1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
|
package imaging
import (
"image"
"image/color"
"math"
)
// FlipH flips the image horizontally (from left to right) and returns the transformed image.
func FlipH(img image.Image) *image.NRGBA {
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW := srcW
dstH := srcH
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(dstH, func(partStart, partEnd int) {
for dstY := partStart; dstY < partEnd; dstY++ {
for dstX := 0; dstX < dstW; dstX++ {
srcX := dstW - dstX - 1
srcY := dstY
srcOff := srcY*src.Stride + srcX*4
dstOff := dstY*dst.Stride + dstX*4
copy(dst.Pix[dstOff:dstOff+4], src.Pix[srcOff:srcOff+4])
}
}
})
return dst
}
// FlipV flips the image vertically (from top to bottom) and returns the transformed image.
func FlipV(img image.Image) *image.NRGBA {
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW := srcW
dstH := srcH
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(dstH, func(partStart, partEnd int) {
for dstY := partStart; dstY < partEnd; dstY++ {
for dstX := 0; dstX < dstW; dstX++ {
srcX := dstX
srcY := dstH - dstY - 1
srcOff := srcY*src.Stride + srcX*4
dstOff := dstY*dst.Stride + dstX*4
copy(dst.Pix[dstOff:dstOff+4], src.Pix[srcOff:srcOff+4])
}
}
})
return dst
}
// Transpose flips the image horizontally and rotates 90 degrees counter-clockwise.
func Transpose(img image.Image) *image.NRGBA {
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW := srcH
dstH := srcW
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(dstH, func(partStart, partEnd int) {
for dstY := partStart; dstY < partEnd; dstY++ {
for dstX := 0; dstX < dstW; dstX++ {
srcX := dstY
srcY := dstX
srcOff := srcY*src.Stride + srcX*4
dstOff := dstY*dst.Stride + dstX*4
copy(dst.Pix[dstOff:dstOff+4], src.Pix[srcOff:srcOff+4])
}
}
})
return dst
}
// Transverse flips the image vertically and rotates 90 degrees counter-clockwise.
func Transverse(img image.Image) *image.NRGBA {
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW := srcH
dstH := srcW
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(dstH, func(partStart, partEnd int) {
for dstY := partStart; dstY < partEnd; dstY++ {
for dstX := 0; dstX < dstW; dstX++ {
srcX := dstH - dstY - 1
srcY := dstW - dstX - 1
srcOff := srcY*src.Stride + srcX*4
dstOff := dstY*dst.Stride + dstX*4
copy(dst.Pix[dstOff:dstOff+4], src.Pix[srcOff:srcOff+4])
}
}
})
return dst
}
// Rotate90 rotates the image 90 degrees counterclockwise and returns the transformed image.
func Rotate90(img image.Image) *image.NRGBA {
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW := srcH
dstH := srcW
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(dstH, func(partStart, partEnd int) {
for dstY := partStart; dstY < partEnd; dstY++ {
for dstX := 0; dstX < dstW; dstX++ {
srcX := dstH - dstY - 1
srcY := dstX
srcOff := srcY*src.Stride + srcX*4
dstOff := dstY*dst.Stride + dstX*4
copy(dst.Pix[dstOff:dstOff+4], src.Pix[srcOff:srcOff+4])
}
}
})
return dst
}
// Rotate180 rotates the image 180 degrees counterclockwise and returns the transformed image.
func Rotate180(img image.Image) *image.NRGBA {
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW := srcW
dstH := srcH
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(dstH, func(partStart, partEnd int) {
for dstY := partStart; dstY < partEnd; dstY++ {
for dstX := 0; dstX < dstW; dstX++ {
srcX := dstW - dstX - 1
srcY := dstH - dstY - 1
srcOff := srcY*src.Stride + srcX*4
dstOff := dstY*dst.Stride + dstX*4
copy(dst.Pix[dstOff:dstOff+4], src.Pix[srcOff:srcOff+4])
}
}
})
return dst
}
// Rotate270 rotates the image 270 degrees counterclockwise and returns the transformed image.
func Rotate270(img image.Image) *image.NRGBA {
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW := srcH
dstH := srcW
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(dstH, func(partStart, partEnd int) {
for dstY := partStart; dstY < partEnd; dstY++ {
for dstX := 0; dstX < dstW; dstX++ {
srcX := dstY
srcY := dstW - dstX - 1
srcOff := srcY*src.Stride + srcX*4
dstOff := dstY*dst.Stride + dstX*4
copy(dst.Pix[dstOff:dstOff+4], src.Pix[srcOff:srcOff+4])
}
}
})
return dst
}
// Rotate rotates an image by the given angle counter-clockwise .
// The angle parameter is the rotation angle in degrees.
// The bgColor parameter specifies the color of the uncovered zone after the rotation.
func Rotate(img image.Image, angle float64, bgColor color.Color) *image.NRGBA {
angle = angle - math.Floor(angle/360)*360
switch angle {
case 0:
return Clone(img)
case 90:
return Rotate90(img)
case 180:
return Rotate180(img)
case 270:
return Rotate270(img)
}
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW, dstH := rotatedSize(srcW, srcH, angle)
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
if dstW <= 0 || dstH <= 0 {
return dst
}
srcXOff := float64(srcW)/2 - 0.5
srcYOff := float64(srcH)/2 - 0.5
dstXOff := float64(dstW)/2 - 0.5
dstYOff := float64(dstH)/2 - 0.5
bgColorNRGBA := color.NRGBAModel.Convert(bgColor).(color.NRGBA)
sin, cos := math.Sincos(math.Pi * angle / 180)
parallel(dstH, func(partStart, partEnd int) {
for dstY := partStart; dstY < partEnd; dstY++ {
for dstX := 0; dstX < dstW; dstX++ {
xf, yf := rotatePoint(float64(dstX)-dstXOff, float64(dstY)-dstYOff, sin, cos)
xf, yf = xf+srcXOff, yf+srcYOff
interpolatePoint(dst, dstX, dstY, src, xf, yf, bgColorNRGBA)
}
}
})
return dst
}
func rotatePoint(x, y, sin, cos float64) (float64, float64) {
return x*cos - y*sin, x*sin + y*cos
}
func rotatedSize(w, h int, angle float64) (int, int) {
if w <= 0 || h <= 0 {
return 0, 0
}
sin, cos := math.Sincos(math.Pi * angle / 180)
x1, y1 := rotatePoint(float64(w-1), 0, sin, cos)
x2, y2 := rotatePoint(float64(w-1), float64(h-1), sin, cos)
x3, y3 := rotatePoint(0, float64(h-1), sin, cos)
minx := math.Min(x1, math.Min(x2, math.Min(x3, 0)))
maxx := math.Max(x1, math.Max(x2, math.Max(x3, 0)))
miny := math.Min(y1, math.Min(y2, math.Min(y3, 0)))
maxy := math.Max(y1, math.Max(y2, math.Max(y3, 0)))
neww := maxx - minx + 1
if neww-math.Floor(neww) > 0.1 {
neww++
}
newh := maxy - miny + 1
if newh-math.Floor(newh) > 0.1 {
newh++
}
return int(neww), int(newh)
}
func interpolatePoint(dst *image.NRGBA, dstX, dstY int, src *image.NRGBA, xf, yf float64, bgColor color.NRGBA) {
dstIndex := dstY*dst.Stride + dstX*4
x0 := int(math.Floor(xf))
y0 := int(math.Floor(yf))
bounds := src.Bounds()
if !image.Pt(x0, y0).In(image.Rect(bounds.Min.X-1, bounds.Min.Y-1, bounds.Max.X, bounds.Max.Y)) {
dst.Pix[dstIndex+0] = bgColor.R
dst.Pix[dstIndex+1] = bgColor.G
dst.Pix[dstIndex+2] = bgColor.B
dst.Pix[dstIndex+3] = bgColor.A
return
}
xq := xf - float64(x0)
yq := yf - float64(y0)
var pxs [4]color.NRGBA
var cfs [4]float64
for i := 0; i < 2; i++ {
for j := 0; j < 2; j++ {
k := i*2 + j
pt := image.Pt(x0+j, y0+i)
if pt.In(bounds) {
l := pt.Y*src.Stride + pt.X*4
pxs[k].R = src.Pix[l+0]
pxs[k].G = src.Pix[l+1]
pxs[k].B = src.Pix[l+2]
pxs[k].A = src.Pix[l+3]
} else {
pxs[k] = bgColor
}
}
}
cfs[0] = (1 - xq) * (1 - yq)
cfs[1] = xq * (1 - yq)
cfs[2] = (1 - xq) * yq
cfs[3] = xq * yq
var r, g, b, a float64
for i := range pxs {
wa := float64(pxs[i].A) * cfs[i]
r += float64(pxs[i].R) * wa
g += float64(pxs[i].G) * wa
b += float64(pxs[i].B) * wa
a += wa
}
if a != 0 {
r /= a
g /= a
b /= a
}
dst.Pix[dstIndex+0] = clamp(r)
dst.Pix[dstIndex+1] = clamp(g)
dst.Pix[dstIndex+2] = clamp(b)
dst.Pix[dstIndex+3] = clamp(a)
}
|
