To draw a straight line, you can use the Pencil tool or the Line tool. The Pencil tool responds to the direction of the mouse. If you drag in a curving motion, Visio draws an arc. If you drag in a straight line, Visio draws a line segment. (See Figure 22-9.) If you're like a lot of people, you try to drag in a straight line and end up with an arc anyway. Fortunately, you can convert arcs to lines and vice versa—or you can use the Line tool, which always creates a straight line.
To create consecutive line segments at once, drag with the Pencil or Line tool to draw the first line segment, and then lift your finger from the mouse button without moving the mouse. Then drag to draw the next line segment. If the lines are crooked, wait until you're done drawing the shape, and then use the Pencil tool to repair crooked line segments.
Figure 22-9. As you drag with the Pencil tool, the pointer provides useful feedback by changing to show whether you're creating an arc or a line.
If you draw with the Pencil tool and end up creating an arc segment when you meant to draw a straight line segment, you can repair the problem without redrawing the entire shape. The technique is a little tricky only in that it requires you to work in the ShapeSheet window, but sometimes that's simpler than starting over. Here's how you do it:
Depending on the shape, the Name column of the Geometry section contains a variable number of rows labeled MoveTo, LineTo, and EllipticalArcTo.
You can't select the vertex you want to change in the ShapeSheet window.
If the shape you're editing is actually a merged shape or a group, you might have difficulty locating a vertex. If the ShapeSheet window includes multiple Geometry sections labeled Geometry 1, Geometry 2, and so on, the shape is a merged shape. Click each cell in the X column for all the Geometry sections until the corresponding vertex is selected on the drawing page, and then proceed to make the change you want.
If you select a group, you won't see a Geometry section at all in the ShapeSheet window, but if you scroll down, you'll see the Group Properties section. What you need to do is subselect the individual shape that contains the geometry you want to change, and then display its ShapeSheet window.
In certain drawing types, it's useful to align shapes to a line that acts as a reference. In Visio, you can drag a guide line out from the rulers and align shapes to that, but the guide's blue line interrupts a drawing. For technical or architectural drawings, you can create a true construction line and format it to look the way you want. Visio refers to these as infinite lines. You can create them by drawing a regular line with the Line tool and then editing the ShapeSheet to convert it to an infinite line, as Figure 22-10 shows.
Figure 22-10. An infinite line extends indefinitely into space and is useful as a reference for dimensions or setouts in construction and architectural drawings.
Follow these steps to create an infinite line:
The Name column contains MoveTo and LineTo rows.
When you need to position shapes along precise 45-degree lines, Visio includes a feature with the rather generic name of drawing aids that works like the dynamic grid. How drawing aids are displayed differs depending on which drawing tool you're using, but like the dynamic grid, they appear on-screen as dotted lines that show you where to draw, as Figure 22-11 shows.
To make drawing aids visible, choose Tools, Snap & Glue, and then select the Drawing Aids check box. Depending on the drawing tool you use, you'll see the following:
Figure 22-11. You can turn on drawing aids to display reference lines at 45-degree intervals.
Together, the shape extension lines and the Line tool make it very easy to create lines that are perfectly tangent to one or two curves, as Figure 22-12 shows.
Figure 22-12. When you display the curve interior tangent extension line, you can draw a line that is perfectly tangent with respect to two curves.
The following steps were provided by the Visio engineer who designed this feature, which he admits many users never discover. But it's cool, and it works. Here's how:
Red signifies "tangent mode." If the line doesn't turn red, try dragging slowly back and forth along the tangent line. Once you enter tangent mode, the line remains tangent to the circle as you drag. You can drag in tangent laps around the circle if you want.
Just as the dynamic grid shows you options for aligning shapes, shape extension lines show you how to draw lines and arcs accurately with respect to other shapes, as Figure 22-13 shows. Displaying shape extension lines is similar to using object snaps in CAD programs. They appear on-screen as dotted lines or snap points when you're using the Line, Arc, Freeform, Pencil, Ellipse, Rectangle, or Connection Point tools.
Figure 22-13. Shape extension lines show you where to snap to precise points on shape geometry.
You can choose to display different types of shape extension lines, which Visio identifies with ScreenTips as you're drawing. For example, you can draw a line that intersects another line at its exact midpoint, or you can ensure that the arc you're drawing begins and ends in exact relationship to existing shapes. Table 22-1 describes each type of shape extension line (except isometric angles, which are described shortly).
Tip - Turn Off ScreenTips
ScreenTips are helpful, but they can also overcrowd your screen. To turn them off, choose Tools, Options, and then click the View tab. Clear the Other ScreenTips check box, and then click OK.
Table 22-1. Shape Extension Lines
Alignment Box Extension
Displays an extension line from the shape's alignment box so that you can align shapes by their edges
Displays an extension line from an arc segment to form an ellipse or from the nearest point on a spline to extend the curve
Center Alignment Axes
Displays an extension line from the nearest the shape's alignment box so that you can align shapes by their centers
Displays a perpendicular line from the nearest endpoint of a line or arc segment so that you can create two right angles with two lines
Curve Interior Tangent
Displays an extension line that shows a curve's tangent at the midpoint of the arc segment so that you can create a tangent to the arc
Displays a perpendicular line from the midpoint of a line or arc segment so that you can create four right angles with two lines
Highlights an endpoint of an arc or line segment so that you can connect a shape or line to a segment's endpoint
Horizontal Line At Endpoint
Displays a horizontal line (with respect to the screen) on the endpoint of a line or arc segment so that you can place a horizontal line on another line's endpoint
Highlights a midpoint of an arc or line segment so that you can connect a shape or line to a segment's midpoint
Vertical Line At Endpoint
Displays a vertical line (with respect to the screen) on the endpoint of a line or arc segment so that you can place a vertical line on another line's endpoint
Extends a line segment from the endpoint you're near so that you can see where the line would be continued
Ellipse Center Point
Highlights the center point of an ellipse so that you can connect lines to the center
Follow these steps to turn on shape extension lines:
If you are drawing isometric diagrams (two-dimensional drawings that represent three-dimensional objects), isometric extension lines can help you draw lines along isometric planes. As Figure 22-14 shows, these lines are simply a type of shape extension line, but they differ from the other types in that you can specify the angle of the line that appears when you draw. When you use a drawing tool, the isometric angle lines appear as dotted lines that extend from a vertex at an angle, or set of angles, that you specify.
Figure 22-14. You can specify a series of isometric angles to provide snap-to points for an isometric drawing.
Follow these steps to display isometric shape extension lines: