the width of the video window.
I've tried using SetWindowPosition but all that does is move the video window around.
I'm new to DirectShow, please help !
Thanks !

You can use the IVMRMixerControl interface of the renderer to zoom in to a part of the video.
You need to switch the filter to "mixing-mode" (before you connect the filter) by calling IVMRFilterConfig::SetNumberOfStreams (2). Connect the Renderer. Now you can set the rect you want to show with a call to IVMRMixerControl::SetOutputRect. You need to provide the rectange you want see with normalized values. This means, if you want to zoom in you will set {-0.5, -0.5, 1.5, 1.5} and if you want to zoom back you will set {0, 0, 1, 1}.

Image Co-Ordinate System Design

I'm diving into something without sufficient background, but I feel like there may be simple solutions that don't require me to have in depth knowledge of the topic.
What I am trying to do is have an image co-ordinate system. Basically the user will supply an image, like a house plan. They can then click on points in the image and create markers (like google maps). The next time they retrieve the map, all the markers they added before are there and they can add new ones.
I need to identify the points these markers are located on so I can store that information. I also need to be able to create a layer on the image that contains the markers and renders them in the exact locations they were placed.
I imagine the easiest way to do this is to use pixel co-ordinates...the rub here is that the image won't be a fixed size since there is a web application and an IPad application, so the co-ordinate system needs to work as long as the image is in the same size ratio.
The server size is .NET and as mentioned there is an IPad app, so the solution needs to be viable given that tech stack.
Any ideas?

Instead of using pixel coordinates in absolute terms, you can use the 0 to 1 range. The top left corner is (0,0), bottom right is (1,1) and the center of the image is (0.5,0.5). This way not matter what image size (or zoom level) you have, the markers will always be in the same place.

My suggestion is don't try to figure out the correlation between the actual image and the coordinates. The only thing I would do is use the resolution of the image, aka 800x600 and use that for your grid. Then overlay your markers using that grid on the image. The points you'd remember would just be X and Y values and maybe a tag name/id.

How to get coordinates of window client area

I can get the coordinates of a windows entire area, and the coordinates of the client area using the GetClientRect and GetWindowRect Win32 calls. My problem is that the GetClientRect always returns 0,0 for the top left. How do I figure out what the actual client region is relative to the window rect?

You can use ClientToScreen to get the coordinates of the upper left (0,0) point in screen coordinates. The RECT returned by GetClientRect will be appropriate to get you the lower right corner (just add to the POINT set by ClientToScreen).

Use ClientToScreen to convert the client coordinates to screen coordinates. The window rect (GetWindowRect) is already in screen coordinates, and includes the non-client area (borders, caption, etc)

And if you are working with WinForms then you can use PointToScreen instead of ClientToScreen for solution proposed by Reed Copsey.

The relation between window rect (with borders etc) and the client rect (inside borders) is most easily found using AdjustWindowRectEx(). Get the window style and ex style of the window, and call that function, to see how much border is on each side.

You can also use the MapWindowPoints function to convert an entire RECT to screen coordinates at once.