From: Kouhei Sutou <kou@...>
Date: 2006-11-11T12:58:41+09:00
Subject: Re: Linux Cairo, webcam displaying images

Hi,

In <45551ebe_5@news.peopletelecom.com.au>
  "Linux Cairo, webcam displaying images" on Sat, 11 Nov 2006 09:00:08 +0900,
  Mike Durham <mdurham@people.net.au> wrote:

> Can anyone please advise me on how to constantly display the output from 
> a webcam using Ruby & Cairo?

Data from webcam (String) -> Gdk::Pixbuf ->
Cairo::ImageSurface.new(data, format, width, height, stride) ->
Cairo::Context.new(Cairo::XXXSurface.new) ->
context.set_source(image_surface) -> context.paint

> The data returned from V4l is a ruby 'string' but how do I display it? 
> At first I thought to display a blank Gdk::Pixbuf of correct size 
> (640x480) and constantly modify it's buffer but I think this might not 
> be possible from within Ruby???

Use Gdk::Pixbuf.new(data, colorspace, has_alpha, bit_per_sample,
                    width, height, rowstride):

  Creates a new Gdk::Pixbuf out of in-memory image
  data. Currently only RGB images with 8 bits per sample
  are supported. Raises an Gdk::PixbufError if there was
  not enough memory.

    * data: Image data in 8-bit/sample packed format(String).
    * colorspace: Color space(GdkColorspace) for image data.
    * has_alpha: true if the data has an opacity channel or false.
    * bits_per_sample: Number of bits per color sample.
    * width: Width of image in pixels.
    * height: Height of image in pixels.
    * rowstride: Distance in bytes between row starts.
    * Returns: A newly-created Gdk::Pixbuf.

Thanks,
--
kou