textobj.go

package gdf

import (
	"encoding/hex"
	"fmt"
)

type TextObj struct {
	Matrix
	LineMatrix Matrix
}

// RawTextCursor returns the x and y coordinates of the point (0,0,1) transformed only by the current text matrix.
func (c *ContentStream) RawTextCursor() Point {
	return Transform(Point{0, 0}, c.TextObj.Matrix)
}

// TextCursor returns the x and y coordinates of the point (0,0,1) transformed by the current text matrix and the current transformation matrix.
func (c *ContentStream) TextCursor() Point {
	p := Transform(Point{0, 0}, c.TextObj.Matrix)
	return Transform(p, c.GS.Matrix)
}

// SetTextMatrix sets the current text object's text matrix and line matrix to m; Tm.
func (c *ContentStream) SetTextMatrix(m Matrix) {
	c.TextObj.Matrix = m
	c.TextObj.LineMatrix = m
	c.buf = cmdf(c.buf, op_Tm, m.A, m.B, m.C, m.D, m.E, m.F)
}

// SetTextOffset offsets the current text object's text matrix by x and y, and sets the text object's line matrix equal to its text matrix.
func (c *ContentStream) SetTextOffset(x, y float64) {
	c.TextObj.Matrix = Mul(c.TextObj.Matrix, Matrix{1, 0, 0, 1, x, y})
	c.LineMatrix = c.TextObj.Matrix
	c.buf = cmdf(c.buf, op_Td, x, y)
}

// SetTextOffsetLeading sets the content stream's current leading to y and then calls c.TextOffset(x, y).
func (c *ContentStream) SetTextOffsetLeading(x, y float64) {
	c.SetLeading(-y)
	c.TextObj.Matrix = Mul(c.TextObj.Matrix, Matrix{1, 0, 0, 1, x, y})
	c.LineMatrix = c.TextObj.Matrix
	c.buf = cmdf(c.buf, op_Td, x, y)
}

// NextLine begins a new text line by setting the current text matrix and line matrix equal to the line matrix offset by (0, -c.Leading); T*.
func (c *ContentStream) NextLine() {
	c.TextObj.Matrix = Mul(c.LineMatrix, Matrix{1, 0, 0, 1, 0, -c.Leading})
	c.LineMatrix = c.TextObj.Matrix
	c.buf = append(c.buf, op_T_X...)
}

// ShowString writes s (without kerning) to c and advances the text matrix by the extent of s; Tj.
func (c *ContentStream) ShowString(s string) {
	ext := FUToPt(c.RawExtent([]rune(s)), c.FontSize)
	b, _ := c.Font.enc.Bytes([]byte(s))
	c.TextObj.Matrix = Mul(c.TextObj.Matrix, Matrix{1, 0, 0, 1, ext, 0})
	c.buf = append(c.buf, '<')
	c.buf = hex.AppendEncode(c.buf, b)
	c.buf = append(c.buf, ">\x20"...)
	c.buf = append(c.buf, op_Tj...)
}

// LineString writes s (without kerning) to c and advances the text matrix by the extent of s; '.
func (c *ContentStream) LineString(s string) {
	ext := FUToPt(c.RawExtent([]rune(s)), c.FontSize)
	b, _ := c.Font.enc.Bytes([]byte(s))
	c.TextObj.Matrix = Mul(c.TextObj.Matrix, Matrix{1, 0, 0, 1, ext, -c.Leading})
	c.buf = append(c.buf, '<')
	c.buf = hex.AppendEncode(c.buf, b)
	c.buf = append(c.buf, ">\x20"...)
	c.buf = append(c.buf, op_APOSTROPHE...)
}

// ShowText writes t (with kerning) to c and advances the text matrix by the extent of t; TJ.
func (c *ContentStream) ShowText(t []rune, kerns []int) error {
	if len(t) != len(kerns) {
		return fmt.Errorf("equal number of runes and kerns required. rune count: %d, kern count: %d", len(t), len(kerns))
	}
	c.buf = append(c.buf, '[')

	tmp := make([]byte, 0, 512)
	for i, r := range t {
		b, _ := c.Font.enc.Bytes([]byte(string(r)))
		tmp = append(tmp, b...)
		if kerns[i] != 0 {
			c.buf = append(c.buf, htxt(tmp)...)
			c.buf = itobuf(-(kerns[i]), c.buf)
			tmp = tmp[:0]
		}
	}
	if len(tmp) != 0 {
		c.buf = append(c.buf, htxt(tmp)...)
	}
	c.buf = append(c.buf, []byte("] TJ\n")...)

	ext, err := c.ExtentKerns(t, kerns)
	if err != nil {
		return err
	}
	ext = FUToPt(ext, c.FontSize)
	c.TextObj.Matrix = Mul(c.TextObj.Matrix, Matrix{1, 0, 0, 1, ext, 0})
	return nil
}