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The Set Grid Button: Set Grid Parameters

The Set Grid button in the Main Window sub-menu of the Attributes Menu or the sub-window Attributes menu brings up a pop-up for setting grid parameters for the window. This allows setting of the grid properties for the present display mode, for normal viewing or for printer output (in the main window) if the Print Control Panel is visible.

If the Show button is active, the grid will be visible. Otherwise, it will not be visible. If the On Top button is active, the grid will be drawn last, after all geometry. Otherwise, it will be drawn first, in which case it is more likely to be obscured by the geometry. The Store and Recall buttons allow a set of grid parameters to be saved in an internal register, to be recalled as needed.

A radio button group is provided to set the presentation style of the axes in physical mode. The choices are No Axes, Plain Axes, and Mark Origin. The Mark Origin choice is the default. The Plain Axes choice does away with the small box at the origin, showing the axes as simple lines. The No Axes choice suppresses the axes entirely. In electrical mode, the axes are always suppressed.

There are text entry areas for the grid resolution and snap number. The resolution is the spacing of the grid lines, in microns. The snap number specifies the possible coordinates, i.e., the coordinate read by Xic when the pointer is in the vicinity. If the snap number is positive, it represents the number of snap locations per grid interval. For example, if 1, the snap locations are on the grid lines, if 2, the snap locations are on the grid lines and midway between the grid lines. If the snap number is negative, it represents the number of grid lines per snap line.

In electrical mode, the snap interval should be a multiple of one micron, to avoid connectivity errors due to numerical roundoff. However, this was not enforced in older releases of Xic. Presently, sub-micron snapping on tenth-micron intervals is accepted, but with a warning issued. This allows older files to be ``repaired'', i.e., objects moved to a one micron grid. This is recommended for files that require it. A sub-micron snapping interval should not be used otherwise, and will not be saved in the technology file produced with the Save Tech button in the Attributes Menu.

There are three ``radio buttons'', Solid, Dots, and Textured that set the basic grid style. Choosing Solid will cause the grid to use continuous lines. The Dots option will use a grid consisting of a small dot or cross at each grid point. When this selection is active, a Cross Size entry area appears. This can be set to values 0-6, indicating the number of pixels to light up around the central dot in the four compass directions. If zero, only the celtral pixel is lit, which can be difficult to see on high-resolution displays. The value 1 generally looks like a much brighter dot. Larger values will appear as a small cross.

If Textured is chosen, a user-specified patterned line will be used, and the line style editing areas become visible. The line style editor allows the user to specify the patterning of the lines used to form the grid. The upper window is a sample of the current line style. The lower window allows the user to set the line style by clicking.

The line pattern starts at the left set bit (blue area) and extends to the right of the display. The pattern is used to ``tile'' the line. The left part of the display is shown in gray to indicate that it is not part of the line style mask. Clicking in this window with button 1 will toggle the bit. Button 2 will clear the bit, and button 3 will set the bit. Multiple bits can be set or toggled by dragging. The line in the preview window will reflect changes in the pattern.

Pressing the Apply button will actually save the new grid parameters in Xic, and redraw the windows. Changes will not be saved unless Apply is pressed.

The Ctrl-G key sequence is mapped by default to a command which also allows certain grid parameters to be set with a command-line interface. Thus, simple keyboard commands can be employed to change grid spacing and visibility. This may be a quicker than the pop-up for simple tasks such as turning the grid on and off. For example, to set the grid spacing to 2.5 microns, one types ``Ctrl-G 2.5 Enter''.

See also the description of the !rg and !sg commands. These can be used to save and restore the grid from registers.


next up previous contents index
Next: The Convert Menu: Data Up: The Main Window Button: Previous: The No Top Symbolic   Contents   Index
Stephen R. Whiteley 2012-04-01