File types:
- GWP ($50) / $5445
Primary references:
- Apple II File Type Note $50/5445, "Teach Document"
- Apple IIgs Toolbox Reference, Volume 3
Teach Documents are text documents with some additional formatting commands. The format is named after a Macintosh program called "TeachText".
The files are essentially TextEdit control contents serialized to a file. The data fork holds the text, while the resource fork has two resources: an rStyleBlock (type=$8012 ID=1) with style information that can be passed directly to TextEdit calls, and a custom resource (type=$7001 ID=1) that holds window position information.
The data fork is plain text, using one of the Macintosh characters sets, such as Mac OS Roman.
The interesting part is the rStyleBlock ($8012) resource, which uses various structures described
in Apple IIgs Toolbox Reference, Volume 3. The resource contains a TextEdit TEFormat
structure (defined on page 49-31):
+$00 / 2: version - version number of structure, should be zero
+$02 / 4: rulerListLength - length, in bytes, of theRulerList
+$06 / N: theRulerList - array of TERuler structures
+$xx / 4: styleListLength - length, in bytes, of theStyleList
+$xx / N: theStyleList - array of TEStyle structures
+$xx / 4: numberOfStyles - numer of StyleItems contained in theStyles
+$xx / N: theStyles - array of StyleItems specifying which actual styles (stored in theStyleList)
apply to which text within the TextEdit record
All documents appear to have a single ruler. It's unclear how multiple rulers would be applied.
TextEdit TERuler structures (defined on page 49-39) are:
+$00 / 2: leftMargin - number of pixels to indent from left edge of text rect (exc. new para)
+$02 / 2: leftIndent - number of pixels to indent from left edge for new paragraphs
+$04 / 2: rightMargin - maximum line length, in pixels from the left edge of text rect
+$06 / 2: just - text justification (0=left, -1=right, 1=center, 2=full)
+$08 / 2: extraLS - line spacing, number of pixels to add between lines (may be negative)
+$0a / 2: flags (reserved)
+$0c / 4: userData - application-specific data
+$10 / 2: tabType - type of tab data (0=none, 1=regular intervals, 2=absolute pixel locations)
+$12 / N: theTabs - array of TabItem structures; tabTerminator field marks end of list
+$xx / 2: tabTerminator - omitted for tabType=0; pixel count for tabType=1; $ffff for tabType=2
These can also appear as rTERuler ($8025) resources, but not in Teach documents. None of these values can be set from the current Teach application.
TextEdit TEStyle structures (defined on page 49-41) are:
+$00 / 4: fontID - font manager ID
+$04 / 2: foreColor - foreground color for text
+$06 / 2: backColor - background color for text
+$08 / 4: userData - application-specific data
The current Teach application doesn't provide a way to set the color, but documents with colored text have been found.
The Apple IIgs Toolbox Reference, Volume 3 describes foreColor values thusly (p.49-41):
Foreground color for the text. Note that all bits in TextEdit color words are significant. TextEdit generates QuickDraw II color patterns by replicating a color word the appropriate number of times for the current resolution (8 times for 640 mode, 16 times for 320 mode). See Chapter 16 [...] for more information on QuickDraw II patterns and dithered colors.
For example, the foreground color value 0x4444 is rendered in 640 mode as alternating red/black pixels.
TextEdit StyleItem structures (defined on page 49-55) are:
+$00 / 4: length - total number of text characters that use this style; -1 indicates unused entry
+$04 / 4: offset - offset, in bytes, into theStyleList array to the TEStyle record
The TabItem structures (defined on page 49-59) are:
+$00 / 2: tabKind - must be $0000
+$02 / 2: tabData - location of absolute tab, expressed as number of pixels from left edge of view
Font ID records are 32-bit values, but have four distinct parts:
+$00 / 2: famNum - font family number
+$02 / 1: fontStyle - style of font (bit flags)
+$03 / 1: fontSize - size of font (in points, 1/72nd of an inch)
See chapter 8 in Apple IIgs Toolbox Reference, Volume 1.
To format the text, walk through the list of StyleItem structures, applying the referenced style to the specified number of characters. The list of styles should exactly span the text.