W3C CSS2 Cascading Style Sheets, level 2 - instructional media + ...

More documents

Recommendations

Info

other descriptors such as x-height, glyph widths, and panose-1 to identify a different tentative font family. If there are matches for all the remaining descriptors, then that is the matching font face for the given element. The ’font-family’ descriptor that is reflected into the <strong>CSS2</strong> properties is the font family that was requested, not whatever name the intelligently matched font may have. UAs that do not implement intelligent matching are considered to fail at this step. 4. If there is no matching font face within the ’font-family’ being processed by step 3, UAs that implement font downloading may proceed to examine the ’src’ descriptor of the tentative font face identified in step 2 or 3 to identify a network resource that is available, and of the correct format. If there are matches for all the remaining descriptors, then that is the matching font face for the given element and the UA may attempt to download this font resource. The UA may choose to block on this download or may choose to proceed to the next step while the font downloads. UAs that do not implement font download, or are not connected to a network, or where the user preferences have disabled font download, or where the requested resource is unavailable for whatever reason, or where the downloaded font cannot be used for whatever reason, are considered to fail at this step. 5. If there is no matching font face within the ’font-family’ being processed by step 3, UAs that implement font synthesis may proceed to examine other descriptors such as ’x-height’, glyph widths, and ’panose-1’ to identify a different tentative font family for synthesis. If there are matches for all the remaining descriptors, then that is the matching font face for the given element and synthesis of the faux font may begin. UAs that do not implement font synthesis are considered to fail at this step. 6. If all of steps 3, 4 and 5 fail, and if there is a next alternative ’font-family’ in the font set, then repeat from step 2 with the next alternative ’font-family’. 7. If there is a matching font face, but it doesn’t contain glyph(s) for the current character(s), and if there is a next alternative ’font-family’ in the font sets, then repeat from step 2 with the next alternative ’font-family’. The ’unicode-range’ descriptor may be used to rapidly eliminate from consideration those font faces that do not have the correct glyphs. If the ’unicode-range’ descriptor indicates that a font contains some glyphs in the correct range, it may be examined by the UA to see if it has that particular one. 8. If there is no font within the family selected in 2, then use the inherited or UA-dependent ’font-family’ value and repeat from step 2, using the best match that can be obtained within this font. If a particular character cannot be displayed using this font, the UA should indicate that a character is not being displayed (for example, using the ’missing character’ glyph). 9. UAs that implement progressive rendering and have pending font downloads may, once download is successful, use the downloaded font as a font family. If the downloaded font is missing some glyphs that the temporary progressive font did contain, the downloaded font is not used for that character and the temporary font continues to be used. Note. The above algorithm can be optimized to avoid having to revisit the <strong>CSS2</strong> properties for each character. 232
The per-descriptor matching rules from (2) above are as follows: 1. ’font-style’ is tried first. ’italic’ will be satisfied if there is either a face in the UA’s font database labeled with the CSS keyword ’italic’ (preferred) or ’oblique’. Otherwise the values must be matched exactly or font-style will fail. 2. ’font-variant’ is tried next. ’normal’ matches a font not labeled as ’small-caps’; ’small-caps’ matches (1) a font labeled as ’small-caps’, (2) a font in which the small caps are synthesized, or (3) a font where all lowercase letters are replaced by uppercase letters. A small-caps font may be synthesized by electronically scaling uppercase letters from a normal font. 3. ’font-weight’ is matched next, it will never fail. (See ’font-weight’ below.) 4. ’font-size’ must be matched within a UA-dependent margin of tolerance. (Typically, sizes for scalable fonts are rounded to the nearest whole pixel, while the tolerance for bitmapped fonts could be as large as 20%.) Further computations, e.g., by ’em’ values in other properties, are based on the ’font-size’ value that is used, not the one that is specified. 15.5.1 Mapping font weight values to font names The ’font-weight’ property values are given on a numerical scale in which the value ’400’ (or ’normal’) corresponds to the "normal" text face for that family. The weight name associated with that face will typically be Book, Regular, Roman, Normal or sometimes Medium. The association of other weights within a family to the numerical weight values is intended only to preserve the ordering of weights within that family. User agents must map names to values in a way that preserves visual order; a face mapped to a value must not be lighter than faces mapped to lower values. There is no guarantee on how a user agent will map font faces within a family to weight values. However, the following heuristics tell how the assignment is done in typical cases: If the font family already uses a numerical scale with nine values (as e.g., OpenType does), the font weights should be mapped directly. If there is both a face labeled Medium and one labeled Book, Regular, Roman or Normal, then the Medium is normally assigned to the ’500’. The font labeled "Bold" will often correspond to the weight value ’700’. If there are fewer then 9 weights in the family, the default algorithm for filling the "holes" is as follows. If ’500’ is unassigned, it will be assigned the same font as ’400’. If any of the values ’600’, ’700’, ’800’, or ’900’ remains unassigned, they are assigned to the same face as the next darker assigned keyword, if any, or the next lighter one otherwise. If any of ’300’, ’200’, or ’100’ remains unassigned, it is assigned to the next lighter assigned keyword, if any, or the next darker otherwise. There is no guarantee that there will be a darker face for each of the ’font-weight’ values; for example, some fonts may have only a normal and a bold face, others may have eight different face weights. The following two examples show typical mappings. 233
Page 1 and 2:
REC-CSS2-19980512 Cascading Style S
Page 3 and 4:
Quick Table of Contents 1 About the
Page 5 and 6:
4.3.4 URL + URN = URI . . . . . . .
Page 7 and 8:
9.7 Relationships between ’displa
Page 9 and 10:
cursive . . . . . . . . . . . . . 2
Page 11:
B.1 New functionality . . . . . . .
Page 14 and 15:
Section 2: An introduction to CSS2
Page 16 and 17:
Initial This part specifies the pro
Page 18 and 19:
The section on Paged Media was in l
Page 21 and 22:
Contents 2 Introduction to CSS2 2.1
Page 23 and 24:
CSS2 has more than 100 different pr
Page 25 and 26:
Adding more rules to the style shee
Page 27:
Simplicity. CSS2 is more complex th
Page 30 and 31:
Document language The encoding lang
Page 32 and 33:
3.2 Conformance This section define
Page 35 and 36:
Contents 4 CSS2 syntax and basic da
Page 37 and 38:
Macro Definition ident name nmstart
Page 39 and 40:
In fact, these two methods may be c
Page 41 and 42:
P[example="public class foo\ {\ pri
Page 43 and 44:
A user agent conforming to a future
Page 45 and 46:
0.28 mm 1.4 mm viewer 28 inch 71 cm
Page 47 and 48:
Example(s): An example without quot
Page 49 and 50:
Values outside the device gamut sho
Page 51 and 52:
When a style sheet resides in a sep
Page 53 and 54:
Contents 5 Selectors 5.1 Pattern ma
Page 55 and 56:
5.2 Selector syntax A simple select
Page 57 and 58:
5.6 Child selectors A child selecto
Page 59 and 60:
Example(s): The following rule hide
Page 61 and 62:
H1#chapter1 { text-align: center }
Page 63 and 64:
Example(s): The following rule sets
Page 65 and 66:
5.11.4 The language pseudo-class: :
Page 67 and 68:
The following CSS2 will make a drop
Page 69 and 70:
6 Assigning property values, Cascad
Page 71 and 72:
BODY { font-size: 10pt } H1 { font-
Page 73 and 74:
6.4.1 Cascading order To find the v
Page 75:
author style sheet and may be overr
Page 78 and 79:
Link to a target medium The bo
Page 80 and 81:
Relationship between media groups a
Page 82 and 83:
Top TM TB TP Margin (Transparent) B
Page 84 and 85:
First element of list Second elemen
Page 86 and 87:
Value: {1,4} | inherit Initial: not
Page 88 and 89:
values, they apply to the top, righ
Page 90 and 91:
’border-color’ Value: {1,4} | t
Page 92 and 93:
Since the initial value of the bord
Page 95 and 96:
Contents 9 Visual formatting model
Page 97 and 98:
9.2 Controlling box generation The
Page 99 and 100:
The P generates a block box, with s
Page 101 and 102:
The properties of the run-in elemen
Page 103 and 104:
Value: static | relative | absolute
Page 105 and 106:
The offset is a fixed distance from
Page 107 and 108:
or like this: Several emphasized wo
Page 109 and 110:
IMG { float: left } BODY, P, IMG {
Page 111 and 112:
image margin paragraph border parag
Page 113 and 114:
Values have the following meanings
Page 115 and 116:
position: fixed; width: 100%; heigh
Page 117 and 118:
Document Window (0,0) (0, 400) 1 Be
Page 119 and 120:
Document Window (0,0) (0, 400) 24 p
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Document Window I used two red hyph
Page 127 and 128:
This text will be beneath everythi
Page 129 and 130:
(U+202C) at the end of the element.
Page 131 and 132:
Contents 10 Visual formatting model
Page 133 and 134:
#div1 { position: absolute; left: 5
Page 135 and 136:
(If the border style is ’none’,
Page 137 and 138:
’max-width’ Value: Initial: App
Page 139 and 140:
10.6.1 Inline, non-replaced element
Page 141 and 142:
Value: Initial: Applies to: | | n
Page 143 and 144:
. We recommend a computed value for
Page 145 and 146:
Contents 11 Visual effects 11.1 Ove
Page 147 and 148:
DIV I didn’t like the play, but t
Page 149 and 150:
(0, 0) (50, 0) clip region (0, 55)
Page 151 and 152:
onclick=’show("container2");hid
Page 153 and 154:
12 Generated content, automatic num
Page 155 and 156:
the pseudo-element will behave as i
Page 157 and 158:
’block’: the pseudo-element is
Page 159 and 160:
Approximate rendering ISO 10646 cod
Page 161 and 162:
Value: [ ? ]+ | none | inherit Ini
Page 163 and 164:
Example(s): The following style she
Page 165 and 166:
first or last line box exists in a
Page 167 and 168:
This is a very short document. This
Page 169 and 170:
decimal Decimal numbers, beginning
Page 171 and 172:
inside The marker box is the first
Page 173 and 174:
OL.alpha { list-style: lower-alpha
Page 175 and 176:
Contents 13 Paged media 13.1 Introd
Page 177 and 178:
Sheet Page box A D Page content B C
Page 179 and 180:
13.2.3 Crop marks: the ’marks’
Page 181 and 182: 13.3.1 Break before/after elements:
Page 183 and 184: Value: | inherit Initial: 2 Applie
Page 185 and 186: 13.4 Cascading in the page context
Page 187 and 188: Contents 14 Colors and Backgrounds
Page 189 and 190: This property sets the background i
Page 191 and 192: User agents may treat ’fixed’ a
Page 193 and 194: 14.3 Gamma correction For informati
Page 195 and 196: Contents 15 Fonts 15.1 Introduction
Page 197 and 198: In the CSS2 font model, as in CSS1,
Page 199 and 200: 15.2.2 Font family: the ’font-fam
Page 201 and 202: normal font. italic Specifies a fon
Page 203 and 204: 1. ultra-condensed 2. extra-condens
Page 205 and 206: Specifies the aspect value. The num
Page 207 and 208: 15.2.5 Shorthand font property: the
Page 209 and 210: menu The font used in menus (e.g.,
Page 211 and 212: Latin fonts Greek fonts Cyrillic fo
Page 213 and 214: page can be displayed. Progressive
Page 215 and 216: 15.3.2 Descriptors for Selecting a
Page 217 and 218: 15.3.3 Descriptors for Font Data Qu
Page 219 and 220: Value: [ [format( [, ]*)] | ] [,
Page 221 and 222: ’stemv’ (Descriptor) Value: In
Page 223 and 224: the extras are ignored. [p. 42] Exa
Page 225 and 226: Swiss 721 light Swiss 721 Swiss 721
Page 227 and 228: The ideal solution would be to have
Page 229 and 230: 15.4.11 Lower Baseline This gives t
Page 231: 15.4.19 Vertical stem width This is
Page 235 and 236: The next example defines a family o
Page 237 and 238: Contents 16 Text 16.1 Indentation:
Page 239 and 240: 16.3.1 Underlining, overlining, str
Page 241 and 242: Example(s): Consider this example:
Page 243 and 244: This property controls capitalizati
Page 245 and 246: Contents 17 Tables 17.1 Introductio
Page 247 and 248: other document languages (such as X
Page 249 and 250: ’table-footer-group’) element T
Page 251 and 252: caption’s margin caption caption
Page 253 and 254: current margins text text text prev
Page 255 and 256: cells rows row groups columns colum
Page 257 and 258: The two algorithms are described be
Page 259 and 260: percentage values of ’height’ r
Page 262 and 263: The lengths specify the distance th
Page 264 and 265: order−width padding padding borde
Page 266 and 267: An example of a table with collapse
Page 268 and 269: Each document language may have dif
Page 270 and 271: 270
Page 272 and 273: help Help is available for the obje
Page 274 and 275: 18.3 User preferences for fonts As
Page 276 and 277: Example(s): For example, to draw a
Page 278 and 279: spatial audio), and paragraphs of c
Page 280 and 281: Value: | | inherit Initial: depen
Page 282 and 283:
Example(s): The following two rules
Page 284 and 285:
far-right Same as ’60deg’. With
Page 286 and 287:
fast Same as 300 words per minute.
Page 288 and 289:
Values have the following meanings:
Page 290 and 291:
290
Page 292 and 293:
SUB { vertical-align: sub } SUP { v
Page 294 and 295:
Dynamic outlines [p. 274] . B.2 Upd
Page 296 and 297:
the native font format on the Amiga
Page 298 and 299:
TrueDoc TrueDoc technology was deve
Page 300 and 301:
Square Cove (4) Obtuse Square Cove
Page 302 and 303:
XHeight Standard/Serifed (4) High/T
Page 304 and 305:
Block Add Block name Unicode range
Page 306 and 307:
This table suggests where such info
Page 308 and 309:
308
Page 310 and 311:
pseudo_page : ’:’ IDENT ; font_
Page 312 and 313:
{num}rad {num}grad {num}ms {num}s {
Page 314 and 315:
[RFC1808] "Relative Uniform Resourc
Page 316 and 317:
[RFC1630] "Universal Resource Ident
Page 318 and 319:
Name ’border-top-width’ [p. 88]
Page 320 and 321:
Name ’list-style-type’ [p. 168]
Page 322 and 323:
Name ’speech-rate’ [p. 285] Val
Page 324 and 325:
Name Values Initial value ’mathli
Page 326 and 327:
’ascent’ (descriptor), 222 aspe
Page 328 and 329:
close-quote, 159, 155 collapsing ma
Page 330 and 331:
font family, 198 font set, 199 font
Page 332 and 333:
definition of, 43 ’letter-spacing
Page 334 and 335:
page model, 175 page selector, 176
Page 336 and 337:
simple selector, 55 ’size’, 177
Page 338:
valid style sheet, 29 value, 41 ver
show all

W3C CSS2 Cascading Style Sheets, level 2 - instructional media + ...

Create successful ePaper yourself

Delete template?

Save as template?