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Documentation of class 'BitmapFont':

Class: BitmapFont

Inheritance
Description
Class protocol
- instance creation
- private
Instance protocol
Examples

Inheritance:

   Object
   |
   +--FontDescription
      |
      +--BitmapFont

Package:: stx:libview

Category:: Graphics-Support

Version:: rev: 1.17 date: 2023/05/26 11:45:09; user: cg; file: BitmapFont.st directory: libview; module: stx stc-classLibrary: libview

Description:

This class demonstrates, that it is possible to define your own
renderers for fonts - you could even write a class which reads 
a truetype font from a ttf file and display those 
(maybe someone finds the time to do this 
 and provides the code to the public domain ?)

Here is a simple & sample implementation of private bitmap fonts;
Glyphs for each character are stored in the instance variable
'characterBitmaps'.
Some sample glyphs can be created with the class' sampleGlyphs method.
The required protocol is found in drawing and accessing.

copyrightCOPYRIGHT (c) 1994 by Claus Gittinger
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

This is a demo example:

THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTOR ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL THE CONTRIBUTOR BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.

Class protocol:

instance creation

new: BitmapFont new glyphs:(self sampleGlyhps).

private

sampleGlyhps: return the bitmap array for a sample font
(only contains glyphs for $a and $z)
smilyGlyhps: return the bitmap array for a smily font
(only contains glyphs for $a, $b and $c)

Instance protocol:

accessing

glyphs: aGlyphArray: set the glyphs array; that is the collection of
bitmaps - one for each character
setAscent: aNumber: set the font's ascent; that is the number of pixels
above the baseline
setDescent: aNumber: set the font's ascent; that is the number of pixels
below the baseline

drawing

displayString: aString from: index1 to: index2 x: x0 y: y in: aGC opaque: opaque: required protocol for new fonts:
- display part of a string, drawing foreground pixels only

private - drawing

drawCharacter: ascii in: aGC x: x y: y opaque: opaque

private - queries

glyphOfCharacter: ascii: return the height of a specific character
heightOfCharacter: ascii: return the height of a specific character
widthOfCharacter: ascii: return the width of a specific character

queries

ascent: return the ascent - the number of pixels above the baseLine
ascentOn: aDevice: return the descent - the number of pixels below the baseLine.
Since I am not device dependent, return my pixel ascent.
descent: return the descent - the number of pixels below the baseLine
descentOn: aDevice: return the descent - the number of pixels below the baseLine.
Since I am not device dependent, return my pixel descent.
height: return the height - the height in pixels of the highest character
heightOf: aString: return the height - the height in pixels of the highest character
heightOn: aDevice: return the height - the height in pixels of the highest character
isFixedWidth: return true if all of the font's characters are equal in
width.
maxAscent: return the maximum ascent;
that's the ascent of the highest character
maxDescent: return the maximum descent;
that's the descent of the highest character
maxHeight: return the maximum height;
that's the height of the highest character
maxWidth: return the maximum width - the width of the widest character in pixels
onDevice: aDevice: return a device representation of the receiver.
Since I am device independent, return the receiver.
width: return the width - the average width in pixels
widthOf: aString from: start to: stop: return the width of a substring
widthOf: aString from: startIndex to: endIndex on: aDevice: return the width of a substring
widthOn: aDevice: return the width - the average width in pixels

Examples:

a label showing characters in a new bitmap font:

  |font l|

  font := (BitmapFont new glyphs:(BitmapFont sampleGlyhps)).
  font setAscent:13; setDescent:3.

  l := Label new.
  l font:font.
  l label:'aazzazaz'.
  l open.

a label showing characters in a new smily font:

  |font l|

  font := (BitmapFont new glyphs:(BitmapFont smilyGlyhps)).
  font setAscent:16; setDescent:0.

  l := Label new.
  l font:font.
  l label:'aabbaaa'.
  l open.

demonstrate, that this font can be used in listViews just as any other font: (well, missing character glyphs are blanked)

  |font top list|

  font := (BitmapFont new glyphs:(BitmapFont sampleGlyhps)).
  font setAscent:13; setDescent:3.

  top := ScrollableView forView:(list := SelectionInListView new).
  list font:font.
  list list:#('a' 'z' 'aaa' 'zzz' 'azaz' 'zaza' 'aa' 'az' 'za' 'hello' 'abcdef' 'xyz').
  top extent:200@200.
  top open.

demonstrate, that this font can be used in textViews just as any other font: (well, missing character glyphs are blanked)

  |font top list|

  font := (BitmapFont new glyphs:(BitmapFont sampleGlyhps)).
  font setAscent:13; setDescent:3.

  top := ScrollableView forView:(list := EditTextView new).
  list font:font.
  list list:#('a' 'z' 'aaa' 'zzz' 'azaz' 'zaza' 'aa' 'az' 'za' 'hello' 'abcdef' 'xyz').
  top extent:200@200.
  top open.

another clock display: defines a font with the 7-segment led bitmaps as glyphs for 0-9, then simply displays the time as a string in that font.

  |glyphs f label|

  glyphs := Array new:256.
  glyphs 
      at:($0 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led0.xpm').
  glyphs 
      at:($1 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led1.xpm').
  glyphs 
      at:($2 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led2.xpm').
  glyphs 
      at:($3 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led3.xpm').
  glyphs 
      at:($4 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led4.xpm').
  glyphs 
      at:($5 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led5.xpm').
  glyphs 
      at:($6 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led6.xpm').
  glyphs 
      at:($7 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led7.xpm').
  glyphs 
      at:($8 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led8.xpm').
  glyphs 
      at:($9 asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/led9.xpm').
  glyphs 
      at:($: asciiValue + 1) 
      put:(Image fromFile:'../../goodies/bitmaps/xpmBitmaps/misc_numbers/ledCol.xpm').

  f := BitmapFont new glyphs:glyphs.

  label := Label new label:(Time now printString).
  label font:f.
  label open

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