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Joe Van Dyk

2005-Aug-03 07:22 UTC

RMagick problem

The following Rails/Ruby code gives me this error: "Zero-length blob
not permitted".

@magick_image = Magick::Image.from_blob(@file.read).first

Where @file is a StringIO object or a File object, depending on the
size of the uploaded file.

@file.read.size returns the expected file size (in bytes).

Any ideas?

Thanks,
Joe

Sebastian Kanthak

2005-Aug-03 08:43 UTC

head link

Re: RMagick problem

Joe Van Dyk wrote:
>The following Rails/Ruby code gives me this error: "Zero-length blob
>not permitted".
>
>@magick_image = Magick::Image.from_blob(@file.read).first
>
>Where @file is a StringIO object or a File object, depending on the
>size of the uploaded file.
>  
>I can''t really explain your behaviour, but that''s how I read
in uploaded
images and it works for me...

           if file.is_a?(StringIO)
                img = Magick::Image::from_blob(file.string).first
            else
                img = Magick::Image::read(file.local_path).first
            end

Cheers
Sebastian

Joe Van Dyk

2005-Aug-03 14:51 UTC

head link

Re: RMagick problem

On 8/3/05, Sebastian Kanthak
<sebastian.kanthak-ZS8b95Whz3sUSW6y5lq3GQ@public.gmane.org>
wrote:> Joe Van Dyk wrote:
> 
> >The following Rails/Ruby code gives me this error: "Zero-length
blob
> >not permitted".
> >
> >@magick_image = Magick::Image.from_blob(@file.read).first
> >
> >Where @file is a StringIO object or a File object, depending on the
> >size of the uploaded file.
> >
> >
> I can''t really explain your behaviour, but that''s how I
read in uploaded
> images and it works for me...
> 
>            if file.is_a?(StringIO)
>                 img = Magick::Image::from_blob(file.string).first
>             else
>                 img = Magick::Image::read(file.local_path).first
>             end
Yeah, I''m not sure why it''s failing either.

Also, File objects support #read, so why do you have that distinction in there?

Sebastian Kanthak

2005-Aug-03 16:22 UTC

head link

Re: RMagick problem

Joe Van Dyk wrote:
>On 8/3/05, Sebastian Kanthak
<sebastian.kanthak-ZS8b95Whz3sUSW6y5lq3GQ@public.gmane.org> wrote:
>  
>
>>           if file.is_a?(StringIO)
>>                img = Magick::Image::from_blob(file.string).first
>>            else
>>                img = Magick::Image::read(file.local_path).first
>>            end
>>    
>>
>
>Also, File objects support #read, so why do you have that distinction in
there?
>  
>mainly, because I''m not so sure if it is a good idea to read a
(possibly
pretty big) image into main memory. I''m not sure what RMagick does, but
it could be optimized to only read the header information and process 
the image in a "streaming" mode.

For a StringIO object it doesn''t really matter, as these are only 
created if the upload is reasonably small, so I can use from_blob 
safely, here.

Sebastian

Joe Van Dyk

2005-Aug-03 19:00 UTC

head link

Re: RMagick problem

On 8/3/05, Sebastian Kanthak
<sebastian.kanthak-ZS8b95Whz3sUSW6y5lq3GQ@public.gmane.org>
wrote:> Joe Van Dyk wrote:
> 
> >On 8/3/05, Sebastian Kanthak
<sebastian.kanthak-ZS8b95Whz3sUSW6y5lq3GQ@public.gmane.org> wrote:
> >
> >
> >>           if file.is_a?(StringIO)
> >>                img = Magick::Image::from_blob(file.string).first
> >>            else
> >>                img = Magick::Image::read(file.local_path).first
> >>            end
> >>
> >>
> >
> >Also, File objects support #read, so why do you have that distinction
in there?
> >
> >
> mainly, because I''m not so sure if it is a good idea to read a
(possibly
> pretty big) image into main memory. I''m not sure what RMagick
does, but
> it could be optimized to only read the header information and process
> the image in a "streaming" mode.
> 
> For a StringIO object it doesn''t really matter, as these are only
> created if the upload is reasonably small, so I can use from_blob
> safely, here.
Ah, good idea.

I still have no idea why it''s giving me "Zero-length blob
not permitted" for this line:
@magick_image = Magick::Image.from_blob(@file.read).first

What''s weird is that if I leave out the .first method call, I
don''t
get that error.  But if I print out the size of @file.read.size, and
then call the Image.from_blob line, then I get the Zero-length blob
error.

It''s driving me crazy.  :(

Joe Van Dyk

2005-Aug-04 02:30 UTC

head link

Fwd: RMagick problem

On 8/3/05, Joe Van Dyk <joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> On 8/3/05, Tim Hunter
<cyclists-P1JKnMZDrucAvxtiuMwx3w@public.gmane.org> wrote:
> > Joe Van Dyk wrote:
> >
> > > The following Rails/Ruby code gives me this error:
"Zero-length blob
> > > not permitted".
> > >
> > > @magick_image = Magick::Image.from_blob(@file.read).first
> > >
> > > Where @file is a StringIO object or a File object, depending on
the
> > > size of the uploaded file.
> > >
> > > @file.read.size returns the expected file size (in bytes).
> > >
> > > Any ideas?
> >
> > Well, it works for me. Here''s my attempt to reproduce the
problem.
> >
> > require ''RMagick''
> > require ''stringio''
> >
> > file = File.open(''Flower_Hat.jpg'')
> > img = Magick::Image.from_blob(file.read).first
> > p img
> >
> > blob = IO.read(''Flower_Hat.jpg'')
> > sio = StringIO.new(blob)
> > img = Magick::Image.from_blob(sio.read).first
> > p img
> >
> >
> > The output is:
> > tim: ~> ruby  test.rb
> >  JPEG 200x250 DirectClass 8-bit 9kb
> >  JPEG 200x250 DirectClass 8-bit 9kb
>
> Yeah, I tried to do that test last night and it worked fine.
>
> So I have no idea why the code is failing inside my Image model.
Here''s my image model.  Perhaps that will give someone some insight.

Say, I''m doing the Magick::Image.from_blob call in #after_save.
Perhaps something weird is happening with @file''s lifetime or
something?

class Image < ActiveRecord::Base
  belongs_to :house
  belongs_to :community
  belongs_to :contractor

  FileLocation = "#{RAILS_ROOT}/public/media/"
  DisplayLocation = "/media"

def file=(file)
    if file.size > 0
      self.content_type = file.content_type.strip
      @file = file
    end
  end

  # Runs after Image is saved, saves the image to the file system.
  def after_save
    if @file
      @magick_image = Magick::Image.from_blob(@file.read).first
      save_full_image
      save_thumbnail_image
      save_rounded_thumbnail_image
      save_medium_image
      save_large_image
    end
  end

  # If image is already a jpeg, then just write it to a file.
  # If it''s not, convert it to a jpeg and then write.
  def save_full_image
    @magick_image.write(full_file)
  end

  # Write a thumbnail to the filesystem
  def save_thumbnail_image
    thumbnailed_magick_image = resize_image_to_exact_size(180,135)
    thumbnailed_magick_image.write(thumbnail_file)
  end

  def save_rounded_thumbnail_image
    thumbnail_image = resize_image_to_exact_size(180, 135)
    color = "#000033"
    corner_width = 15
    corners = Magick::Draw.new
    corners.stroke(color)
    corners.fill_opacity(0)
    corners.stroke_width(15)
    corners.roundrectangle(0, 0,
                           thumbnail_image.columns, thumbnail_image.rows,
                           corner_width, corner_width)
    corners.draw(thumbnail_image)
    thumbnail_image.write(rounded_thumbnail_file)
  end

  # Resizes a Magick image to an exact size, keeping the same aspect ratio
  def resize_image_to_exact_size(width, height)
    new_aspect_ratio = width.to_f / height.to_f
    old_aspect_ratio = @magick_image.columns.to_f / @magick_image.rows.to_f

    if old_aspect_ratio < new_aspect_ratio
      # Image too tall, geometry string should restrict height
      geometry_string = "#{width}"
    else
      # Image too wide or just right, geometry string should
      # restrict width
      geometry_string = "x#{height}"
    end

    # Get the resized image
    resized_image = resize_image(geometry_string)

    # Return the resized, crop image
    resized_image.crop(Magick::CenterGravity, width, height)
  end

  def resize_image(geometry_string)
    logger.debug "resizing image to #{geometry_string}"
    @magick_image.change_geometry(geometry_string) do |w, h, img|
      img.resize(w, h)
    end
  end

  def save_medium_image
    medium_image = resize_image("275")
    medium_image.write(medium_file)
  end

  def save_large_image
    large_image = resize_image("500")
    large_image.write(large_file)
  end



  # Delete images from filesystem
  def after_destroy
    File.delete(full_file) if File.exist? "#{full_file}"
    File.delete(thumbnail_file) if File.exist? "#{thumbnail_file}"
    File.delete(rounded_thumbnail_file) if File.exist?
"#{rounded_thumbnail_file}"
    File.delete(medium_file) if File.exist? "#{medium_file}"
    File.delete(large_file) if File.exist? "#{large_file}"
  end

  # Returns the filesystem location of the image file
  def full_file
    "#{FileLocation}/full/#{id}.jpg"
  end
  def thumbnail_file
    "#{FileLocation}/thumbnail/#{id}.jpg"
  end
  def rounded_thumbnail_file
    "#{FileLocation}/rounded_thumbnail/#{id}.jpg"
  end
  def medium_file
    "#{FileLocation}/medium/#{id}.jpg"
  end
  def large_file
    "#{FileLocation}/large/#{id}.jpg"
  end


  # Returns the location of the image to the browser
  def full
    "#{DisplayLocation}/full/#{id}.jpg"
  end
  def thumbnail
    "#{DisplayLocation}/thumbnail/#{id}.jpg"
  end
  def medium
    "#{DisplayLocation}/medium/#{id}.jpg"
  end
  def large
    "#{DisplayLocation}/large/#{id}.jpg"
  end
  def rounded_thumbnail
    "#{DisplayLocation}/rounded_thumbnail/#{id}.jpg"
  end def resize
    if File.exist? full_file
      @file = File.open full_file
      save
    end
  end
end

Joe Van Dyk

2005-Aug-04 04:43 UTC

head link

Re: RMagick problem

On 8/3/05, Joe Van Dyk <joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> On 8/3/05, Joe Van Dyk
<joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > On 8/3/05, Tim Hunter
<cyclists-P1JKnMZDrucAvxtiuMwx3w@public.gmane.org> wrote:
> > > Joe Van Dyk wrote:
> > >
> > > > The following Rails/Ruby code gives me this error:
"Zero-length blob
> > > > not permitted".
> > > >
> > > > @magick_image = Magick::Image.from_blob(@file.read).first
> > > >
> > > > Where @file is a StringIO object or a File object, depending
on the
> > > > size of the uploaded file.
> > > >
> > > > @file.read.size returns the expected file size (in bytes).
> > > >
> > > > Any ideas?
> > >
> > > Well, it works for me. Here''s my attempt to reproduce
the problem.
> > >
> > > require ''RMagick''
> > > require ''stringio''
> > >
> > > file = File.open(''Flower_Hat.jpg'')
> > > img = Magick::Image.from_blob(file.read).first
> > > p img
> > >
> > > blob = IO.read(''Flower_Hat.jpg'')
> > > sio = StringIO.new(blob)
> > > img = Magick::Image.from_blob(sio.read).first
> > > p img
> > >
> > >
> > > The output is:
> > > tim: ~> ruby  test.rb
> > >  JPEG 200x250 DirectClass 8-bit 9kb
> > >  JPEG 200x250 DirectClass 8-bit 9kb
> >
> > Yeah, I tried to do that test last night and it worked fine.
> >
> > So I have no idea why the code is failing inside my Image model.
> 
> Here''s my image model.  Perhaps that will give someone some
insight.
> 
> Say, I''m doing the Magick::Image.from_blob call in #after_save.
> Perhaps something weird is happening with @file''s lifetime or
> something?
> 
> class Image < ActiveRecord::Base
>   belongs_to :house
>   belongs_to :community
>   belongs_to :contractor
> 
>   FileLocation = "#{RAILS_ROOT}/public/media/"
>   DisplayLocation = "/media"
> 
> def file=(file)
>     if file.size > 0
>       self.content_type = file.content_type.strip
>       @file = file
>     end
>   end
> 
>   # Runs after Image is saved, saves the image to the file system.
>   def after_save
>     if @file
>       @magick_image = Magick::Image.from_blob(@file.read).first
>       save_full_image
>       save_thumbnail_image
>       save_rounded_thumbnail_image
>       save_medium_image
>       save_large_image
>     end
>   end
> 
>   # If image is already a jpeg, then just write it to a file.
>   # If it''s not, convert it to a jpeg and then write.
>   def save_full_image
>     @magick_image.write(full_file)
>   end
> 
>   # Write a thumbnail to the filesystem
>   def save_thumbnail_image
>     thumbnailed_magick_image = resize_image_to_exact_size(180,135)
>     thumbnailed_magick_image.write(thumbnail_file)
>   end
> 
>   def save_rounded_thumbnail_image
>     thumbnail_image = resize_image_to_exact_size(180, 135)
>     color = "#000033"
>     corner_width = 15
>     corners = Magick::Draw.new
>     corners.stroke(color)
>     corners.fill_opacity(0)
>     corners.stroke_width(15)
>     corners.roundrectangle(0, 0,
>                            thumbnail_image.columns, thumbnail_image.rows,
>                            corner_width, corner_width)
>     corners.draw(thumbnail_image)
>     thumbnail_image.write(rounded_thumbnail_file)
>   end
> 
>   # Resizes a Magick image to an exact size, keeping the same aspect ratio
>   def resize_image_to_exact_size(width, height)
>     new_aspect_ratio = width.to_f / height.to_f
>     old_aspect_ratio = @magick_image.columns.to_f / @magick_image.rows.to_f
> 
>     if old_aspect_ratio < new_aspect_ratio
>       # Image too tall, geometry string should restrict height
>       geometry_string = "#{width}"
>     else
>       # Image too wide or just right, geometry string should
>       # restrict width
>       geometry_string = "x#{height}"
>     end
> 
>     # Get the resized image
>     resized_image = resize_image(geometry_string)
> 
>     # Return the resized, crop image
>     resized_image.crop(Magick::CenterGravity, width, height)
>   end
> 
>   def resize_image(geometry_string)
>     logger.debug "resizing image to #{geometry_string}"
>     @magick_image.change_geometry(geometry_string) do |w, h, img|
>       img.resize(w, h)
>     end
>   end
> 
>   def save_medium_image
>     medium_image = resize_image("275")
>     medium_image.write(medium_file)
>   end
> 
>   def save_large_image
>     large_image = resize_image("500")
>     large_image.write(large_file)
>   end
> 
> 
> 
>   # Delete images from filesystem
>   def after_destroy
>     File.delete(full_file) if File.exist? "#{full_file}"
>     File.delete(thumbnail_file) if File.exist?
"#{thumbnail_file}"
>     File.delete(rounded_thumbnail_file) if File.exist?
> "#{rounded_thumbnail_file}"
>     File.delete(medium_file) if File.exist? "#{medium_file}"
>     File.delete(large_file) if File.exist? "#{large_file}"
>   end
> 
>   # Returns the filesystem location of the image file
>   def full_file
>     "#{FileLocation}/full/#{id}.jpg"
>   end
>   def thumbnail_file
>     "#{FileLocation}/thumbnail/#{id}.jpg"
>   end
>   def rounded_thumbnail_file
>     "#{FileLocation}/rounded_thumbnail/#{id}.jpg"
>   end
>   def medium_file
>     "#{FileLocation}/medium/#{id}.jpg"
>   end
>   def large_file
>     "#{FileLocation}/large/#{id}.jpg"
>   end
> 
> 
>   # Returns the location of the image to the browser
>   def full
>     "#{DisplayLocation}/full/#{id}.jpg"
>   end
>   def thumbnail
>     "#{DisplayLocation}/thumbnail/#{id}.jpg"
>   end
>   def medium
>     "#{DisplayLocation}/medium/#{id}.jpg"
>   end
>   def large
>     "#{DisplayLocation}/large/#{id}.jpg"
>   end
>   def rounded_thumbnail
>     "#{DisplayLocation}/rounded_thumbnail/#{id}.jpg"
>   end def resize
>     if File.exist? full_file
>       @file = File.open full_file
>       save
>     end
>   end
> end
> 

I''ll be damned.  Moving 
@magick_image = Magick::Image.from_blob(@file.read).first
from Image#after_save to Image#file= fixed the problem.

So, apparently, something weird happens to @file before
Image#after_save is called.  Any ideas?

Simen Brekken

2005-Aug-04 08:01 UTC

head link

Re: RMagick problem

I''ve had this problem too, changing my setter to image_file= solved all
my problems, I suspect AR/CGI/something is using @file during the 
after_save phase.

SIMEN BREKKEN / born to synthesize.

Joe Van Dyk wrote:> On 8/3/05, Joe Van Dyk
<joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> 
>>On 8/3/05, Joe Van Dyk
<joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>
>>>On 8/3/05, Tim Hunter
<cyclists-P1JKnMZDrucAvxtiuMwx3w@public.gmane.org> wrote:
>>>
>>>>Joe Van Dyk wrote:
>>>>
>>>>
>>>>>The following Rails/Ruby code gives me this error:
"Zero-length blob
>>>>>not permitted".
>>>>>
>>>>>@magick_image = Magick::Image.from_blob(@file.read).first
>>>>>
>>>>>Where @file is a StringIO object or a File object, depending
on the
>>>>>size of the uploaded file.
>>>>>
>>>>>@file.read.size returns the expected file size (in bytes).
>>>>>
>>>>>Any ideas?
>>>>
>>>>Well, it works for me. Here''s my attempt to reproduce
the problem.
>>>>
>>>>require ''RMagick''
>>>>require ''stringio''
>>>>
>>>>file = File.open(''Flower_Hat.jpg'')
>>>>img = Magick::Image.from_blob(file.read).first
>>>>p img
>>>>
>>>>blob = IO.read(''Flower_Hat.jpg'')
>>>>sio = StringIO.new(blob)
>>>>img = Magick::Image.from_blob(sio.read).first
>>>>p img
>>>>
>>>>
>>>>The output is:
>>>>tim: ~> ruby  test.rb
>>>> JPEG 200x250 DirectClass 8-bit 9kb
>>>> JPEG 200x250 DirectClass 8-bit 9kb
>>>
>>>Yeah, I tried to do that test last night and it worked fine.
>>>
>>>So I have no idea why the code is failing inside my Image model.
>>
>>Here''s my image model.  Perhaps that will give someone some
insight.
>>
>>Say, I''m doing the Magick::Image.from_blob call in #after_save.
>>Perhaps something weird is happening with @file''s lifetime or
>>something?
>>
>>class Image < ActiveRecord::Base
>>  belongs_to :house
>>  belongs_to :community
>>  belongs_to :contractor
>>
>>  FileLocation = "#{RAILS_ROOT}/public/media/"
>>  DisplayLocation = "/media"
>>
>>def file=(file)
>>    if file.size > 0
>>      self.content_type = file.content_type.strip
>>      @file = file
>>    end
>>  end
>>
>>  # Runs after Image is saved, saves the image to the file system.
>>  def after_save
>>    if @file
>>      @magick_image = Magick::Image.from_blob(@file.read).first
>>      save_full_image
>>      save_thumbnail_image
>>      save_rounded_thumbnail_image
>>      save_medium_image
>>      save_large_image
>>    end
>>  end
>>
>>  # If image is already a jpeg, then just write it to a file.
>>  # If it''s not, convert it to a jpeg and then write.
>>  def save_full_image
>>    @magick_image.write(full_file)
>>  end
>>
>>  # Write a thumbnail to the filesystem
>>  def save_thumbnail_image
>>    thumbnailed_magick_image = resize_image_to_exact_size(180,135)
>>    thumbnailed_magick_image.write(thumbnail_file)
>>  end
>>
>>  def save_rounded_thumbnail_image
>>    thumbnail_image = resize_image_to_exact_size(180, 135)
>>    color = "#000033"
>>    corner_width = 15
>>    corners = Magick::Draw.new
>>    corners.stroke(color)
>>    corners.fill_opacity(0)
>>    corners.stroke_width(15)
>>    corners.roundrectangle(0, 0,
>>                           thumbnail_image.columns,
thumbnail_image.rows,
>>                           corner_width, corner_width)
>>    corners.draw(thumbnail_image)
>>    thumbnail_image.write(rounded_thumbnail_file)
>>  end
>>
>>  # Resizes a Magick image to an exact size, keeping the same aspect
ratio
>>  def resize_image_to_exact_size(width, height)
>>    new_aspect_ratio = width.to_f / height.to_f
>>    old_aspect_ratio = @magick_image.columns.to_f /
@magick_image.rows.to_f
>>
>>    if old_aspect_ratio < new_aspect_ratio
>>      # Image too tall, geometry string should restrict height
>>      geometry_string = "#{width}"
>>    else
>>      # Image too wide or just right, geometry string should
>>      # restrict width
>>      geometry_string = "x#{height}"
>>    end
>>
>>    # Get the resized image
>>    resized_image = resize_image(geometry_string)
>>
>>    # Return the resized, crop image
>>    resized_image.crop(Magick::CenterGravity, width, height)
>>  end
>>
>>  def resize_image(geometry_string)
>>    logger.debug "resizing image to #{geometry_string}"
>>    @magick_image.change_geometry(geometry_string) do |w, h, img|
>>      img.resize(w, h)
>>    end
>>  end
>>
>>  def save_medium_image
>>    medium_image = resize_image("275")
>>    medium_image.write(medium_file)
>>  end
>>
>>  def save_large_image
>>    large_image = resize_image("500")
>>    large_image.write(large_file)
>>  end
>>
>>
>>
>>  # Delete images from filesystem
>>  def after_destroy
>>    File.delete(full_file) if File.exist? "#{full_file}"
>>    File.delete(thumbnail_file) if File.exist?
"#{thumbnail_file}"
>>    File.delete(rounded_thumbnail_file) if File.exist?
>>"#{rounded_thumbnail_file}"
>>    File.delete(medium_file) if File.exist? "#{medium_file}"
>>    File.delete(large_file) if File.exist? "#{large_file}"
>>  end
>>
>>  # Returns the filesystem location of the image file
>>  def full_file
>>    "#{FileLocation}/full/#{id}.jpg"
>>  end
>>  def thumbnail_file
>>    "#{FileLocation}/thumbnail/#{id}.jpg"
>>  end
>>  def rounded_thumbnail_file
>>    "#{FileLocation}/rounded_thumbnail/#{id}.jpg"
>>  end
>>  def medium_file
>>    "#{FileLocation}/medium/#{id}.jpg"
>>  end
>>  def large_file
>>    "#{FileLocation}/large/#{id}.jpg"
>>  end
>>
>>
>>  # Returns the location of the image to the browser
>>  def full
>>    "#{DisplayLocation}/full/#{id}.jpg"
>>  end
>>  def thumbnail
>>    "#{DisplayLocation}/thumbnail/#{id}.jpg"
>>  end
>>  def medium
>>    "#{DisplayLocation}/medium/#{id}.jpg"
>>  end
>>  def large
>>    "#{DisplayLocation}/large/#{id}.jpg"
>>  end
>>  def rounded_thumbnail
>>    "#{DisplayLocation}/rounded_thumbnail/#{id}.jpg"
>>  end def resize
>>    if File.exist? full_file
>>      @file = File.open full_file
>>      save
>>    end
>>  end
>>end
>>
> 
> 
> 
> I''ll be damned.  Moving 
> @magick_image = Magick::Image.from_blob(@file.read).first
> from Image#after_save to Image#file= fixed the problem.
> 
> So, apparently, something weird happens to @file before
> Image#after_save is called.  Any ideas?

rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org

2005-Aug-04 12:53 UTC

head link

Re: Fwd: RMagick problem

Hi !

Joe Van Dyk said the following on 2005-08-03 22:30:> On 8/3/05, Joe Van Dyk
<joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>   # Resizes a Magick image to an exact size, keeping the same aspect ratio
>   def resize_image_to_exact_size(width, height)
>     new_aspect_ratio = width.to_f / height.to_f
>     old_aspect_ratio = @magick_image.columns.to_f / @magick_image.rows.to_f
> 
>     if old_aspect_ratio < new_aspect_ratio
>       # Image too tall, geometry string should restrict height
>       geometry_string = "#{width}"
>     else
>       # Image too wide or just right, geometry string should
>       # restrict width
>       geometry_string = "x#{height}"
>     end
There''s no need to do that.  RMagick''s documentation says
about geometry
strings:

"By default, the width and height are maximum values. That is, the image 
is expanded or contracted to fit the width and height value while 
maintaining the aspect ratio of the image."

http://studio.imagemagick.org/RMagick/doc/imusage.html#geometry

Hope that helps !
François

Joe Van Dyk

2005-Aug-04 15:36 UTC

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Re: Fwd: RMagick problem

On 8/4/05, rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
<rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org>
wrote:> Hi !
> 
> Joe Van Dyk said the following on 2005-08-03 22:30:
> > On 8/3/05, Joe Van Dyk
<joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >   # Resizes a Magick image to an exact size, keeping the same aspect
ratio
> >   def resize_image_to_exact_size(width, height)
> >     new_aspect_ratio = width.to_f / height.to_f
> >     old_aspect_ratio = @magick_image.columns.to_f /
@magick_image.rows.to_f
> >
> >     if old_aspect_ratio < new_aspect_ratio
> >       # Image too tall, geometry string should restrict height
> >       geometry_string = "#{width}"
> >     else
> >       # Image too wide or just right, geometry string should
> >       # restrict width
> >       geometry_string = "x#{height}"
> >     end
> 
> There''s no need to do that.  RMagick''s documentation says
about geometry
> strings:
> 
> "By default, the width and height are maximum values. That is, the
image
> is expanded or contracted to fit the width and height value while
> maintaining the aspect ratio of the image."
> 
> http://studio.imagemagick.org/RMagick/doc/imusage.html#geometry
> 
> Hope that helps !
> François
If you look again, you''ll notice I have two resize methods.  One
resize method that just resizes an image, keeping the same aspect
ratio.  And then the resize_to_exact_size method that resizes an image
to an exact size.

See http://jerrymahan.com/contents/show/front .  You''ll notice that
those thumbnails on the right are all the exact same size (same height
and width).  But the original images all had differently aspect
ratios.  To make sure that all the thumbnails are the exact same size,
I had to do some additional calculations.  (or so it appeared to me)

François Beausoleil

2005-Aug-05 13:35 UTC

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Re: Fwd: RMagick problem

Joe Van Dyk said the following on 2005-08-04 11:36:> On 8/4/05, rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
<rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org> wrote:
> 
> If you look again, you''ll notice I have two resize methods.  One
> resize method that just resizes an image, keeping the same aspect
> ratio.  And then the resize_to_exact_size method that resizes an image
> to an exact size.
Ha, I didn''t notice that.  Then, in the geometry page, simply append an
exclamation mark to your geometry string, as mentionned on 
http://studio.imagemagick.org/RMagick/doc/struct.html#Geometry

If your original is 640x328 and you do:
   img.change_geometry("320x240")
the cols and rows will be:  320x164, while if you do:

   img.change_geometry("320x240!")
cols and rows will be 320 and 240, respectively.

Hope that helps !
François

Rails - Aug 2005 - RMagick problem

RMagick problem

Re: RMagick problem

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Re: RMagick problem

Fwd: RMagick problem

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Re: Fwd: RMagick problem