Illustrator owns a LivePaint tool, CorelDRAW owns the same function and with the next release, Inkscape also offers the same tool under the name "Paint Bucket tool".

I would love to see such a function in Xara Xtreme.

Regards,
Remi

This is the description of the planned Paint Bucket tool from Inkscape:

Paint Bucket tool
The new Paint Bucket tool works exactly as you would expect: click in any area bounded on all sides and it will fill it with color. Being a vector tool, however, Inkscape's Paint Bucket just creates a new path that "fills in" the area in which you clicked.

It is important to note that the tool is perceptual, not geometric. That is, when looking for the boundaries around the point you clicked, it takes for such boundaries any visible color changes. This means that filling will stop at gradients, blurs, and even the color boundaries in imported bitmaps, but will ignore any paths or other objects that are fully (or almost) transparent or for any other reason do not stand out from the background. In short, it will work exactly as if you were filling a rasterized version of your image in a bitmap editor like Photoshop or GIMP - but will give you a vector object to work with.

For example, now you can scan a pencil sketch, import the bitmap into Inkscape, and quickly fill all its cells with colors even without tracing the bitmap first. This is a very convenient and interactive way of digitizing your paper drawings, making the traditional bitmap tracing unnecessary in many cases.

Internally, the tool works by performing a bitmap-based flood fill on a rendered version of the visible canvas, then tracing the resulting fill using potrace and placing the traced path into the document.

It places the rendered path onto the current layer, so you can have a layer on top (for example, "Inks") and select the layer below ("Colors") and do the fills so that they always appear below the Inks.

The resolution of the bitmap image used to perform the trace is dependent upon your current zoom level -- the more zoomed in to an area that you are, the higher the resolution of the bitmap-based flood fill. So, if you are got a fill that is too imprecise, has rough corners, or don't go into small nooks and appendices where it is supposed to go, just undo, zoom in closer and repeat filling from the same point. Conversely, if the fill leaks out through a small gap, zoom out to make the gap less visible and fill again.

Like all object-creating tools, the Paint Bucket may use the last-set style for the objects it creates (this is the default), or it can use its own fixed style. You can switch between these modes on this tool's page in Inkscape Preferences (Ctrl+Shift+P).

In the tool's Controls bar:

  • Tolerance (set in per cent units) controls how large must be color difference at a point (compared to the initial click point) to stop the fill. Zero tolerance means only the area of strictly the same color will be filled; the larger the tolerance, the easier it will be for the fill to leak into adjacent different-color areas. The default value is 10%.
  • You can control the amount of inset/outset to be applied to the created fill path. Setting a positive outset causes fill paths to be larger than the filled bitmap area (good for eliminating anti-aliasing errors), while setting a negative outset causes the path to be smaller. This works the same as the Outset and Inset path commands.
  • Paint Bucket's perceptual fill can use either all visible colors or specific color channels. You can restrict the fill algorithm to the following channels:
    • Red
    • Green
    • Blue
    • Hue
    • Saturation
    • Lightness
    • Alpha
  • A style swatch on the far right of the bar shows the style that will be used for the next fill object you create.


The tool's shortcuts are:
  • Single click performs filling from the click point.
  • Shift+click performs filling from the click point and then unions the resulting path with the selected path. This way, if your first attempt did not fill in all of the desired area, you can Shift+click the remaining corner to fill it in separately and combine the result with the result of the previous fill.


Some potential improvements to the tool are:
  • If the [Ctrl] key is held down, clicking on an object changes the fill color to the current fill color, and [Shift]-[Ctrl] changes the stroke color to the current stroke color


source: http://wiki.inkscape.org/wiki/index.php/ReleaseNotes046