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math/fixed: add some Point and Rectangle methods.

These are analogous to the image.Point and image.Rectangle methods in
the standard library.

Change-Id: If8997421a9aeb31d29cfe5eefb79cc481a39df82
Reviewed-on: https://go-review.googlesource.com/34753
Reviewed-by: David Crawshaw <crawshaw@golang.org>
changes/53/34753/3
Nigel Tao 3 years ago
parent
commit
1ff62c9216
2 changed files with 172 additions and 30 deletions
  1. +2
    -30
      font/font.go
  2. +170
    -0
      math/fixed/fixed.go

+ 2
- 30
font/font.go View File

@@ -222,7 +222,7 @@ func BoundBytes(f Face, s []byte) (bounds fixed.Rectangle26_6, advance fixed.Int
}
b.Min.X += advance
b.Max.X += advance
bounds = grow(bounds, b)
bounds = bounds.Union(b)
advance += a
prevC = c
}
@@ -246,41 +246,13 @@ func BoundString(f Face, s string) (bounds fixed.Rectangle26_6, advance fixed.In
}
b.Min.X += advance
b.Max.X += advance
bounds = grow(bounds, b)
bounds = bounds.Union(b)
advance += a
prevC = c
}
return
}

func empty(r fixed.Rectangle26_6) bool {
return r.Min.X >= r.Max.X || r.Min.Y >= r.Max.Y
}

// grow returns the smallest rectangle containing both b and b2.
func grow(b, b2 fixed.Rectangle26_6) fixed.Rectangle26_6 {
if empty(b) {
return b2
}
if empty(b2) {
return b
}

if b.Min.X > b2.Min.X {
b.Min.X = b2.Min.X
}
if b.Min.Y > b2.Min.Y {
b.Min.Y = b2.Min.Y
}
if b.Max.X < b2.Max.X {
b.Max.X = b2.Max.X
}
if b.Max.Y < b2.Max.Y {
b.Max.Y = b2.Max.Y
}
return b
}

// MeasureBytes returns how far dot would advance by drawing s with f.
//
// It is equivalent to MeasureString(string(s)) but may be more efficient.


+ 170
- 0
math/fixed/fixed.go View File

@@ -167,6 +167,11 @@ func (p Point26_6) Div(k Int26_6) Point26_6 {
return Point26_6{p.X * 64 / k, p.Y * 64 / k}
}

// In returns whether p is in r.
func (p Point26_6) In(r Rectangle26_6) bool {
return r.Min.X <= p.X && p.X < r.Max.X && r.Min.Y <= p.Y && p.Y < r.Max.Y
}

// Point52_12 is a 52.12 fixed-point coordinate pair.
//
// It is analogous to the image.Point type in the standard library.
@@ -194,6 +199,11 @@ func (p Point52_12) Div(k Int52_12) Point52_12 {
return Point52_12{p.X * 4096 / k, p.Y * 4096 / k}
}

// In returns whether p is in r.
func (p Point52_12) In(r Rectangle52_12) bool {
return r.Min.X <= p.X && p.X < r.Max.X && r.Min.Y <= p.Y && p.Y < r.Max.Y
}

// R returns the integer values minX, minY, maxX, maxY as a Rectangle26_6.
//
// For example, passing the integer values (0, 1, 2, 3) yields
@@ -230,6 +240,86 @@ type Rectangle26_6 struct {
Min, Max Point26_6
}

// Add returns the rectangle r translated by p.
func (r Rectangle26_6) Add(p Point26_6) Rectangle26_6 {
return Rectangle26_6{
Point26_6{r.Min.X + p.X, r.Min.Y + p.Y},
Point26_6{r.Max.X + p.X, r.Max.Y + p.Y},
}
}

// Sub returns the rectangle r translated by -p.
func (r Rectangle26_6) Sub(p Point26_6) Rectangle26_6 {
return Rectangle26_6{
Point26_6{r.Min.X - p.X, r.Min.Y - p.Y},
Point26_6{r.Max.X - p.X, r.Max.Y - p.Y},
}
}

// Intersect returns the largest rectangle contained by both r and s. If the
// two rectangles do not overlap then the zero rectangle will be returned.
func (r Rectangle26_6) Intersect(s Rectangle26_6) Rectangle26_6 {
if r.Min.X < s.Min.X {
r.Min.X = s.Min.X
}
if r.Min.Y < s.Min.Y {
r.Min.Y = s.Min.Y
}
if r.Max.X > s.Max.X {
r.Max.X = s.Max.X
}
if r.Max.Y > s.Max.Y {
r.Max.Y = s.Max.Y
}
// Letting r0 and s0 be the values of r and s at the time that the method
// is called, this next line is equivalent to:
//
// if max(r0.Min.X, s0.Min.X) >= min(r0.Max.X, s0.Max.X) || likewiseForY { etc }
if r.Empty() {
return Rectangle26_6{}
}
return r
}

// Union returns the smallest rectangle that contains both r and s.
func (r Rectangle26_6) Union(s Rectangle26_6) Rectangle26_6 {
if r.Empty() {
return s
}
if s.Empty() {
return r
}
if r.Min.X > s.Min.X {
r.Min.X = s.Min.X
}
if r.Min.Y > s.Min.Y {
r.Min.Y = s.Min.Y
}
if r.Max.X < s.Max.X {
r.Max.X = s.Max.X
}
if r.Max.Y < s.Max.Y {
r.Max.Y = s.Max.Y
}
return r
}

// Empty returns whether the rectangle contains no points.
func (r Rectangle26_6) Empty() bool {
return r.Min.X >= r.Max.X || r.Min.Y >= r.Max.Y
}

// In returns whether every point in r is in s.
func (r Rectangle26_6) In(s Rectangle26_6) bool {
if r.Empty() {
return true
}
// Note that r.Max is an exclusive bound for r, so that r.In(s)
// does not require that r.Max.In(s).
return s.Min.X <= r.Min.X && r.Max.X <= s.Max.X &&
s.Min.Y <= r.Min.Y && r.Max.Y <= s.Max.Y
}

// Rectangle52_12 is a 52.12 fixed-point coordinate rectangle. The Min bound is
// inclusive and the Max bound is exclusive. It is well-formed if Min.X <=
// Max.X and likewise for Y.
@@ -238,3 +328,83 @@ type Rectangle26_6 struct {
type Rectangle52_12 struct {
Min, Max Point52_12
}

// Add returns the rectangle r translated by p.
func (r Rectangle52_12) Add(p Point52_12) Rectangle52_12 {
return Rectangle52_12{
Point52_12{r.Min.X + p.X, r.Min.Y + p.Y},
Point52_12{r.Max.X + p.X, r.Max.Y + p.Y},
}
}

// Sub returns the rectangle r translated by -p.
func (r Rectangle52_12) Sub(p Point52_12) Rectangle52_12 {
return Rectangle52_12{
Point52_12{r.Min.X - p.X, r.Min.Y - p.Y},
Point52_12{r.Max.X - p.X, r.Max.Y - p.Y},
}
}

// Intersect returns the largest rectangle contained by both r and s. If the
// two rectangles do not overlap then the zero rectangle will be returned.
func (r Rectangle52_12) Intersect(s Rectangle52_12) Rectangle52_12 {
if r.Min.X < s.Min.X {
r.Min.X = s.Min.X
}
if r.Min.Y < s.Min.Y {
r.Min.Y = s.Min.Y
}
if r.Max.X > s.Max.X {
r.Max.X = s.Max.X
}
if r.Max.Y > s.Max.Y {
r.Max.Y = s.Max.Y
}
// Letting r0 and s0 be the values of r and s at the time that the method
// is called, this next line is equivalent to:
//
// if max(r0.Min.X, s0.Min.X) >= min(r0.Max.X, s0.Max.X) || likewiseForY { etc }
if r.Empty() {
return Rectangle52_12{}
}
return r
}

// Union returns the smallest rectangle that contains both r and s.
func (r Rectangle52_12) Union(s Rectangle52_12) Rectangle52_12 {
if r.Empty() {
return s
}
if s.Empty() {
return r
}
if r.Min.X > s.Min.X {
r.Min.X = s.Min.X
}
if r.Min.Y > s.Min.Y {
r.Min.Y = s.Min.Y
}
if r.Max.X < s.Max.X {
r.Max.X = s.Max.X
}
if r.Max.Y < s.Max.Y {
r.Max.Y = s.Max.Y
}
return r
}

// Empty returns whether the rectangle contains no points.
func (r Rectangle52_12) Empty() bool {
return r.Min.X >= r.Max.X || r.Min.Y >= r.Max.Y
}

// In returns whether every point in r is in s.
func (r Rectangle52_12) In(s Rectangle52_12) bool {
if r.Empty() {
return true
}
// Note that r.Max is an exclusive bound for r, so that r.In(s)
// does not require that r.Max.In(s).
return s.Min.X <= r.Min.X && r.Max.X <= s.Max.X &&
s.Min.Y <= r.Min.Y && r.Max.Y <= s.Max.Y
}

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