Class: JPEG::Encoder

Inherits:
Object
  • Object
show all
Defined in:
ext/jpeg/jpeg.c

Instance Method Summary collapse

Constructor Details

#initialize(width, height, opts) ⇒ Object

initialize encoder object

Parameters:

  • width (Integer) —

    width of input image (px)

  • height (Integer) —

    height of input image (px)

  • opts (Hash) —

    options to initialize object

Options Hash (opts):

  • :pixel_format (Symbol) —

    specifies the format of the input image. possible values are: YUV422 YUYV RGB565 RGB RGB24 BGR BGR24 YUV444 YCbCr RGBX RGB32 BGRX BGR32 GRAYSCALE

  • :quality (Integer) —

    specifies the quality of the compressed image. You can specify from 0 (lowest) to 100 (best).

  • :dct_method (Symbol) —

    specifies how encoding is handled. possible values are: FASTEST ISLOW IFAST FLOAT



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# File 'ext/jpeg/jpeg.c', line 992

static VALUE
rb_encoder_initialize(int argc, VALUE *argv, VALUE self)
{
  jpeg_encode_t* ptr;
  VALUE exc;
  VALUE wd;
  VALUE ht;
  VALUE opt;

  /*
   * initialize
   */
  exc = Qnil;

  TypedData_Get_Struct(self, jpeg_encode_t, &jpeg_encoder_data_type, ptr);

  /*
   * parse arguments
   */
  rb_scan_args(argc, argv, "2:", &wd, &ht, &opt);

  /*
   * argument check
   */
  do {
    if (TYPE(wd) != T_FIXNUM) {
      exc = create_argument_error("invalid width");
      break;
    }

    if (TYPE(ht) != T_FIXNUM) {
      exc = create_argument_error("invalid height");
      break;
    }
  } while (0);

  /*
   * set context
   */ 
  if (!RTEST(exc)) {
    exc = set_encoder_context(ptr, FIX2INT(wd), FIX2INT(ht), opt);
  }

  /*
   * post process
   */
  if (RTEST(exc)) rb_exc_raise(exc);

  return Qtrue;
}

Instance Method Details

#encode(raw) ⇒ String Also known as: compress, <<

encode data

Returns encoded JPEG data.

Parameters:

  • raw (String) —

    raw image data to encode.

Returns:

  • (String) —

    encoded JPEG data.



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# File 'ext/jpeg/jpeg.c', line 1265

static VALUE
rb_encoder_encode(VALUE self, VALUE data)
{
  VALUE ret;
  int state;
  jpeg_encode_t* ptr;

  /*
   * initialize
   */
  ret   = Qnil;
  state = 0;

  TypedData_Get_Struct(self, jpeg_encode_t, &jpeg_encoder_data_type, ptr);

  /*
   * argument check
   */
  Check_Type(data, T_STRING);

  if (RSTRING_LEN(data) < ptr->data_size) {
    ARGUMENT_ERROR("image data is too short");
  }

  if (RSTRING_LEN(data) > ptr->data_size) {
    ARGUMENT_ERROR("image data is too large");
  }

  /*
   * alloc memory
   */
  jpeg_mem_dest(&ptr->cinfo, &ptr->buf.mem, &ptr->buf.size); 
  if (ptr->buf.mem == NULL) {
    RUNTIME_ERROR("jpeg_mem_dest() failed");
  }

  /*
   * prepare
   */
  SET_DATA(ptr, data);

  /*
   * do encode
   */
  ret = rb_protect(do_encode, (VALUE)ptr, &state);

  /*
   * post process
   */
  CLR_DATA(ptr);

  if (ptr->buf.mem != NULL) {
    free(ptr->buf.mem);

    ptr->buf.mem  = NULL;
    ptr->buf.size = 0;
  }

  if (state != 0) rb_jump_tag(state);

  return ret;
}