node-canvas/src/Image.cc

//
// Image.cc
//
// Copyright (c) 2010 LearnBoost <tj@learnboost.com>
//

#include "Canvas.h"
#include "Image.h"
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <node_buffer.h>

#ifdef HAVE_JPEG
#include <jpeglib.h>
#endif

#ifdef HAVE_GIF
#include <gif_lib.h>
typedef struct {
  uint8_t *buf;
  unsigned len;
  unsigned pos;
} gif_data_t;
#endif

Persistent<FunctionTemplate> Image::constructor;

/*
 * Read closure used by loadFromBuffer.
 */

typedef struct {
  unsigned len;
  uint8_t *buf;
} read_closure_t;

/*
 * Initialize Image.
 */

void
Image::Initialize(Handle<Object> target) {
  HandleScope scope;

  // Constructor
  constructor = Persistent<FunctionTemplate>::New(FunctionTemplate::New(Image::New));
  constructor->InstanceTemplate()->SetInternalFieldCount(1);
  constructor->SetClassName(String::NewSymbol("Image"));

  // Prototype
  Local<ObjectTemplate> proto = constructor->PrototypeTemplate();
  proto->SetAccessor(String::NewSymbol("src"), GetSrc, SetSrc);
  proto->SetAccessor(String::NewSymbol("complete"), GetComplete);
  proto->SetAccessor(String::NewSymbol("width"), GetWidth);
  proto->SetAccessor(String::NewSymbol("height"), GetHeight);
  proto->SetAccessor(String::NewSymbol("onload"), GetOnload, SetOnload);
  proto->SetAccessor(String::NewSymbol("onerror"), GetOnerror, SetOnerror);
  target->Set(String::NewSymbol("Image"), constructor->GetFunction());
}

/*
 * Initialize a new Image.
 */

Handle<Value>
Image::New(const Arguments &args) {
  HandleScope scope;
  Image *img = new Image;
  img->Wrap(args.This());
  return args.This();
}

/*
 * Get complete boolean.
 */

Handle<Value>
Image::GetComplete(Local<String>, const AccessorInfo &info) {
  HandleScope scope;
  Image *img = ObjectWrap::Unwrap<Image>(info.This());
  return scope.Close(Boolean::New(Image::COMPLETE == img->state));
}

/*
 * Get width.
 */

Handle<Value>
Image::GetWidth(Local<String>, const AccessorInfo &info) {
  HandleScope scope;
  Image *img = ObjectWrap::Unwrap<Image>(info.This());
  return scope.Close(Number::New(img->width));
}
/*
 * Get height.
 */

Handle<Value>
Image::GetHeight(Local<String>, const AccessorInfo &info) {
  HandleScope scope;
  Image *img = ObjectWrap::Unwrap<Image>(info.This());
  return scope.Close(Number::New(img->height));
}

/*
 * Get src path.
 */

Handle<Value>
Image::GetSrc(Local<String>, const AccessorInfo &info) {
  HandleScope scope;
  Image *img = ObjectWrap::Unwrap<Image>(info.This());
  return scope.Close(String::New(img->filename ? img->filename : ""));
}

/*
 * Set src path.
 */

void
Image::SetSrc(Local<String>, Local<Value> val, const AccessorInfo &info) {
  HandleScope scope;
  Image *img = ObjectWrap::Unwrap<Image>(info.This());
  cairo_status_t status = CAIRO_STATUS_READ_ERROR;

  // url string
  if (val->IsString()) {
    String::AsciiValue src(val);
    if (img->filename) free(img->filename);
    img->filename = strdup(*src);
    status = img->load();
  // Buffer
  } else if (Buffer::HasInstance(val)) {
    uint8_t *buf = (uint8_t *) Buffer::Data(val->ToObject());
    unsigned len = Buffer::Length(val->ToObject());
    status = img->loadFromBuffer(buf, len);
  }

  // check status
  if (status) {
    img->error(Canvas::Error(status));
  } else {
    img->loaded();
  }
}

/*
 * Load image data from `buf` by sniffing
 * the bytes to determine format.
 */

cairo_status_t
Image::loadFromBuffer(uint8_t *buf, unsigned len) {
  if (isPNG(buf)) return loadPNGFromBuffer(buf);
#ifdef HAVE_GIF
  if (isGIF(buf)) return loadGIFFromBuffer(buf, len);
#endif
#ifdef HAVE_JPEG
  if (isJPEG(buf)) return loadJPEGFromBuffer(buf, len);
#endif
  return CAIRO_STATUS_READ_ERROR;
}

/*
 * Load PNG data from `buf`.
 */

cairo_status_t
Image::loadPNGFromBuffer(uint8_t *buf) {
  read_closure_t closure;
  closure.len = 0;
  closure.buf = buf;
  _surface = cairo_image_surface_create_from_png_stream(readPNG, &closure);
  cairo_status_t status = cairo_surface_status(_surface);
  if (status) return status;
  return CAIRO_STATUS_SUCCESS;
}

/*
 * Read PNG data.
 */

cairo_status_t
Image::readPNG(void *c, uint8_t *data, unsigned int len) {
  read_closure_t *closure = (read_closure_t *) c;
  memcpy(data, closure->buf + closure->len, len);
  closure->len += len;
  return CAIRO_STATUS_SUCCESS;
}

/*
 * Get onload callback.
 */

Handle<Value>
Image::GetOnload(Local<String>, const AccessorInfo &info) {
  Image *img = ObjectWrap::Unwrap<Image>(info.This());
  return img->onload;
}

/*
 * Set onload callback.
 */

void
Image::SetOnload(Local<String>, Local<Value> val, const AccessorInfo &info) {
  if (val->IsFunction()) {
    Image *img = ObjectWrap::Unwrap<Image>(info.This());
    img->onload = Persistent<Function>::New(Handle<Function>::Cast(val));
  }
}

/*
 * Get onerror callback.
 */

Handle<Value>
Image::GetOnerror(Local<String>, const AccessorInfo &info) {
  Image *img = ObjectWrap::Unwrap<Image>(info.This());
  return img->onerror;
}

/*
 * Set onerror callback.
 */

void
Image::SetOnerror(Local<String>, Local<Value> val, const AccessorInfo &info) {
  if (val->IsFunction()) {
    Image *img = ObjectWrap::Unwrap<Image>(info.This());
    img->onerror = Persistent<Function>::New(Handle<Function>::Cast(val));
  }
}

/*
 * Initialize a new Image.
 */

Image::Image() {
  filename = NULL;
  _surface = NULL;
  width = height = 0;
  state = DEFAULT;
}

/*
 * Destroy image and associated surface.
 */

Image::~Image() {
  if (_surface) {
    V8::AdjustAmountOfExternalAllocatedMemory(-4 * width * height);
    cairo_surface_destroy(_surface);
  }
  if (filename) free(filename);
}

/*
 * Initiate image loading.
 */

cairo_status_t
Image::load() {
  if (LOADING != state) {
    state = LOADING;
    return loadSurface();
  }
  return CAIRO_STATUS_READ_ERROR;
}

/*
 * Invoke onload (when assigned) and assign dimensions.
 */

void
Image::loaded() {
  HandleScope scope;
  state = COMPLETE;

  width = cairo_image_surface_get_width(_surface);
  height = cairo_image_surface_get_height(_surface);
  // TODO: adjust accordingly when re-assigned src
  V8::AdjustAmountOfExternalAllocatedMemory(4 * width * height);

  if (!onload.IsEmpty()) {
    TryCatch try_catch;
    onload->Call(Context::GetCurrent()->Global(), 0, NULL);
    onload.Dispose();
    if (try_catch.HasCaught()) {
      error(try_catch.Exception());
    }
  }
}

/*
 * Invoke onerror (when assigned) with the given err.
 */

void
Image::error(Local<Value> err) {
  HandleScope scope;
  if (!onerror.IsEmpty()) {
    Local<Value> argv[1] = { err };
    TryCatch try_catch;
    onerror->Call(Context::GetCurrent()->Global(), 1, argv);
    onerror.Dispose();
    if (try_catch.HasCaught()) {
      FatalException(try_catch);
    }
  }
}

/*
 * Load cairo surface from the image src.
 * 
 * TODO: better format detection
 * TODO: support more formats
 * TODO: use node IO or at least thread pool
 */

cairo_status_t
Image::loadSurface() {
  switch (extension(filename)) {
    case Image::PNG:
      return loadPNG();
#ifdef HAVE_GIF
    case Image::GIF:
      return loadGIF();
#endif
#ifdef HAVE_JPEG
    case Image::JPEG:
      return loadJPEG();
#endif
    default:
      return CAIRO_STATUS_READ_ERROR;
  }
}

/*
 * Load PNG.
 */

cairo_status_t
Image::loadPNG() {
  _surface = cairo_image_surface_create_from_png(filename);
  return cairo_surface_status(_surface);
}

// GIF support

#ifdef HAVE_GIF

/*
 * Return the alpha color for `gif` at `frame`, or -1.
 */

int
get_gif_transparent_color(GifFileType *gif, int frame) {
  ExtensionBlock *ext = gif->SavedImages[frame].ExtensionBlocks;
  int len = gif->SavedImages[frame].ExtensionBlockCount;
  for (int x = 0; x < len; ++x, ++ext) {
    if ((ext->Function == GRAPHICS_EXT_FUNC_CODE) && (ext->Bytes[0] & 1)) {
      return ext->Bytes[3] == 0 ? 0 : (uint8_t) ext->Bytes[3]; 
    }
  }
  return -1;
}

/*
 * Memory GIF reader callback.
 */

int
read_gif_from_memory(GifFileType *gif, GifByteType *buf, int len) {
  gif_data_t *data = (gif_data_t *) gif->UserData;
  if ((data->pos + len) > data->len) len = data->len - data->pos;
  memcpy(buf, data->pos + data->buf, len);
  data->pos += len;
  return len;
}

/*
 * Load GIF.
 */

cairo_status_t
Image::loadGIF() {
  FILE *stream = fopen(filename, "r");
  if (!stream) return CAIRO_STATUS_READ_ERROR;

  fseek(stream, 0L, SEEK_END);
  int len = ftell(stream);
  fseek(stream, 0L, SEEK_SET);

  uint8_t *buf = (uint8_t *) malloc(len);

  if (!buf) {
    fclose(stream);
    return CAIRO_STATUS_NO_MEMORY;
  }

  size_t read = fread(buf, len, 1, stream);
  fclose(stream);

  cairo_status_t result = CAIRO_STATUS_READ_ERROR;
  if (1 == read) result = loadGIFFromBuffer(buf, len);
  free(buf);

  return result;
}

/*
 * Load give from `buf` and the given `len`.
 */

cairo_status_t
Image::loadGIFFromBuffer(uint8_t *buf, unsigned len) {
  int i = 0;
  GifFileType* gif;

  gif_data_t gifd = { buf, len, 0 };

  if ((gif = DGifOpen((void*) &gifd, read_gif_from_memory)) == NULL)
    return CAIRO_STATUS_READ_ERROR; 

  if (GIF_OK != DGifSlurp(gif)) {
    DGifCloseFile(gif);
    return CAIRO_STATUS_READ_ERROR;
  }

  width = gif->SWidth;
  height = gif->SHeight;

  uint8_t *data = (uint8_t *) malloc(width * height * 4);
  if (!data) {
    DGifCloseFile(gif);
    return CAIRO_STATUS_NO_MEMORY;
  }

  GifImageDesc *img = &gif->SavedImages[i].ImageDesc;

  // local colormap takes precedence over global
  ColorMapObject *colormap = img->ColorMap
    ? img->ColorMap
    : gif->SColorMap;

  int bgColor = 0;
  int alphaColor = get_gif_transparent_color(gif, i);
  if (gif->SColorMap) bgColor = (uint8_t) gif->SBackGroundColor;
  else if(alphaColor >= 0) bgColor = alphaColor;

  uint8_t *src_data = (uint8_t*) gif->SavedImages[i].RasterBits;
  uint32_t *dst_data = (uint32_t*) data;

  if (!gif->Image.Interlace) {
    if (width == img->Width && height == img->Height) {
      for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
          *dst_data = ((*src_data == alphaColor) ? 0 : 255) << 24
            | colormap->Colors[*src_data].Red << 16
            | colormap->Colors[*src_data].Green << 8
            | colormap->Colors[*src_data].Blue;

          dst_data++;
          src_data++;
        }
      }
    } else {
      // Image does not take up whole "screen" so we need to fill-in the background
      int bottom = img->Top + img->Height;
      int right = img->Left + img->Width;

      for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
          if ((y < img->Top) || (y >= bottom) || (x < img->Left) || (x >= right)) {
            *dst_data = ((bgColor == alphaColor) ? 0 : 255) << 24
              | colormap->Colors[bgColor].Red << 16
              | colormap->Colors[bgColor].Green << 8
              | colormap->Colors[bgColor].Blue;
          } else {
            *dst_data = ((*src_data == alphaColor) ? 0 : 255) << 24
              | colormap->Colors[*src_data].Red << 16
              | colormap->Colors[*src_data].Green << 8
              | colormap->Colors[*src_data].Blue;
          }

          dst_data++;
          src_data++;
        }
      } 
    }
  } else { 
    // Image is interlaced so that it streams nice over 14.4k and 28.8k modems :)
    // We first load in 1/8 of the image, followed by another 1/8, followed by
    // 1/4 and finally the remaining 1/2.
    int ioffs[] = { 0, 4, 2, 1 };
    int ijumps[] = { 8, 8, 4, 2 };

    uint8_t *src_ptr = src_data;
    uint32_t *dst_ptr;

    for(int z = 0; z < 4; z++) {
      for(int y = ioffs[z]; y < height; y += ijumps[z]) {
        dst_ptr = dst_data + width * y;
        for(int x = 0; x < width; ++x) {
          *dst_ptr = ((*src_ptr == alphaColor) ? 0 : 255) << 24
            | (colormap->Colors[*src_ptr].Red) << 16
            | (colormap->Colors[*src_ptr].Green) << 8
            | (colormap->Colors[*src_ptr].Blue);

          dst_ptr++;
          src_ptr++;
        }
      }
    }
  }

  DGifCloseFile(gif);

  // New image surface
  _surface = cairo_image_surface_create_for_data(
      data
    , CAIRO_FORMAT_ARGB32
    , width
    , height
    , cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, width));

  cairo_status_t status = cairo_surface_status(_surface);

  if (status) {
    free(data);
    return status;
  }

  return CAIRO_STATUS_SUCCESS;
}
#endif /* HAVE_GIF */

// JPEG support

#ifdef HAVE_JPEG

/*
 * Load jpeg from buffer.
 */

cairo_status_t
Image::loadJPEGFromBuffer(uint8_t *buf, unsigned len) {
  // TODO: remove this duplicate logic
  // JPEG setup
  struct jpeg_decompress_struct info;
  struct jpeg_error_mgr err;
  info.err = jpeg_std_error(&err);
  jpeg_create_decompress(&info);
  jpeg_mem_src(&info, buf, len);
  jpeg_read_header(&info, 1);
  jpeg_start_decompress(&info);
  width = info.output_width;
  height = info.output_height;

  // Data alloc
  int stride = width * 4;
  uint8_t *data = (uint8_t *) malloc(width * height * 4);
  if (!data) return CAIRO_STATUS_NO_MEMORY;
  
  uint8_t *src = (uint8_t *) malloc(width * 3);
  if (!src) {
    free(data);
    return CAIRO_STATUS_NO_MEMORY;
  }

  // Copy RGB -> ARGB
  for (int y = 0; y < height; ++y) {
    jpeg_read_scanlines(&info, &src, 1);
    uint32_t *row = (uint32_t *)(data + stride * y);
    for (int x = 0; x < width; ++x) {
      int bx = 3 * x;
      uint32_t *pixel = row + x;
      *pixel = 255 << 24
        | src[bx + 0] << 16
        | src[bx + 1] << 8
        | src[bx + 2];
    }
  }

  // New image surface
  _surface = cairo_image_surface_create_for_data(
      data
    , CAIRO_FORMAT_ARGB32
    , width
    , height
    , cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, width));

  // Cleanup
  free(src);
  jpeg_finish_decompress(&info);
  jpeg_destroy_decompress(&info);
  cairo_status_t status = cairo_surface_status(_surface);

  if (status) {
    free(data);
    return status;
  }

  return CAIRO_STATUS_SUCCESS;
}

/*
 * Load JPEG, convert RGB to ARGB.
 */

cairo_status_t
Image::loadJPEG() {
  FILE *stream = fopen(filename, "r");
  if (!stream) return CAIRO_STATUS_READ_ERROR;

  // JPEG setup
  struct jpeg_decompress_struct info;
  struct jpeg_error_mgr err;
  info.err = jpeg_std_error(&err);
  jpeg_create_decompress(&info);
  jpeg_stdio_src(&info, stream);
  jpeg_read_header(&info, 1);
  jpeg_start_decompress(&info);
  width = info.output_width;
  height = info.output_height;

  // Data alloc
  int stride = width * 4;
  uint8_t *data = (uint8_t *) malloc(width * height * 4);
  if (!data) return CAIRO_STATUS_NO_MEMORY;
  
  uint8_t *src = (uint8_t *) malloc(width * 3);
  if (!src) {
    free(data);
    return CAIRO_STATUS_NO_MEMORY;
  }

  // Copy RGB -> ARGB
  for (int y = 0; y < height; ++y) {
    jpeg_read_scanlines(&info, &src, 1);
    uint32_t *row = (uint32_t *)(data + stride * y);
    for (int x = 0; x < width; ++x) {
      int bx = 3 * x;
      uint32_t *pixel = row + x;
      *pixel = 255 << 24
        | src[bx + 0] << 16
        | src[bx + 1] << 8
        | src[bx + 2];
    }
  }

  // New image surface
  _surface = cairo_image_surface_create_for_data(
      data
    , CAIRO_FORMAT_ARGB32
    , width
    , height
    , cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, width));

  // Cleanup
  free(src);
  fclose(stream);
  jpeg_finish_decompress(&info);
  jpeg_destroy_decompress(&info);
  cairo_status_t status = cairo_surface_status(_surface);

  if (status) {
    free(data);
    return status;
  }

  return CAIRO_STATUS_SUCCESS;
}

#endif /* HAVE_JPEG */

/*
 * Return UNKNOWN, JPEG, or PNG based on the filename.
 */

Image::type
Image::extension(const char *filename) {
  size_t len = strlen(filename);
  filename += len;
  if (len >= 5 && 0 == strcmp(".jpeg", filename - 5)) return Image::JPEG;
  if (len >= 4 && 0 == strcmp(".gif", filename - 4)) return Image::GIF;
  if (len >= 4 && 0 == strcmp(".jpg", filename - 4)) return Image::JPEG;
  if (len >= 4 && 0 == strcmp(".png", filename - 4)) return Image::PNG;
  return Image::UNKNOWN;
}

/*
 * Sniff bytes for JPEG's magic number ff d8.
 */

int
Image::isJPEG(uint8_t *data) {
  return 0xff == data[0] && 0xd8 == data[1];
}

/*
 * Sniff bytes 0..2 for "GIF".
 */

int
Image::isGIF(uint8_t *data) {
  return 'G' == data[0] && 'I' == data[1] && 'F' == data[2];
}

/*
 * Sniff bytes 1..3 for "PNG".
 */

int
Image::isPNG(uint8_t *data) {
  return 'P' == data[1] && 'N' == data[2] && 'G' == data[3];
}