46 lines
1.0 KiB
Go
46 lines
1.0 KiB
Go
|
// Copyright 2014 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 portable
|
||
|
|
|
||
|
|
import "image"
|
||
|
|
|
||
|
|
func affine(dst *image.RGBA, src *image.RGBA, a [3][3]float32) {
|
||
|
|
srcb := src.Bounds()
|
||
|
|
b := dst.Bounds()
|
||
|
|
|
||
|
|
for y := b.Min.Y; y < b.Max.Y; y++ {
|
||
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
||
|
|
sx, sy := pt(a, x, y)
|
||
|
|
if !inBounds(srcb, sx, sy) {
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
c := bilinear(src, sx, sy)
|
||
|
|
off := (y-dst.Rect.Min.Y)*dst.Stride + (x-dst.Rect.Min.X)*4
|
||
|
|
dst.Pix[off+0] = c.R
|
||
|
|
dst.Pix[off+1] = c.G
|
||
|
|
dst.Pix[off+2] = c.B
|
||
|
|
dst.Pix[off+3] = c.A
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func inBounds(b image.Rectangle, x, y float32) bool {
|
||
|
|
if x < float32(b.Min.X) || x >= float32(b.Max.X) {
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
if y < float32(b.Min.Y) || y >= float32(b.Max.Y) {
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
|
||
|
|
func pt(a [3][3]float32, x0, y0 int) (x1, y1 float32) {
|
||
|
|
fx := float32(x0) + 0.5
|
||
|
|
fy := float32(y0) + 0.5
|
||
|
|
x1 = fx*a[0][0] + fy*a[0][1] + a[0][2]
|
||
|
|
y1 = fx*a[1][0] + fy*a[1][1] + a[1][2]
|
||
|
|
return x1, y1
|
||
|
|
}
|