Grid
The Settings->Grid submenu allows you to change the grid settings:
Settings->Grid->Show Grid will toggle between
displaying the grid on the canvas and
hiding it. If there is enough memory available, the grid will be
stored as a bitmap in order to improve redraw speed.
-
Settings->Grid->Lock Grid will
toggle between locking and unlocking the grid. If the grid is
locked, mouse clicks will be translated to the nearest tick mark.
This means that if you use a mouse click to set the location of
a control point when constructing a path, the
point will be placed at the nearest tick mark. This also means that
when you move a point while in
edit mode, the point will be moved
in intervals of the gap between tick marks. Note that locking the
grid does not affect the keyboard or menu driven functions, such as
Navigate->Go To (F5) or emulate a
primary-click (F4).
When the grid is locked, the status bar will show the image
otherwise it will show the image
. You can double-click on this image to toggle
the state.
Warning: if you lock the grid, you will be unable to use the mouse to select narrow paths that lie between tick marks as mouse clicks will be translated to the nearest tick mark, unless you use the drag rectangle (which may select other objects as well). Similarly, if the size of the control points is less than the gap between the tick marks, you will not be able to select control points using the mouse whilst in edit mode. (You will however be able to select them using the Next Control (F6) of Previous Control (Shift-F6) popup menu item.)
- Settings->Grid->Grid Settings will produce a
dialog box in which you can specify the position of the tick marks
and the units used. You can also open this dialog box by
double-clicking on the top left corner between the rulers, where the
current grid unit is displayed.
Available grid types:
- a rectangular grid with the origin at the top left hand corner of the canvas (Figure 3.1(a));
- a radial grid with the origin at the centre of the canvas (Figure 3.1(b));
- an isometric grid with the origin at the top left hand corner of the canvas where the major divisions indicate the length of each side of the equilateral triangles forming the grid (Figure 3.1(c));
- a typesetting grid after Tschichold (see [3, p. 40]). This is the only grid that checks the display page setting. If an even numbered page is displayed, the verso grid is shown (Figure 3.2(a)), otherwise the recto grid is shown (see Figure 3.2(b)). The recto grid is used for the default All Pages setting. Note that you are limited to only fourteen locations if you have the grid lock on. The settings for this grid style are the same as for the rectangular grid and are only applied to the rulers. The origin is the top left corner of the canvas for both the recto and verso displays.
Note: the grid unit is independent of the storage unit. However, it's a good idea to choose a grid unit and storage unit that have a convenient conversion factor between them. For example, mm storage unit and cm grid unit. Regardless of the grid used, co-ordinates are always stored as left-handed rectangular co-ordinates where the origin is at the top left. This may cause slight rounding errors in the conversion between rectangular and radial co-ordinates. If you are using a radial grid and you change the paper size or orientation, the grid origin will shift but the objects will maintain their original positions relative to the top left corner of the canvas.
(a) 
(b) 
(c) Figure 3.1: Available regular grids: (a) rectangular grid; (b) radial grid; (c) isomorphic grid 
(a) 
(b) Figure 3.2: Tschichold grid: (a) verso (even pages); (b) recto (odd pages)