QuickDraw Text
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QuickDraw Text is the part of the MacOS used for
drawing and displaying textual information on the screen
and other raster devices. Along with several performance
improvements, the following changes have been
implemented:
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- A variety of QuickDraw Text bug fixes related to
drawing text at large font sizes (greater than 200 point)
have been added. This allows drawing of antialiased text
over 200 point.
DrawString performance has been
improved.
- The size of the font table fragment cache has been
changed to accommodate larger, more complex fonts.
Normally, when the font table fragment cache is
allocated, its size used to be determined by computation
purely based on available physical RAM. This
determination gave a default size of 144K cache for
systems with up to 48MB of RAM, 216K for systems with up
to 96MB of RAM, and 288K above that. While this works
well for simple Latin fonts, there are some fonts that
are so complex that they exceeded this cache size. There
was no recourse in these cases; the font would not render
correctly, because the entire metamorphosis table could
not be loaded all at once. So the system now checks for
the presence of an optional
'fcsz' resource,
4 bytes
long, which contains an override to the calculated limit
described above. The value in this resource may be
whatever is desired; however, there are two constraints.
First, if the value in the resource is less than the
calculated value, then the calculated value is used and
the resource value is ignored. Second, the value in the
resource is constrained to being no greater than 1/16th
the size of physical RAM. If the resource value is
greater than this, it will be reduced to exactly this
value.
- The new calls
SetAntialiasedTextEnabled,
IsAntiAliasedTextEnabled,
QDTextBounds, and FetchFontInfo
have been added to InterfaceLib. These routines are
documented below.
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Compatibility Warning:
Developers linking against the routines
SetAntialiasedTextEnabled,
IsAntiAliasedTextEnabled,
QDTextBounds, and
FetchFontInfo in InterfaceLib who would
like to have their products run with previous versions
of the system software should weak-link against these
new symbols. Unless this is done, the Code Fragment
Manager will refuse to launch applications using the
new symbols when an older version of InterfaceLib is
being used. Developers weak-linking against any of the
new symbols in InterfaceLib should check to ensure
that the routines they weak link against are defined
before calling them.
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- A new routine for retrieving the pixel dimensions
of text that will be drawn on the screen have been added
to QuickDraw Text. This routine can be called from
PowerPC applications linking against the shared library
InterfaceLib in the System file. The new
routines are defined as follows:
FetchFontInfo
OSErr FetchFontInfo(SInt16 fontID,
SInt16 fontSize,
SInt16 fontStyle,
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fontID is the font ID number for a
font.
fontSize is the font size in pixels.
fontStyle contains the font style flags
for the font.
info is a pointer to a font information
record where the result will be stored.
FetchFontInfo returns the same
information as GetFontInfo, except, rather
than gathering information about the font settings from
the current GrafPort, this information is
provided as parameters to the routine. If
FetchFontInfo returns an error, the fields
in the FontInfo record will be set to zero.
(The error code returned is the value returned by
FMSwapFont.)
- A new routine for retrieving the pixel dimensions
of text that will be drawn on the screen have been added
to QuickDraw Text. This routine can be called from
PowerPC applications linking against the shared library
InterfaceLib in the System file. The new
routines are defined as follows:
QDTextBounds
void QDTextBounds(short byteCount,
const void* textAddr,
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byteCount is the number of bytes of text
contained in the buffer located at the address contained
in the value textAddr.
textAddr points to byteCount
bytes of textual data.
bounds is a pointer to a
Rect structure whose coordinates will be
calculated by QDTextBounds. On return,
bounds will contain the bounding coordinates for the
entire image (including parts of the image that may
extend beyond the first and last pen positions after the
text has been drawn) that will be drawn for the text
(given the font settings in the current
GrafPort). Note that the coordinates
returned are relative to the current pen position (as if
the pen were located at the origin). For example, in
Listing 3, we use QDTextBounds to draw a
rectangle around the text's image. Notice how in this
example the bounds returned by QDTextBounds
are offset using the current pen position, so that the
text drawing and the rectangle drawing occur using the
same coordinate system.
Listing 3. Using QDTextBounds to
discover where text will be drawn.
Rect bounds;
char *text = "sample text";
Point where;
SetPt(&where, 100, 100);
MoveTo(where.h, where.v);
PenSize(1,1);
QDTextBounds(text, strlen(text), &bounds);
OffsetRect(&bounds, where.h, where.v);
InsetRect(&bounds, -1, -1);
FrameRect(&bounds);
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The leftmost edge of the text's image can either be
to the right or the left of the pen position, and the
rightmost edge of the text's image may be to the left or
the right of the final pen position.
- A variety of bug fixes allowing ATM to behave
correctly in the system.
- A number of bugs affecting the drawing and
measurement of double-byte text were fixed.
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