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Diffstat (limited to 'vendor/golang.org/x/image/math')
-rw-r--r-- | vendor/golang.org/x/image/math/fixed/fixed.go | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/vendor/golang.org/x/image/math/fixed/fixed.go b/vendor/golang.org/x/image/math/fixed/fixed.go new file mode 100644 index 000000000..cc7bac79e --- /dev/null +++ b/vendor/golang.org/x/image/math/fixed/fixed.go @@ -0,0 +1,202 @@ +// Copyright 2015 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package fixed implements fixed-point integer types. +package fixed + +import ( + "fmt" +) + +// TODO: implement fmt.Formatter for %f and %g. + +// I returns the integer value i as an Int26_6. +// +// For example, passing the integer value 2 yields Int26_6(128). +func I(i int) Int26_6 { + return Int26_6(i << 6) +} + +// Int26_6 is a signed 26.6 fixed-point number. +// +// The integer part ranges from -33554432 to 33554431, inclusive. The +// fractional part has 6 bits of precision. +// +// For example, the number one-and-a-quarter is Int26_6(1<<6 + 1<<4). +type Int26_6 int32 + +// String returns a human-readable representation of a 26.6 fixed-point number. +// +// For example, the number one-and-a-quarter becomes "1:16". +func (x Int26_6) String() string { + const shift, mask = 6, 1<<6 - 1 + if x >= 0 { + return fmt.Sprintf("%d:%02d", int32(x>>shift), int32(x&mask)) + } + x = -x + if x >= 0 { + return fmt.Sprintf("-%d:%02d", int32(x>>shift), int32(x&mask)) + } + return "-33554432:00" // The minimum value is -(1<<25). +} + +// Floor returns the greatest integer value less than or equal to x. +// +// Its return type is int, not Int26_6. +func (x Int26_6) Floor() int { return int((x + 0x00) >> 6) } + +// Round returns the nearest integer value to x. Ties are rounded up. +// +// Its return type is int, not Int26_6. +func (x Int26_6) Round() int { return int((x + 0x20) >> 6) } + +// Ceil returns the least integer value greater than or equal to x. +// +// Its return type is int, not Int26_6. +func (x Int26_6) Ceil() int { return int((x + 0x3f) >> 6) } + +// Int52_12 is a signed 52.12 fixed-point number. +// +// The integer part ranges from -2251799813685248 to 2251799813685247, +// inclusive. The fractional part has 12 bits of precision. +// +// For example, the number one-and-a-quarter is Int52_12(1<<12 + 1<<10). +type Int52_12 int64 + +// String returns a human-readable representation of a 52.12 fixed-point +// number. +// +// For example, the number one-and-a-quarter becomes "1:1024". +func (x Int52_12) String() string { + const shift, mask = 12, 1<<12 - 1 + if x >= 0 { + return fmt.Sprintf("%d:%04d", int64(x>>shift), int64(x&mask)) + } + x = -x + if x >= 0 { + return fmt.Sprintf("-%d:%04d", int64(x>>shift), int64(x&mask)) + } + return "-2251799813685248:0000" // The minimum value is -(1<<51). +} + +// Floor returns the greatest integer value less than or equal to x. +// +// Its return type is int, not Int52_12. +func (x Int52_12) Floor() int { return int((x + 0x000) >> 12) } + +// Round returns the nearest integer value to x. Ties are rounded up. +// +// Its return type is int, not Int52_12. +func (x Int52_12) Round() int { return int((x + 0x800) >> 12) } + +// Ceil returns the least integer value greater than or equal to x. +// +// Its return type is int, not Int52_12. +func (x Int52_12) Ceil() int { return int((x + 0xfff) >> 12) } + +// P returns the integer values x and y as a Point26_6. +// +// For example, passing the integer values (2, -3) yields Point26_6{128, -192}. +func P(x, y int) Point26_6 { + return Point26_6{Int26_6(x << 6), Int26_6(y << 6)} +} + +// Point26_6 is a 26.6 fixed-point coordinate pair. +// +// It is analogous to the image.Point type in the standard library. +type Point26_6 struct { + X, Y Int26_6 +} + +// Add returns the vector p+q. +func (p Point26_6) Add(q Point26_6) Point26_6 { + return Point26_6{p.X + q.X, p.Y + q.Y} +} + +// Sub returns the vector p-q. +func (p Point26_6) Sub(q Point26_6) Point26_6 { + return Point26_6{p.X - q.X, p.Y - q.Y} +} + +// Mul returns the vector p*k. +func (p Point26_6) Mul(k Int26_6) Point26_6 { + return Point26_6{p.X * k / 64, p.Y * k / 64} +} + +// Div returns the vector p/k. +func (p Point26_6) Div(k Int26_6) Point26_6 { + return Point26_6{p.X * 64 / k, p.Y * 64 / k} +} + +// Point52_12 is a 52.12 fixed-point coordinate pair. +// +// It is analogous to the image.Point type in the standard library. +type Point52_12 struct { + X, Y Int52_12 +} + +// Add returns the vector p+q. +func (p Point52_12) Add(q Point52_12) Point52_12 { + return Point52_12{p.X + q.X, p.Y + q.Y} +} + +// Sub returns the vector p-q. +func (p Point52_12) Sub(q Point52_12) Point52_12 { + return Point52_12{p.X - q.X, p.Y - q.Y} +} + +// Mul returns the vector p*k. +func (p Point52_12) Mul(k Int52_12) Point52_12 { + return Point52_12{p.X * k / 4096, p.Y * k / 4096} +} + +// Div returns the vector p/k. +func (p Point52_12) Div(k Int52_12) Point52_12 { + return Point52_12{p.X * 4096 / k, p.Y * 4096 / k} +} + +// R returns the integer values minX, minY, maxX, maxY as a Rectangle26_6. +// +// For example, passing the integer values (0, 1, 2, 3) yields +// Rectangle26_6{Point26_6{0, 64}, Point26_6{128, 192}}. +// +// Like the image.Rect function in the standard library, the returned rectangle +// has minimum and maximum coordinates swapped if necessary so that it is +// well-formed. +func R(minX, minY, maxX, maxY int) Rectangle26_6 { + if minX > maxX { + minX, maxX = maxX, minX + } + if minY > maxY { + minY, maxY = maxY, minY + } + return Rectangle26_6{ + Point26_6{ + Int26_6(minX << 6), + Int26_6(minY << 6), + }, + Point26_6{ + Int26_6(maxX << 6), + Int26_6(maxY << 6), + }, + } +} + +// Rectangle26_6 is a 26.6 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. +// +// It is analogous to the image.Rectangle type in the standard library. +type Rectangle26_6 struct { + Min, Max Point26_6 +} + +// 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. +// +// It is analogous to the image.Rectangle type in the standard library. +type Rectangle52_12 struct { + Min, Max Point52_12 +} |