Patent Application
20080046468
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The invention will now be described with reference to
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration of specific embodiments. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. The leading digit(s) of reference numbers appearing in the figures corresponds to the Figure number, with the exception that the same reference number is used throughout to refer to an identical component which appears in multiple figures.
The method is particularly useful for written languages having discontinuous character codes of font data.
According to the embodiment of the font processing method, a Universal Character Set (UCS) is utilized, whereby each character of a written language is assigned a unique number (character code). Here, a UCS-2 coding system is used as an example, wherein each character code comprises 2 bytes, i.e., an upper significant byte and a lower significant byte.
The font database 11 stores a plurality of font files, each of which corresponds to a character identified by a character code. Each of the font files is stored at a font file address. These font files of a fixed size, such as 24, 32, 36 bytes, and the like, are stored in consecutive storage space of the font database 11. Note that one font file only means font data of one character. In actual, the font data of characters is stored in consecutive storage space of static memory, but stored in separate physical files governed by a file system.
For example, the character code is set according to a Universal character set (UCS) coding system, wherein each character of a written language is assigned a unique integer number (a character code, or a code value). Here, the character code comprises 2 bytes, i.e., an upper significant byte (USB) and a lower significant byte (LSB).
Character codes are grouped into USB groups according to USB values thereof. For example, a USB group identified by index 0 contains character codes within a range from “0x0000” to “0x00FF” with USB values “0x00”. A USB group identified by index 1 contains character codes within a range from “0x0100” to “0x01FF” with USB values “0x01”. A USB group identified by index 255 contains character codes within a range from “0xFF00” to “0xFFFF” with USB values “0xFF”. Furthermore, character codes within a USB group are grouped into LSB range groups according to continuity of LSB values thereof. For example, LSB values of character codes {164, 167, 168, 175, 176, 177}, i.e. {0x00A4, 0x00A7, 0x00A8, 0x00AF, 0x00B0, 0x00B1}, are grouped into three LSB range groups {164}, {167, 168}, {175, 176, 177} according to continuity of LSB values thereof. The storage unit 13 stores a font array 131 and a LSB range array 133. The font array 131 stores at most 256 font items, and each font item stores profile data related to LSB range groups of a corresponding USB group. An exemplary data structure of the font array 131 is presented in the following:
When a character code is given, a corresponding font file is retrieved from font database 11 by the processor 15. The processor 15 locates a corresponding font file with a given character code according to the font array 131 and the LSB range array 133. The located font file is then retrieved.
The font processing system of
Steps S22˜28 are executed to retrieve a font file corresponding to the given character code presenting the given character. In step S22, the USB value of the received character code is acquired. In step S23, a font item of the font array 131 is acquired, storing profile data of a USB group corresponding to the acquired USB value. In step S24, it is determined whether a total number of LSB range groups for the USB group is zero by inspecting the acquired font item, e.g. USBFontArray[i].nEntries=0, where i represents the USB value, and if so, the given character code correspond to no font files, and the method ends. Otherwise, the method proceeds to step S25. In step S25, multiple LSB range items related to the acquired USB group are acquired, and the acquired LSB range items are searched for the given character code. For example, a start index of LSB range items related to the acquired USB group, denoted as “Is”, is determined as USBFontArray[i].nInitial, and an end index of LSB range items related to the acquired USB group, denoted as “Ie”, is determined as USBFontArray[i].nInitial+USBFontArray[i].nEntries-1, where i represents the USB value. The acquired LSB range items include LSBRangeArray[Is] to LSBRangeArray[Ie]. The step S25 may employee a well-known binary search algorithm to search the acquired LSB range items. If the LSB value of given character code is between the variable “nInitialRangeVal” and “nFinalRangeVal” of one of the acquired LSB range items, the given character code is located in this LSB range item, otherwise, the given character code is not located in one of the acquired LSB range items. In step S26, it is determined whether a LSB range item can be located for the given character code, and if so, the method proceeds to step S27, otherwise, the method ends. In step S27, an address of the font file corresponding to the given character code is determined according to the located LSB range item. For example, the address of the font file is determined as FONT_DATABASE_OFFSET+LSBRangeArrary[j].nInitialFontOffset+(c&0x00FF-LSBRangeArray[j].nInitialRangeVal)×FONT_SIZE, where the constant “FONT_DATABASE_OFFSET” represents an address of the beginning of the font database 11, j represents an index of the located LSB range item, c represents the given character code, the constant “FONT_SIZE” represents the fixed font size. Here, font files stored in the font database 11 have the same size, such as 24, 32, 36 bytes, and the like.
In step S28, the font file is retrieved according to the font file address determined in step S27. In step S29, the content of the retrieved font file is displayed on the display device 19.
In the following, examples for font processing are described.
An embodiment of the font database 11 is described. The font database 11 comprises font files, denoted as F[164] to F[257], corresponding to the following character codes:
The character code is set according to a UCS2 coding system, wherein the character code comprises 2 bytes, i.e., an upper significant byte and a lower significant byte. The character codes are grouped into two USB groups according to USB values thereof.
The first USB group identified by index 0 comprises font files corresponding to character codes less then 255, i.e., having the USB value as 0. The second USB group identified by index 1 comprises font files corresponding to character codes in the range of 256˜511, i.e., having the USB value as 1.
In other words, the first USB group comprises font files corresponding to the following character codes:
{164,167,168,175,176,177,183,215,224,225,232,233,234,236,237,242,243, 247,249,250,252}.
The second USB group comprises font files corresponding to character codes “257”, and the other USB groups in the font database 11 do not comprise any font files.
In addition, character codes of each USB group are further grouped into LSB range groups according to continuity thereof.
Character codes of the first USB group are organized into 12 LSB range groups:
R001{164}, R002{167,168}, R003{175,176,177}, R004{183}, R005{215}, R006{224,225}, R007{232,233,234}, R008{236,237}, R009{242,243}, R010{247}, R011{249,250}, R012{252}.
Only one LSB range group R101 of the second USB group comprises the character code (257).
A font array 131 and a LSB range array 133 corresponding to the font database 11 are established. The font array stores two font items 131a and 131b. The LSB range array 133 stores thirteen LSB range items 133a to 133m.
The font item 131a stores information identifying the beginning index of the LSB range items, and a total number of LSB range items for the first USB group. The font item 131b stores information identifying the beginning index of the LSB range items, and a total number of LSB range items for the second USB group.
Accordingly, the font item 131a stores nInitial=1 and nEntries=12, specifying that the beginning index of the LSB range items for the first USB group is 1, and the total number of the LSB range items for the first USB group is 12. Similarly, the font item 131b stores nInitial=13 and nEntries=1, specifying that the beginning index of the LSB range items for the second USB is 13, and the total number of the LSB range items of the second USB group is 1.
The LSB range array 133 stores information specifying a minimum character code and a maximum character code, and an offset of the font file (font file start address) corresponding to the minimum character code for each LSB range group, e.g. one of R001˜R012 and R101. The specified information for LSB range group R001˜R012 and R101 are stored in LSB range items 133a to 133m.
Here, each of the font files is 32 bytes. Accordingly, the LSB range groups R001˜R012 and R101 can be defined as shown in Table 1.
The minimum and maximum character codes specified in the LSB range item can be recorded using the lower significant byte of the corresponding character code. Accordingly, because the lower significant byte of the character code 257 is 1, the LSB range item corresponding to the LSB range group R101 is recorded as {1,1,672}.
With reference to
In the following, the alphanumeric value “c” is used as an example.
A character code “23322(0x5b1a)” corresponding to the alphanumeric value “c” is received (step S21). In step S22, the USB value of the given character code is acquired. Here, the USB value is 91 (0x5b). In step S23, a font item of the font array 131 corresponding to the acquired USB value is acquired, denoted as USBFontArray[91]. In step S24, it is determined whether a total number of LSB range groups for the acquired USB group is zero, and if so, the given character code correspond to no font files, and the method ends, otherwise, the method proceeds to step S25. In step S25, multiple LSB range items related to the acquired USB group are acquired, and the acquired LSB range items are searched for the given character code.
If the font item USBFontArray[91] is specified as {Ri, N}, wherein Ri is a start index of LSB range items related to the acquired USB group, and N is a total number of LSB range items for the USB group, an end index of LSB range item (Rf) for the USB group can be determined accordingly. Here, the f=(i+N−1). Each LSB range item between the Ri and Rf specifies minimum and maximum LSB values. A binary search is then performed to locate a relevant LSB range item. For example, if the LSB value of given character code (23322) exceeds the minimum LSB of a LSB range Rm, and the LSB value of given character code (23322) is lower than the maximum LSB of the LSB range Rm, it can be determined that the given character code (23322) is located in the LSB range Rm. In step S26, it is determined whether the LSB range Rm comprising the given character code has been found, and if so, the method proceeds to step S27, otherwise, the method ends. In step S27, the font file address of the font file corresponding to the given character code (23322) is determined. Here, each character has the same font size. Accordingly, the offset of the font file can be determined according to the offset of the font file corresponding to the beginning character code of the LSB range Rm and the font size.
In step S28, the font file is retrieved according to the offset of the font file determined in step S27. In step S29, the content of retrieved font file is displayed on the display device 19.
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1850/DEL/2006 | Aug 2006 | IN | national |
