Using Fonts and Character Primitives (1.2)
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Using Fonts and Character Primitives
You can use the font and character functions to perform the following
tasks:
♦ Select a font from the public fonts loaded with Control Panel.
♦ Select a font from a library of private fonts loaded by the application.
♦ Draw a string of text using the selected font.
♦ Scale, translate, and rotate a string of text from an outline font.
♦ Scale, shear, and alter the direction of a string of text from image and
outline fonts.
Selecting a Public Font
To select a public font, you must perform the following tasks:
♦ Call the GpiQueryFonts function, passing the QF_PUBLIC flag, a NULL
pointer to the font's face name, and a count of 0 to determine the number
of available public fonts.
♦ Copy this number (the GpiQueryFonts return value) into an integer
variable.
♦ Call GpiQueryFonts again, passing the QF_PUBLIC flag, a NULL pointer to
the font's face name, and the count returned by the previous call.
♦ Examine the metrics, looking for the face name and attributes of the font
that your application needs.
♦ Copy the appropriate metrics from the font that suits your application
into a FATTRS structure.
♦ Initialize a local identifier (lcid) for the new font.
♦ Call the GpiCreateLogFont function, passing a local identifier for the
font, the address of an empty array of eight characters, and the address
of the FATTRS structure.
♦ Examine the return value from GpiCreateLogFont. If the function was
successful, it should be 2.
♦ Pass the local identifier to the GpiSetCharSet function, assigning the
font to your application's presentation space.
The following code fragment shows how to select a Helvetica public font:
i = 0;
while (!strcomp(afm[i++].szFacename, "Helv"));
lFontCount = GpiQueryFonts(hps,
QF_PUBLIC,
NULL,
&lCount,
(LONG) (sizeof(fm)),
(PFONTMETRICS) afm);
lCount = lFontCount;
lFontCount = GpiQueryFonts(hps,
QF_PUBLIC,
NULL,
&lCount,
(LONG) (sizeof(fm)),
(PFONTMETRICS) afm);
fat.usRecordLength = sizeof(fat);
fat.fsSelection = afm[i].fsSelection;
fat.lMatch = afm[i].lMatch;
strcpy(fat.szFacename, afm[i].szFacename);
fat.idRegistry = afm[i].idRegistry;
fat.usCodePage = afm[i].usCodePage;
fat.lMaxBaselineExt = afm[i].lMaxBaselineExt;
fat.lAveCharWidth = afm[i].lAveCharWidth;
fat.fsType = afm[i].fsType;
fat.fsFontUse = 0;
GpiCreateLogFont(hps,
(PSTR8) chName,
lcid,
(PFATTRS) &fat);
GpiSetCharSet(hps, lcid);
Drawing Text
Before drawing text, you must determine which of the four text-output
functions you should use. The following list describes the specific purpose
of each text-output function:
Function name Purpose
────────────────────────────────────────────────────────────────────────────
GpiCharString This function draws a string of text starting at the
current position.
GpiCharStringAt This function draws a string of text starting at a point
that you pass as a function argument. It is identical to
a function sequence of GpiMove, GpiCharString.
GpiCharStringPos This function alters the intercharacter spacing in a
string of text in order to shade a special rectangle
that surrounds a string of text, to draw a string of
text in halftones, or to clip a string of text to a
special rectangle. This function starts drawing the text
at the current position.
GpiCharStringPosAt This function alters the intercharacter spacing in a
string of text in order to shade a special rectangle
that surrounds a string of text, to draw a string of
text in halftones, or to clip a string of text to a
special rectangle. This function starts drawing the text
at a point that you pass as one of the function
arguments.
The following code fragment shows how to load an array of characters with
the string "MS OS/2 Presentation Manager", set the current position to the
point (100,100) by calling the GpiMove function, and then draw the string by
calling the GpiCharString function:
ptl.x = 100; ptl.y = 100;
GpiMove (hps, &ptl);
GpiCharString(hps, 28L, "MS OS/2 Presentation Manager");
Transforming Text from an Outline Font
The following code fragment shows how to rotate a string of text 90 degrees
counterclockwise by using the model transformation:
matlfTransform.fxM11 = MAKEFIXED(1, 0); /* translates text */
matlfTransform.fxM12 = MAKEFIXED(0, 0);
matlfTransform.lM13 = 0L;
matlfTransform.fxM21 = MAKEFIXED(0, 0);
matlfTransform.fxM22 = MAKEFIXED(1, 0);
matlfTransform.lM23 = 0L;
matlfTransform.lM31 = -300L;
matlfTransform.lM32 = -100L;
matlfTransform.lM33 = 1L;
GpiSetModelTransformMatrix(hps, 9L, &matlfTransform,
TRANSFORM_REPLACE);
matlfTransform.fxM11 = MAKEFIXED(0, 0); /* rotates text */
matlfTransform.fxM12 = MAKEFIXED(1, 0);
matlfTransform.lM13 = 0L;
matlfTransform.fxM21 = -MAKEFIXED(1, 0);
matlfTransform.fxM22 = MAKEFIXED(0, 0);
matlfTransform.lM23 = 0L;
matlfTransform.lM31 = 0L;
matlfTransform.lM32 = 0L;
matlfTransform.lM33 = 1L;
GpiSetModelTransformMatrix(hps, 9L, &matlfTransform, TRANSFORM_ADD);
matlfTransform.fxM11 = MAKEFIXED(1, 0); /* translates again */
matlfTransform.fxM12 = MAKEFIXED(0, 0);
matlfTransform.lM13 = 0L;
matlfTransform.fxM21 = MAKEFIXED(0, 0);
matlfTransform.fxM22 = MAKEFIXED(1, 0);
matlfTransform.lM23 = 0L;
matlfTransform.lM31 = 300L;
matlfTransform.lM32 = 100L;
matlfTransform.lM33 = 1L;
GpiSetModelTransformMatrix(hps, 9L, &matlfTransform, TRANSFORM_ADD);
ptl.x = 100;
ptl.y = 100;
GpiMove(hps, &ptl);
GpiCharString(hps, 28L, "MS OS/2 Presentation Manager");
Transforming Text from an Image Font
The following code fragment shows how to double the size of the character
box, set the character mode to 2, and then print a string of text:
GpiQueryCharBox(hps, &sizfxBox);
sizfxBox.cx = 2 * sizfxBox.cx;
sizfxBox.cy = 2 * sizfxBox.cy;
GpiSetCharBox(hps, &sizfxBox);
ptl.x = 100;
ptl.y = 100;
GpiMove(hps, &ptl);
GpiCharString(hps, 28L, "MS OS/2 Presentation Manager");
♦