Merge pull request #8 from guzba/master

bestspeed png encode + a bit of jpg

src/pixie/fileformats/jpg.nim

@@ -12,6 +12,7 @@ type
   Jpg = object
     width, height: int
     components: array[3, Component]
+    quantizationTables: array[4, array[64, uint8]]
 
 template failInvalid() =
   raise newException(PixieError, "Invalid JPG buffer, unable to load")
@@ -71,10 +72,59 @@ proc decodeSOF(jpg: var Jpg, data: seq[uint8], pos: var int) =
     pos += 3
 
 proc decodeDHT(data: seq[uint8], pos: var int) =
-  skipSegment(data, pos)
+  # skipSegment(data, pos)
+  # debugEcho pos
+  let
+    segmentLen = readSegmentLen(data, pos)
+    stop = pos + segmentLen
+  pos += 2
 
-proc decodeDQT(data: seq[uint8], pos: var int) =
-  skipSegment(data, pos)
+  while stop - pos >= 17:
+    let info = data[pos]
+    if (info and 0b11100000) != 0:
+      failInvalid()
+
+    var counts: array[17, int]
+    for codeLen in 1 .. 16:
+      counts[codeLen] = data[pos + codeLen].int
+
+    debugEcho counts
+
+    pos += 17
+
+    for codeLen in 1 .. 16:
+      discard
+
+    break
+
+  pos = stop
+
+proc decodeDQT(jpg: var Jpg, data: seq[uint8], pos: var int) =
+  let
+    segmentLen = readSegmentLen(data, pos)
+    stop = pos + segmentLen
+  pos += 2
+
+  while stop - pos >= 65:
+    let
+      info = data[pos]
+      qt = info and 0b00001111
+      precision = info and 0b11110000
+
+    if qt > 3:
+      failInvalid()
+
+    if precision != 0:
+      raise newException(
+        PixieError, "Unsuppored JPG qantization table precision"
+      )
+
+    inc pos
+
+    for i in 0 ..< 64:
+      jpg.quantizationTables[qt][i] = data[pos + i]
+
+    pos += 64
 
 proc decodeSOS(data: seq[uint8], pos: var int) =
   let segmentLen = readSegmentLen(data, pos)
@@ -144,7 +194,7 @@ proc decodeJpg*(data: seq[uint8]): Image =
     of 0xC4: # Define Huffman Tables
       decodeDHT(data, pos)
     of 0xDB: # Define Quantanization Table(s)
-      decodeDQT(data, pos)
+      jpg.decodeDQT(data, pos)
     # of 0xDD: # Define Restart Interval
     of 0xDA: # Start of Scan
       decodeSOS(data, pos)

src/pixie/fileformats/png.nim

@@ -469,7 +469,7 @@ proc encodePng*(
 
   let compressed =
     try:
-      compress(filtered, DefaultCompression, dfZlib)
+      compress(filtered, BestSpeed, dfZlib)
     except ZippyError:
       raise newException(
         PixieError, "Unexpected error compressing PNG image data"

tests/benchmark_png.nim

@@ -1,16 +1,27 @@
-import pixie/fileformats/png, stb_image/read as stbi, fidget/opengl/perf, nimPNG
+import pixie/fileformats/png, stb_image/read as stbi, stb_image/write as stbr,
+  fidget/opengl/perf, nimPNG
 
 let data = readFile("tests/data/lenna.png")
 
-timeIt "pixie":
+timeIt "pixie decode":
   for i in 0 ..< 100:
     discard decodePng(cast[seq[uint8]](data))
 
-timeIt "nimPNG":
+timeIt "pixie encode":
+  let decoded = decodePng(cast[seq[uint8]](data))
+  for i in 0 ..< 1:
+    discard encodePng(decoded).len
+
+timeIt "nimPNG decode":
   for i in 0 ..< 100:
     discard decodePNG32(data)
 
-timeIt "stb_image":
+timeIt "nimPNG encode":
+  let decoded = decodePNG32(data)
+  for i in 0 ..< 100:
+    discard encodePNG32(decoded.data, decoded.width, decoded.height).pixels.len
+
+timeIt "stb_image decode":
   for i in 0 ..< 100:
     var width, height, channels: int
     discard loadFromMemory(
@@ -20,3 +31,15 @@ timeIt "stb_image":
       channels,
       stbi.RGBA
     )
+
+timeIt "stb_image encode":
+  var width, height, channels: int
+  let decoded = loadFromMemory(
+    cast[seq[byte]](data),
+    width,
+    height,
+    channels,
+    stbi.RGBA
+  )
+  for i in 0 ..< 100:
+    discard writePNG(width, height, channels, decoded).len