How to get the image data such as RGB from a viewport?

Replies to This Discussion

Permalink Reply by Damien Alomar on July 12, 2010 at 10:11pm

The best I could find was this example here on the developer wiki, and it doesn't have a .NET example...

http://wiki.mcneel.com/developer/sdksamples/screencaptureview

There are several things about this example that are useful/intersting. First of all, you're going to end up at either Doc.DrawToDC or Doc.RenderToDC, which is the method that's doing the capturing if you will. What that method needs is a device context to write the data to. In the example it uses the MRhinoDib class, which looks pretty lean on the dotNET side. I'm not sure if its possible to create your own device context to draw to, but the one in the RhinoSDK only has a WriteToFile method. Since you're probably looking to access the data directly, as opposed to writing the file and reading it back in, I don't think this is going to be as helpful.

Hopefully that provides you with enough info to start playing around with it. Maybe some of the larger brains can swoop down and fill in the large blanks that exist in getting this kind of thing moving.

Permalink Reply by Daniel Xiong on July 12, 2010 at 10:13pm

Thanks Damien, I will play with it.

Permalink Reply by David Rutten on July 13, 2010 at 1:14am

You can also use Rhino Commands to copy the viewport bitmap into the clipboard, then get the image clipboard contents.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Daniel Xiong on July 13, 2010 at 4:05am

Do you mean load and run Rhino commands in VB.Net component in Grasshopper?

Permalink Reply by David Rutten on July 13, 2010 at 4:08am

Yes, you should be able to run rhino commands from within a VB.NET component. It's not quite as 'nice' as doing it all in code, but it will save you from writing a lot of difficult code yourself.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Daniel Xiong on July 13, 2010 at 4:14am

Thanks David. Is it done by CRhinoScriptCommand? Sorry for bothering you, I am really new to .net and really struggling.

Permalink Reply by David Rutten on July 13, 2010 at 8:02am

Hi Daniel,

Private Sub RunScript(ByRef A As Object)
   RMA.Rhino.RhUtil.RhinoApp().RunScript("-_ViewCaptureToClipboard _Enter")

   Dim img As Image = Windows.Forms.Clipboard.GetImage()

   Dim bmp As New Bitmap(20, 20, Imaging.PixelFormat.Format24bppRgb)
   Dim grp As Graphics = Graphics.FromImage(bmp)
   grp.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBicubic
   grp.DrawImage(img, 0, 0, 20, 20)

   Dim R As int32 = 0
   Dim G As int32 = 0
   Dim B As Int32 = 0

   For i As Int32 = 0 To bmp.Width - 1
     For j As Int32 = 0 To bmp.Height - 1
       Dim col As Color = bmp.GetPixel(i, j)
       R += col.R
       G += col.G
       B += col.B
     Next
   Next

   R = Convert.ToInt32(R / 400)
   G = Convert.ToInt32(G / 400)
   B = Convert.ToInt32(B / 400)

   A = Color.FromArgb(R, G, B)
End Sub

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by David Rutten on July 13, 2010 at 8:08am

File written with 0.7.0032, you'll need 0.7.X to open it. Using the old SDK instead of RhinoCommon.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Attachments:

• GetAverageViewportColour.ghx, 34 KB

Permalink Reply by Daniel Xiong on July 13, 2010 at 8:54am

Thanks so much for your help David!

Permalink Reply by Suryansh Chandra on July 14, 2010 at 5:05am

5 mins here, and I'm already soaking up so much.. "Windows.Forms.Clipboard.GetImage" is my thought for the day!

Though I wish there was some way to 'watch' the clip board, and trigger a recompute in GH when the image would change. I know, I know.. the Timer, but perhaps some way of not recomputing all the time, but only when needed.

Permalink Reply by David Rutten on July 14, 2010 at 6:16am

It's not easy, but it seems possible to make a Clipboard event watcher:

http://www.radsoftware.com.au/articles/clipboardmonitor.aspx

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Suryansh Chandra on July 14, 2010 at 8:21am

wonderful! one more thing to fiddle around with now.