1// Copyright 2009 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// Package image implements a basic 2-D image library. 6// 7// The fundamental interface is called Image. An Image contains colors, which 8// are described in the image/color package. 9// 10// Values of the Image interface are created either by calling functions such 11// as NewRGBA and NewPaletted, or by calling Decode on an io.Reader containing 12// image data in a format such as GIF, JPEG or PNG. Decoding any particular 13// image format requires the prior registration of a decoder function. 14// Registration is typically automatic as a side effect of initializing that 15// format's package so that, to decode a PNG image, it suffices to have 16// import _ "image/png" 17// in a program's main package. The _ means to import a package purely for its 18// initialization side effects. 19// 20// See "The Go image package" for more details: 21// https://golang.org/doc/articles/image_package.html 22package image 23 24import ( 25 "image/color" 26) 27 28// Config holds an image's color model and dimensions. 29type Config struct { 30 ColorModel color.Model 31 Width, Height int 32} 33 34// Image is a finite rectangular grid of color.Color values taken from a color 35// model. 36type Image interface { 37 // ColorModel returns the Image's color model. 38 ColorModel() color.Model 39 // Bounds returns the domain for which At can return non-zero color. 40 // The bounds do not necessarily contain the point (0, 0). 41 Bounds() Rectangle 42 // At returns the color of the pixel at (x, y). 43 // At(Bounds().Min.X, Bounds().Min.Y) returns the upper-left pixel of the grid. 44 // At(Bounds().Max.X-1, Bounds().Max.Y-1) returns the lower-right one. 45 At(x, y int) color.Color 46} 47 48// PalettedImage is an image whose colors may come from a limited palette. 49// If m is a PalettedImage and m.ColorModel() returns a color.Palette p, 50// then m.At(x, y) should be equivalent to p[m.ColorIndexAt(x, y)]. If m's 51// color model is not a color.Palette, then ColorIndexAt's behavior is 52// undefined. 53type PalettedImage interface { 54 // ColorIndexAt returns the palette index of the pixel at (x, y). 55 ColorIndexAt(x, y int) uint8 56 Image 57} 58 59// pixelBufferLength returns the length of the []uint8 typed Pix slice field 60// for the NewXxx functions. Conceptually, this is just (bpp * width * height), 61// but this function panics if at least one of those is negative or if the 62// computation would overflow the int type. 63// 64// This panics instead of returning an error because of backwards 65// compatibility. The NewXxx functions do not return an error. 66func pixelBufferLength(bytesPerPixel int, r Rectangle, imageTypeName string) int { 67 totalLength := mul3NonNeg(bytesPerPixel, r.Dx(), r.Dy()) 68 if totalLength < 0 { 69 panic("image: New" + imageTypeName + " Rectangle has huge or negative dimensions") 70 } 71 return totalLength 72} 73 74// RGBA is an in-memory image whose At method returns color.RGBA values. 75type RGBA struct { 76 // Pix holds the image's pixels, in R, G, B, A order. The pixel at 77 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4]. 78 Pix []uint8 79 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 80 Stride int 81 // Rect is the image's bounds. 82 Rect Rectangle 83} 84 85func (p *RGBA) ColorModel() color.Model { return color.RGBAModel } 86 87func (p *RGBA) Bounds() Rectangle { return p.Rect } 88 89func (p *RGBA) At(x, y int) color.Color { 90 return p.RGBAAt(x, y) 91} 92 93func (p *RGBA) RGBAAt(x, y int) color.RGBA { 94 if !(Point{x, y}.In(p.Rect)) { 95 return color.RGBA{} 96 } 97 i := p.PixOffset(x, y) 98 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 99 return color.RGBA{s[0], s[1], s[2], s[3]} 100} 101 102// PixOffset returns the index of the first element of Pix that corresponds to 103// the pixel at (x, y). 104func (p *RGBA) PixOffset(x, y int) int { 105 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4 106} 107 108func (p *RGBA) Set(x, y int, c color.Color) { 109 if !(Point{x, y}.In(p.Rect)) { 110 return 111 } 112 i := p.PixOffset(x, y) 113 c1 := color.RGBAModel.Convert(c).(color.RGBA) 114 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 115 s[0] = c1.R 116 s[1] = c1.G 117 s[2] = c1.B 118 s[3] = c1.A 119} 120 121func (p *RGBA) SetRGBA(x, y int, c color.RGBA) { 122 if !(Point{x, y}.In(p.Rect)) { 123 return 124 } 125 i := p.PixOffset(x, y) 126 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 127 s[0] = c.R 128 s[1] = c.G 129 s[2] = c.B 130 s[3] = c.A 131} 132 133// SubImage returns an image representing the portion of the image p visible 134// through r. The returned value shares pixels with the original image. 135func (p *RGBA) SubImage(r Rectangle) Image { 136 r = r.Intersect(p.Rect) 137 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 138 // either r1 or r2 if the intersection is empty. Without explicitly checking for 139 // this, the Pix[i:] expression below can panic. 140 if r.Empty() { 141 return &RGBA{} 142 } 143 i := p.PixOffset(r.Min.X, r.Min.Y) 144 return &RGBA{ 145 Pix: p.Pix[i:], 146 Stride: p.Stride, 147 Rect: r, 148 } 149} 150 151// Opaque scans the entire image and reports whether it is fully opaque. 152func (p *RGBA) Opaque() bool { 153 if p.Rect.Empty() { 154 return true 155 } 156 i0, i1 := 3, p.Rect.Dx()*4 157 for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ { 158 for i := i0; i < i1; i += 4 { 159 if p.Pix[i] != 0xff { 160 return false 161 } 162 } 163 i0 += p.Stride 164 i1 += p.Stride 165 } 166 return true 167} 168 169// NewRGBA returns a new RGBA image with the given bounds. 170func NewRGBA(r Rectangle) *RGBA { 171 return &RGBA{ 172 Pix: make([]uint8, pixelBufferLength(4, r, "RGBA")), 173 Stride: 4 * r.Dx(), 174 Rect: r, 175 } 176} 177 178// RGBA64 is an in-memory image whose At method returns color.RGBA64 values. 179type RGBA64 struct { 180 // Pix holds the image's pixels, in R, G, B, A order and big-endian format. The pixel at 181 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*8]. 182 Pix []uint8 183 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 184 Stride int 185 // Rect is the image's bounds. 186 Rect Rectangle 187} 188 189func (p *RGBA64) ColorModel() color.Model { return color.RGBA64Model } 190 191func (p *RGBA64) Bounds() Rectangle { return p.Rect } 192 193func (p *RGBA64) At(x, y int) color.Color { 194 return p.RGBA64At(x, y) 195} 196 197func (p *RGBA64) RGBA64At(x, y int) color.RGBA64 { 198 if !(Point{x, y}.In(p.Rect)) { 199 return color.RGBA64{} 200 } 201 i := p.PixOffset(x, y) 202 s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857 203 return color.RGBA64{ 204 uint16(s[0])<<8 | uint16(s[1]), 205 uint16(s[2])<<8 | uint16(s[3]), 206 uint16(s[4])<<8 | uint16(s[5]), 207 uint16(s[6])<<8 | uint16(s[7]), 208 } 209} 210 211// PixOffset returns the index of the first element of Pix that corresponds to 212// the pixel at (x, y). 213func (p *RGBA64) PixOffset(x, y int) int { 214 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8 215} 216 217func (p *RGBA64) Set(x, y int, c color.Color) { 218 if !(Point{x, y}.In(p.Rect)) { 219 return 220 } 221 i := p.PixOffset(x, y) 222 c1 := color.RGBA64Model.Convert(c).(color.RGBA64) 223 s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857 224 s[0] = uint8(c1.R >> 8) 225 s[1] = uint8(c1.R) 226 s[2] = uint8(c1.G >> 8) 227 s[3] = uint8(c1.G) 228 s[4] = uint8(c1.B >> 8) 229 s[5] = uint8(c1.B) 230 s[6] = uint8(c1.A >> 8) 231 s[7] = uint8(c1.A) 232} 233 234func (p *RGBA64) SetRGBA64(x, y int, c color.RGBA64) { 235 if !(Point{x, y}.In(p.Rect)) { 236 return 237 } 238 i := p.PixOffset(x, y) 239 s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857 240 s[0] = uint8(c.R >> 8) 241 s[1] = uint8(c.R) 242 s[2] = uint8(c.G >> 8) 243 s[3] = uint8(c.G) 244 s[4] = uint8(c.B >> 8) 245 s[5] = uint8(c.B) 246 s[6] = uint8(c.A >> 8) 247 s[7] = uint8(c.A) 248} 249 250// SubImage returns an image representing the portion of the image p visible 251// through r. The returned value shares pixels with the original image. 252func (p *RGBA64) SubImage(r Rectangle) Image { 253 r = r.Intersect(p.Rect) 254 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 255 // either r1 or r2 if the intersection is empty. Without explicitly checking for 256 // this, the Pix[i:] expression below can panic. 257 if r.Empty() { 258 return &RGBA64{} 259 } 260 i := p.PixOffset(r.Min.X, r.Min.Y) 261 return &RGBA64{ 262 Pix: p.Pix[i:], 263 Stride: p.Stride, 264 Rect: r, 265 } 266} 267 268// Opaque scans the entire image and reports whether it is fully opaque. 269func (p *RGBA64) Opaque() bool { 270 if p.Rect.Empty() { 271 return true 272 } 273 i0, i1 := 6, p.Rect.Dx()*8 274 for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ { 275 for i := i0; i < i1; i += 8 { 276 if p.Pix[i+0] != 0xff || p.Pix[i+1] != 0xff { 277 return false 278 } 279 } 280 i0 += p.Stride 281 i1 += p.Stride 282 } 283 return true 284} 285 286// NewRGBA64 returns a new RGBA64 image with the given bounds. 287func NewRGBA64(r Rectangle) *RGBA64 { 288 return &RGBA64{ 289 Pix: make([]uint8, pixelBufferLength(8, r, "RGBA64")), 290 Stride: 8 * r.Dx(), 291 Rect: r, 292 } 293} 294 295// NRGBA is an in-memory image whose At method returns color.NRGBA values. 296type NRGBA struct { 297 // Pix holds the image's pixels, in R, G, B, A order. The pixel at 298 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4]. 299 Pix []uint8 300 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 301 Stride int 302 // Rect is the image's bounds. 303 Rect Rectangle 304} 305 306func (p *NRGBA) ColorModel() color.Model { return color.NRGBAModel } 307 308func (p *NRGBA) Bounds() Rectangle { return p.Rect } 309 310func (p *NRGBA) At(x, y int) color.Color { 311 return p.NRGBAAt(x, y) 312} 313 314func (p *NRGBA) NRGBAAt(x, y int) color.NRGBA { 315 if !(Point{x, y}.In(p.Rect)) { 316 return color.NRGBA{} 317 } 318 i := p.PixOffset(x, y) 319 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 320 return color.NRGBA{s[0], s[1], s[2], s[3]} 321} 322 323// PixOffset returns the index of the first element of Pix that corresponds to 324// the pixel at (x, y). 325func (p *NRGBA) PixOffset(x, y int) int { 326 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4 327} 328 329func (p *NRGBA) Set(x, y int, c color.Color) { 330 if !(Point{x, y}.In(p.Rect)) { 331 return 332 } 333 i := p.PixOffset(x, y) 334 c1 := color.NRGBAModel.Convert(c).(color.NRGBA) 335 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 336 s[0] = c1.R 337 s[1] = c1.G 338 s[2] = c1.B 339 s[3] = c1.A 340} 341 342func (p *NRGBA) SetNRGBA(x, y int, c color.NRGBA) { 343 if !(Point{x, y}.In(p.Rect)) { 344 return 345 } 346 i := p.PixOffset(x, y) 347 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 348 s[0] = c.R 349 s[1] = c.G 350 s[2] = c.B 351 s[3] = c.A 352} 353 354// SubImage returns an image representing the portion of the image p visible 355// through r. The returned value shares pixels with the original image. 356func (p *NRGBA) SubImage(r Rectangle) Image { 357 r = r.Intersect(p.Rect) 358 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 359 // either r1 or r2 if the intersection is empty. Without explicitly checking for 360 // this, the Pix[i:] expression below can panic. 361 if r.Empty() { 362 return &NRGBA{} 363 } 364 i := p.PixOffset(r.Min.X, r.Min.Y) 365 return &NRGBA{ 366 Pix: p.Pix[i:], 367 Stride: p.Stride, 368 Rect: r, 369 } 370} 371 372// Opaque scans the entire image and reports whether it is fully opaque. 373func (p *NRGBA) Opaque() bool { 374 if p.Rect.Empty() { 375 return true 376 } 377 i0, i1 := 3, p.Rect.Dx()*4 378 for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ { 379 for i := i0; i < i1; i += 4 { 380 if p.Pix[i] != 0xff { 381 return false 382 } 383 } 384 i0 += p.Stride 385 i1 += p.Stride 386 } 387 return true 388} 389 390// NewNRGBA returns a new NRGBA image with the given bounds. 391func NewNRGBA(r Rectangle) *NRGBA { 392 return &NRGBA{ 393 Pix: make([]uint8, pixelBufferLength(4, r, "NRGBA")), 394 Stride: 4 * r.Dx(), 395 Rect: r, 396 } 397} 398 399// NRGBA64 is an in-memory image whose At method returns color.NRGBA64 values. 400type NRGBA64 struct { 401 // Pix holds the image's pixels, in R, G, B, A order and big-endian format. The pixel at 402 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*8]. 403 Pix []uint8 404 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 405 Stride int 406 // Rect is the image's bounds. 407 Rect Rectangle 408} 409 410func (p *NRGBA64) ColorModel() color.Model { return color.NRGBA64Model } 411 412func (p *NRGBA64) Bounds() Rectangle { return p.Rect } 413 414func (p *NRGBA64) At(x, y int) color.Color { 415 return p.NRGBA64At(x, y) 416} 417 418func (p *NRGBA64) NRGBA64At(x, y int) color.NRGBA64 { 419 if !(Point{x, y}.In(p.Rect)) { 420 return color.NRGBA64{} 421 } 422 i := p.PixOffset(x, y) 423 s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857 424 return color.NRGBA64{ 425 uint16(s[0])<<8 | uint16(s[1]), 426 uint16(s[2])<<8 | uint16(s[3]), 427 uint16(s[4])<<8 | uint16(s[5]), 428 uint16(s[6])<<8 | uint16(s[7]), 429 } 430} 431 432// PixOffset returns the index of the first element of Pix that corresponds to 433// the pixel at (x, y). 434func (p *NRGBA64) PixOffset(x, y int) int { 435 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*8 436} 437 438func (p *NRGBA64) Set(x, y int, c color.Color) { 439 if !(Point{x, y}.In(p.Rect)) { 440 return 441 } 442 i := p.PixOffset(x, y) 443 c1 := color.NRGBA64Model.Convert(c).(color.NRGBA64) 444 s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857 445 s[0] = uint8(c1.R >> 8) 446 s[1] = uint8(c1.R) 447 s[2] = uint8(c1.G >> 8) 448 s[3] = uint8(c1.G) 449 s[4] = uint8(c1.B >> 8) 450 s[5] = uint8(c1.B) 451 s[6] = uint8(c1.A >> 8) 452 s[7] = uint8(c1.A) 453} 454 455func (p *NRGBA64) SetNRGBA64(x, y int, c color.NRGBA64) { 456 if !(Point{x, y}.In(p.Rect)) { 457 return 458 } 459 i := p.PixOffset(x, y) 460 s := p.Pix[i : i+8 : i+8] // Small cap improves performance, see https://golang.org/issue/27857 461 s[0] = uint8(c.R >> 8) 462 s[1] = uint8(c.R) 463 s[2] = uint8(c.G >> 8) 464 s[3] = uint8(c.G) 465 s[4] = uint8(c.B >> 8) 466 s[5] = uint8(c.B) 467 s[6] = uint8(c.A >> 8) 468 s[7] = uint8(c.A) 469} 470 471// SubImage returns an image representing the portion of the image p visible 472// through r. The returned value shares pixels with the original image. 473func (p *NRGBA64) SubImage(r Rectangle) Image { 474 r = r.Intersect(p.Rect) 475 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 476 // either r1 or r2 if the intersection is empty. Without explicitly checking for 477 // this, the Pix[i:] expression below can panic. 478 if r.Empty() { 479 return &NRGBA64{} 480 } 481 i := p.PixOffset(r.Min.X, r.Min.Y) 482 return &NRGBA64{ 483 Pix: p.Pix[i:], 484 Stride: p.Stride, 485 Rect: r, 486 } 487} 488 489// Opaque scans the entire image and reports whether it is fully opaque. 490func (p *NRGBA64) Opaque() bool { 491 if p.Rect.Empty() { 492 return true 493 } 494 i0, i1 := 6, p.Rect.Dx()*8 495 for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ { 496 for i := i0; i < i1; i += 8 { 497 if p.Pix[i+0] != 0xff || p.Pix[i+1] != 0xff { 498 return false 499 } 500 } 501 i0 += p.Stride 502 i1 += p.Stride 503 } 504 return true 505} 506 507// NewNRGBA64 returns a new NRGBA64 image with the given bounds. 508func NewNRGBA64(r Rectangle) *NRGBA64 { 509 return &NRGBA64{ 510 Pix: make([]uint8, pixelBufferLength(8, r, "NRGBA64")), 511 Stride: 8 * r.Dx(), 512 Rect: r, 513 } 514} 515 516// Alpha is an in-memory image whose At method returns color.Alpha values. 517type Alpha struct { 518 // Pix holds the image's pixels, as alpha values. The pixel at 519 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1]. 520 Pix []uint8 521 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 522 Stride int 523 // Rect is the image's bounds. 524 Rect Rectangle 525} 526 527func (p *Alpha) ColorModel() color.Model { return color.AlphaModel } 528 529func (p *Alpha) Bounds() Rectangle { return p.Rect } 530 531func (p *Alpha) At(x, y int) color.Color { 532 return p.AlphaAt(x, y) 533} 534 535func (p *Alpha) AlphaAt(x, y int) color.Alpha { 536 if !(Point{x, y}.In(p.Rect)) { 537 return color.Alpha{} 538 } 539 i := p.PixOffset(x, y) 540 return color.Alpha{p.Pix[i]} 541} 542 543// PixOffset returns the index of the first element of Pix that corresponds to 544// the pixel at (x, y). 545func (p *Alpha) PixOffset(x, y int) int { 546 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*1 547} 548 549func (p *Alpha) Set(x, y int, c color.Color) { 550 if !(Point{x, y}.In(p.Rect)) { 551 return 552 } 553 i := p.PixOffset(x, y) 554 p.Pix[i] = color.AlphaModel.Convert(c).(color.Alpha).A 555} 556 557func (p *Alpha) SetAlpha(x, y int, c color.Alpha) { 558 if !(Point{x, y}.In(p.Rect)) { 559 return 560 } 561 i := p.PixOffset(x, y) 562 p.Pix[i] = c.A 563} 564 565// SubImage returns an image representing the portion of the image p visible 566// through r. The returned value shares pixels with the original image. 567func (p *Alpha) SubImage(r Rectangle) Image { 568 r = r.Intersect(p.Rect) 569 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 570 // either r1 or r2 if the intersection is empty. Without explicitly checking for 571 // this, the Pix[i:] expression below can panic. 572 if r.Empty() { 573 return &Alpha{} 574 } 575 i := p.PixOffset(r.Min.X, r.Min.Y) 576 return &Alpha{ 577 Pix: p.Pix[i:], 578 Stride: p.Stride, 579 Rect: r, 580 } 581} 582 583// Opaque scans the entire image and reports whether it is fully opaque. 584func (p *Alpha) Opaque() bool { 585 if p.Rect.Empty() { 586 return true 587 } 588 i0, i1 := 0, p.Rect.Dx() 589 for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ { 590 for i := i0; i < i1; i++ { 591 if p.Pix[i] != 0xff { 592 return false 593 } 594 } 595 i0 += p.Stride 596 i1 += p.Stride 597 } 598 return true 599} 600 601// NewAlpha returns a new Alpha image with the given bounds. 602func NewAlpha(r Rectangle) *Alpha { 603 return &Alpha{ 604 Pix: make([]uint8, pixelBufferLength(1, r, "Alpha")), 605 Stride: 1 * r.Dx(), 606 Rect: r, 607 } 608} 609 610// Alpha16 is an in-memory image whose At method returns color.Alpha16 values. 611type Alpha16 struct { 612 // Pix holds the image's pixels, as alpha values in big-endian format. The pixel at 613 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*2]. 614 Pix []uint8 615 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 616 Stride int 617 // Rect is the image's bounds. 618 Rect Rectangle 619} 620 621func (p *Alpha16) ColorModel() color.Model { return color.Alpha16Model } 622 623func (p *Alpha16) Bounds() Rectangle { return p.Rect } 624 625func (p *Alpha16) At(x, y int) color.Color { 626 return p.Alpha16At(x, y) 627} 628 629func (p *Alpha16) Alpha16At(x, y int) color.Alpha16 { 630 if !(Point{x, y}.In(p.Rect)) { 631 return color.Alpha16{} 632 } 633 i := p.PixOffset(x, y) 634 return color.Alpha16{uint16(p.Pix[i+0])<<8 | uint16(p.Pix[i+1])} 635} 636 637// PixOffset returns the index of the first element of Pix that corresponds to 638// the pixel at (x, y). 639func (p *Alpha16) PixOffset(x, y int) int { 640 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2 641} 642 643func (p *Alpha16) Set(x, y int, c color.Color) { 644 if !(Point{x, y}.In(p.Rect)) { 645 return 646 } 647 i := p.PixOffset(x, y) 648 c1 := color.Alpha16Model.Convert(c).(color.Alpha16) 649 p.Pix[i+0] = uint8(c1.A >> 8) 650 p.Pix[i+1] = uint8(c1.A) 651} 652 653func (p *Alpha16) SetAlpha16(x, y int, c color.Alpha16) { 654 if !(Point{x, y}.In(p.Rect)) { 655 return 656 } 657 i := p.PixOffset(x, y) 658 p.Pix[i+0] = uint8(c.A >> 8) 659 p.Pix[i+1] = uint8(c.A) 660} 661 662// SubImage returns an image representing the portion of the image p visible 663// through r. The returned value shares pixels with the original image. 664func (p *Alpha16) SubImage(r Rectangle) Image { 665 r = r.Intersect(p.Rect) 666 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 667 // either r1 or r2 if the intersection is empty. Without explicitly checking for 668 // this, the Pix[i:] expression below can panic. 669 if r.Empty() { 670 return &Alpha16{} 671 } 672 i := p.PixOffset(r.Min.X, r.Min.Y) 673 return &Alpha16{ 674 Pix: p.Pix[i:], 675 Stride: p.Stride, 676 Rect: r, 677 } 678} 679 680// Opaque scans the entire image and reports whether it is fully opaque. 681func (p *Alpha16) Opaque() bool { 682 if p.Rect.Empty() { 683 return true 684 } 685 i0, i1 := 0, p.Rect.Dx()*2 686 for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ { 687 for i := i0; i < i1; i += 2 { 688 if p.Pix[i+0] != 0xff || p.Pix[i+1] != 0xff { 689 return false 690 } 691 } 692 i0 += p.Stride 693 i1 += p.Stride 694 } 695 return true 696} 697 698// NewAlpha16 returns a new Alpha16 image with the given bounds. 699func NewAlpha16(r Rectangle) *Alpha16 { 700 return &Alpha16{ 701 Pix: make([]uint8, pixelBufferLength(2, r, "Alpha16")), 702 Stride: 2 * r.Dx(), 703 Rect: r, 704 } 705} 706 707// Gray is an in-memory image whose At method returns color.Gray values. 708type Gray struct { 709 // Pix holds the image's pixels, as gray values. The pixel at 710 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1]. 711 Pix []uint8 712 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 713 Stride int 714 // Rect is the image's bounds. 715 Rect Rectangle 716} 717 718func (p *Gray) ColorModel() color.Model { return color.GrayModel } 719 720func (p *Gray) Bounds() Rectangle { return p.Rect } 721 722func (p *Gray) At(x, y int) color.Color { 723 return p.GrayAt(x, y) 724} 725 726func (p *Gray) GrayAt(x, y int) color.Gray { 727 if !(Point{x, y}.In(p.Rect)) { 728 return color.Gray{} 729 } 730 i := p.PixOffset(x, y) 731 return color.Gray{p.Pix[i]} 732} 733 734// PixOffset returns the index of the first element of Pix that corresponds to 735// the pixel at (x, y). 736func (p *Gray) PixOffset(x, y int) int { 737 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*1 738} 739 740func (p *Gray) Set(x, y int, c color.Color) { 741 if !(Point{x, y}.In(p.Rect)) { 742 return 743 } 744 i := p.PixOffset(x, y) 745 p.Pix[i] = color.GrayModel.Convert(c).(color.Gray).Y 746} 747 748func (p *Gray) SetGray(x, y int, c color.Gray) { 749 if !(Point{x, y}.In(p.Rect)) { 750 return 751 } 752 i := p.PixOffset(x, y) 753 p.Pix[i] = c.Y 754} 755 756// SubImage returns an image representing the portion of the image p visible 757// through r. The returned value shares pixels with the original image. 758func (p *Gray) SubImage(r Rectangle) Image { 759 r = r.Intersect(p.Rect) 760 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 761 // either r1 or r2 if the intersection is empty. Without explicitly checking for 762 // this, the Pix[i:] expression below can panic. 763 if r.Empty() { 764 return &Gray{} 765 } 766 i := p.PixOffset(r.Min.X, r.Min.Y) 767 return &Gray{ 768 Pix: p.Pix[i:], 769 Stride: p.Stride, 770 Rect: r, 771 } 772} 773 774// Opaque scans the entire image and reports whether it is fully opaque. 775func (p *Gray) Opaque() bool { 776 return true 777} 778 779// NewGray returns a new Gray image with the given bounds. 780func NewGray(r Rectangle) *Gray { 781 return &Gray{ 782 Pix: make([]uint8, pixelBufferLength(1, r, "Gray")), 783 Stride: 1 * r.Dx(), 784 Rect: r, 785 } 786} 787 788// Gray16 is an in-memory image whose At method returns color.Gray16 values. 789type Gray16 struct { 790 // Pix holds the image's pixels, as gray values in big-endian format. The pixel at 791 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*2]. 792 Pix []uint8 793 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 794 Stride int 795 // Rect is the image's bounds. 796 Rect Rectangle 797} 798 799func (p *Gray16) ColorModel() color.Model { return color.Gray16Model } 800 801func (p *Gray16) Bounds() Rectangle { return p.Rect } 802 803func (p *Gray16) At(x, y int) color.Color { 804 return p.Gray16At(x, y) 805} 806 807func (p *Gray16) Gray16At(x, y int) color.Gray16 { 808 if !(Point{x, y}.In(p.Rect)) { 809 return color.Gray16{} 810 } 811 i := p.PixOffset(x, y) 812 return color.Gray16{uint16(p.Pix[i+0])<<8 | uint16(p.Pix[i+1])} 813} 814 815// PixOffset returns the index of the first element of Pix that corresponds to 816// the pixel at (x, y). 817func (p *Gray16) PixOffset(x, y int) int { 818 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*2 819} 820 821func (p *Gray16) Set(x, y int, c color.Color) { 822 if !(Point{x, y}.In(p.Rect)) { 823 return 824 } 825 i := p.PixOffset(x, y) 826 c1 := color.Gray16Model.Convert(c).(color.Gray16) 827 p.Pix[i+0] = uint8(c1.Y >> 8) 828 p.Pix[i+1] = uint8(c1.Y) 829} 830 831func (p *Gray16) SetGray16(x, y int, c color.Gray16) { 832 if !(Point{x, y}.In(p.Rect)) { 833 return 834 } 835 i := p.PixOffset(x, y) 836 p.Pix[i+0] = uint8(c.Y >> 8) 837 p.Pix[i+1] = uint8(c.Y) 838} 839 840// SubImage returns an image representing the portion of the image p visible 841// through r. The returned value shares pixels with the original image. 842func (p *Gray16) SubImage(r Rectangle) Image { 843 r = r.Intersect(p.Rect) 844 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 845 // either r1 or r2 if the intersection is empty. Without explicitly checking for 846 // this, the Pix[i:] expression below can panic. 847 if r.Empty() { 848 return &Gray16{} 849 } 850 i := p.PixOffset(r.Min.X, r.Min.Y) 851 return &Gray16{ 852 Pix: p.Pix[i:], 853 Stride: p.Stride, 854 Rect: r, 855 } 856} 857 858// Opaque scans the entire image and reports whether it is fully opaque. 859func (p *Gray16) Opaque() bool { 860 return true 861} 862 863// NewGray16 returns a new Gray16 image with the given bounds. 864func NewGray16(r Rectangle) *Gray16 { 865 return &Gray16{ 866 Pix: make([]uint8, pixelBufferLength(2, r, "Gray16")), 867 Stride: 2 * r.Dx(), 868 Rect: r, 869 } 870} 871 872// CMYK is an in-memory image whose At method returns color.CMYK values. 873type CMYK struct { 874 // Pix holds the image's pixels, in C, M, Y, K order. The pixel at 875 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*4]. 876 Pix []uint8 877 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 878 Stride int 879 // Rect is the image's bounds. 880 Rect Rectangle 881} 882 883func (p *CMYK) ColorModel() color.Model { return color.CMYKModel } 884 885func (p *CMYK) Bounds() Rectangle { return p.Rect } 886 887func (p *CMYK) At(x, y int) color.Color { 888 return p.CMYKAt(x, y) 889} 890 891func (p *CMYK) CMYKAt(x, y int) color.CMYK { 892 if !(Point{x, y}.In(p.Rect)) { 893 return color.CMYK{} 894 } 895 i := p.PixOffset(x, y) 896 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 897 return color.CMYK{s[0], s[1], s[2], s[3]} 898} 899 900// PixOffset returns the index of the first element of Pix that corresponds to 901// the pixel at (x, y). 902func (p *CMYK) PixOffset(x, y int) int { 903 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4 904} 905 906func (p *CMYK) Set(x, y int, c color.Color) { 907 if !(Point{x, y}.In(p.Rect)) { 908 return 909 } 910 i := p.PixOffset(x, y) 911 c1 := color.CMYKModel.Convert(c).(color.CMYK) 912 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 913 s[0] = c1.C 914 s[1] = c1.M 915 s[2] = c1.Y 916 s[3] = c1.K 917} 918 919func (p *CMYK) SetCMYK(x, y int, c color.CMYK) { 920 if !(Point{x, y}.In(p.Rect)) { 921 return 922 } 923 i := p.PixOffset(x, y) 924 s := p.Pix[i : i+4 : i+4] // Small cap improves performance, see https://golang.org/issue/27857 925 s[0] = c.C 926 s[1] = c.M 927 s[2] = c.Y 928 s[3] = c.K 929} 930 931// SubImage returns an image representing the portion of the image p visible 932// through r. The returned value shares pixels with the original image. 933func (p *CMYK) SubImage(r Rectangle) Image { 934 r = r.Intersect(p.Rect) 935 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 936 // either r1 or r2 if the intersection is empty. Without explicitly checking for 937 // this, the Pix[i:] expression below can panic. 938 if r.Empty() { 939 return &CMYK{} 940 } 941 i := p.PixOffset(r.Min.X, r.Min.Y) 942 return &CMYK{ 943 Pix: p.Pix[i:], 944 Stride: p.Stride, 945 Rect: r, 946 } 947} 948 949// Opaque scans the entire image and reports whether it is fully opaque. 950func (p *CMYK) Opaque() bool { 951 return true 952} 953 954// NewCMYK returns a new CMYK image with the given bounds. 955func NewCMYK(r Rectangle) *CMYK { 956 return &CMYK{ 957 Pix: make([]uint8, pixelBufferLength(4, r, "CMYK")), 958 Stride: 4 * r.Dx(), 959 Rect: r, 960 } 961} 962 963// Paletted is an in-memory image of uint8 indices into a given palette. 964type Paletted struct { 965 // Pix holds the image's pixels, as palette indices. The pixel at 966 // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*1]. 967 Pix []uint8 968 // Stride is the Pix stride (in bytes) between vertically adjacent pixels. 969 Stride int 970 // Rect is the image's bounds. 971 Rect Rectangle 972 // Palette is the image's palette. 973 Palette color.Palette 974} 975 976func (p *Paletted) ColorModel() color.Model { return p.Palette } 977 978func (p *Paletted) Bounds() Rectangle { return p.Rect } 979 980func (p *Paletted) At(x, y int) color.Color { 981 if len(p.Palette) == 0 { 982 return nil 983 } 984 if !(Point{x, y}.In(p.Rect)) { 985 return p.Palette[0] 986 } 987 i := p.PixOffset(x, y) 988 return p.Palette[p.Pix[i]] 989} 990 991// PixOffset returns the index of the first element of Pix that corresponds to 992// the pixel at (x, y). 993func (p *Paletted) PixOffset(x, y int) int { 994 return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*1 995} 996 997func (p *Paletted) Set(x, y int, c color.Color) { 998 if !(Point{x, y}.In(p.Rect)) { 999 return 1000 } 1001 i := p.PixOffset(x, y) 1002 p.Pix[i] = uint8(p.Palette.Index(c)) 1003} 1004 1005func (p *Paletted) ColorIndexAt(x, y int) uint8 { 1006 if !(Point{x, y}.In(p.Rect)) { 1007 return 0 1008 } 1009 i := p.PixOffset(x, y) 1010 return p.Pix[i] 1011} 1012 1013func (p *Paletted) SetColorIndex(x, y int, index uint8) { 1014 if !(Point{x, y}.In(p.Rect)) { 1015 return 1016 } 1017 i := p.PixOffset(x, y) 1018 p.Pix[i] = index 1019} 1020 1021// SubImage returns an image representing the portion of the image p visible 1022// through r. The returned value shares pixels with the original image. 1023func (p *Paletted) SubImage(r Rectangle) Image { 1024 r = r.Intersect(p.Rect) 1025 // If r1 and r2 are Rectangles, r1.Intersect(r2) is not guaranteed to be inside 1026 // either r1 or r2 if the intersection is empty. Without explicitly checking for 1027 // this, the Pix[i:] expression below can panic. 1028 if r.Empty() { 1029 return &Paletted{ 1030 Palette: p.Palette, 1031 } 1032 } 1033 i := p.PixOffset(r.Min.X, r.Min.Y) 1034 return &Paletted{ 1035 Pix: p.Pix[i:], 1036 Stride: p.Stride, 1037 Rect: p.Rect.Intersect(r), 1038 Palette: p.Palette, 1039 } 1040} 1041 1042// Opaque scans the entire image and reports whether it is fully opaque. 1043func (p *Paletted) Opaque() bool { 1044 var present [256]bool 1045 i0, i1 := 0, p.Rect.Dx() 1046 for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ { 1047 for _, c := range p.Pix[i0:i1] { 1048 present[c] = true 1049 } 1050 i0 += p.Stride 1051 i1 += p.Stride 1052 } 1053 for i, c := range p.Palette { 1054 if !present[i] { 1055 continue 1056 } 1057 _, _, _, a := c.RGBA() 1058 if a != 0xffff { 1059 return false 1060 } 1061 } 1062 return true 1063} 1064 1065// NewPaletted returns a new Paletted image with the given width, height and 1066// palette. 1067func NewPaletted(r Rectangle, p color.Palette) *Paletted { 1068 return &Paletted{ 1069 Pix: make([]uint8, pixelBufferLength(1, r, "Paletted")), 1070 Stride: 1 * r.Dx(), 1071 Rect: r, 1072 Palette: p, 1073 } 1074} 1075