jpg + stb for now

README.md

@@ -2,13 +2,13 @@
 
 ⚠️ WARNING: This library is still in heavy development. ⚠️
 
-Pixie is a 2D graphics library similar to [Cairo](https://www.cairographics.org/) and [Skia](https://skia.org) written entirely in Nim.
+Pixie is a 2D graphics library similar to [Cairo](https://www.cairographics.org/) and [Skia](https://skia.org) written (almost) entirely in Nim.
 
 Features include:
 * Drawing paths, shapes and curves
 * Complex masking
 * Shadows, glows and effects
-* Loading image file formats (PNG, BMP, + more in development)
+* Loading image file formats (PNG, BMP, JPG + more in development)
 
 This library is being actively developed and is not yet ready for use. Since you've managed to stumble onto it, give it a star and check back soon!
 

src/pixie.nim

@@ -1,7 +1,7 @@
 ## Public interface to you library.
 
 import pixie/images, pixie/masks, pixie/paths, pixie/common, pixie/blends,
-  pixie/fileformats/bmp, pixie/fileformats/png, pixie/fileformats/jpg,
+  pixie/fileformats/bmp, pixie/fileformats/png, pixie/fileformats/jpgstb,
   flatty/binny, os
 
 export images, masks, paths, common, blends

src/pixie/fileformats/jpgstb.nim

@@ -0,0 +1,20 @@
+import pixie/images, pixie/common, pixie/fileformats/stb_image/stb_image
+
+const
+  jpgStartOfImage* = [0xFF.uint8, 0xD8]
+
+proc decodeJpg*(data: seq[uint8]): Image =
+  ## Decodes the JPEG into an Image.
+  var
+    width: int
+    height: int
+  let pixels = loadFromMemory(data, width, height)
+
+  result = newImage(width, height)
+  copyMem(result.data[0].addr, pixels[0].unsafeAddr, pixels.len)
+
+proc decodeJpg*(data: string): Image {.inline.} =
+  decodeJpg(cast[seq[uint8]](data))
+
+proc encodeJpg*(image: Image): string =
+  raise newException(PixieError, "Encoding JPG not supported yet")

src/pixie/fileformats/stb_image/stb_image.c

@@ -0,0 +1,2 @@
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"

src/pixie/fileformats/stb_image/stb_image.nim

@@ -0,0 +1,41 @@
+import pixie/common
+
+when defined(windows) and defined(vcc):
+  {.pragma: stbcall, stdcall.}
+else:
+  {.pragma: stbcall, cdecl.}
+
+{.compile: "stb_image.c".}
+
+proc stbi_image_free(retval_from_stbi_load: pointer)
+  {.importc: "stbi_image_free", stbcall.}
+
+proc stbi_load_from_memory(
+  buffer: ptr cuchar,
+  len: cint,
+  x, y, channels_in_file: var cint,
+  desired_channels: cint
+): ptr cuchar
+  {.importc: "stbi_load_from_memory", stbcall.}
+
+
+proc loadFromMemory*(buffer: seq[uint8], width, height: var int): seq[uint8] =
+  var outWidth, outHeight, outComponents: cint
+  let data = stbi_load_from_memory(
+    cast[ptr cuchar](buffer[0].unsafeAddr),
+    buffer.len.cint,
+    outWidth,
+    outHeight,
+    outComponents,
+    4
+  )
+  if data == nil:
+    raise newException(PixieError, "Loading JPG failed")
+
+  width = outWidth.int
+  height = outHeight.int
+
+  result.setLen(width * height * 4)
+  copyMem(result[0].addr, data, result.len)
+
+  stbi_image_free(data)

tests/test_images.nim

@@ -3,7 +3,7 @@ import pixie, chroma, vmath, strutils, os
 proc writeAndCheck(image: Image, fileName: string) =
   image.writeFile(fileName)
   let masterFileName = fileName.replace("tests/images/", "tests/images/masters/")
-  if not existsFile(masterFileName):
+  if not fileExists(masterFileName):
     echo "Master file: " & masterFileName & " not found!"
     quit(-1)
   var master = readImage(fileName)

tests/test_jpg.nim

@@ -1,4 +1,4 @@
-import pixie/fileformats/jpg
+import pixie/fileformats/jpgstb
 
 let original = readFile("tests/images/jpg/jpeg420exif.jpg")