A <text> in a <clipPath> was dropped with a warning, so a clip path made
only of text had no content and the art it clipped was hidden. The
clipPath content model in CSS Masking Module Level 1 lists text and use
(https://www.w3.org/TR/css-masking-1/#ClipPathElement).
The importer now clips by the text's glyph outlines, together with any
shapes in the same clip path, and keeps clipPathUnits, the transforms,
clip-rule, visibility, the conditional processing attributes and a clip
path on the text. A <use> in a clip path that shows a text clips the
same way, placed by the <use>; a clip path on the <use> applies in the
<use>'s user space, and a reference goes to the first element with the
id. When the clip path holds only one visible text, with no clip path
of its own and no even-odd clip rule, the clipping path of the clip
group is the text object with no fill or stroke, the same structure
Make Clipping Mask produces for type. A text or a <use> with an id in a
clip path can still be shown by a <use> outside it. Each text's
outlines are laid out once, however many elements use the clip path.
A transform set by a style rule or a style attribute on a text now
places it, as it does a shape. Before, only the transform attribute was
read, inside and outside clip paths.
An embedded Type 1 font's eexec part is decrypted and its charstrings read,
so its glyphs and widths are used instead of the installed or fallback
font's. Codes are decoded through the font's Encoding, so fonts that place
glyphs at low codes no longer lose their type.
Adds composefont, the CIDInit and FontSetInit procedure sets and the CMap
operators, so EPS with CID-keyed fonts (as pdftops -level3 writes) opens.
Type 0 fonts with FMapType 9 decode their codes through the CMap's codespace
ranges and CID mappings, and the Identity CMaps are predefined.
Only a Stroke Style filter's widths written as one centered array come in as the drawn look. A Stroke Offset stroke and widths written for each side stay live with their profile.
A composite (Type 0) font with the 8/8 mapping picks a descendant font
and a code in it with each pair of bytes (PLRM 3rd ed., 5.10). The reader
set its strings as type in a font of the composite font's name, the
bytes read as Latin-1 and at a thousand times the size, so EPS from
pdftops of a PDF with embedded TrueType fonts showed nothing, or one
black shape, where its type was.
Characters now go to their descendants: a Type 42 font's glyphs are drawn
from the TrueType outlines its sfnts strings carry (Adobe Technical Note
5012), by the glyph index CharStrings gives their names, spaced by their
own widths or the show operator's numbers; charpath and stringwidth read
them too. A Type 3 descendant runs its procedures, and a descendant found
by name sets its character as type at the composite font's size.
A pattern's definition (in either form) and a brush's art were read
without the file's art styles, so an object there with a style came in
as the look it draws, with a "drawn look" note, while the same object on
a layer or in a symbol came in as itself with its effects live. The
three definition readers now take the art styles as the symbol reader
does, and an object in a pattern's art with a style in the file's style
list keeps that graphic style's id.
An art styles section inside a symbol's, a pattern's or a brush's art
is now skipped, so it no longer replaces the file's own art styles.
The modern type reader read key 35 of a character style only for
Tate-chu-yoko (3). A run whose key 35 is 1 (Standard), in the run, its
character style or the document's defaults, now opens with Standard
Vertical Roman Alignment on, so its half-width characters stand upright
in vertical type. Horizontal type keeps the mark with no change to its
layout. A value of 2 (rotated), 3, any other value and no key at all
leave it off, VectorCraft's default.
- ate.rs: Style reads the flag and passes it to CharStyle, with a unit
test over defaults, character styles, run overrides and bad values.
- tests_native.rs: a vertical and a horizontal story with Standard,
rotated and unset runs; the test of values the reader ignores also
checks the flag.
- import_fuzz.rs: the vertical fixture also checks the flag.
- docs/file-format-parity.md: one line on the mapping.
File › Open and File › Place read HEIC and HEIF still images (.heic,
.heif) through heic-rs 0.1.4, the pure-Rust decoder photocraft-heif
uses, and store the pixels as PNG. Single pictures and grids of tiles,
8 to 10 bits, with or without an alpha image, are read with the
container's rotation, mirror and crop applied. A grid without a color
box of its own takes its tiles'. When neither the image nor its tiles
have an nclx box, the HEVC stream's video signal type gives the
samples' matrix and range. An RGB ICC profile, or Display P3 with the
sRGB curve named by an nclx box or, without a color box, by the
stream, is converted to sRGB. The EXIF resolution tags size the image;
without them it is 72 ppi. When the container's rotations turn the
image an odd number of quarter turns, the resolution's axes swap with
the pixels'.
Image sequences, images that aren't HEVC-coded, grids of cropped tiles
and images past the pixel allowance are refused with a message before
the pixels are decoded. The allowance counts each coded picture at the
size its sequence parameter sets give it.
The decoder is in the engine's `heif` feature, which is on by default
and listed by the desktop, CLI and web apps. A build without it still
recognizes the files and refuses them with a message.
A Scatter brush in a .ai or EPS file's editing data always came into
the Brushes panel keeping its art's colors. A Scatter brush whose last
15 numbers start with 1 now opens in Tints, and one whose numbers start
with 0 keeps its art's colors. Other values are not read and keep the
art's colors. The field before the art's name does not decide it: an
object whose first field is 1 is read by its 15 numbers, and a Scatter
object with 8 numbers is still left out.
A brush's art usually comes in a group after its frame, an unpainted
rectangle around the art. The reader kept that rectangle as part of
the brush's art. It now leaves out a frame at the art's bounds (within
1/1000 pt): an unnamed, unpainted rectangle with its four corners in
order, closed, or open with its first corner again at the end, and no
settings of its own (shown, unlocked, at full opacity in Normal, with
no effects, note or other attributes). A wider frame stays in the art,
and so do a path that crosses the corners, an open path along three
sides and a rectangle with settings of its own. A group left with one
object becomes that object, unless it has a state or look of its own
(hidden, locked, isolated, knockout, an opacity, a blend mode, a name,
a mask, a note or another setting, or an appearance); then it stays a
group without the frame. The rule applies to every brush art section.
Existing files with such brushes now open with Tints and without the
extra frame path in the brush's art. With an exact frame, the pieces
that a Scatter or Art brush draws along a path stay where they were.
The Scatter, Art and Pattern brush colorization options, Tints among
them, are described on pages 281-282 of
https://web.archive.org/web/20210601162814/https://helpx.adobe.com/pdf/illustrator_reference.pdf#page=281
Tests cover Scatter brushes whose numbers start with 1 and 0, with a
first field of 1 and 2, and an 8-number object. They cover frames kept
or left out (exact, wider, open, filled, named, crossing the corners,
along three sides, with a note, Show Center or hidden), a group's own
state and note kept, and the pieces a Scatter and an Art brush draw
along a path with and without the frame. The import fuzz test reads
brush art after frames of any corners and paint.
The legacy reader skipped `bindrepeat Tg` (section 15.3.4 of the version 7
file format specification). It now reads the binding punctuation bit:
1 and 3 set the paragraph's Burasagari to Force, and 0 and 2 set it to
none, which is VectorCraft's own mapping. The value is modal, lasts into
the next text object, and an operand other than 0 to 3 leaves it as it
was. The repeat character, `TG`, `Xu` and `Tu` are still skipped.
docs/mcp.md and the `ParaStyle::burasagari` doc comment name the legacy
`.ai` case as the exception to imported text keeping `none`.
The Character Styles and Paragraph Styles panel menus get Load Character
Styles... or Load Paragraph Styles..., and Load All Styles..., which add the
styles of a document picked in an open dialog in one undo step
(charStyle.load, paraStyle.load, textStyle.loadAll). The swatches,
patterns and symbols the styles use come along as Paste brings them, in
use order, so a style or pattern renamed on the way in keeps its links.
A style the document already has, under its name or a numbered copy of
it, is not added again; another style whose name is taken is added under
a free name. The file's Normal styles, and styles with a blank name or
attributes that do not read, are not loaded.
A Warp on type, on the object or on one of its fills or strokes, opened
as a live effect with no check. Where the live warp draws a different
shape from the art saved in the file, the type moved and changed size.
Warped type is now compared with its saved art once it is laid out,
with the comparison and the per-file budget that envelopes use. Type
that draws as its saved art stays editable with the effect live. Other
warped type opens as that art, not as editable type, with one note that
counts them, and saving over the file asks first. The art's box goes
back into the comparison with the page. Type stays live without a
comparison when its saved art paints nothing or draws type of its own,
and in frames of threaded type.
Legacy type in a composite font such as HeiseiMin-W3-83pv-RKSJ-H was
decoded one byte to a character, so Japanese, Chinese and Korean type
opened as unrelated single-byte characters, and the font name kept the
CMap.
Tf now finds a predefined CMap at the end of the font name, unless a TZ
gives the font encoding pairs, and the font is the name without it.
Strings in that font are read by the CMap's code space, mapped to CIDs
with the predefined CMaps craft-pdf carries, then to Unicode by the
character collection's CID-to-Unicode CMap. Codes the CMap doesn't map
are dropped. A -V CMap is read with its -H form's codes. Codes in the
Unicode CMaps (UCS2, UTF8, UTF16, UTF32) are read as Unicode; those
helpers follow mockydevs' #6067. A 0x0D byte ends a paragraph and a 0x09
byte is a tab in these fonts too.
The predefined CMaps craft-pdf doesn't carry (RKSJ, 78-RKSJ, 78ms-RKSJ,
78-EUC, 78, Add, Ext, NWP, GB, CNS1, KSC, B5 and the Hong Kong B5 sets
other than HKscs-B5) are read with the nearest
carried CMap, which can give a different character for some codes.
GBT, GBT-EUC, GBTpc-EUC, CNS2 and KSC-Johab type still decodes byte by
byte, with the CMap removed from the font name.
Docs: docs/file-format-parity.md.
Type on a path from a file's text document opened as Rainbow on its
baseline, not flipped, whatever Type on a Path Options the frame kept.
Each frame now keeps its effect (Rainbow, Skew, 3D Ribbon, Stair Step,
Gravity), Align to Path (Ascender, Descender, Center, Baseline) and Flip.
A code or flag that can't be read leaves that option at its default.
Flipped type opens with the frame's path reversed once, after a copied
object takes its own art path, and an open path's end bracket stays so
the type starts where the file's range ends.
Spacing is still fitted from the file's layout. The fit now measures along
the path when Align to Path moves the baselines off it, and it follows the
glyphs' feet under 3D Ribbon, whose baselines stay level.
The editing copy of a PDF-compatible .ai left out the Graphic Styles
panel's styles and objects' links to them, with a warning. They are now
written as art styles:
- The panel's styles come first in %AI9_BeginArtStyles and are listed in
its order in %AI9_BeginArtStyleList after the palette, with their
fills, strokes, transparency and effects. Fills and strokes may have
transparency and effects of their own, and a style may also hold Warp,
Transform, Free Distort, Pucker & Bloat, Twist, Zig Zag or Gaussian
Blur. A style of an object's own holds the same effects as before.
- A path, compound path or group linked to a graphic style names it when
it has the style's appearance, the style is written, and the reader
reads that style on that object. Objects linked
to a new document's styles keep their link: the panel is written for
them too.
- The writer reads each style back with the reader before it writes
it. A style with gradient or pattern fills, with anything the
reader does not read back, with a name another style has, with a name
over 1,024 bytes or past 4,096 styles is left out with a warning. Other
links are left out with a warning, and a panel with no style written
warns that it opens with a new document's styles. No graphic style is
written on a large canvas, with a warning.
Graphic styles:
https://helpx.adobe.com/illustrator/desktop/special-effects-styles/apply-graphic-styles/apply-graphic-styles.html
Tests: the round trip of the panel's styles and of links; each effect a
style can hold; the forms written; the list's limits; duplicate names; an
empty panel; links left out; a style's opacity at the written precision;
a large canvas; Twist and Transform on an object with no link; a link
to a style whose Transform moves the outline, with and without an
opacity mask; the
reader's reading of warp numbers; fuzz cases for damaged written styles.
Docs: docs/file-format-parity.md.
The editing copy of a PDF-compatible .ai wrote an object's live effects
as their result (geometry effects) or left them out (the others).
Objects with effects the .ai reader reads are now written as art styles:
- An object is written as its drawn look (a group of its vector art as
its geometry effects leave it, without shadows, glows or feathers,
with the object's transparency after it), then the object itself on
%_ lines (its points painted with nothing, or with its gradient fill
placed on the outline it draws; a group with its members), its name
and opacity mask, and
1 (style) XW naming its style.
- Styles are written in a non-printing block after the symbols, in
%AI9_BeginArtStyles: a chain of the stack of fills and strokes (with
the contents where the appearance puts them), the effects and the
object's transparency. Objects of the same appearance share a style.
- The effects written are the ones the reader reads on objects, with
their settings in the units it reads them in: Drop Shadow, Inner Glow,
Outer Glow, Feather, Round Corners, Scribble, Convert to Shape, Offset
Path, Outline Object, Outline Stroke and Pathfinder > Add.
- Each style is read back before it is written, by a new reader
function, read_art_style, which runs the reader's style parser and its
reading of a graphic style with the object's own gradient. An object
whose style reads back differently (several fills or strokes, fills
or strokes with transparency or effects of their own, pattern fills,
other effects), a filled object that fills by the even-odd rule (a
style's fill fills by the non-zero rule), a group whose effects change
its members' outlines while a member is written on another outline
(strokes as filled outlines, pattern fills as tiles, gradients that
fit their object), or one in a container whose own
effects change its members, is written as its drawn look with the
warning, and a style that is not written leaves no gradient
definition behind. Graphic styles and links to them are left out with
a warning. No art style is written on a large canvas.
Appearance attributes:
https://helpx.adobe.com/illustrator/using/appearance-attributes.html
Tests: the round trip of objects with each effect, a gradient fill, a
group with transparency and a mask, Pathfinder > Add and a hidden
effect; the same bytes on a second write; the forms written; the
objects the reader would not read; a large canvas; the warning for
graphic styles; filled even-odd objects; a gradient placed on the
outline Offset Path draws; a style that is not written; effects in a
pattern a drawn look uses; the reader's check of a style; fuzz cases
for damaged written styles.
Docs: docs/file-format-parity.md.
Key 30 of a paragraph's attributes holds its tab stops: each its position
(key 0) and alignment (key 1: 0 left, 1 center, 2 right, 3 decimal).
They were not read, so tabs fell on the default stops. At most 1,024 are
read a paragraph and 2^20 copied into a story's paragraphs, past which the
default stops apply with a warning. The fuzz test feeds hostile paragraph
attributes: alignments, auto leading, hyphenation options and tab stops.
A .ai or EPS whose editing data defines symbols but has no layers came
in as its PDF part or page without symbols, and Other Library in the
Symbols panel listed none. Such a file, and a file read as its PDF part
or page because its layers can't be used, now gets the symbols its
editing data defines before its first layer, as a file read from its
layers does: File > Open shows them in the Symbols panel in the order
of the symbol list, and Other Library lists them in a library panel.
- Each symbol keeps its registration point. A symbol that holds an
instance of a symbol the file doesn't define is left out, and an
object linked to a listed graphic style keeps the link.
- The symbols' art takes ids of the document, the art of opacity masks
in it included, and the images it shows come with it. Instances
drawn too deep are removed with the usual note.
- The global and spot colors the art is linked to come in as swatches.
A color whose name another swatch has takes that swatch's place when
it is a default swatch of a file without a palette; otherwise it
comes in under a free variant of the name ("Ink 2"), which the art
then names.
- Symbol art keeps the editing data's units, as in a file read from its
layers, so in a file in larger units its linked graphic styles are
drawn at the scaled size and the symbol art is not.
- The art of the patterns a palette or brush brings into a file read as
its PDF part or page now also takes new ids for its opacity masks.
Part of #3349
The legacy reader skipped `TV`, `Tv`, `Ty` and `TY` of section 15.3.4 of
the version 7 file format specification, so type set with `1 TV` opened
horizontal.
- `TV` sets a text object's writing direction. VectorCraft keeps one
direction for each text object, the one in force at its first
character, with a warning when a later character has another.
- `Ty` marks a Kumi block as a Tate-chu-yoko run, which is VectorCraft's
own mapping, and `TY` does the same in horizontal type. A `TY` block in
vertical type opens unmarked. Two blocks with nothing between them open
as one block.
- `Tv` sets Standard Vertical Roman Alignment.
All four are modal, and an operand other than 0 or 1 leaves the value as
it was.
Docs: docs/file-format-parity.md.
The reader gives an Xy right after a compound path or a text object to
that object. The writer now writes XR before the Xy of type, images and
guides, so type next to type, a compound path before type, image or
guide, and type before an image or guide keep their own opacity, blend
mode and knockout shape flag.
- Type keeps its Isolate Blending and Knockout Group state in a state
block after its text object, as its outlines did on their group.
- The reader no longer gives a layer the Xy before its last text object.
- The ASCII85 end marker of the text document stays on one line.
- The warning and docs/file-format-parity.md also list area type in an
open frame, type on an open path whose ends meet, type of only white
space and threads of type on a path as written as outlines.
- README.md, ROADMAP.md, docs/gaps.md, docs/roadmap.md and
docs/target-app-parity.md describe the editing copy a saved .ai holds.
- clip_path's doc comment is back on clip_path.
- import_fuzz reaches threaded area type and vertical type.
The editing copy of a PDF-compatible .ai wrote every text object as its
outlines. Point type, area type and type on a path are now written as
text: a text object in the layers that names its story, and the text
document after the document data (%AI11_BeginTextDocument) holding the
stories.
- Each story holds its characters (a paragraph ends in \r, a forced line
break is \x03), its character runs (font, size, leading, tracking,
baseline shift, horizontal and vertical scale, solid fill and stroke
with its weight, capitals, Tate-chu-yoko) and its paragraph runs
(alignment, indents, space before and after, hyphenation, right-to-left
direction).
- Point type keeps its point and, when it is turned, its matrix. Type
scaled by one factor, such as all type on a large canvas, has its scale
in its sizes, frame and path. Area type keeps its frame, rows,
columns, gutters and first baseline, type on a path its path and where
it starts and ends, and vertical type its orientation. A threaded story
is one story through its frames in order. Area type and type on a path
carry their frame's path in the layers as well.
- Type the text document can't hold is written as its outlines, with a
warning: type in opacity masks, pattern tiles and art cut to a clipping
object, mirrored type, turned or unevenly scaled area type and type on
a path, frames of several parts, area type that flows around a text wrap,
threads whose frames differ in orientation or include a frame written
as outlines, type and stories past the sizes the reader reads, and type
with inline graphics, ruby, gradient or pattern paint or an appearance
or opacity mask of its own. Other character and paragraph attributes are left out, with
a warning.
Tracking is written as a whole number of thousandths of an em, and
solid paints as simple paints; tracking that isn't a whole number is
rounded, with the warning.
Each construct is written in the form VectorCraft's .ai reader reads
(crates/eps/src/import/ate.rs at 36ef34dfdd: Texts::read :407, story
:501, frame :456, para :562, style :588, paint :622, AreaFrame::read
:284; the text object in import/ai/read/art.rs:15 and its path in
import/ai/frames.rs:26), and the tests read the written data back
through that reader. The scripting
reference documents the same attributes on the reading side (text frame
kinds, columnCount, columnGutter, rowCount, startTValue, endTValue,
orientation, and the character attributes):
https://web.archive.org/web/20160410101607/https://wwwimages.adobe.com/content/dam/Adobe/en/devnet/illustrator/sdk/CC2014/Illustrator%20Scripting%20Reference%20-%20JavaScript.pdf
The reader now closes a text object's frame path painted with a closing
operator (n, f, s, b, h), so area type's frame comes back closed; places
point type whose story keeps no composed lines at its frame's point;
keeps a story's last empty paragraph (only the \r that ends the story is
dropped); gives type made from the text document its text object's lock,
as it gives it its visibility; and gives type its text object's knockout
shape flag, as it gives it its opacity and blend mode.
Tests: the round trip of every kind of type and its state, a second
write of what is read back giving the same bytes, the text document and
stubs, scaled point type, a story split between threaded frames, the
fallbacks and the warnings, and the engine's editing copy with every save
option; a fuzz case for damaged text documents and stubs.
Docs: docs/file-format-parity.md.
A path with an Art brush comes in as the path, with the brush on its
stroke at its weight, instead of as its drawn look, when the brush
stretches art of solid-filled paths along the path, unflipped, at 100% in
Tints. The art runs on the side of the path the file draws it.
The drawn look stays for other colorizations and widths; Proportional,
between-guides and flipped brushes; type; a path with settings of its own,
a variable width, effects, a swatch stroke or an entry that isn't read;
and art with strokes, gradients, patterns, masks or effects, or no length.
A brushed stroke, Calligraphic ones too, takes the brush the Brushes panel
keeps under its name, and an image with a brush keeps its drawn look.
In every document, Tints and Tints and Shades take art in black ink alone
by its ink amount, and a process or gray stroke color's tints and shades
stay in that color's model.
Place and Expand bring the brushes the art uses, renaming on conflict.
Part of #637.
When Distort Appearance is on and the size a `.ai` saves for an
envelope's contents (`AIDeformArtWidthKey`, `AIDeformArtHeightKey`)
matches the contents' bounds with strokes, the reader now maps the
contents from that stroked box. It used to map them from the geometric
bounds, half a stroke inside that box, so an envelope of stroked art
could differ from its drawn art and keep the drawn art with a note.
Envelope Options hold the box's margins as `boundsMargin`, shares of the
geometric bounds at the top, bottom, left and right. Native files write
them only when they are not zero, and `object.envelope.info` reports
them then. Leaving Edit Contents measures them again when the strokes
reach differently than when Edit Contents began, and the node holds
what they measured then until it leaves. New envelopes have no
margins, so their results do not change. Contents with no width or no
height, such as one straight line, get no margins.
Docs: docs/mcp.md, docs/target-app-parity.md.
A section scan lexed a /ForeignObject's /Data, a /Binary dictionary's data and a text document's data as tokens. A `%_` line of that data holding a `(` opened a string, so the section ran past its end marker: the editing data failed to read, or the art after it was misread. Reader::section now skips the data up to its `~>`, as the reader does for art outside a section. Data without its `~>` before the section's end marker is not skipped. The scan for swatch names does the same.
A group whose style holds Effect › Pathfinder › Intersect, Exclude, Subtract,
Minus Back, Divide, Outline, Trim, Merge, Crop, Hard Mix or Soft Mix now opens
with its members editable and the effect live, as Add already did
(https://helpx.adobe.com/illustrator/desktop/manage-objects/reshape-transform-objects/combine-objects-using-pathfinder-effects.html).
The Command numbers 1 to 10 are VectorCraft's own reader rules, learned from
saved files. Soft Mix's number 11, and reading its Mix from 0.01 to 1 as a
Mixing Rate of Mix times 100, are also VectorCraft's own reader rules.
These still open as the drawn look:
- Trap, and the effect on a path, on type, on a layer or on a fill or stroke.
- Any operation whose saved Pathfinder Options (Precision, Remove Redundant
Points, Divide and Outline Will Remove Unpainted Artwork), ConvertCustom,
Mix or Trap settings differ from the values the reader accepts, although
only Soft Mix uses Mix and none of these operations uses the Trap settings.
The import fuzz test now also gives the style every option with any Mix, and
checks that a live Soft Mix's rate is from 1 to 100.
The reader measured a symbol's definition only to find the page art an
instance covered, so every file with a placed symbol instance opened
with that instance as drawn art, or as its page.
- Each `%AI14_BeginSymbol` definition is read by a reader of its own into
a symbol of the document, with its art (in the symbol's space, y down),
the registration point its dictionary gives
(`AI13PatternRegistrationType`, 1 to 9 from the top left) and the
instances of other symbols in its art. A definition whose art isn't
read whole isn't kept: type, placed files, non-native art, pattern
fills, a gradient or an image the reader can't read or place, and
anything else the reader doesn't read. Its instances come in as the
page draws them, within the box of the art that is read. A definition
that holds an instance of a symbol the file doesn't have isn't kept
either, nor is a definition holding an instance of one of those, and
their instances aren't read. A definition after the first layer isn't
read.
- `%AI24_BeginSymbolList` orders the symbols as the Symbols panel lists
them. A name read twice is numbered ("Dot 2"), and instances name the
first symbol with the file's name.
- `/SymbolInstance` with `/SymbolRef` and `/RTransformMatrix` comes in as
a live instance, with the hide and lock set before it and the opacity,
blending mode, isolation and knockout of the `Xy` after it, as a
group's. An instance with appearance changes of its own
(`AI19SymbolAppearanceMap`), of a symbol that isn't read, or placed
only by `/Matrix` or `/Transform`, comes in as the page draws it.
- Symbol art takes the gradients and art styles read before it, and an
object in it linked to a listed graphic style keeps the link.
- In a symbol's art, the matrices of instances, gradients and images are
read in the canvas's space, y up, about the canvas point of the ruler
origin. Without `%AI3_TemplateBox` an image can't be placed, so the
symbol isn't kept.
- At most 4,096 definitions are read, and a symbol list names at most
16,384 symbols.
Tests: reader tests for each case above, and fuzz cases for damaged and
hostile symbol data.
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