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// Copyright 2010 The Freetype-Go Authors. All rights reserved.
// Use of this source code is governed by your choice of either the
// FreeType License or the GNU General Public License version 2 (or
// any later version), both of which can be found in the LICENSE file.
package raster
import (
"fmt"
"math"
"github.com/mattermost/platform/Godeps/_workspace/src/golang.org/x/image/math/fixed"
)
// maxAbs returns the maximum of abs(a) and abs(b).
func maxAbs(a, b fixed.Int26_6) fixed.Int26_6 {
if a < 0 {
a = -a
}
if b < 0 {
b = -b
}
if a < b {
return b
}
return a
}
// pNeg returns the vector -p, or equivalently p rotated by 180 degrees.
func pNeg(p fixed.Point26_6) fixed.Point26_6 {
return fixed.Point26_6{-p.X, -p.Y}
}
// pDot returns the dot product p·q.
func pDot(p fixed.Point26_6, q fixed.Point26_6) fixed.Int52_12 {
px, py := int64(p.X), int64(p.Y)
qx, qy := int64(q.X), int64(q.Y)
return fixed.Int52_12(px*qx + py*qy)
}
// pLen returns the length of the vector p.
func pLen(p fixed.Point26_6) fixed.Int26_6 {
// TODO(nigeltao): use fixed point math.
x := float64(p.X)
y := float64(p.Y)
return fixed.Int26_6(math.Sqrt(x*x + y*y))
}
// pNorm returns the vector p normalized to the given length, or zero if p is
// degenerate.
func pNorm(p fixed.Point26_6, length fixed.Int26_6) fixed.Point26_6 {
d := pLen(p)
if d == 0 {
return fixed.Point26_6{}
}
s, t := int64(length), int64(d)
x := int64(p.X) * s / t
y := int64(p.Y) * s / t
return fixed.Point26_6{fixed.Int26_6(x), fixed.Int26_6(y)}
}
// pRot45CW returns the vector p rotated clockwise by 45 degrees.
//
// Note that the Y-axis grows downwards, so {1, 0}.Rot45CW is {1/√2, 1/√2}.
func pRot45CW(p fixed.Point26_6) fixed.Point26_6 {
// 181/256 is approximately 1/√2, or sin(π/4).
px, py := int64(p.X), int64(p.Y)
qx := (+px - py) * 181 / 256
qy := (+px + py) * 181 / 256
return fixed.Point26_6{fixed.Int26_6(qx), fixed.Int26_6(qy)}
}
// pRot90CW returns the vector p rotated clockwise by 90 degrees.
//
// Note that the Y-axis grows downwards, so {1, 0}.Rot90CW is {0, 1}.
func pRot90CW(p fixed.Point26_6) fixed.Point26_6 {
return fixed.Point26_6{-p.Y, p.X}
}
// pRot135CW returns the vector p rotated clockwise by 135 degrees.
//
// Note that the Y-axis grows downwards, so {1, 0}.Rot135CW is {-1/√2, 1/√2}.
func pRot135CW(p fixed.Point26_6) fixed.Point26_6 {
// 181/256 is approximately 1/√2, or sin(π/4).
px, py := int64(p.X), int64(p.Y)
qx := (-px - py) * 181 / 256
qy := (+px - py) * 181 / 256
return fixed.Point26_6{fixed.Int26_6(qx), fixed.Int26_6(qy)}
}
// pRot45CCW returns the vector p rotated counter-clockwise by 45 degrees.
//
// Note that the Y-axis grows downwards, so {1, 0}.Rot45CCW is {1/√2, -1/√2}.
func pRot45CCW(p fixed.Point26_6) fixed.Point26_6 {
// 181/256 is approximately 1/√2, or sin(π/4).
px, py := int64(p.X), int64(p.Y)
qx := (+px + py) * 181 / 256
qy := (-px + py) * 181 / 256
return fixed.Point26_6{fixed.Int26_6(qx), fixed.Int26_6(qy)}
}
// pRot90CCW returns the vector p rotated counter-clockwise by 90 degrees.
//
// Note that the Y-axis grows downwards, so {1, 0}.Rot90CCW is {0, -1}.
func pRot90CCW(p fixed.Point26_6) fixed.Point26_6 {
return fixed.Point26_6{p.Y, -p.X}
}
// pRot135CCW returns the vector p rotated counter-clockwise by 135 degrees.
//
// Note that the Y-axis grows downwards, so {1, 0}.Rot135CCW is {-1/√2, -1/√2}.
func pRot135CCW(p fixed.Point26_6) fixed.Point26_6 {
// 181/256 is approximately 1/√2, or sin(π/4).
px, py := int64(p.X), int64(p.Y)
qx := (-px + py) * 181 / 256
qy := (-px - py) * 181 / 256
return fixed.Point26_6{fixed.Int26_6(qx), fixed.Int26_6(qy)}
}
// An Adder accumulates points on a curve.
type Adder interface {
// Start starts a new curve at the given point.
Start(a fixed.Point26_6)
// Add1 adds a linear segment to the current curve.
Add1(b fixed.Point26_6)
// Add2 adds a quadratic segment to the current curve.
Add2(b, c fixed.Point26_6)
// Add3 adds a cubic segment to the current curve.
Add3(b, c, d fixed.Point26_6)
}
// A Path is a sequence of curves, and a curve is a start point followed by a
// sequence of linear, quadratic or cubic segments.
type Path []fixed.Int26_6
// String returns a human-readable representation of a Path.
func (p Path) String() string {
s := ""
for i := 0; i < len(p); {
if i != 0 {
s += " "
}
switch p[i] {
case 0:
s += "S0" + fmt.Sprint([]fixed.Int26_6(p[i+1:i+3]))
i += 4
case 1:
s += "A1" + fmt.Sprint([]fixed.Int26_6(p[i+1:i+3]))
i += 4
case 2:
s += "A2" + fmt.Sprint([]fixed.Int26_6(p[i+1:i+5]))
i += 6
case 3:
s += "A3" + fmt.Sprint([]fixed.Int26_6(p[i+1:i+7]))
i += 8
default:
panic("freetype/raster: bad path")
}
}
return s
}
// Clear cancels any previous calls to p.Start or p.AddXxx.
func (p *Path) Clear() {
*p = (*p)[:0]
}
// Start starts a new curve at the given point.
func (p *Path) Start(a fixed.Point26_6) {
*p = append(*p, 0, a.X, a.Y, 0)
}
// Add1 adds a linear segment to the current curve.
func (p *Path) Add1(b fixed.Point26_6) {
*p = append(*p, 1, b.X, b.Y, 1)
}
// Add2 adds a quadratic segment to the current curve.
func (p *Path) Add2(b, c fixed.Point26_6) {
*p = append(*p, 2, b.X, b.Y, c.X, c.Y, 2)
}
// Add3 adds a cubic segment to the current curve.
func (p *Path) Add3(b, c, d fixed.Point26_6) {
*p = append(*p, 3, b.X, b.Y, c.X, c.Y, d.X, d.Y, 3)
}
// AddPath adds the Path q to p.
func (p *Path) AddPath(q Path) {
*p = append(*p, q...)
}
// AddStroke adds a stroked Path.
func (p *Path) AddStroke(q Path, width fixed.Int26_6, cr Capper, jr Joiner) {
Stroke(p, q, width, cr, jr)
}
// firstPoint returns the first point in a non-empty Path.
func (p Path) firstPoint() fixed.Point26_6 {
return fixed.Point26_6{p[1], p[2]}
}
// lastPoint returns the last point in a non-empty Path.
func (p Path) lastPoint() fixed.Point26_6 {
return fixed.Point26_6{p[len(p)-3], p[len(p)-2]}
}
// addPathReversed adds q reversed to p.
// For example, if q consists of a linear segment from A to B followed by a
// quadratic segment from B to C to D, then the values of q looks like:
// index: 01234567890123
// value: 0AA01BB12CCDD2
// So, when adding q backwards to p, we want to Add2(C, B) followed by Add1(A).
func addPathReversed(p Adder, q Path) {
if len(q) == 0 {
return
}
i := len(q) - 1
for {
switch q[i] {
case 0:
return
case 1:
i -= 4
p.Add1(
fixed.Point26_6{q[i-2], q[i-1]},
)
case 2:
i -= 6
p.Add2(
fixed.Point26_6{q[i+2], q[i+3]},
fixed.Point26_6{q[i-2], q[i-1]},
)
case 3:
i -= 8
p.Add3(
fixed.Point26_6{q[i+4], q[i+5]},
fixed.Point26_6{q[i+2], q[i+3]},
fixed.Point26_6{q[i-2], q[i-1]},
)
default:
panic("freetype/raster: bad path")
}
}
}
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