Following feedback from users in the field, there are an extended set of features available to the standard chamber sketch.

Any or all of these can be incorporated into a custom app designed to your own specification if required.

With the standard sketch you tap on the buttons to make elements like arrows appear on the diagram, then move them to wherever you want them to go.

This means that components are added in sequence, one at at time.

Once accustomed to this, some users feel that they can create sketches faster if the buttons act as a toggle that enables a certain element. It's then possible to tap on the diagram to instantly place the item where you want, rather than just putting it in the same place every time and moving it from there.

After being positioned and the button toggled off, the various items can then be adjusted as normal.

Lines and arrows require two taps - one for the beginning and one for the end, whereas letters, circles etc just need one tap to position them.

Let's see this in action. Note the position of the finger taps.

In addition to the standard sketch, outline or solid rectangles are available.

These are placed on the diagram in the same manner as above, and can then be tapped to become active and resized with the same handles as arrows and lines.

For large inspection chambers, it's possible to have too many ducts to display with just placing circles or squares on the diagram.

In these circumstances, you can use the grid tool by tapping on the button with a rectangle divided into small squares.

This will bring up a dialog asking for the number of rows and columns required.

Once you enter the data, the app will draw a grid and add the required number of ducts.

Individual ducts can then be tapped on to cycle through different states:

Once you're happy with the grid, it can be resized and rotated in the same way as the cover/chamber.

Tapping on the diagram background will remove the handles and lock the grid in place. Simply tap on it again to bring back the controls so you can move it around and change the state of the ducts if required.

In the standard sketch the north arrow is fixed, but if required this can be made to rotate using the device compass, similar to the location sketch.