diff options
Diffstat (limited to 'adapter/img')
| -rw-r--r-- | adapter/img/sixel.nim | 137 |
1 files changed, 86 insertions, 51 deletions
diff --git a/adapter/img/sixel.nim b/adapter/img/sixel.nim index e06b85e7..8f215261 100644 --- a/adapter/img/sixel.nim +++ b/adapter/img/sixel.nim @@ -15,12 +15,31 @@ import std/algorithm import std/options import std/os +import std/posix import std/strutils import types/color import utils/sandbox import utils/twtstr +const STDOUT_FILENO = 1 + +proc writeAll(data: pointer; size: int) = + var n = 0 + while n < size: + let i = write(STDOUT_FILENO, addr cast[ptr UncheckedArray[uint8]](data)[n], + int(size) - n) + assert i >= 0 + n += i + +proc puts(s: string) = + if s.len > 0: + writeAll(unsafeAddr s[0], s.len) + +proc die(s: string) {.noreturn.} = + puts(s) + quit(1) + const DCSSTART = "\eP" const ST = "\e\\" @@ -59,11 +78,11 @@ func find(bands: seq[SixelBand]; c: int): int = return i return -1 -proc setU32BE(s: var string; n: uint32) = - s[0] = char(n and 0xFF) - s[1] = char((n shr 8) and 0xFF) - s[2] = char((n shr 16) and 0xFF) - s[3] = char((n shr 24) and 0xFF) +proc setU32BE(s: var string; n: uint32; at: int) = + s[at] = char(n and 0xFF) + s[at + 1] = char((n shr 8) and 0xFF) + s[at + 2] = char((n shr 16) and 0xFF) + s[at + 3] = char((n shr 24) and 0xFF) proc putU32BE(s: var string; n: uint32) = s &= char(n and 0xFF) @@ -199,10 +218,19 @@ proc quantize(s: string; bgcolor: ARGBColor; palette: int): Node = return root type - QuantMap = array[4096, seq[tuple[idx: int; c: RGBColor]]] + QuantMap = object + map: array[4096, seq[tuple[idx: int; c: RGBColor]]] + imap: array[4096, int] ColorPair = tuple[c: RGBColor; n: uint32] +func quantHash(c: RGBColor): int = + # take top 4 bits of each component - note this means bits 4..7, + # the 8th bit is always 0 (as 100 is the highest color component). + return ((int(c.r shr 3) and 0xF) shl 8) or + ((int(c.g shr 3) and 0xF) shl 4) or + (int(c.b shr 3) and 0xF) + proc flatten(node: Node; map: var QuantMap; cols: var seq[ColorPair]) = if node.leaf: cols.add((node.c, node.n)) @@ -222,65 +250,68 @@ proc flatten(node: Node; outs: var string; palette: int): QuantMap = let c = it.c # 2 is RGB outs &= '#' & $n & ";2;" & $c.r & ';' & $c.g & ';' & $c.b - let i = (int(c.r shr 4) shl 8) or - (int(c.g shr 4) shl 4) or - (int(c.b shr 4)) - map[i].add((n, c)) + let i = quantHash(c) + map.map[i].add((n, c)) + # for empty buckets in the hash map: copy over the closest match + var todo: seq[int] = @[] + var pi = -9999 # make sure this gets overridden in imap + for i, it in map.map.mpairs: + if it.len == 0: + if pi >= 0: + map.imap[i] = pi + todo.add(i) + else: + for j in todo: + if abs(j - pi) > abs(j - i): + map.imap[j] = i + todo.setLen(0) + pi = i return map proc getColor(map: QuantMap; c: RGBColor): int = - var i = (int(c.r shr 4) shl 8) or - (int(c.g shr 4) shl 4) or - int(c.b shr 4) - if map[i].len == 0: - var j = i - while true: - dec i - inc j - if i >= 0 and map[i].len > 0: - break - if j < map.len and map[j].len > 0: - i = j - break - assert i >= 0 or j < map.len # assuming map isn't empty... + let i = quantHash(c) var minDist = uint32.high var resIdx = -1 - for (idx, ic) in map[i]: - var d = uint32(abs(int32(c.r) - int32(ic.r))) + + var j = i + if map.map[j].len == 0: + j = map.imap[i] + for (idx, ic) in map.map[j]: + let d = uint32(abs(int32(c.r) - int32(ic.r))) + uint32(abs(int32(c.g) - int32(ic.g))) + uint32(abs(int32(c.b) - int32(ic.b))) if d < minDist: minDist = d resIdx = idx - assert resIdx != -1 return resIdx proc encode(s: string; width, height, offx, offy, cropw: int; halfdump: bool; bgcolor: ARGBColor; palette: int) = - if width == 0 or height == 0: - return # done... + # reserve one entry for transparency + # (this is necessary so that cropping works properly when the last + # sixel would not fit on the screen, and also for images with !(height % 6).) + let palette = palette - 1 + let node = s.quantize(bgcolor, palette) # prelude - var outs = "" + var outs = "Cha-Image-Dimensions: " & $width & 'x' & $height & "\n\n" + let preludeLenPos = outs.len if halfdump: # reserve size for prelude outs &= "\0\0\0\0" else: outs &= DCSSTART & 'q' # set raster attributes outs &= "\"1;1;" & $width & ';' & $height - # reserve one entry for empty lines - let node = s.quantize(bgcolor, palette - 1) let map = node.flatten(outs, palette) if halfdump: # prepend prelude size - let L = outs.len - 4 # subtract length field - outs.setU32BE(uint32(L)) - stdout.write(outs) + let L = outs.len - 4 - preludeLenPos # subtract length field + outs.setU32BE(uint32(L), preludeLenPos) + puts(outs) let W = width * 4 let H = W * height var n = offy * W var ymap = "" var totalLen = 0 - while n < H: + while true: if halfdump: ymap.putU32BE(uint32(totalLen)) var bands = newSeq[SixelBand]() @@ -311,25 +342,28 @@ proc encode(s: string; width, height, offx, offy, cropw: int; halfdump: bool; outs &= '$' if n >= H: outs &= ST + totalLen += outs.len + break else: outs &= '-' - totalLen += outs.len - stdout.write(outs) + totalLen += outs.len + puts(outs) if halfdump: ymap.putU32BE(uint32(totalLen)) ymap.putU32BE(uint32(ymap.len)) - stdout.write(ymap) + outs &= ymap + puts(outs) + else: + puts(outs) proc parseDimensions(s: string): (int, int) = let s = s.split('x') if s.len != 2: - stdout.writeLine("Cha-Control: ConnectionError 1 wrong dimensions") - return + die("Cha-Control: ConnectionError 1 wrong dimensions\n") let w = parseUInt32(s[0], allowSign = false) let h = parseUInt32(s[1], allowSign = false) if w.isNone or w.isNone: - stdout.writeLine("Cha-Control: ConnectionError 1 wrong dimensions") - return + die("Cha-Control: ConnectionError 1 wrong dimensions\n") return (int(w.get), int(h.get)) proc main() = @@ -337,11 +371,10 @@ proc main() = let scheme = getEnv("MAPPED_URI_SCHEME") let f = scheme.after('+') if f != "x-sixel": - stdout.writeLine("Cha-Control: ConnectionError 1 unknown format " & f) - return + die("Cha-Control: ConnectionError 1 unknown format " & f) case getEnv("MAPPED_URI_PATH") of "decode": - stdout.writeLine("Cha-Control: ConnectionError 1 not implemented") + die("Cha-Control: ConnectionError 1 not implemented\n") of "encode": let headers = getEnv("REQUEST_HEADERS") var width = 0 @@ -362,23 +395,25 @@ proc main() = of "Cha-Image-Crop-Width": let q = parseUInt32(s, allowSign = false) if q.isNone: - stdout.writeLine("Cha-Control: ConnectionError 1 wrong palette") - return + die("Cha-Control: ConnectionError 1 wrong palette\n") cropw = int(q.get) of "Cha-Image-Sixel-Halfdump": halfdump = true of "Cha-Image-Sixel-Palette": let q = parseUInt16(s, allowSign = false) if q.isNone: - stdout.writeLine("Cha-Control: ConnectionError 1 wrong palette") - return + die("Cha-Control: ConnectionError 1 wrong palette\n") palette = int(q.get) of "Cha-Image-Background-Color": bgcolor = parseLegacyColor0(s) if cropw == -1: cropw = width + if palette == -1: + palette = 16 + if width == 0 or height == 0: + puts("Cha-Image-Dimensions: 0x0\n") + quit(0) # done... let s = stdin.readAll() - stdout.write("Cha-Image-Dimensions: " & $width & 'x' & $height & "\n\n") s.encode(width, height, offx, offy, cropw, halfdump, bgcolor, palette) main() |