Thuban Extensions for measuring distance, area and making selections based on user drawn shapes

[Barry Windridge]

Hi Didrik

Here are some issues that I am aware of with the selection tools:

1) The tools only search through the first part of multi-part shapes.
That is, the selection may fail to pick up multi part shapes or kick
up a multi part shape tht is only partly enclosed in the slection
shape.

2) the select by polygon tool only checks if all points of a shape are
inside the drawn polygon. Hence it will fail if a concave part of the
polygon intersects a segment of the shape without excluding any point
in the shape.


These issues and any other issues that are identified will be fixed in
the next issue of these tools which will most likely include the
features of phase 2 listed below.

Proposed features of phase two of the selection tools:

1) Fix errors in existing versions.
2) Extend tools to handle shapes that intersect the drawn graphics.
3) Create a dialog box that allows users to select whether a tool will
select shapes contained within the drawn shape or shapes that
intersect the drawn shape.
4) The same dialog box will also allow the user also select whether
using the selection tools will (for a layer):
    i)  create a new selection,
    ii) add to the existing selection,
    iii) remove shapes from the exisiting selection,
4) Make the "selection" a property of the layer. This will allow
multiple layers to have selections. As part of this the popup menu
displayed when a user right mouse clicks on a layer in the legend will
include options to:
    i)   clear the existing selection for the layer,
    ii)  invert the existing selection,
    iii) select all fetures in a layer,
5) Make the following selection display attributes properties of the layer:
    i) selection stroke colour,
    ii) selection fill colour,
   iii) selection stroke width,
   iv) selection fill pattern,
6) Exend the layer properties dialog to to allow the user to set the
selection display attributes.
7) Save & restore selection display attributes as part of the layer
attributes in the session file.


On 8/10/06, Didrik Pinte <dpinte at itae.be> wrote:
> Hi Barry,
>
> Great tools, i'll try to test them a lot in the next weeks.
>
> Didrik
>
>
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