The Adobe Type 1 Font Format book (PDF: 445 KB) - Adobe Partners

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28 Adobe Type 1 Font Format Script language programs to create combinations of paths involving characters with reliable winding number orientations. On some implementations of Type 1 BuildChar, this orientation is expected; some rendering algorithms depend on it. Figure 3e. Construct subpaths in the correct direction 3.6 Overlapping Paths A single closed outline should not intersect itself; this can cause winding number problems. If two filled subpaths in a character overlap, there may be no problem when the character is filled. However, a Type 1 font program can also be stroked along its outline when the user changes the PaintType entry in the font dictionary to 2. In this case, overlapping subpaths will be visible in the output; this yields undesirable visual results in outlined characters. Always construct the character paths with outlined output in mind. Figure 3f. Avoid overlapping subpaths Filled character Stroked character: incorrect Stroked character: correct
CHAPTER 4 Technical Design Considerations At first it may seem that character outlines need not differ much from other graphic outlines. However, the requirements of letterforms impose more stringent requirements on a character outline if it is to look good. Making a PostScript language implementation of a typeface design involves two essential considerations: • The character paths must accurately express the true analog shapes of the original design. • Certain conventions must be observed to help the interpreter accurately scale for all sizes. Failure to observe either of these conventions can result in uneven stems, unwanted pixels, poor curve shapes, and poor transitions from straight to curved sections. While there are no hard and fast rules for font outline design in a Type 1 font program, paying attention to the guidelines discussed in this chapter will help ensure pleasing results. 4.1 Points at Extremes An endpoint (first or last point of a lineto or curveto) should be placed at most horizontal or vertical extremes. This implies that most curves should not include more than 90 degrees of arc. The placement of extreme points aids the rendering algorithms in properly reproducing the major features of characters. Of course, points may be placed anywhere else on the character outline, as long as the important extremes are defined as well. It is not necessary to place an endpoint at extremes of very small curves such as the tips of curved serifs. 29
Page 1 and 2: Adobe Type 1 Font Format Adobe Syst
Page 3 and 4: Contents Chapter 1: Introduction ..
Page 5 and 6: Appendix 1: Private Dictionary Entr
Page 7 and 8: CHAPTER 1 Introduction This documen
Page 9 and 10: Type 1 font programs have several a
Page 11 and 12: Some Type 1 font rendering software
Page 13 and 14: CHAPTER 2 Font Program Organization
Page 15 and 16: 2.2 Font Dictionary Constructing a
Page 17 and 18: Example 1. %!FontType1-1.0: Symbol
Page 19 and 20: ment in the %%VMusage comment; the
Page 21 and 22: and range. The operand stack for ch
Page 23 and 24: Finally, the definefont operator ma
Page 25 and 26: 2. Uncertain distribution: If the f
Page 27 and 28: CHAPTER 3 Character Outline Conside
Page 29 and 30: n Figure 3b. Origin, width, left si
Page 31 and 32: Nearly all roman Type 1 font progra
Page 33: image and imagemask operators are n
Page 37 and 38: Figure 4b. Make smooth transitions
Page 39 and 40: It is possible to carry consistency
Page 41 and 42: CHAPTER 5 Private Dictionary The Pr
Page 43 and 44: • All subsequent pairs describe t
Page 45 and 46: The value associated with FamilyBlu
Page 47 and 48: default value of BlueShift is 7. Th
Page 49 and 50: The entry StemSnapV is an array of
Page 51 and 52: 5.12 lenIV The lenIV entry is an in
Page 53 and 54: CHAPTER 6 CharStrings Dictionary Th
Page 55 and 56: encoding values are listed. The com
Page 57 and 58: name of both components of an accen
Page 59 and 60: ather than as part of the main outl
Page 61 and 62: Subroutine Commands callothersubr a
Page 63 and 64: Figure 6a. Character level stem hin
Page 65 and 66: Encode the integers according to ch
Page 67 and 68: CHAPTER 7 Encryption Type 1 font pr
Page 69 and 70: To Decrypt a Sequence of Ciphertext
Page 71 and 72: Apply charstring encryption to prod
Page 73 and 74: CHAPTER 8 Using Subroutines A Type
Page 75 and 76: The pop commands following the subr
Page 77 and 78: Example 1. 40 575 hsbw Set left sid
Page 79 and 80: Figure 8b. Appropriate and inapprop
Page 81 and 82: To encode two Bézier curve segment
Page 83 and 84: Insert the coordinate of the refere
Page 85 and 86:
CHAPTER 9 Special Font Organization
Page 87 and 88:
ignores one of the groups by means
Page 89 and 90:
CHAPTER 10 Adobe Type Manager Compa
Page 91 and 92:
10.3 Keywords Values for certain ke
Page 93 and 94:
APPENDIX 1 Private Dictionary Entri
Page 95 and 96:
APPENDIX 2 Charstring Command Value
Page 97 and 98:
APPENDIX 3 OtherSubrs Programs The
Page 99 and 100:
mtx currentmatrix pop mtx 0 get abs
Page 101 and 102:
ifelse} ifelse} ifelse {systemdict
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APPENDIX 4 Changes This document de
Page 106 and 107:
100 Adobe Type 1 Font Format measur
Page 108 and 109:
102 Adobe Type 1 Font Format O oper
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Colophon This book was produced usi
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