Class: PDFium::Image

Inherits:
Object
  • Object
show all
Defined in:
ext/pdfium_ext/image.cc,
ext/pdfium_ext/image.cc

Overview

A Image can represent either a Page that has been rendered to a Image via Page#as_image

Or an embedded image on a Page, obtained via Page#images

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#bounds ⇒ Object (readonly)

Returns the bouding box of the image as a BoundingBox

#height ⇒ Object

Height of the image in pixels (Fixnum)

#index ⇒ Object (readonly)

Returns the index of the image on the page. Note: The index method is only provided as a convience method. It has no relation to the position of images on the page. Do not depend on the top-left image being index 0, even if it often is.

#width ⇒ Object

Width of the image in pixels (Fixnum)

Instance Method Details

#as_science ⇒ ImageScience instance

Converts to an ImageScience bitmap and returns it. The ImageScience (github.com/seattlerb/image_science) library must be installed and required before calling this method or a NameError: uninitialized constant ImageScience exception will be raised.

Example

pdf = PDFium::Document.new( "test.pdf" )
page = pdf.pages.first
page.images.each do | image |
    image.as_science.cropped_thumbnail 100 do |thumb|
        thumb.save "image-#{image.index}-cropped.png"
    end
end

Returns:

  • (ImageScience instance) 


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# File 'ext/pdfium_ext/image.cc', line 207

VALUE
image_as_science(VALUE self){
    VALUE RBImageScience = rb_const_get(rb_cObject, rb_intern("ImageScience"));
    FIBITMAP *image = render_to_bitmap(self, FIF_BMP);

    VALUE instance = Data_Wrap_Struct(RBImageScience, NULL, NULL, image);
    rb_iv_set(instance, "@file_type", INT2FIX(FIF_BMP));
    return instance;
}

#data(: format) ⇒ Object

Used in conjuction with Document.from_memory this can render be used to render a PDF’s pages completely in memory.

Example rendering a PDF to AWS without hitting disk

# Assuming AWS::S3 is already authorized elsewhere
bucket = AWS::S3.new.buckets['my-pdfs']
pdf = PDFium::Document.from_memory bucket.objects['secrets.pdf'].read
pdf.pages.each do | page |
  path = "secrets/page-#{page.number}.jpg"
  bucket.objects[path].write page.as_image(height: 1000).data(:jpg)
  page.images.each do | image |
    path = "secrets/page-#{page.number}-image-#{image.index}.png"
    bucket.objects[path].write image.data(:png)
  end
end

Parameters:

  • format (symbol) —

    any file extension recogized by FreeImage.

Returns:

  • String containing binary data for the image in the specified format.



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# File 'ext/pdfium_ext/image.cc', line 271

static VALUE
image_data(VALUE self, VALUE rb_format)
{
    VALUE path = RB::to_s(rb_format);
    const char* type = StringValuePtr(path);

    FREE_IMAGE_FORMAT format = FreeImage_GetFIFFromFilename(type);
    if((format == FIF_UNKNOWN) || !FreeImage_FIFSupportsWriting(format)) {
        rb_raise(rb_eArgError, "Unable to write to a image of that type");
    }

    FIBITMAP *image = render_to_bitmap(self, format);

    FIMEMORY *mem = FreeImage_OpenMemory(); //mem_buffer, buf.st_size);

    bool success = FreeImage_SaveToMemory(format, image, mem, 0);
    if (!success){
        FreeImage_Unload(image);
        rb_raise(rb_eArgError, "Unable to save image to memory buffer");
    }

    long size = FreeImage_TellMemory(mem);

    char *buffer = ALLOC_N(char, size);

    FreeImage_SeekMemory(mem, 0L, SEEK_SET);

    FreeImage_ReadMemory(buffer, size, 1, mem);

    FreeImage_Unload(image);

    FreeImage_CloseMemory(mem);
    VALUE ret = rb_str_new(buffer, size);

    xfree(buffer);
    return ret;
}

#save(file) ⇒ Boolean

Save image to a file

Parameters:

  • file (String, Pathname) —

    path to file to save image to

Returns:

  • (Boolean) —

    indicating success or failure



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# File 'ext/pdfium_ext/image.cc', line 227

VALUE
image_save(VALUE self, VALUE rb_file){
    // figure out the desired format from the file extension
    const char* file = StringValuePtr(rb_file);

    FREE_IMAGE_FORMAT format = FreeImage_GetFIFFromFilename(file);
    if((format == FIF_UNKNOWN) || !FreeImage_FIFSupportsWriting(format)) {
        rb_raise(rb_eArgError, "Unable to write to a image of that type");
    }

    FIBITMAP *image = render_to_bitmap(self, format);

    bool success = FreeImage_Save(format, image, file, 0);

    // unload the image
    FreeImage_Unload(image);

    return success ? Qtrue : Qfalse;
}