JP2009093631A - Document-encoding apparatus and document-encoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for improving the compression efficiency with respect to a structured document, where a plurality of decimals having fewer digits are described without having to impose a heavy load on analysis processing of the structured document. <P>SOLUTION: Digit counts c' beyond the decimal point of attribute values in a structured document are acquired (S404). The detected attribute values are transformed into numeric character strings representing integers, by manipulating the decimal point positions of the attribute values, according to the maximum number of acquired digits (S406). The transformed numeric character strings, and the maximum number of digits C are encoded (S407). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structured document encoding technique.

  Conventionally, in the XML language specification formulated by the W3C, when data is described in the XML language, it is generally encoded by a character encoding method such as UTF-8 or UTF-16. When data described as attribute values and element contents is data other than characters such as integers and decimals, encoding as characters makes the size larger than the original data and takes time for analysis processing.

  In binary XML technology such as the Fast Infoset (ISO / IEC 24824-1) specification established by ISO, attribute values and element contents in XML data can be encoded not only with characters but also with original data types such as integers and decimals. . As a result, data size compression and analysis processing time could be shortened.

Patent Document 1 discloses that a character string that repeatedly appears multiple times is replaced with a shorter byte string in XML data element names, attribute names, and numerical values, and compression is performed.
JP 2005-215950 A

  However, there is a case where the compression effect cannot be obtained with the conventional technology for data including coordinate values such as graphics, maps, drawings and the like.

  In conventional binary XML technology, decimal values are encoded in the IEEE754 (IEEE Standard for Binary Floating-Point Arithmetic (ANSI / IEEE Std 754-1985)) format, which is a data format on a computer, in order to shorten the analysis processing time. To do. When encoding in the IEEE 754 format, since the encoding size needs to be at least 4 bytes, a compression effect cannot be obtained with a decimal with a small number of digits such as -0.1 or 0.2. Therefore, in the case of a structured document in which a large number of decimals having a small number of digits such as SVG are described, even if the analysis processing time can be shortened, the compression effect cannot be obtained so much.

  The present invention has been made in view of the above problems, and improves the compression efficiency for a structured document in which a large number of decimals having a small number of digits are described without imposing a heavy load on the analysis processing of the structured document. It aims at providing the technique for.

  In order to achieve the object of the present invention, for example, a document encoding apparatus of the present invention comprises the following arrangement.

That is, a document encoding apparatus that encodes a structured document,
Detecting means for detecting each attribute value in the structured document;
Obtaining means for obtaining the number of digits after the decimal point of each attribute value detected by the detecting means;
By operating the decimal point position of each attribute value according to the maximum number of digits acquired by the acquisition unit, each attribute value detected by the detection unit is converted into a numeric character string representing an integer value. Conversion means for converting;
And encoding means for encoding each numeric character string by the conversion means and the maximum number of digits.

  In order to achieve the object of the present invention, for example, a document encoding apparatus of the present invention comprises the following arrangement.

That is, a document encoding apparatus that encodes a structured document,
Detecting means for detecting each attribute value in the structured document;
In the arrangement order of the attribute values detected by the detection means, calculation means for calculating a difference value between the attribute values in order from the top;
Obtaining means for obtaining the number of digits after the decimal point of each difference value calculated by the calculating means;
By operating the decimal point position of each difference value according to the maximum number of digits acquired by the acquisition means, each difference value calculated by the calculation means is converted into a numeric character string representing an integer value. Conversion means for converting;
Encoding means for encoding each numerical character string by the conversion means, the attribute value at the head position in the arrangement order of each attribute value detected by the detection means, and the maximum number of digits,
The encoding means encodes the attribute at the head position in the IEEE754 format.

  In order to achieve the object of the present invention, for example, a document encoding method of the present invention comprises the following arrangement.

That is, a document encoding method performed by a document encoding apparatus that encodes a structured document,
A detection step for detecting each attribute value in the structured document;
An acquisition step of acquiring the number of digits after the decimal point of each attribute value detected in the detection step;
By manipulating the decimal point position of each attribute value according to the maximum number of digits acquired in the acquisition step, each attribute value detected in the detection step is converted into a numeric character string representing an integer value. A conversion process to convert;
An encoding step for encoding each numeric character string by the conversion step and the maximum number of digits is provided.

  In order to achieve the object of the present invention, for example, a document encoding method of the present invention comprises the following arrangement.

That is, a document encoding method performed by a document encoding apparatus that encodes a structured document,
A detection step for detecting each attribute value in the structured document;
In the arrangement order of the attribute values detected in the detection step, a calculation step for calculating a difference value between the attribute values in order from the top,
An acquisition step of acquiring the number of digits after the decimal point of each difference value calculated in the calculation step;
By operating the decimal point position of each difference value according to the maximum number of digits acquired in the acquisition step, each difference value calculated in the calculation step is converted into a numeric character string representing an integer value. A conversion process to convert;
An encoding step for encoding each numeric character string by the conversion step, an attribute value at the head position in the arrangement order of each attribute value detected by the detection step, and the maximum number of digits, and
In the encoding step, the attribute at the head position is encoded in the IEEE754 format.

  According to the configuration of the present invention, it is possible to improve the compression efficiency for a structured document in which a large number of decimals having a small number of digits are described without imposing a heavy load on the analysis processing of the structured document.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a block diagram illustrating a hardware configuration example of a computer applicable to the document encoding apparatus according to the present embodiment. Note that the configuration of the apparatus applicable to the document encoding apparatus according to the present embodiment is not limited to the configuration illustrated in FIG. 1, and various modifications can be considered by those skilled in the art. Further, the document encoding apparatus according to the present embodiment is not limited to being realized by a single apparatus, and the document encoding apparatus according to the present embodiment is realized by a cooperative operation by a plurality of apparatuses. Also good. In this case, a plurality of devices are connected via a network such as a LAN.

  In FIG. 1, a CPU 101 controls the entire computer 100 using programs and data stored in a ROM 102 and a RAM 103, and executes each process described later as what the computer 100 performs.

  The ROM 102 stores setting data of the computer 100, a boot program, data of parameters that do not need to be changed, and the like.

  The RAM 103 has an area for temporarily storing programs and data loaded from the external storage device 104, data received from the outside via the network interface 106, and the like. Furthermore, the RAM 103 also has a work area used when the CPU 101 executes various processes.

  The external storage device 104 is a large-capacity information storage device represented by a hard disk drive device. The external storage device 104 stores an OS (operating system) and programs and data for causing the CPU 101 to execute each process described later that is executed by the computer 100. The external storage device 104 stores structured document data to be processed, which will be described later, as a file. Programs and data stored in the external storage device 104 are appropriately loaded into the RAM 103 under the control of the CPU 101 and are processed by the CPU 101.

  The input interface 105 is configured by a keyboard, a mouse, and the like, and can input various instructions to the CPU 101 when operated by an operator of the computer 100.

  The network interface 106 is used to connect the computer 100 to a LAN, the Internet, or the like, and the computer 100 can perform data communication with an external device via the network interface 106.

  A bus 107 connects the above-described units.

  The storage device that can be connected to the computer 100 is not limited to the external storage device 104, and the following may be provided in the computer 100. That is, a memory card, an optical disk such as a flexible disk (FD) and a Compact Disk (CD) that can be attached to and detached from the computer 100, a magnetic or optical card, an IC card, and the like.

  Next, structured document encoding processing performed by the computer 100 will be described.

  Devices with few hardware resources such as mobile phones, digital cameras, and printers are required to reduce the size of XML data as structured documents and to increase the speed of parsing processing. Conventionally, an encoding technique called binary XML has been used as a technique for solving such a problem. In binary XML, the structure of XML data such as elements and attributes is encoded into binary data, and the values of elements and attributes are encoded in original data types such as integers and decimals. By using binary data, the data size becomes smaller and the parsing process is faster than character encoding such as UTF-8 and UTF-16.

  However, there is a problem in the case of a structured document in which a large number of decimals having a small number of digits are described, such as the SVG specification (http://www.w3.org/Graphics/SVG) formulated by the W3C.

  FIG. 2 is a diagram illustrating an example of SVG. In the SVG shown in FIG. 2, many numerical values are described in the keyTimes attribute. These numerical values indicate the timing of the animation processing, and are decimal values of 0 to 1 that represent the ratio within the entire time. These values are not limited in the number of digits, but are generally specified by small decimal numbers such as “0.01” and “0.02” as shown in FIG. Further, in the SVG shown in FIG. 2, many real values representing coordinate information are described in the d attribute of the path. The decimal part of these real values is not limited in the number of digits, but is generally specified by a real value including a decimal part with a small number of digits such as “3.183” and “-0.911” as shown in FIG. Often to do.

  When binary XML is applied to the SVG of FIG. 2, real values can be encoded in the IEEE 754 format. The IEEE754 format is a format composed of a sign, an exponent part, and a mantissa part as shown in FIG. At least 4 bytes are required. FIG. 3 shows an example for 0.01, but the length does not change between the numeric character string and the IEEE754 format.

  In the SVG of FIG. 2, a numerical character string of about 3 to 6 bytes is described. When many such descriptions are included, even if binary XML is applied, the analysis processing time can be reduced, but the data size can hardly be reduced.

  FIG. 4 is a flowchart of a process for encoding SVG. In the description of the flowchart of FIG. 4, the SVG shown in FIG. 2 is used as an example of the SVG. Programs and data for causing the CPU 101 to execute processing according to the flowchart of FIG. 4 and SVG data as a structured document are stored in the external storage device 104. Therefore, the CPU 101 loads such programs, data, and SVG data into the RAM 103, and executes processing using these loaded programs. As a result, the computer 100 executes processing according to the flowchart of FIG. 4 described below.

  First, before executing the processing according to the flowchart of FIG. 4, the encoding target portion is designated in advance in the SVG data. If all values are to be encoded, there is no need to specify them.

  In the present embodiment, it is assumed that, in the SVG data of FIG. 2, the keyTimes attribute in which decimal values with a small number of digits are consecutive is designated as an encoding target. That is, the keyTimes attribute of the animateTransform element is specified. Also, the decimal separator “;” listed as the attribute value is specified.

  Next, the SVG data in FIG. 2 is loaded from the external storage device 104 to the RAM 103. Note that the method for acquiring the data of the SVG of FIG. 2 in the RAM 103 is not particularly limited.

  And the process according to the flowchart of FIG. 4 is started.

  First, in step S401, the SVG data (in the structured document) input to the RAM 103 as an encoding target is sequentially referred to, and it is determined whether the referred portion is the keyTimes attribute of the animateTransform element. As a result of the determination, if it is not the keyTimes attribute of the animateTransform element, the process proceeds to step S402. In step S <b> 402, binary XML encoding is performed on the referenced portion as usual. In the example of FIG. 2, the conventional binary XML encoding is performed on the value of the d attribute.

  On the other hand, if the result of determination in step S401 is that the keyTimes attribute of the animateTransform element, processing proceeds to step S403.

  In step S403, it is checked whether all numeric character strings (attribute values) in the keyTimes attribute of the animateTransform element have been extracted. If all numeric character strings have been extracted as a result of the check, the process proceeds to step S405. If all numeric character strings have not been extracted, the process proceeds to step S404.

  In step S404, first, a numeric character string (attribute value) that has not yet been extracted in the keyTimes attribute of the animateTransform element is extracted. A numeric character string is extracted by using a delimiter “;” designated in advance. In FIG. 2, 0, 0.01, 0.02, 0.1, and 1 are separated by “;”, so these numerical character strings are extracted. Even without using a designated delimiter, it is possible to sequentially check the character string of the attribute value from the beginning and detect a valid numerical character string as a single numerical character string.

  Then, the number of digits c ′ after the decimal point of the extracted numerical character string is acquired. Here, the number of digits c ′ can be calculated by counting the number of characters from the position of the decimal point character “.” To the end of the attribute value.

  In other words, the fact that the process has advanced from step S403 to step S405 means that the number of digits c 'after the decimal point has been obtained for all numeric character strings (attribute values) in the keyTimes attribute of the animateTransform element.

  In step S405, the maximum value (maximum number of digits) C is obtained from the number of digits c 'acquired in step S404 for all numeric character strings (attribute values) in the keyTimes attribute of the animateTransform element.

  Here, after extracting the numeric character string, an integer encoding method of the extracted attribute value (decimal value) is determined. To convert a decimal value into an integer, you must temporarily move (manipulate) the decimal point position. The moved decimal point position is restored during analysis. This processing is overhead compared to the case of encoding in the IEEE754 format. In the present embodiment, in order to reduce the overhead, the same integer coding format is used in the structure portion designated in advance. If the overhead is negligible, a separate integer encoding format may be used.

Here, each detected decimal value can be converted into an integer by moving at least C decimal points in decimal notation. Therefore, a method for encoding an integer value obtained by multiplying the decimal value by 10 ^C is determined as a common integer encoding method for this structure portion. In the present embodiment, since it is C = 2, as shown in FIG. 5, a method of encoding an integer value obtained by 10 ^two-fold decimal values, determined as a common integer encoding method of this structural part . FIG. 5 is a diagram for explaining the encoding of each numeric character string.

  After the integer encoding method is determined, each detected decimal value is encoded. Encoding can be performed by converting a decimal numeric character string into the IEEE754 format, converting it to a power of 10, and converting it into an integer. However, once converting to the IEEE 754 format has a large overhead, in this embodiment, the decimal value is integer-coded in the state of the numeric character string.

Accordingly, in step S406, a numeric character string representing an integer value obtained by multiplying the numeric character string by 10 ^C is generated. In other words, such processing is performed by subtracting the difference (C−c ′) between the number of digits c ′ and the maximum number of digits C obtained for the numeric character string below the integer value resulting from omitting the decimal point from the numeric character string This is a process of generating a numerical character string representing an integer value obtained by adding only 0.

  By performing the processing in step S406 for all numeric character strings, as shown in FIG. 5, “0” → “000”, “0.01” → “001”, “0.02” → “002”, respectively. “,” “0.1” → “010”, “1” → “100”.

  Finally, in step S407, the numerical character strings generated in step S406 and the maximum number of digits C are encoded for all numerical character strings. In the present embodiment, encoding is performed as binary XML. When encoding, it is described as a part of other data.

  Conventionally, in binary XML, as shown in FIG. 5, when attributes are encoded, description is made in the order of a code (0x9c) indicating an attribute structure, a code indicating a data type of an attribute value, and an attribute value. Each decimal value is encoded in a numeric character string or IEEE 754 format, and the format in which it is encoded is indicated by a data type.

  The data type is defined as shown in FIG. 6, and is 0x17 for character strings, 0x1a for IEEE754 single precision (float), and 0x1b for double precision (double). Therefore, in the present embodiment, the data type definition is expanded as shown in FIG. 6, and 0x3 * is a 1-byte integer, 0x31 is a power of 10, 0x32 is a power of 10, and so on. In this embodiment, since it is a square of 10, the data type is 0x32. Using this data type, encoding is performed as binary XML as shown in FIG. The description of the data type of the attribute value is 0x32, and the decimal values are 1-byte integers of “0” → 0x00, “0.01” → 0x01, “0.02” → 0x02, “0.1” → 0x0a, “1” → 0x64, respectively. Is encoded. As described above, the data size can be reduced even with a decimal value having a small number of digits.

  The integerization referred to here includes encoding a fixed decimal point position and a numerical value by using a decimal value as a fixed-point number.

  On the decoding side, since the integer encoding method is described in the data type of the encoded data, inverse conversion is performed according to the described method to obtain the original decimal value. In the present embodiment, since the integer coding method is unified within the structure portion, it is possible to reduce the overhead by performing inverse conversion after performing a series of calculation processes.

[Second Embodiment]
In the present embodiment, a case will be described in which the encoding method described in the first embodiment is applied to the d attribute of the SVG illustrated in FIG. As with the keyTimes attribute, many real values including a decimal part with a small number of digits are described in the d attribute. However, as shown in FIG. 2, the d attribute includes a real value including a decimal part having a slightly larger number of digits than the keyTimes attribute such as “198.784” and “59.762”. In such a case, integer encoding may increase the size, and encoding in the IEEE 754 format may be better. Therefore, in the present embodiment, a case will be described in which the IEEE754 format and the integer encoding are switched according to the numerical value to be encoded.

  Since the flowchart of the encoding process according to the present embodiment is basically the same as that shown in FIG. 4, the encoding process according to the present embodiment will be described below with reference to FIG.

  First, before executing the processing according to the flowchart of FIG. 4, the encoding target portion is designated in advance in the SVG data. If all real values are to be encoded, there is no need to specify them.

  In the present embodiment, it is assumed that the d attribute of the path element is designated as an encoding target in the SVG data of FIG. Also, real-valued delimiters “M”, “c”, “,” listed as attribute values are designated.

  Next, the SVG data in FIG. 2 is loaded from the external storage device 104 to the RAM 103. Note that the method for acquiring the data of the SVG of FIG. 2 in the RAM 103 is not particularly limited.

  And the process according to the flowchart of FIG. 4 is started.

  First, in step S401, the SVG data input to the RAM 103 as an encoding target is sequentially referred to, and it is determined whether the referred portion is the d attribute of the path element. As a result of the determination, if it is not the d attribute of the path element, the process proceeds to step S402. In step S <b> 402, binary XML encoding is performed on the referenced portion as usual.

  On the other hand, if the result of determination in step S401 is d attribute of the path element, processing proceeds to step S403.

  In step S403, it is checked whether all numeric character strings (attribute values) in the d attribute of the path element have been extracted. If all numeric character strings have been extracted as a result of the check, the process proceeds to step S405. If all numeric character strings have not been extracted, the process proceeds to step S404.

  In step S404, first, a numeric character string (attribute value) that has not been extracted in the d attribute of the path element is extracted. For the extraction of the numerical character string, predetermined delimiters “M”, “c”, “,” are used. In this embodiment, numeric character strings to be extracted are 198.784, 59.762, 3.183, -0.911, 4.972, -2.825, 5.366, and -5.742. Similar to the first embodiment, it is possible to detect a numeric character string without using a designated delimiter.

  Then, the number of digits c ′ after the decimal point of the extracted numerical character string is acquired.

  That is, the process proceeds from step S403 to step S405 means that the number of digits c 'after the decimal point is acquired for all numeric character strings (attribute values) in the d attribute of the path element.

  In step S405, the maximum value (maximum number of digits) C is obtained from the number of digits c 'acquired in step S404 for all numeric character strings (attribute values) in the d attribute of the path element.

  In step S405, the value of C is determined, but in the present embodiment, unlike the first embodiment, it is determined as follows.

  In drawing processing such as SVG, the required numerical accuracy can be determined in advance. Therefore, in this embodiment, the number of digits 3 after the decimal point, which is a numerical accuracy designated in advance, is determined as the value of C.

  Here, before determining the encoding method, it is determined whether to apply integer encoding. In order to make a determination, a threshold value is set in advance.

  Integer coding is meaningless if the size is larger than when encoding with IEEE754. When encoded with IEEE754, the minimum length is 4 bytes. If it becomes smaller than 4 bytes, the encoding size can be reduced. In the present embodiment, integer encoding is applied when encoding is performed to an integer of 2 bytes or less that can provide a sufficient size reduction effect. The threshold value may be a bit unit instead of a byte unit. However, since a shift process is required at the time of analysis, the threshold is a byte unit in this embodiment.

  A 2-byte integer can represent a value of −32768 to 32767 using a two's complement expression. When a real number is converted into an integer, if it is between -32768 and 32767, integer encoding should be applied. In other words, the numerical range is within a numerical range determined based on a size set in advance as the data size of the encoding result.

Next, in step S406, as in the first embodiment, a numeric character string representing an integer value obtained by multiplying the numeric character string by 10 ^C is generated. By performing the process in step S406 for all the numeric character strings, the following conversion results are obtained as shown in FIG. That is, “198.784” → “198784”, “59.762” → “59762”, “3.183” → “3183”, “−0.911” → “−0911”, “4.972” → Numerical character strings “4972”, “−2.825” → “−2825” → “5.366” → “5366”, and “−5.742” → “−5742” are obtained.

  Next, it is determined whether or not the numerical value represented by the numerical character string obtained by such conversion falls within the numerical range of -32768 to 32767. Such determination can be made by comparing numerical character strings or numerical values. This can be determined by comparing the lengths of character strings.

  The stored numeric character string is encoded as binary XML as it is, as in the first embodiment. On the other hand, for numeric character strings that do not fit, the numeric character string before conversion (conversion source) in step S406 is encoded as binary XML in the IEEE754 format. In this embodiment, as shown in FIG. 7, it is determined that the coordinate information 198.784, 59.762 of the drawing command M is encoded in the IEEE754 format, and other real values are determined to be integer encoded.

  This determination need not use the method described above, and can also be performed using information described in the SVG. In the description of the d attribute of the SVG path element, a drawing command and numerical information necessary for processing are listed. At this time, if the drawing command is an uppercase letter such as M or C, it is determined to be an absolute value expression, and if it is a lowercase letter such as c, it is determined to be a relative value expression. As shown in FIG. 2, the absolute value expression tends to be a numerical value having a larger number of digits than the relative value expression. Therefore, identification characters indicating absolute value expression and relative value expression are designated in advance, and it is determined that encoding is performed in the IEEE754 format if the absolute value expression is used, and integer coding is performed if the relative value expression is used.

  However, since this determination is not a strict determination, some erroneous determinations can be considered. Even if an erroneous determination is made, a sufficient effect can be obtained without any problem in processing only when the encoding method according to the present embodiment is not partially optimally applied.

  In the present embodiment, the same result can be obtained regardless of which method is used.

  Finally, in step S407, the numeric character string generated in step S406, the numeric character string before conversion, and the maximum number of digits C are encoded for all numeric character strings. In the present embodiment, encoding is performed as binary XML. When encoding, it is described as a part of other data.

  7 is encoded as binary XML using the data type definition of FIG. The data type of the decimal value of the drawing command M is 0x1a, and the data type of the other decimal values is a 2-byte integer that is the third power of 10 and is 0x43. The decimal values are 198.784 → 0x4346c8b4, 59.762 → 0x426f0c4a, 3.183 → 0x0c6f, −0.911 → 0xfc71, 4.972 → 0x136c, −2.825 → 0xf4f7, 5.366 → 0x14f6, − 5.742 → 0xe992.

  As in the first embodiment, the decoding side performs inverse conversion according to the data type of the encoded data, and acquires the original real value.

[Third Embodiment]
In the present embodiment, a case will be described in which the encoding method described in the first embodiment is applied to the values attribute of the SVG illustrated in FIG. Many numeric values are also described in the values attribute. These numbers enumerate certain value changes during animation and are used with the keyTimes attribute. The value of the values attribute is determined to be described in absolute value expression. Looking at each value, unlike the first and second embodiments, such as -418 and -446.71, there are many values exceeding 2 bytes when integer-coded. Therefore, in the present embodiment, encoding for values described in such an absolute value expression will be described.

  The encoding process according to this embodiment will be described below.

  First, in the SVG data, an encoding target portion is designated in advance. If all values are to be encoded, there is no need to specify them.

  In the present embodiment, it is assumed that the values attribute of the animateTransform element is specified as an encoding target in the SVG data of FIG. In addition, the delimiters “,”, “;” of real values listed as attribute values are designated.

  Next, the SVG data in FIG. 2 is loaded from the external storage device 104 to the RAM 103. Note that the method for acquiring the data of the SVG of FIG. 2 in the RAM 103 is not particularly limited.

  First, the SVG data input to the RAM 103 as an encoding target is sequentially referred to, and it is determined whether the referred portion is the values attribute of the animateTransform element. If it is not the values attribute of the animateTransform element as a result of the determination, the referenced portion is encoded in the conventional binary XML format.

  On the other hand, in the case of the values attribute of the animateTransform element, it is checked whether or not all numeric character strings (attribute values) in the values attribute of the animateTransform element have been extracted. If all numeric character strings have not been extracted as a result of the check, first, a numeric character string (attribute value) that has not yet been extracted in the values attribute of the animateTransform element is extracted. A numeric character string is extracted using delimiters “,” and “;” designated in advance. In the present embodiment, numeric character strings to be extracted are −68, −418, −101.49, −446.71, −126.52, −465.24, −139.49, −469.29, − 139.8 and -458.14. Similar to the first embodiment, it is possible to detect a numeric character string without using a designated delimiter.

  Next, a difference value of numerical character strings between sets (difference value between attribute values) is calculated from the top in the arrangement order of the sets of numerical character strings separated by delimiters. As a result, (−33.49, −28.71), (−25.03, −18.53), (−12.97, −4.05), and (−0.31, 11.15) are calculated.

  In the following, these difference values are subject to integer encoding. Note that in the arrangement order of the sets, the set (−68, −418) at the head position is an absolute value, and is therefore an object to be encoded by the IEEE754 method.

  Then, the number of digits c ′ after the decimal point of each difference value is acquired.

Next, the maximum value (maximum number of digits) C is obtained from the number of digits c ′ acquired for each difference value. Then, a numerical character string representing an integer value obtained by multiplying the difference value by 10 ^C is generated. Finally, in step S407, the set at the head position, each difference value, and the maximum number of digits C are encoded. Also in the present embodiment, encoding is performed as binary XML.

  FIG. 10 is a diagram showing a result of extending the data type definition shown in FIG. Specifically, the difference is calculated and integer coding is performed. This is expressed by setting the first bit to 1. In the present embodiment, as shown in FIG. 8, the data type of the first coordinate is 0x1a, and the data type of the remaining coordinates is a 2-byte integer that is a square of 10 and therefore 0xc2. The decimal values are 0xc2880000, 0xc3d10000, x0f2eb, 0xf4c9, 0xf639, 0xf8c3, 0xfaef, 0xfe6b, 0xffe1,0x045b, respectively.

  As described above, the data size can be reduced even with a decimal number described in absolute value.

  As in the first embodiment, the decoding side performs inverse conversion according to the data type of the encoded data to obtain the original decimal value.

[Fourth Embodiment]
In the present embodiment, XML data to be encoded is converted in advance into a data format that facilitates integer encoding.

  The SVG specification defines a transform attribute. The transform attribute is for converting the coordinate system of the described coordinate value, and can describe the transformation process before the drawing process.

  FIG. 9 is a diagram illustrating an example of attribute values of the d attribute of the path element in SVG. As shown in FIG. 9, a plurality of real value data is described in the d attribute of the path element.

  In the encoding process according to the present embodiment, first, in the flowchart of FIG. 4, the processes in steps S401 to S405 are performed in the same manner as in the first embodiment.

Since the real value described in the d attribute in FIG. 9 has a maximum of three digits after the decimal point, in step S405,
As C, “3” is determined. When encoding each real value, an integer value multiplied by 10 ³ is encoded instead of encoding in IEEE754 format.

  To restore each value, it is necessary to multiply by 0.001. Therefore, a description of the transform attribute is added to the SVG data so that the drawing process can be performed correctly. scale (X) is a description of the conversion process in which the coordinate value is multiplied by X. Since it is multiplied by 0.001, describe transform = scale (0.001). The description element can be a container element g as shown in Example 1 of FIG. 9 and a graphic element path as shown in Example 2.

  The added transform attribute is encoded by a normal binary XML encoding method.

  As described above, when the specification of the numerical conversion process is supported by the specification on the application data side such as SVG, the proposed method can be made without depending on the binary encoding format by editing the data in advance. Can be applied.

  In addition, about each above-mentioned embodiment, it may be used in combination as appropriate, and the processing in each embodiment may be executed in parallel, or may be executed by switching appropriately according to various conditions. Also good.

[Other Embodiments]
The present invention can take the form of, for example, a system, apparatus, method, program, or computer-readable storage medium. Specifically, the present invention may be applied to a system composed of a plurality of devices, or may be applied to an apparatus composed of a single device.

  Note that the present invention can also be achieved in the following forms. That is, a software program that realizes the functions of the above-described embodiments (a program corresponding to the above-described flowchart) is directly or remotely supplied to a system or apparatus. This can also be achieved by the computer of the system or apparatus reading and executing the supplied program code.

  Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. In other words, the present invention includes a computer program itself for realizing the functional processing of the present invention.

  In that case, as long as it has the function of a program, it may be in the form of object code, a program executed by an interpreter, script data supplied to the OS, or the like.

  Examples of the recording medium for supplying the program include the following. Namely, floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card, ROM, DVD (DVD-ROM, DVD-) R).

  Other program supply methods include the following. The browser of the client computer is used to connect to a homepage on the Internet, and the computer program itself of the present invention or a compressed file including an automatic installation function is downloaded from the homepage to a recording medium such as a hard disk. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the present invention.

  In addition, the program of the present invention is encrypted, stored in a storage medium such as a CD-ROM, distributed to users, and key information for decryption is downloaded from a homepage via the Internet to users who have cleared predetermined conditions. Let It is also possible to execute the encrypted program by using the key information and install the program on a computer.

  The functions of the above-described embodiments can also be realized by a computer executing a read program. That is, by executing the program, the functions of the above-described embodiments are realized, and an OS running on the computer performs part or all of the actual processing based on the instruction of the program. The function of the above-described embodiment can also be realized by the processing.

  Further, the functions of the above-described embodiments are realized by the following processing. That is, the program read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Then, based on the instructions of the program, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

It is a block diagram which shows the hardware structural example of the computer applicable to the document encoding apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of SVG. It is a figure explaining the format of IEEE754 format. It is a flowchart of the process which encodes SVG. It is a figure explaining encoding of each numerical character string. It is a figure explaining the definition of a data type. It is a figure explaining the conversion result. It is a figure explaining the conversion result. It is a figure which shows the example of the attribute value of d attribute of the path element in SVG. It is a figure explaining the expansion result of the data type definition shown in FIG.

Claims (10)

A document encoding device for encoding a structured document,
Detecting means for detecting each attribute value in the structured document;
Obtaining means for obtaining the number of digits after the decimal point of each attribute value detected by the detecting means;
By operating the decimal point position of each attribute value according to the maximum number of digits acquired by the acquisition unit, each attribute value detected by the detection unit is converted into a numeric character string representing an integer value. Conversion means for converting;
A document encoding apparatus comprising: encoding means for encoding each numeric character string by the conversion means and the maximum number of digits. 2. The document encoding apparatus according to claim 1, wherein the conversion unit generates a numeric character string representing an integer value obtained by multiplying an attribute value by 10 ^C , where C is the maximum number of digits. The encoding means includes
Among numerical character strings as conversion results by the conversion means, for numerical character strings indicating numerical values that do not fall within a numerical range determined based on a size set in advance as the data size of the encoding result, the numerical value of the conversion source The document encoding apparatus according to claim 1, wherein the character string is encoded in an IEEE 754 format. A document encoding device for encoding a structured document,
Detecting means for detecting each attribute value in the structured document;
In the arrangement order of the attribute values detected by the detection means, calculation means for calculating a difference value between the attribute values in order from the top;
Obtaining means for obtaining the number of digits after the decimal point of each difference value calculated by the calculating means;
By operating the decimal point position of each difference value according to the maximum number of digits acquired by the acquisition means, each difference value calculated by the calculation means is converted into a numeric character string representing an integer value. Conversion means for converting;
Encoding means for encoding each numerical character string by the conversion means, the attribute value at the head position in the arrangement order of each attribute value detected by the detection means, and the maximum number of digits,
The document encoding apparatus, wherein the encoding means encodes the attribute at the head position in IEEE754 format.   The document encoding apparatus according to any one of claims 1 to 4, wherein the encoding unit performs encoding by binary XML.   6. The document encoding apparatus according to claim 1, wherein the structured document is SVG. A document encoding method performed by a document encoding apparatus for encoding a structured document,
A detection step for detecting each attribute value in the structured document;
An acquisition step of acquiring the number of digits after the decimal point of each attribute value detected in the detection step;
By manipulating the decimal point position of each attribute value according to the maximum number of digits acquired in the acquisition step, each attribute value detected in the detection step is converted into a numeric character string representing an integer value. A conversion process to convert;
A document encoding method comprising: an encoding step for encoding each numerical character string obtained by the conversion step and the maximum number of digits. A document encoding method performed by a document encoding apparatus for encoding a structured document,
A detection step for detecting each attribute value in the structured document;
In the arrangement order of the attribute values detected in the detection step, a calculation step for calculating a difference value between the attribute values in order from the top,
An acquisition step of acquiring the number of digits after the decimal point of each difference value calculated in the calculation step;
By operating the decimal point position of each difference value according to the maximum number of digits acquired in the acquisition step, each difference value calculated in the calculation step is converted into a numeric character string representing an integer value. A conversion process to convert;
An encoding step for encoding each numeric character string by the conversion step, an attribute value at the head position in the arrangement order of each attribute value detected by the detection step, and the maximum number of digits, and
In the encoding step, the attribute at the head position is encoded in IEEE754 format.   A program for causing a computer to execute the document encoding method according to claim 7 or 8.   A computer-readable storage medium storing the program according to claim 9.

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