JP3057947B2 - Data converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outline font data defined by a straight line and a curve.
From a cubic curve defined by four points of control point-second control point-end point, defined by four points of start point-control point-end point or four points of start point-first control point-second control point-end point 2 The present invention relates to a data conversion device for converting data into a next curve.

[0002]

2. Description of the Related Art In general, the mainstream formats for expressing the outline of a character as outline font data are: 1) a straight line and a cubic Bezier curve 2) a straight line and a quadratic curve Some are defined by B-spline curves.

Conventionally, the conversion from 2) to 1) has been easily performed by an equation since the conversion of not only a straight line portion but also a curved portion is a conversion from a quadratic expression to a cubic expression. Also, from 1) to 2)
Although the linear part can be converted by the equation, the curve part can be converted from the cubic equation to the quadratic equation. Therefore, by performing complicated numerical calculations, the cubic curve
It was approximated to a quadratic curve or recreated from the beginning using a straight line and a quadratic curve.

[0004]

However, the numerical calculation for approximating a cubic curve with a quadratic curve is complicated,
It put a great burden on U. In addition, since the creation of the outline font data requires a lot of man-hours, independently creating both of the above-mentioned formats 1) and 2) has a very large work overhead.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is possible to convert outline font data from a cubic curve to a quadratic curve by a simple method that reduces the load on the CPU. Therefore, an object of the present invention is to provide a data conversion device capable of improving the efficiency of outline font creation.

[0006]

In order to achieve this object, a data converter according to claim 1 defines a contour of a character by using two coordinate values of a start point and an end point as shown in FIG. The first line is a cubic curve defined by the first straight line and four start point-first control point-second control point-end point coordinate values.
The first outline font data, which is data defined by the curve, is defined by a second straight line defined by two start point and end point coordinate values and three start point-control point-end point coordinate values. A second curve, which is a quadratic curve, or 2 defined by coordinate values of four points of a start point, a first control point, a second control point, and an end point
An apparatus for converting into second outline font data that is data defined by a third curve that is a next curve,
Reading means for reading a first straight line or a first curve of the first outline font data; a starting point of the first straight line as a starting point of the second straight line; and an ending point of the first straight line as a second straight line. A straight line conversion means for outputting as an end point, and a straight line passing through the start point of the first curve and the first control point, and a straight line passing through the end point and the second control point, with the start point of the first curve being the start point of the second curve. First curve conversion means for converting the intersection into a second curve defined by three points having an intersection as a control point of the second curve and an end point of the first curve as an end point of the second curve; Start point of the third
A first point which is an intersection of a first auxiliary straight line which is a straight line passing through the start point and the first control point of the first curve and a second auxiliary straight line which is a straight line passing through the end point and the second control point And a second point which is a midpoint of a line segment connecting the start point and the end point of the first curve, and obtains a first curve at an intersection of a straight line passing through the first point and the second point and the first curve. A third auxiliary straight line, which is a tangent, is derived, an intersection of the first auxiliary straight line and the third auxiliary straight line is set as a first control point of a third curve, and an intersection of the second auxiliary straight line and the third auxiliary straight line is set as a third curve. A second control point for converting the end point of the first curve into a third curve defined by four points as the end point of the third curve; and the second or third curve An approximation degree judging unit for judging whether or not it is sufficiently close to the original first curve, a dividing unit for dividing the first curve to generate a plurality of new curves, The first curve is converted to a second curve by the line conversion means, and when the result is determined to be sufficiently close by the approximation degree determination means, the second curve is output. If it is determined by the determining means that the first curve is not close, the first curve is converted into the third curve by the second curve converting means, and if the result is determined to be sufficiently close by the approximation degree determining means, the second curve is converted. The third curve is output, and when it is determined that the first curve is not close, the first curve is divided by the dividing means, and the above-described processing is repeated for each of the divided curves, so that one first curve is obtained. Comprises conversion means for converting into a plurality of second or third curves, and writing means for writing the second straight line, the second curve and the third curve as predetermined second outline font data at a predetermined location. ing.

In a data conversion apparatus according to a second aspect, the conversion means includes the first curve conversion means, the approximation degree determination means, and the division means, and the first curve conversion means uses the first curve conversion means to convert the first curve. Is converted to the second curve, if the approximation degree determination means determines that the result is sufficiently close, the second curve is output. If the result is not close, the division is performed. By dividing the first curve by the means and repeating each of the divided curves as the first curve,
Convert the first curve into one or more second curves.

Further, in the data conversion apparatus according to a third aspect, the conversion means has the second curve conversion means, the approximation degree determination means, and the division means, and the first curve conversion means uses the first curve conversion means to convert the first curve into the first curve. Is converted to the third curve, when the approximation degree determination means determines that the result is sufficiently close, the third curve is output. By dividing the first curve with, and repeating the above processing with each of the divided curves as the first curve,
Is converted into one or more third curves.

Further, the first curve may be a cubic Bezier curve, and the second and third curves may be two-dimensional Bezier curves.
It may be a next B-spline curve.

[0010]

In the data converter according to the first aspect of the present invention, the straight line conversion means sets the start point of the first straight line to the start point of the second straight line and sets the end point of the first straight line to the end point of the second straight line. The first curve conversion means 11 sets the start point of the first curve as the start point of the second curve, the start point of the first curve and the first
The intersection defined by a straight line passing through the control point and an end point and a straight line passing through the second control point is defined as a control point of the second curve, and the end point of the first curve is defined as three points defined as an end point of the second curve. Convert to a second curve. Further, the second curve conversion means 12 sets the start point of the first curve as the start point of the third curve, and the first auxiliary straight line, the end point, and the second control line, which are straight lines passing through the start point of the first curve and the first control point. A first point, which is an intersection of the second auxiliary straight line 2 which is a straight line passing through the points, and a second point, which is a midpoint of a line connecting the start point and the end point of the first curve, are obtained. A third auxiliary straight line, which is a tangent to the first curve at the intersection of the straight line passing through the two points and the first curve, is derived, and the intersection of the first auxiliary line and the third auxiliary straight line is subjected to the first control of the third curve. Points, the second auxiliary straight line and the third
The intersection of the auxiliary straight line is set as the second control point of the third curve, and the end point of the first curve is converted into a third curve defined by four points as the end point of the third curve.

Then, the approximation degree determining means 13 determines whether the second or third curve is sufficiently close or not close to the original first curve, and the dividing means 14 determines whether the first curve is Divide to generate multiple new curves.

The conversion means 3 converts the first curve into the second curve by the first curve conversion means 11, and when the result is determined by the approximation degree determination means 13 to be sufficiently close, the conversion is performed. Output the second curve. When it is determined that the first curve is not close enough and insufficient, the first curve is converted into the third curve by the second curve conversion means 12, and the result is determined by the approximation degree determination means 13 to be sufficiently close. If so, the third
Is output, and if it is determined that it is not close enough, the first curve is divided by the dividing means 14 and the above-described processing is repeated for each of the divided curves to obtain the first curve.
Is converted into one or more second or third curves.

Further, the conversion means according to claim 2, when the result of conversion of the first curve into the second curve by the curve conversion means is determined to be sufficiently close by the approximation degree determination means, Output the second curve. If it is determined that the first curve is not close enough, the first curve is divided by the dividing means,
The first curve is converted into one or a plurality of second curves by repeating the above processing with each of the divided curves as the first curve.

Further, when the result of converting the first curve into the third curve by the curve converting means is judged to be sufficiently close by the approximation degree judging means, the conversion means of the third aspect may further comprise the third means. A curve is output, and when it is determined that the curve is not close enough and insufficient, the first curve is divided by the dividing means, and each of the divided curves is set as the first curve, and the above processing is repeated. Convert the curve into one or more third curves.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, an outline font of format 1 defined by a straight line and a cubic Bezier curve (hereinafter simply referred to as a cubic curve) is converted into a straight line and a quadratic B-spline curve (hereinafter simply a quadratic curve). This will be described using an example of a data conversion device that converts the data into an outline font of the format 2 defined by the above.

The cubic curve of the present embodiment is defined by the coordinate values of four points of a starting point, a first control point, a second control point, and an end point. The cubic curve P can be expressed as a function of the parameter t, and p0, p1, p2,
A cubic curve defined by the coordinates of p3 can be expressed by the following equation.

[0018]

(Equation 1)

The quadratic curve of the present embodiment is defined by three coordinate values of a start point-control point-end point, and a quadratic curve of a start point-first control point-second control point-end point. Sometimes defined by coordinate values. The quadratic curve Q is represented by a function of the parameter t. In the case of three points, the quadratic curve defined by the coordinates of q0, q1, q2 is

[0020]

(Equation 2)

In the case of four points, q0, q1, q2
The quadratic curve defined by the coordinates of q3 is

[0022]

(Equation 3)

Can be expressed by

FIG. 2 shows a block diagram of the data converter of this embodiment. In this data conversion device, a data bus 20 connects a CPU 21, a program memory 22, a working memory 23, a first format memory 24 and a second format memory 25.

The CPU 21 performs various calculations and controls performed by the data conversion apparatus.
A program in which the processing performed in U21 is described is stored. The working memory 23 is a memory for storing temporary data during execution of the processing of this embodiment. Then, the first format memory 24 and the second format memory 25 store respective format data.

Next, the data conversion processing for one character in the data conversion apparatus thus configured will be described with reference to the flowchart of FIG.

First, a read pointer is set at the position of the head data of a desired character (S31). Next, data of one straight line or one curve, that is, data of a cubic curve (this straight line or data in units of curves is referred to as segment data) is used as the first data.
The data is read from the format memory 24 (S32). That is, the start point and the end point are read out in the case of a straight line, and the start point, the first control point, the second control point, and the end point are read out in the case of a cubic curve.

Then, it is determined whether or not the read segment data is straight line data (S33). If the segment data is straight line data (S33: YES), the starting point of the straight line is converted as the starting point of the converted straight line, and the ending point of the straight line is converted as the ending point of the converted straight line (S34). If it is determined that the segment data is not linear data, that is, it is curve data (S33: NO), a curve conversion process is performed (S35). This processing will be described later in detail.

Subsequently, the segment data converted in S34 and S35 is written to a predetermined position in the second format memory 25 (S36). Next, it is determined whether or not the processing of all data for one character has been completed (S37). If the processing has been completed (S37: YES), this processing is completed,
If the processing has not been completed (S37: NO), the processing from S32 is repeated.

Next, the above-described curve conversion processing in S35 will be described with reference to the flowchart of FIG.

First, the cubic curves p0, p1, p2, p3
Into three-node quadratic curves q0, q1, q2 (S4
1). As shown in FIG. 5, the starting point q0 after the conversion is p
0, and the converted control point q1 is the intersection of the straight line l1 passing through the start point p0 of the cubic curve and the first control point p1, and the straight line l2 passing through the end point p3 of the cubic curve and the second control point p2. And The end point q2 after the conversion is the end point p3 of the cubic curve.

Next, it is determined whether or not the quadratic curve obtained in S41 is sufficiently close to the original cubic curve (S42). As shown in FIG. 6, this method includes dividing points (excluding a start point and an end point) obtained by dividing a cubic curve into four equal parts, a normal line at that point, and S41.
Sum of the distances of intersections with the quadratic curve obtained in (d0 + d2
When + d3) is smaller than a certain threshold value, it is determined that it is sufficiently close, that is, it is determined to be OK, and this curve conversion processing ends.

On the other hand, if the sum (d0 + d2 + d3) of the distance between the quadrant of the cubic curve and the normal line at that point and the quadratic curve obtained in S41 is larger than a certain threshold value, S42 is reached. Is NG, and as shown in FIG.
The cubic curves p0, p1, p2, and p3 are converted to quadratic curves q of four contact points.
It is converted into 0, q1, q2, q3 (S43). Note that the starting point q0 after the conversion is p0. The first control point and the second control point after the conversion are determined as follows. A straight line l1 passing through the starting point of the cubic curve and the first control point, a straight line passing through the ending point of the cubic curve and the second control point are defined as a straight line l2, an intersection k of the straight lines l1 and l2, a starting point of the cubic curve, A straight line passing through the middle point c of the line segment connecting the end point is defined as a straight line 13. A tangent at the intersection s of the straight line 13 and the cubic curve is defined as a straight line 14. Here, q1 is defined as the intersection of the straight line 11 and the straight line 14, and
q2 is defined as the intersection of the straight line l2 and the straight line l4. further,
The end point q3 after the conversion is p3.

Next, in the same processing as in S41, S43
The degree of approximation of the quadratic curve obtained in (1) is confirmed (S44). If the determination in S44 is OK, the curve conversion processing ends.

If the judgment in S44 is NG, as shown in FIG. 8, the cubic curves Q0, Q1, Q
2 and Q3 are divided to generate new cubic curves A and B (S45). That is, as shown in FIG. 8, in the cubic curve defined by Q0, Q1, Q2, and Q3, the middle point of Q0-Q1 is P1, and the middle point of Q1-Q2 is P1.
2. If the midpoint of Q2-Q3 is P3, the midpoint of P1-P2 is P4, the midpoint of P2-P3 is P5, and the midpoint of P4-P5 is P6, a cubic curve A, Q0, P
1, P4, P6 and a cubic curve B, that is, P6, P5
It can be divided into P3 and Q3.

The curve A and the curve B divided in this way are respectively subjected to curve conversion processing, and
The curve conversion process and the division process in S45 are executed for each cubic curve (S46 to S49). Therefore,
The division process and the curve conversion process are repeatedly executed until it is determined that the approximation degree is OK.

As described above, the data conversion device includes the CPU 2
In a simple method that reduces the burden on 1, it is possible to easily perform data conversion from one defined by a straight line and a cubic Bézier curve to one defined by a straight line and a quadratic B-spline curve. Efficiency can be improved.

Next, a modified example of the above-described curve conversion processing will be described with reference to FIG.

First, a quadratic curve of three nodes is generated in the same manner as in S41, and it is determined whether or not this quadratic curve is sufficiently close to the original cubic curve (S42). When the sum (d0 + d2 + d3) of the distance between the quadrant of the cubic curve and the normal line at that point and the quadratic curve obtained in S41 is smaller than a certain threshold value (S42.OK) , This curve conversion process ends.

When the sum of the distances (d0 + d2 + d3) of the intersections between the quadrant of the cubic curve and the normal line at that point and the quadratic curve obtained in S41 is larger than a certain threshold value (S42). NG), the same division processing as in S45 is performed. Then, the divided curves A and B are sequentially subjected to the curve conversion processing, and the curves S41, S42, S
The processing of 45 is executed for each cubic curve (S54 to S57). Therefore, in the approximation degree determination processing, OK
Until it is determined, the division process and the curve conversion process are repeatedly executed.

Further, a modified example of the curve conversion processing will be described with reference to FIG.

First, a quadratic curve of four nodes is generated in the same manner as in S43, and it is determined whether the quadratic curve is sufficiently close to the original cubic curve (S42). If the sum (d0 + d2 + d3) of the distance between the quadrant of the cubic curve and the normal line at that point and the quadratic curve obtained in S43 is smaller than a certain threshold value (S42.OK) , This curve conversion process ends.

When the sum of the distances (d0 + d2 + d3) of the intersections between the quadrant of the cubic curve and the normal line at that point and the quadratic curve obtained in S41 is larger than a certain threshold value (S42). NG), the same division processing as in S45 is performed. Then, the divided curves A and B are sequentially subjected to the curve conversion processing, and the above-described S43, S42, S
The processing of 45 is executed for each cubic curve (S64 to S67). Therefore, in the approximation degree determination processing, OK
Until it is determined, the division process and the curve conversion process are repeatedly executed.

Various other applications are possible without departing from the spirit of the present invention.

[0045]

As is apparent from the above description, according to each data converter of the present invention, the outline font data can be converted from a cubic curve to a quadratic curve by a simple method with a reduced load on the CPU. Conversion becomes possible, and the efficiency of outline font creation can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is a block diagram of a data conversion device according to the present embodiment.

FIG. 3 is a flowchart of a data conversion process according to the embodiment.

FIG. 4 is a flowchart of a curve conversion process according to the present embodiment.

FIG. 5 is an explanatory diagram of a three-point conversion process according to the present embodiment.

FIG. 6 is an explanatory diagram of a four-point conversion process according to the present embodiment.

FIG. 7 is an explanatory diagram of an approximation degree determination process of the embodiment.

FIG. 8 is an explanatory diagram of a division process according to the present embodiment.

FIG. 9 is a flowchart of a curve conversion process according to the second embodiment.

FIG. 10 is a flowchart of a curve conversion process according to the third embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 reading means 2 linear conversion means 3 conversion means 4 writing means 11 first curve conversion means 12 second curve conversion means 13 approximation degree determination means 14 division means

Claims (6)

(57) [Claims] 1. A shape of a contour line of a character is defined by a first straight line defined by two start point-end point coordinate values and four start point-first control point-second control point-end point coordinate values. 3 defined
The first outline font data, which is data defined by the first curve, which is the next curve, is converted into a second straight line defined by the coordinate values of two points, a start point and an end point, and three points of a start point, a control point, and an end point.
A second curve which is a quadratic curve defined by coordinate values of points, or a second curve which is a quadratic curve defined by coordinate values of four points of a start point-first control point-second control point-end point 3. A data conversion device for converting data into a second outline font data which is data defined by a third curve, wherein said reading means reads a first straight line or a first curve of said first outline font data; Straight line conversion means for outputting the start point of the first straight line as the start point of the second straight line, and outputting the end point of the first straight line as the end point of the second straight line; , The intersection of the straight line passing through the start point and the first control point of the first curve and the straight line passing through the end point and the second control point is taken as the control point of the second curve, and the end point of the first curve is taken as the end point of the first curve. A second curve that is converted into a second curve defined by three points that are the end points of the second curve A curve conversion means, a starting point of the first curve as a starting point of the third curve, and a first auxiliary straight line, an end point, and a second control point which are straight lines passing through the starting point of the first curve and the first control point. A first point, which is an intersection of a second auxiliary straight line that passes through, and a second point, which is a midpoint of a line connecting the start point and the end point of the first curve, are obtained.
A third auxiliary straight line that is a tangent to the first curve at the intersection of the straight line passing through the point and the second point and the first curve is derived, and the intersection of the first auxiliary straight line and the third auxiliary straight line is defined as a third line. The first control point of the curve is defined, the intersection of the second auxiliary straight line and the third auxiliary straight line is defined as the second control point of the third curve, and the end point of the first curve is defined as four end points of the third curve. Second curve conversion means for converting into a third curve, and approximation degree determination means for determining whether the second or third curve is sufficiently close to the original first curve, Dividing means for dividing the first curve to generate a plurality of new curves; converting the first curve into the second curve by the first curve converting means; If it is determined that the means is sufficiently close, the second curve is output,
If the approximation degree determination means determines that the distance is not close, the second curve conversion means converts the first curve into the third curve, and the result is sufficiently close by the closeness degree determination means. If it is determined, the third curve is output. If it is not close, the first curve is divided by the dividing means, and the above processing is repeated for each of the divided curves. Conversion means for converting the first curve into one or a plurality of second or third curves, and converting the second straight line, the second curve and the third curve into the second or third curve
And a writing means for writing the outline font data at a predetermined location. 2. A shape of a contour line of a character is defined by a first straight line defined by two start point-end point coordinate values and four start point-first control point-second control point-end point coordinate values. 3 defined
The first outline font data, which is data defined by the first curve, which is the next curve, is converted into a second straight line defined by the coordinate values of two points, a start point and an end point, and three points of a start point, a control point, and an end point.
What is claimed is: 1. A data conversion device for converting into a second outline font data which is data defined by a second curve which is a quadratic curve defined by a coordinate value of a point, comprising: Reading means for reading a straight line or a first curve; linear conversion for outputting a start point of the first straight line as a start point of the second straight line and outputting an end point of the first straight line as an end point of the second straight line Means, a starting point of the first curve being a starting point of the second curve, and an intersection of a straight line passing through the starting point of the first curve and the first control point with a straight line passing through the end point and the second control point is defined as a second point. Curve conversion means for converting the second curve into a second curve defined by three points where the control point of the first curve is the control point of the first curve and the end point of the first curve is the end point of the second curve. Approximation degree judgment to judge whether it is sufficiently close to the curve 1 Means for dividing the first curve to generate a plurality of new curves; and a result obtained by converting the first curve into the second curve by the curve conversion means, the degree of approximation determining means When it is determined that the distance is sufficiently close, the second curve is output. When it is determined that the distance is not close, the first curve is divided by the dividing means. A conversion means for converting the first curve into one or a plurality of second curves by repeating the above processing as a first curve; and converting the second straight line and the second curve into the second curve. A data conversion device comprising writing means for writing outline font data at a predetermined location. 3. The shape of the outline of the character is represented by a first straight line defined by two start point-end point coordinate values and four start point-first control point-second control point-end point coordinate values. 3 defined
The first outline font data, which is data defined by the first curve that is a next curve, is a quadratic curve defined by the coordinate values of four points of a start point, a first control point, a second control point, and an end point. What is claimed is: 1. A data conversion device for converting into a second outline font data which is data defined by a third curve, a reading means for reading a first straight line or a first curve of the first outline font data, Straight line conversion means for outputting a start point of the first straight line as a start point of the second straight line, and outputting an end point of the first straight line as an end point of the second straight line; The first auxiliary line, which is the start point of the third curve, and is the intersection of the first auxiliary line, which is a straight line passing through the start point of the first curve and the first control point, and the second auxiliary line, which is the straight line passing through the end point and the second control point. The point and the start and end points of the first curve I asked a second point is the midpoint of the line segment I, the first
A third auxiliary straight line that is a tangent to the first curve at the intersection of the straight line passing through the point and the second point and the first curve is derived, and the intersection of the first auxiliary straight line and the third auxiliary straight line is defined as a third line. The first control point of the curve is defined, the intersection of the second auxiliary straight line and the third auxiliary straight line is defined as the second control point of the third curve, and the end point of the first curve is defined as four end points of the third curve. Curve conversion means for converting the first curve into a third curve, and approximation degree determination means for determining whether the third curve is sufficiently close to the original first curve. Dividing means for dividing and generating a plurality of new curves; and a result obtained by converting the first curve into the third curve by the curve converting means is determined to be sufficiently close by the approximation degree determining means. In such a case, the third curve is output. A conversion unit configured to convert the first curve into one or a plurality of third curves by dividing the line and repeating the above processing with each of the divided curves as the first curve; Writing means for writing a straight line and a third curve in a predetermined location as the second outline font data. 4. The data conversion device according to claim 1, wherein the first curve is a cubic Bezier curve. 5. The apparatus according to claim 1, wherein said second curve is a quadratic B-spline curve having three nodes.
Data conversion device as described. 6. The method according to claim 1, wherein the third curve is a quadratic B-spline curve having four nodes.
Data conversion device as described.