Simple Glyphs - Introduction
In a TrueType font, glyph shapes are described by their outlines. A glyph outline consists of a series of contours. Contours are composed of straight lines and curves. Curves are defined by a series of points that describe second order Bézier-splines. The TrueType Bézier-spline format uses two types of points to define curves, those that are on the curve and those that are off the curve. Any combination of off and on curve points is acceptable when defining a curve. Straight lines are defined by two consecutive on curve points.
Contours that need to be filled black must have a clockwise direction. If we want to make a white area inside an existing contour we must make the direction of the new contour counter clockwise. Contour direction is determined by seeing in which direction the point index values increase or decrease. Contour direction is from the smaller point index to the larger. The general rule is that the contour direction should be such that "black is on the right". Using the glyph "O" as an example, the outer contour should travel clockwise, and the inner contour counter clockwise.
Click the Correct contour directions button on the Validation toolbar to correct the direction of all misoriented contours in a simple glyph or select Direction from the Edit menu to change the direction of the selected contour(s).
The character "4" is represented by a glyph with two contours. One contour you see as the black area and the white area within this glyph is the other contour.
From the Drawing toolbar you can change the way you can modify the glyph. In the Glyph Edit window, you can change between Contour and Point mode by double clicking inside the edit area, select the Mode from the View menu or use the appropriate button on the Drawing toolbar. The main difference between Contour mode and Point mode is that in Contour mode all operations are related to the contours while in Point mode you can change parts of the contours (e.g. move, add and delete points).
Holding down the Shift key while dragging points or contours restricts movement so the selection moves only in the x or y direction.
In the Glyph Edit window (in Point mode) the rectangles represent on curve points and the circles off curve points.
Tip You can nudge the selected contour(s) or point(s) up, down, left, or right by pressing the arrow keys. By holding down the Ctrl key and pressing the arrow keys finer nudging is available.