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package gofpdf
import (
"fmt"
"math"
)
// Routines in this file are translated from the work of Moritz Wagner and
// Andreas Würmser.
// The matrix used for generalized transformations of text, drawings and images.
type TransformMatrix struct {
A, B, C, D, E, F float64
}
// Set up a transformation context for subsequent text, drawings and images.
// The typical usage is to immediately follow a call to this method with a call
// to one or more of the transformation methods such as TransformScale(),
// TransformSkew(), etc. This is followed by text, drawing or image output and
// finally a call to TransformEnd(). All transformation contexts must be
// properly ended prior to outputting the document.
//
// See tutorial 17 for transformation examples.
func (f *Fpdf) TransformBegin() {
f.transformNest++
f.out("q")
}
// Scale the width of the following text, drawings and images. scaleWd is the
// percentage scaling factor. (x, y) is center of scaling.
func (f *Fpdf) TransformScaleX(scaleWd, x, y float64) {
f.TransformScale(scaleWd, 100, x, y)
}
// Scale the height of the following text, drawings and images. scaleHt is the
// percentage scaling factor. (x, y) is center of scaling.
func (f *Fpdf) TransformScaleY(scaleHt, x, y float64) {
f.TransformScale(100, scaleHt, x, y)
}
// Uniformly scale the width and height of the following text, drawings and
// images. s is the percentage scaling factor for both width and height. (x, y)
// is center of scaling.
func (f *Fpdf) TransformScaleXY(s, x, y float64) {
f.TransformScale(s, s, x, y)
}
// Generally scale the following text, drawings and images. scaleWd and scaleHt
// are the percentage scaling factors for width and height. (x, y) is center of
// scaling.
func (f *Fpdf) TransformScale(scaleWd, scaleHt, x, y float64) {
if scaleWd == 0 || scaleHt == 0 {
f.err = fmt.Errorf("Scale factor cannot be zero")
return
}
y = (f.h - y) * f.k
x *= f.k
scaleWd /= 100
scaleHt /= 100
f.Transform(TransformMatrix{scaleWd, 0, 0,
scaleHt, x * (1 - scaleWd), y * (1 - scaleHt)})
}
// Horizontally mirror the following text, drawings and images. x is the axis
// of reflection.
func (f *Fpdf) TransformMirrorHorizontal(x float64) {
f.TransformScale(-100, 100, x, f.y)
}
// Vertically mirror the following text, drawings and images. y is the axis
// of reflection.
func (f *Fpdf) TransformMirrorVertical(y float64) {
f.TransformScale(100, -100, f.x, y)
}
// Symmetrically mirror the following text, drawings and images on the point
// specified by (x, y).
func (f *Fpdf) TransformMirrorPoint(x, y float64) {
f.TransformScale(-100, -100, x, y)
}
// Symmetrically mirror the following text, drawings and images on the line
// defined by angle and the point (x, y). angles is specified in degrees and
// measured counter-clockwise from the 3 o'clock position.
func (f *Fpdf) TransformMirrorLine(angle, x, y float64) {
f.TransformScale(-100, 100, x, y)
f.TransformRotate(-2*(angle-90), x, y)
}
// Move the following text, drawings and images horizontally by the amount
// specified by tx.
func (f *Fpdf) TransformTranslateX(tx float64) {
f.TransformTranslate(tx, 0)
}
// Move the following text, drawings and images vertically by the amount
// specified by ty.
func (f *Fpdf) TransformTranslateY(ty float64) {
f.TransformTranslate(0, ty)
}
// Move the following text, drawings and images horizontally and vertically by
// the amounts specified by tx and ty.
func (f *Fpdf) TransformTranslate(tx, ty float64) {
f.Transform(TransformMatrix{1, 0, 0, 1, tx * f.k, -ty * f.k})
}
// Rotate the following text, drawings and images around the center point (x,
// y). angle is specified in degrees and measured counter-clockwise from the 3
// o'clock position.
func (f *Fpdf) TransformRotate(angle, x, y float64) {
y = (f.h - y) * f.k
x *= f.k
angle = angle * math.Pi / 180
var tm TransformMatrix
tm.A = math.Cos(angle)
tm.B = math.Sin(angle)
tm.C = -tm.B
tm.D = tm.A
tm.E = x + tm.B*y - tm.A*x
tm.F = y - tm.A*y - tm.B*x
f.Transform(tm)
}
// Horizontally skew the following text, drawings and images keeping the point
// (x, y) stationary. angleX ranges from -90 degrees (skew to the left) to 90
// degrees (skew to the right).
func (f *Fpdf) TransformSkewX(angleX, x, y float64) {
f.TransformSkew(angleX, 0, x, y)
}
// Vertically skew the following text, drawings and images keeping the point
// (x, y) stationary. angleY ranges from -90 degrees (skew to the bottom) to 90
// degrees (skew to the top).
func (f *Fpdf) TransformSkewY(angleY, x, y float64) {
f.TransformSkew(0, angleY, x, y)
}
// Generally skew the following text, drawings and images keeping the point (x,
// y) stationary. angleX ranges from -90 degrees (skew to the left) to 90
// degrees (skew to the right). angleY ranges from -90 degrees (skew to the
// bottom) to 90 degrees (skew to the top).
func (f *Fpdf) TransformSkew(angleX, angleY, x, y float64) {
if angleX <= -90 || angleX >= 90 || angleY <= -90 || angleY >= 90 {
f.err = fmt.Errorf("Skew values must be between -90° and 90°")
return
}
x *= f.k
y = (f.h - y) * f.k
var tm TransformMatrix
tm.A = 1
tm.B = math.Tan(angleY * math.Pi / 180)
tm.C = math.Tan(angleX * math.Pi / 180)
tm.D = 1
tm.E = -tm.C * y
tm.F = -tm.B * x
f.Transform(tm)
}
// Generally transform the following text, drawings and images according to the
// specified matrix. It is typically easier to use the various methods such as
// TransformRotate() and TransformMirrorVertical() instead.
func (f *Fpdf) Transform(tm TransformMatrix) {
if f.transformNest > 0 {
f.outf("%.5f %.5f %.5f %.5f %.5f %.5f cm",
tm.A, tm.B, tm.C, tm.D, tm.E, tm.F)
} else if f.err == nil {
f.err = fmt.Errorf("Transformation context is not active")
}
}
// Apply a transformation that was begun with a call to TransformBegin().
func (f *Fpdf) TransformEnd() {
if f.transformNest > 0 {
f.transformNest--
f.out("Q")
} else {
f.err = fmt.Errorf("Error attempting to end transformation operation out of sequence")
}
}
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