forked from lug/matterbridge
53cafa9f3d
This commit adds support for go/cgo tgs conversion when building with the -tags `cgo` The default binaries are still "pure" go and uses the old way of converting. * Move lottie_convert.py conversion code to its own file * Add optional libtgsconverter * Update vendor * Apply suggestions from code review * Update bridge/helper/libtgsconverter.go Co-authored-by: Wim <wim@42.be>
72 lines
1.7 KiB
Go
72 lines
1.7 KiB
Go
// Copyright 2012 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 apng
|
|
|
|
// intSize is either 32 or 64.
|
|
const intSize = 32 << (^uint(0) >> 63)
|
|
|
|
func abs(x int) int {
|
|
// m := -1 if x < 0. m := 0 otherwise.
|
|
m := x >> (intSize - 1)
|
|
|
|
// In two's complement representation, the negative number
|
|
// of any number (except the smallest one) can be computed
|
|
// by flipping all the bits and add 1. This is faster than
|
|
// code with a branch.
|
|
// See Hacker's Delight, section 2-4.
|
|
return (x ^ m) - m
|
|
}
|
|
|
|
// paeth implements the Paeth filter function, as per the PNG specification.
|
|
func paeth(a, b, c uint8) uint8 {
|
|
// This is an optimized version of the sample code in the PNG spec.
|
|
// For example, the sample code starts with:
|
|
// p := int(a) + int(b) - int(c)
|
|
// pa := abs(p - int(a))
|
|
// but the optimized form uses fewer arithmetic operations:
|
|
// pa := int(b) - int(c)
|
|
// pa = abs(pa)
|
|
pc := int(c)
|
|
pa := int(b) - pc
|
|
pb := int(a) - pc
|
|
pc = abs(pa + pb)
|
|
pa = abs(pa)
|
|
pb = abs(pb)
|
|
if pa <= pb && pa <= pc {
|
|
return a
|
|
} else if pb <= pc {
|
|
return b
|
|
}
|
|
return c
|
|
}
|
|
|
|
// filterPaeth applies the Paeth filter to the cdat slice.
|
|
// cdat is the current row's data, pdat is the previous row's data.
|
|
func filterPaeth(cdat, pdat []byte, bytesPerPixel int) {
|
|
var a, b, c, pa, pb, pc int
|
|
for i := 0; i < bytesPerPixel; i++ {
|
|
a, c = 0, 0
|
|
for j := i; j < len(cdat); j += bytesPerPixel {
|
|
b = int(pdat[j])
|
|
pa = b - c
|
|
pb = a - c
|
|
pc = abs(pa + pb)
|
|
pa = abs(pa)
|
|
pb = abs(pb)
|
|
if pa <= pb && pa <= pc {
|
|
// No-op.
|
|
} else if pb <= pc {
|
|
a = b
|
|
} else {
|
|
a = c
|
|
}
|
|
a += int(cdat[j])
|
|
a &= 0xff
|
|
cdat[j] = uint8(a)
|
|
c = b
|
|
}
|
|
}
|
|
}
|