DigitizerDemo is a proof-of-concept application that demonstrates how the crosshair digitizer can be extended and combined with additional components to build a useful science application.
To use the application, start it via the web link (webstart). A split window should come up and eventually a spectrogram will be visible. The right pane of the split window contains an empty table that will collect the digitized points.
Once the application has loaded the data for the initial axis setting, left click on the spectrogram. Two things happen. One, the x,y,z tuple of the data point selected is displayed next to the digitizer location. x and y come from looking up the mouse pointer position on the axes, and the z value comes from the closest point in the spectrogram dataset. Two, a vertical slice pops up. This has a faint gray bar indicating the y position of the slice. So you can see that this is designed for finding cut-offs in the spectra.
As the digitizer is moved, the vertical slicer and x,y,z points update. The cursor arrow keys can also be used to precisely move the digitizer (with the left mouse button depressed). When the cut-off location is satisfactory, a key press (e.g. a number key), will copy the current point over to the table, along with the keystroke character. This process is repeated until the cut-off for the spectrogram is complete.
There are a number of axis controls that will be useful in the process. One may zoom in on either axis by left clicking on an axis and dragging the mouse over the desired range. To go back to the previous range, right click on the axis and select "Back." The horizontal time axis has hidden "scan buttons" at its end that are revealed when the mouse wanders over them. Pressing a scan button will advance the axis to the next or previous frame in time.
The table allows some editing of the data. If one clicks on a row of the table, it will be highlited in blue, then a right-click on that row will provide the option to delete the row. A range of rows can be selected by holding the shift key while clicking on a second row. Then right-click again to delete all the rows. A non-contiguous group of rows can be selected by holding the control key while selecting multiple rows. Again, right-click will delete the selected rows.
The button "Update" (alpha version) will cause the points of the table to be displayed on the spectrogram. The "Save..." button allows the table to be saved to an ascii file, and "Load..." will read in a file of the save format, replacing any data that was in the table.