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This section describes some features that have been added to DRAW since the DRAW manual was last revised. Some of them are experimental and may not remain in future versions of DRAW.
Lines and curves can be drawn freehand, as an alternative to specifying line end-points or knots. To go into freehand drawing mode, pick up with the cursor the brush symbol shown in the menu inside a small square. Then draw on the screen in the usual way: press a mouse button, move the mouse around, and release the mouse button. The trajectory of the brush-cursor is painted on the screen as you move along. But when you have finished, the trajectory is erased and replaced by a smooth curve fitted through knots that have been automatically selected along the trajectory. Some smoothing of the trajectory is done in order to eliminate irregularities (due mainly to the mouse). The curve now behaves like any curve.
DRAW tries to help you in two ways:
If the trajectory that you draw seems to have little curvature, it will be replaced by a straight line rather than a curve.
If you use the grid button (BLUE), DRAW will force the trajectory (and thus the resulting line or curve) to start and end on a grid point.
These two features should help in drawing horizontal and vertical lines on the grid mesh: boxes, rectangles, diagrams, etc.
DRAW permits you to introduce color into pictures that are to be printed on a color printer. Curves, lines, and text can be in black or in one of six basic colors: yellow, magenta, cyan, red, green, and violet (actually a dark blue).
Eight commands in the menu pertain to color. Seven of them are tags representing available colors, each identified by a single letter (B, Y, M, C, R, G, V) inside a small circle. The color commands are used in two ways. Simply clicking a color tag selects the current color in the same way the current brush or current font are selected; all objects that you draw subsequently will be in that color. You can also pick a color tag from the menu and then click RED over each object you want to assign that color.
If you click the COLOR OFF menu command, it will change to COLOR ON, and every object in the picture will have a tag attached to it showing its color.
Command line parameters
You can specify a number of parameters in the command line that you use to invoke DRAW. Each parameter consists of a decimal number, followed by "/", followed by a letter. Default values are used when the parameters are omitted or if the values you supply seem unreasonable.
n/SThe maximum number of splines (curves and lines) that a picture can contain. The default is 200.
n/KThe maximum number of knots a curve can have. The default is 100.
n/TThe maximum number of text captions that a picture can contain. The default is 100.
n/GThe grid spacing, in Alto screen units. The default is 16.
n/DThe length, in screen units, of line segments in dashed curves and lines. The default is 16.
n/OThe length, in screen units, of omitted line segments in dashed curves and lines. The default is 8.
>Draw 250/S 50/K 8/GCR
The user profile
Your user profile (file User.cm) may contain a DRAW section supplying settings for DRAW. First, you may include up to four font definitions that determine the fonts available in the menu for text captions. A font definition has the form
where n is the font number (0 to 3). If you do put any font definitions in your user profile, then only those fonts are used by DRAW; if you don’t include any font definitions, DRAW uses a standard set consisting of Helvetica12, Helvetica12B, Helvetica8, and Arrows10.
Second, you can define the actual thickness of the four sizes of brushes DRAW uses to paint lines and curves. A thickness definition has the form
where n is a number identifying the brush (0 to 3 from top to bottom in the menu) and width is half the thickness of the line in micas (one mica is .001 cm or 1/2540 inch). The default thicknesses for brushes 0 to 3 are 16, 32, 64, and 128 micas.
An example of a reasonable user profile section for DRAW might be: