From e1e8d058a33f7566f9c565d04b0d8b56f9645c35 Mon Sep 17 00:00:00 2001 From: Dimitri Sokolyuk Date: Wed, 25 Apr 2018 09:28:54 +0200 Subject: add vendor --- vendor/golang.org/x/image/vp8l/transform.go | 299 ++++++++++++++++++++++++++++ 1 file changed, 299 insertions(+) create mode 100644 vendor/golang.org/x/image/vp8l/transform.go (limited to 'vendor/golang.org/x/image/vp8l/transform.go') diff --git a/vendor/golang.org/x/image/vp8l/transform.go b/vendor/golang.org/x/image/vp8l/transform.go new file mode 100644 index 0000000..06543da --- /dev/null +++ b/vendor/golang.org/x/image/vp8l/transform.go @@ -0,0 +1,299 @@ +// 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 vp8l + +// This file deals with image transforms, specified in section 3. + +// nTiles returns the number of tiles needed to cover size pixels, where each +// tile's side is 1<> bits +} + +const ( + transformTypePredictor = 0 + transformTypeCrossColor = 1 + transformTypeSubtractGreen = 2 + transformTypeColorIndexing = 3 + nTransformTypes = 4 +) + +// transform holds the parameters for an invertible transform. +type transform struct { + // transformType is the type of the transform. + transformType uint32 + // oldWidth is the width of the image before transformation (or + // equivalently, after inverse transformation). The color-indexing + // transform can reduce the width. For example, a 50-pixel-wide + // image that only needs 4 bits (half a byte) per color index can + // be transformed into a 25-pixel-wide image. + oldWidth int32 + // bits is the log-2 size of the transform's tiles, for the predictor + // and cross-color transforms. 8>>bits is the number of bits per + // color index, for the color-index transform. + bits uint32 + // pix is the tile values, for the predictor and cross-color + // transforms, and the color palette, for the color-index transform. + pix []byte +} + +var inverseTransforms = [nTransformTypes]func(*transform, []byte, int32) []byte{ + transformTypePredictor: inversePredictor, + transformTypeCrossColor: inverseCrossColor, + transformTypeSubtractGreen: inverseSubtractGreen, + transformTypeColorIndexing: inverseColorIndexing, +} + +func inversePredictor(t *transform, pix []byte, h int32) []byte { + if t.oldWidth == 0 || h == 0 { + return pix + } + // The first pixel's predictor is mode 0 (opaque black). + pix[3] += 0xff + p, mask := int32(4), int32(1)<> t.bits) * tilesPerRow + predictorMode := t.pix[q+1] & 0x0f + q += 4 + for x := int32(1); x < t.oldWidth; x++ { + if x&mask == 0 { + predictorMode = t.pix[q+1] & 0x0f + q += 4 + } + switch predictorMode { + case 0: // Opaque black. + pix[p+3] += 0xff + + case 1: // L. + pix[p+0] += pix[p-4] + pix[p+1] += pix[p-3] + pix[p+2] += pix[p-2] + pix[p+3] += pix[p-1] + + case 2: // T. + pix[p+0] += pix[top+0] + pix[p+1] += pix[top+1] + pix[p+2] += pix[top+2] + pix[p+3] += pix[top+3] + + case 3: // TR. + pix[p+0] += pix[top+4] + pix[p+1] += pix[top+5] + pix[p+2] += pix[top+6] + pix[p+3] += pix[top+7] + + case 4: // TL. + pix[p+0] += pix[top-4] + pix[p+1] += pix[top-3] + pix[p+2] += pix[top-2] + pix[p+3] += pix[top-1] + + case 5: // Average2(Average2(L, TR), T). + pix[p+0] += avg2(avg2(pix[p-4], pix[top+4]), pix[top+0]) + pix[p+1] += avg2(avg2(pix[p-3], pix[top+5]), pix[top+1]) + pix[p+2] += avg2(avg2(pix[p-2], pix[top+6]), pix[top+2]) + pix[p+3] += avg2(avg2(pix[p-1], pix[top+7]), pix[top+3]) + + case 6: // Average2(L, TL). + pix[p+0] += avg2(pix[p-4], pix[top-4]) + pix[p+1] += avg2(pix[p-3], pix[top-3]) + pix[p+2] += avg2(pix[p-2], pix[top-2]) + pix[p+3] += avg2(pix[p-1], pix[top-1]) + + case 7: // Average2(L, T). + pix[p+0] += avg2(pix[p-4], pix[top+0]) + pix[p+1] += avg2(pix[p-3], pix[top+1]) + pix[p+2] += avg2(pix[p-2], pix[top+2]) + pix[p+3] += avg2(pix[p-1], pix[top+3]) + + case 8: // Average2(TL, T). + pix[p+0] += avg2(pix[top-4], pix[top+0]) + pix[p+1] += avg2(pix[top-3], pix[top+1]) + pix[p+2] += avg2(pix[top-2], pix[top+2]) + pix[p+3] += avg2(pix[top-1], pix[top+3]) + + case 9: // Average2(T, TR). + pix[p+0] += avg2(pix[top+0], pix[top+4]) + pix[p+1] += avg2(pix[top+1], pix[top+5]) + pix[p+2] += avg2(pix[top+2], pix[top+6]) + pix[p+3] += avg2(pix[top+3], pix[top+7]) + + case 10: // Average2(Average2(L, TL), Average2(T, TR)). + pix[p+0] += avg2(avg2(pix[p-4], pix[top-4]), avg2(pix[top+0], pix[top+4])) + pix[p+1] += avg2(avg2(pix[p-3], pix[top-3]), avg2(pix[top+1], pix[top+5])) + pix[p+2] += avg2(avg2(pix[p-2], pix[top-2]), avg2(pix[top+2], pix[top+6])) + pix[p+3] += avg2(avg2(pix[p-1], pix[top-1]), avg2(pix[top+3], pix[top+7])) + + case 11: // Select(L, T, TL). + l0 := int32(pix[p-4]) + l1 := int32(pix[p-3]) + l2 := int32(pix[p-2]) + l3 := int32(pix[p-1]) + c0 := int32(pix[top-4]) + c1 := int32(pix[top-3]) + c2 := int32(pix[top-2]) + c3 := int32(pix[top-1]) + t0 := int32(pix[top+0]) + t1 := int32(pix[top+1]) + t2 := int32(pix[top+2]) + t3 := int32(pix[top+3]) + l := abs(c0-t0) + abs(c1-t1) + abs(c2-t2) + abs(c3-t3) + t := abs(c0-l0) + abs(c1-l1) + abs(c2-l2) + abs(c3-l3) + if l < t { + pix[p+0] += uint8(l0) + pix[p+1] += uint8(l1) + pix[p+2] += uint8(l2) + pix[p+3] += uint8(l3) + } else { + pix[p+0] += uint8(t0) + pix[p+1] += uint8(t1) + pix[p+2] += uint8(t2) + pix[p+3] += uint8(t3) + } + + case 12: // ClampAddSubtractFull(L, T, TL). + pix[p+0] += clampAddSubtractFull(pix[p-4], pix[top+0], pix[top-4]) + pix[p+1] += clampAddSubtractFull(pix[p-3], pix[top+1], pix[top-3]) + pix[p+2] += clampAddSubtractFull(pix[p-2], pix[top+2], pix[top-2]) + pix[p+3] += clampAddSubtractFull(pix[p-1], pix[top+3], pix[top-1]) + + case 13: // ClampAddSubtractHalf(Average2(L, T), TL). + pix[p+0] += clampAddSubtractHalf(avg2(pix[p-4], pix[top+0]), pix[top-4]) + pix[p+1] += clampAddSubtractHalf(avg2(pix[p-3], pix[top+1]), pix[top-3]) + pix[p+2] += clampAddSubtractHalf(avg2(pix[p-2], pix[top+2]), pix[top-2]) + pix[p+3] += clampAddSubtractHalf(avg2(pix[p-1], pix[top+3]), pix[top-1]) + } + p, top = p+4, top+4 + } + } + return pix +} + +func inverseCrossColor(t *transform, pix []byte, h int32) []byte { + var greenToRed, greenToBlue, redToBlue int32 + p, mask, tilesPerRow := int32(0), int32(1)<> t.bits) * tilesPerRow + for x := int32(0); x < t.oldWidth; x++ { + if x&mask == 0 { + redToBlue = int32(int8(t.pix[q+0])) + greenToBlue = int32(int8(t.pix[q+1])) + greenToRed = int32(int8(t.pix[q+2])) + q += 4 + } + red := pix[p+0] + green := pix[p+1] + blue := pix[p+2] + red += uint8(uint32(greenToRed*int32(int8(green))) >> 5) + blue += uint8(uint32(greenToBlue*int32(int8(green))) >> 5) + blue += uint8(uint32(redToBlue*int32(int8(red))) >> 5) + pix[p+0] = red + pix[p+2] = blue + p += 4 + } + } + return pix +} + +func inverseSubtractGreen(t *transform, pix []byte, h int32) []byte { + for p := 0; p < len(pix); p += 4 { + green := pix[p+1] + pix[p+0] += green + pix[p+2] += green + } + return pix +} + +func inverseColorIndexing(t *transform, pix []byte, h int32) []byte { + if t.bits == 0 { + for p := 0; p < len(pix); p += 4 { + i := 4 * uint32(pix[p+1]) + pix[p+0] = t.pix[i+0] + pix[p+1] = t.pix[i+1] + pix[p+2] = t.pix[i+2] + pix[p+3] = t.pix[i+3] + } + return pix + } + + vMask, xMask, bitsPerPixel := uint32(0), int32(0), uint32(8>>t.bits) + switch t.bits { + case 1: + vMask, xMask = 0x0f, 0x01 + case 2: + vMask, xMask = 0x03, 0x03 + case 3: + vMask, xMask = 0x01, 0x07 + } + + d, p, v, dst := 0, 0, uint32(0), make([]byte, 4*t.oldWidth*h) + for y := int32(0); y < h; y++ { + for x := int32(0); x < t.oldWidth; x++ { + if x&xMask == 0 { + v = uint32(pix[p+1]) + p += 4 + } + + i := 4 * (v & vMask) + dst[d+0] = t.pix[i+0] + dst[d+1] = t.pix[i+1] + dst[d+2] = t.pix[i+2] + dst[d+3] = t.pix[i+3] + d += 4 + + v >>= bitsPerPixel + } + } + return dst +} + +func abs(x int32) int32 { + if x < 0 { + return -x + } + return x +} + +func avg2(a, b uint8) uint8 { + return uint8((int32(a) + int32(b)) / 2) +} + +func clampAddSubtractFull(a, b, c uint8) uint8 { + x := int32(a) + int32(b) - int32(c) + if x < 0 { + return 0 + } + if x > 255 { + return 255 + } + return uint8(x) +} + +func clampAddSubtractHalf(a, b uint8) uint8 { + x := int32(a) + (int32(a)-int32(b))/2 + if x < 0 { + return 0 + } + if x > 255 { + return 255 + } + return uint8(x) +} -- cgit v1.2.3