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Create a bitmap and display it using Gtk# in C#

I'm a MAC user so I can't use Windows Forms. I'm trying to figure out Gtk# myself but there is little to no tutorials and documentation to be found on the internet. I want to create a bitmap, draw something in it and display it. So far, I came with this and that displays a window:
Application.Init();
Window Win = new Window("Ray Tracing #2");
Win.Resize(480, 480);
Win.ShowAll();
Application.Run();
However, I would like to manipulate with the window, so let's say: add a bitmap for a start.
I know that to create a bitmap I must write:
System.Drawing.Image IMG = new Bitmap(640, 640);
but what then?

All right, let's try to fix all the problems at once:
You can find a Gtk# tutorial in ZetCode.
If you are going to mess with graphics, then you need to know about Cairo#.
I have a Github repository for my students with a simple demo using both Gtk# and Cairo.
I have another Github repository with a CSV-based spreadsheet application.
My advise is not to rely on the visual designer present in MonoDevelop/XamarinStudio, but to understand how the toolkit works and use it directly. Nowadays graphic toolkits are easy to use enough, and this way you are not tied to any editor/environment.
About your specific question, Bitmap pertains to the WinForms's universe (in fact, it is within the Drawing namespace), you should use a Gtk.Image. Let's create a scrolled panel (though it is called a "window"), and use it to show the bitmap.
var swScroll = new Gtk.ScrolledWindow();
var picBox = new Gtk.Image( "/path/to/image.jpg" );
var vbox = new VBox( false, 5 );
swScroll.AddWithViewport( picBox );
vbox.PackStart( swScroll, true, true, 5 );
this.Add( vbox );
this.ShowAll();
You can build an empty image with a specific size or whatever. Explore the constructors available for Gtk.Image.
Hope this helps!

Save Image in PictureBox with overlapping Controls

I am developing an application in which user can select an image in a picture box.
After that he can right click on the image and add a user control which will again display an Image along with some text. This user control can be added any number of times.
User can also re-position the user controls as per need.
All this functionality has been implemented and is working fine.
Now, the requirement is to save the Image along with the user control.
Above you can see the complete image which needs to be saved. Back image is the picture box image and the user control (small images with text).
When user will click on save button the image should get saved on his disk as a single image.
This is a windows application developed in C#.
I want to know that whether this functionality can be achieved or not. If yes, then please guide me in the right direction.

If you create a copy of the bitmap then with the Graphics.DrawImage() you can draw those images onto it. You need to calculate the position of those controls.
Look here for DrawImage: http://msdn.microsoft.com/en-us/library/42807xh1.aspx
example:
Bitmap copy = new Bitmap(OriginalBitmap);
Graphics g = Graphics.FromImage(copy);
g.DrawImage(arrowBitmap, new Point(..));
copy.Save(...);

A very simple and straight forward solution exists, has been thought of by Microsoft and includes these steps:
Instead of PictureBox use a Panel and instead of using the Image property of the PictureBox use the BackgroundImage property of the Panel
note: By using also the BackgroundImageLayout property you can quite easily instruct the Panel to stretch, center or zoom the image (I'm presuming the default value which is tile is not a good option in your case)
Instead of placing the other user controls at higher Z order but alongside the previous PictureBox place them inside the Panel
Use the Control.DrawToBitmap method like so:
private void button1_Click(object sender, EventArgs e) {
var bmp = new Bitmap(this.panel1.Width, this.panel1.Height);
this.panel1.DrawToBitmap(bmp, new Rectangle(Point.Empty, bmp.Size));
bmp.Save(#"D:\test.png", ImageFormat.Png);
}
That will result in your controls begin rendered along with the picture:
Furthermore, and if your scenario allows it, you could simply use the DrawToBitmap method with any control which contains all of the actors you wish to render, for instance the actual Form.

Drawing on Video within C#

I am making an application that will allow users to apply certain tools to analyse videos & images. I need help with how i actaully draw/write on the video loaded into windows media player within my form and being able to save it on. It needs to be able to lert the user draw freehand and shapes on it.
Thanks in Advance,
Chris :)

This is a non-trivial, if not impossible task to accomplish with the wmp control in winforms.
I don't know of any way to actually draw on the wmp but you could draw on a transparent panel overlaid over the wmp. This will not work will the video is playing but you can show the drawing while it is paused. I have used this technique to draw over a 3rd party video control that works similarly to wmp.(Edit - this does not seem to work with the wmp control)
However, as real transparent panels are also rather tricky in winforms, another way would be to grab an image from the video and draw on the overlaid image. Again, only when it is paused.
This commercial control does enable drawing over the video. It has an event that fires every frame that you can use to do the drawing. The big downside, though is that you can't really do anything too fancy as your drawing routine needs to finish before the next frame is drawn.
I would strongly encourage you to use WPF(even if its a wpf control hosted within a winforms app) to show your video. It is a whole lot easier to draw on video(including playing video) in wpf.
EDIT
I just tested drawing over the wmp using a transparent panel and its doesn't behave as my 3rd party control did,so I suggest you do the video playing bit in WPF and host that in your winforms app. (I just tested that too using #Callums inkcanvas suggestion and it works like a charm)

If you are using WPF, try placing an InkCanvas on top of your video and setting the Background to transparent. You can then save and load up the shapes the users draw on top of the video.
A little proof-of-concept with a picture instead of a video:
I suspect you may be using WinForms though, where this may be more difficult. If so, a good excuse to learn WPF!
EDIT: With WinForms, you would have to make your own custom control that acts as a transparent overlay and add brush strokes to it. It would be extremely hard to implement well (with transparent background, which doesn't play well with
WinForms). I would recommend using WPF if you are still at a stage you can change your application's UI. WPF works on XP and up.
EDIT2: After googling, there are some InkCanvas equivalents that people have made for WinForms, but I have no idea how good they are and may not support transparent backgrounds.
You could always have the video that you want annotated in a new WPF window and the rest of your application in WinForms.

I have found how to do this.
Here is one way in WPF using Canvas
private void buttonPlayVideo_Click(object sender, RoutedEventArgs e)
{
Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();
dlg.Filter = "All Files|*.*";
Nullable<bool> result = dlg.ShowDialog();
if (result == true) {
MediaPlayer mp = new MediaPlayer();
mp.Open(new Uri(filename));
VideoDrawing vd = new VideoDrawing();
vd.Player = mp;
vd.Rect = new Rect(0, 0, 960, 540);
DrawingBrush db = new DrawingBrush(vd);
canvas.Background = db;
mp.Play();
}
}
then create mouse events for Canvas and draw with it
Point startPoint, endPoint;
private void canvas_MouseDown(object sender, MouseButtonEventArgs e)
{
startPoint = e.GetPosition(canvas);
}
private void canvas_MouseUp(object sender, MouseButtonEventArgs e)
{
endPoint = e.GetPosition(canvas);
Line myLine = new Line();
myLine.Stroke = System.Windows.Media.Brushes.LightSteelBlue;
myLine.X1 = startPoint.X;
myLine.Y1 = startPoint.Y;
myLine.X2 = endPoint.X;
myLine.Y2 = endPoint.Y;
myLine.HorizontalAlignment = HorizontalAlignment.Left;
myLine.VerticalAlignment = VerticalAlignment.Center;
myLine.StrokeThickness = 2;
canvas.Children.Add(myLine);
}

This can be done in WinForms but it is not easy. There is transparent form support with alpha blending in WinForms. Use the following CreateParams for the transparent overlay form: WS_EX_LAYERED, WS_EX_TRANSPARENT. Check the MSDN references for this type of window: http://msdn.microsoft.com/en-us/library/ms997507.aspx, http://msdn.microsoft.com/en-us/library/ms632599%28VS.85%29.aspx#layered.
Put a transparent form above your video control and you can draw anything you want on it. Move and resize events need to be coordinated between your video window and the transparent form above it. Redrawing the overlay needs to use UpdateLayeredWindow() in user32.dll.
I learned quite a bit from this example: http://www.codeproject.com/Articles/13558/AlphaGradientPanel-an-extended-panel.

You might look at XNA (www.xna.com) from Microsoft. It is made for managed languages like c# and should support video.
I've only used it for drawing in c#, but it gets the job done.
I should also note that XNA will function as part of a regular Windows Forms app. For what it's worth, I have also prototyped something like this with Flash; Flash allows you to import each frame of the movie file into the editor and create a SWF that can respond to user interaction.
However, this approach is useless if you need to update the movie in real-time. Flash (last I checked) could only import the movie at design time.

Ok, by far and away the best way of doing this is to use Silverlight. Silverlight supports all of the major streaming formats and also provides complete access to the framebuffer.
Easy :-)

Showing image / text on screen without forms in c#

How can I show something on screen wihtout using forms?
Actually, I want to show some text and images popping on screen.

EDIT: just like i said HERE
What you can do is to create a alphatransparent form that draws the PNG and position it at the correct location and bind move etc.
http://www.codeproject.com/KB/GDI-plus/perpxalpha_sharp.aspx
PerPixelAlphaForm transparentImageForm = new PerPixelAlphaForm();
transparentImageForm.SetBitmap(<IMAGE GOES HERE>,<OPACITY GOES HERE>);
//opacity is the opacity that the image will be drawn with, a value of 255 = all transparent parts will be alpha/transparent just as much as the original PNG etc..
and you can put a timer that calls SetBitmap and changes the Opacity to fade in/out the image on the screen
And you can generate the text (on the fly) in a nice way with code from THIS article
and pass that image to the SetBitmap of the AlphaTransparent form.
EDIT: OR GO TO WPF.

I don't think you can: a form is equivalent to a window, and Windows applications draw into a window and not directly onto the screen (unless perhaps it's the backgroun/wallpaper, which I don't know about).

I think that's overdoing it but XNA will allow you to draw to the screen, but it is meant to be used for games so you will have trouble fitting it to a normal application.

Display filter C#

It's a little hard to explain what I need but i'll try:
I need to write application (winform) which will be some kind of filter to image/other forms behind it. With one exception - all behind form should looks as is except of red (for example) color, which have to be replaced to any other specified color, white for example.
So let's imagine I have opened windows Word with few lines of text. With red and black letters.
So when i place my application above this text - it should "filter" red symbols and fill them to white.
So as i understand this task: i have to snap area behind the form, then process it (replace colors) and after draw this image on my form body.
Any links or keywords for solution?
UPD:
so - this is my final solution:
do form transparent (using TransparencyKey and BackColor properties)
place picturebox over the form
when we need to update image in picturebox - we replace current image with pictureBox1.Image = null;, then refreshing form with (this.Refresh()) and do new snapshot
thanks for all ;-)
UPD 2:
sample http://dl.dropbox.com/u/4486681/result.png
UPD 3:
here are sources

you can create a snapshot of the desktop using the following code:
public Bitmap CaptureScreen()
{
Bitmap b = new Bitmap(SystemInformation.VirtualScreen.Width, SystemInformation.VirtualScreen.Height);
Graphics g = Graphics.FromImage(b);
g.CopyFromScreen(0, 0, 0, 0, b.Size);
g.Dispose();
return b;
}
Replace the dimensions and position with the coordinates of your form. This way you get a bitmap of what's behind your form. Then you can do the color replacement on that bitmap.
Please note that due to settings like ClearType and other anti-aliasing mechanisms, you have to also take into account "intermediate pixels" when doing the color replacement. Otherwise things will look funny :-)

I don't know if this can be done at all (let's see what others answer :-).
You can get a handle to the screen device context, which gives you a bitmap of the screen.
HDC dc = GetDC(NULL);
(This is C++, you'll have to use P/Invoke, or create a mixed-mode library in C++)
Then you can redraw a region of the screen with your filtering process.
Now the problems start:
how do you know that the pixels in your interesting region has changed ?
if the region changes, are the changes visible or are they hidden by your own drawing.
You could have a button somewhere that hides your own app momentarily and shows it back when re-pressed, and filters the new content.
Good luck. Any possibility of sharing the user scenario ?