better png benchmark, use bestspeed

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