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## Text annotation objects

Figure 12

Figure 13

Text annotation objects, shown in figure, are created by clicking the Text button in the Create new area on the Objects tab. Text annotation objects are simple 2D text objects that are drawn on top of plots in the visualization window and are useful for adding titles or classification levels to a visualization. Text annotation objects can be placed anywhere in the visualization window and you can set their size, text, colors, and font properties.

Text annotation objects are placed using 2D coordinates where the X, and Y values are in the range [0,1]. The point (0,0) corresponds to the lower left corner of the visualization window and the point (1,1) corresponds to the upper right of the visualization window. The 2D coordinate used to position the text annotation matches the text annotation's lower left corner. To position a text annotation object, enter a new 2D coordinate into the Lower left text field. You can also click the down arrow next to the Lower left text field to interactively choose a new lower left coordinate for the text annotation using the screen positioning control, which represents the visualization window. The screen positioning control, shown in figure, lets you move a set of cross-hairs to any point on a square area that represents the visualization window. Once you release the left mouse button, the location of the cross-hairs is used as the new coordinate for the text annotation object's lower left corner.

Figure 14

Text annotations objects are currently sized using a percentage of the visualization window's width. When you specify a width for the text annotation object, you are setting its maximum width. To set the width for a text annotation, type a new width value into the Width spin box or use its the +/- arrows to increase or decrease the size of the text annotation object. The height of the text depends on the length and composition of the text that the text annotation will display. Text annotation objects will likely be changed in the near future so they are specified in terms of visualization window height instead of width so it is easier to make different text annotation objects have the same font size when they display different lines of text.

To set the text that a text annotation object displays, type a new string into the Text text field. You can make the text annotation object display any characters that you type in but you can also use the $time wildcard string to make the text annotation object display the time for the current time state of the active database. A text string of the form: Time=$time will display Time=10 in the visualization window when the active database's time is 10. Whatever text you enter for the text annotation object is used to identify the text annotation object in the Annotation objects list.

Text annotation objects can be displayed in any color, including the visualization window's foreground color. You can also set the opacity for text annotation objects to make them transparent. If you want to set the color for a text annotation object, you must first turn off the Use foreground color check box. Once that check box is turned off, the text annotation uses the color that you pick for it instead of the visualization window's foreground color. To change the color for a text annotation object, click the Text color button and choose a new color from the Popup color menu. To change the opacity, use the opacity slider next to the Text color button.

In addition to being able to set the position, size, message, and color for the text annotation object, you can also choose from 3 different fonts (Arial, Courier, and Times) and set certain font display properties such as bold, italic, and shadow.