Computer method and apparatus for converting compressed characters for display in full size

• US 5,404,436 A
• Filed: 11/27/1991
• Issued: 04/04/1995
• Est. Priority Date: 11/27/1991
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Hamilton, Robert H.
• Primary Examiner(s): Herndon, Heather R.
• Assistant Examiner(s): FEILD, JOSEPH H
• Application Number:
  US07/800,666
• Time in Patent Office: 1,224 Days
• Field of Search: 364/419.09, 395/150, 395/151, 395/128, 345/26, 345/128, 345/194, 345/202
• US Class Current: 345/472
• CPC Class Codes: G06K 15/02 using printers
• CPC Class Codes: G06K 2215/0028 characterised by the format per se
• CPC Class Codes: G06K 2215/004 Generic data transformation
• CPC Class Codes: G09G 5/24 Generation of individual character patterns

Abstract

The invention method and apparatus employs font metrics data related to font bitmaps for characters of a desired font. Position offsets of pieces in composite characters are read from the font metrics data and are converted to the appropriate pixel offset to adjust the bitmaps of subject compressed font characters. The adjusted bitmaps of the different pieces of a subject composite character are combined to form a working bitmap which represents each piece of the composite character in full size in the subject font. Screen display of composite characters decompressed to full-size is supported by the formed working bitmaps.

Claims

1. In a digital processor, a method of converting compressed composite characters of a display font comprising the steps of:

selecting the compressed composite characters from display font bitmaps of the display font, each bitmap representation of a selected compressed composite character in the display font bitmaps comprising a bitmap representation of a compressed base piece and a bitmap representation of at least one other piece and the display font bitmaps comprising a bitmap representation of a full-sized form of each compressed base piece;

converting each selected compressed composite character to a full-sized decompressed composite character by combining the bitmap representation of the full-sized form of each compressed base piece with the bitmap representations of the other pieces of each selected compressed composite character, said converting being performed independent of user interaction;

generating converted bitmap representations of the full-sized decompressed composite characters; and

adding the converted bitmap representations of the full-sized decompressed composite characters to the display font bitmaps to support display of said selected compressed composite characters in full size on a display system.

2. A method as claimed in claim 1 wherein:

the step of converting includes;

reading character data from a font metrics file of the font, said character data including sizes of characters in the font, sizes of pieces of the selected composite characters including base pieces and other pieces, and position offsets of pieces in the selected composite characters referenced to respective base pieces of the selected composite characters, said position offsets being defined in font metrics units;

converting the position offsets of the other pieces in the selected composite characters to pixel offsets of the other pieces; and

for each piece in the selected composite characters, combining the pixel offsets with a bitmap representation of the piece to form an adjusted bitmap representation of the piece in full size; and

the step of generating converted bitmap representations includes combining the adjusted bitmap representations of base pieces with the adjusted bitmap representations of the respective other pieces, such that for each selected composite character, the adjusted bitmap representation of the base piece of the selected composite character is combined with the adjusted bitmap representation of respective other pieces of the selected composite character to form the representation of the selected composite character in full size.

3. A method as claimed in claim 1 wherein the step of generating converted bitmap representations of the full-sized decompressed composite characters includes generating adjusted display font bitmaps by modifying the display font bitmaps to include the full-sized decompressed characters.

4. In a digital processor having a memory, a method of converting font bitmaps of compressed composite characters for full-size character display, comprising the steps of:

storing in the memory a font metrics file and corresponding display font bitmaps for presenting compressed characters of a desired font to a computer display system, the display font bitmaps providing representations of at least (a) full-sized characters including capital letters, and (b) compressed characters including composite characters in the font, each composite character being formed of more than one piece and one of said pieces being a base piece formed of a compressed form of a full-sized character in the font;

from the stored display font bitmaps, selecting desired compressed characters including composite characters;

using the fount metrics file in the memory, for each selected compressed character, converting the stored display font bitmap representation of the character to a representation of the character decompressed to full size by combining the bitmap representation of each full-sized form of each compressed base piece with the bitmap representations of the other pieces of each selected compressed composite character;

adding the decompressed representations to the stored display font bitmaps, such that the display font bitmaps support display of the decompressed characters in full size.

5. A method as claimed in claim 4 wherein:

the step of selecting compressed characters includes selecting from the stored display font bitmaps composite characters having base pieces which comprise corresponding equivalent capital letters in the font, but in compressed form; and

the step of converting includes for each selected composite character, forming a representation of the composite character having a base piece comprising the corresponding equivalent capital letter decompressed to full size in the font.

6. A method as claimed in claim 5 wherein:

the selected composite characters further comprise other pieces comprising diacritical marks in the font;

the stored display font bitmaps further provide bitmap representations of the diacritical marks; and

the step of converting further includes for each selected composite character, forming a representation of the composite character by combining the provided display font bitmap representation of the corresponding equivalent full-sized capital letter and the stored display font bitmap representation of a respective diacritical mark for each of the other pieces in the selected composite character.

7. A method as claimed in claim 4 wherein:

the step of providing includes storing the display font bitmaps in a bitmap distribution format file read by the computer display system to display characters; and

the step of adding includes modifying the bitmap distribution format file to create a modified bitmap distribution format file which contains the representations of the decompressed characters, the modified bitmap distribution format file supporting display of characters in full size.

8. A method as claimed in claim 7 wherein:

(a) the stored display font bitmaps provide separate representations of the pieces in composite characters; and

(b) the step of converting includes converting the selected composite characters by;

(i) reading character data from the font metrics file, including the sizes of characters in the font, the sizes of pieces of the selected composite characters, and position offsets of other pieces in the selected composite characters referenced to respective base pieces of the selected composite characters, said position offsets being defined in font metrics units;

(ii) converting the position offsets of pieces in the selected composite characters to pixel offsets being compatible with the bitmap distribution format file;

(iii) for each piece in the selected composite characters, adding the determined pixel offsets to the stored display font bitmap representation of the piece to form an adjusted bitmap representation of the piece in full size; and

(iv) forming decompressed representations of the selected composite characters by combining the adjusted bitmap representations of base pieces with the adjusted bitmap representations of the respective other pieces, such that for each selected composite character, the adjusted bitmap representation of the base piece of the selected composite character is combined with the adjusted bitmap representation of respective other pieces of the selected composite character to form the working representation of the selected composite character in full size.

9. A computer apparatus for converting compressed characters of a display font, comprising:

a memory storing font metrics files and corresponding display font bitmaps presenting characters of a desired font for display on a computer display system, the display font bitmaps providing representations of at least (a) full-sized characters including capital letters, and (b) compressed characters including composite characters in the font, each composite character being formed of more than one piece said pieces comprising a base piece formed of a compressed form of a full-sized character in the font and other pieces;

a processor coupled to the memory for;

(i) executing a selection module under control of the computer apparatus for accessing the memory and for selecting desired compressed characters including composite characters from the display font bitmaps and;

(ii) executing a processor routine to automatically convert the stored font bitmap representation of each selected compressed character to a decompressed representation of the character decompressed to full size by combining the bitmap representation of each full-sized form of each compressed base piece with the bitmap representations of the other pieces of each selected compressed composite character, the processor routine accessing the memory and using the font metrics file to convert the bitmap representation of each selected character; and

bitmap generation means coupled to receive the decompressed representations from the processor routine and to add the decompressed representations for the selected composite characters to the stored display font bitmaps to support display of the selected composite characters in full size.

10. Computer apparatus as claimed in claim 9 wherein:

the selected compressed characters include composite characters having a base piece comprising a capital letter in the font, but in compressed form; and

for each selected composite character, the processor routine forms a decompressed representation of the composite character having a base piece comprising the respective corresponding equivalent capital letter in the font decompressed to full size.

11. Computer apparatus as claimed in claim 10 wherein:

the selected composite characters further comprise other pieces comprising diacritical marks in the font;

the display font bitmaps further provide representations of the other pieces; and

for each selected composite character, the processor routine forms a decompressed representation of the composite character by combining the stored display font bitmap representation of the corresponding equivalent full-sized capital letter and the display font bitmap representation of respective other pieces in the selected composite character.

12. Computer apparatus as claimed in claim 9 wherein:

the display font bitmaps are stored in the memory in a bitmap distribution format file read by the computer display system to display characters; and

the bitmap generation means further modifies the bitmap distribution format file to create a modified bitmap distribution format file which contains the representations of the decompressed characters, the modified bitmap distribution format file supporting display of characters in full size.

13. Computer apparatus as claimed in claim 12 wherein:

(a) the display font bitmaps stored in the memory provide separate representations of the pieces in composite characters; and

(b) for converting selected composite characters, the processor routine includes;

(i) a reading module for reading character data from the font metrics file, said data including the sizes of characters in the font, the sizes of pieces of the selected composite characters, and position offsets formed of indications of relative positions of other pieces in the selected composite characters referenced to respective base pieces, said position offsets being defined in font metrics units;

(ii) a processing module coupled to the reading module for converting the position offsets of pieces in the selected composite characters to pixel offsets, the pixel offsets being compatible with the bitmap distribution format file;

(iii) a data adding module responsive to the processing module, for each piece in the selected composite characters, the data adding module adding the determined pixel offsets to the stored display font bitmap representation of the piece, to form an adjusted bitmap representation of the piece in full size; and

(iv) a combiner coupled to the data adding module for forming decompressed representations of the selected composite characters by combining the adjusted bitmap representations of base pieces with the adjusted bitmap representations of the respective other pieces, such that for each selected composite character, the adjusted bitmap representation of the base piece of the selected composite character is combined with the adjusted bitmap representation of the other pieces of the selected composite character to form the working representation of the selected composite character in full size.