15 Replies Latest reply: Mar 19, 2013 1:44 AM by Test Screen Name RSS

    PDF form field rectangle out of page coordinates

    ToM_1st Community Member

      Hi,

       

      recently i came across a PDF file which had a (text) form field with the following rectangle coordinates:

       

      LowerLeft:  170;850

      UpperRight: 475;862

       

      The page itself had: 595;841 whereas MediaBox=CropBox=BleedBox=TrimBox.

       

      Thus the y coordinate is out of the page so to speak.

      The adobe reader displays the field at the upper top of the page but within the boundaries of the page.

      Maybe it does correct/fix it?

       

      My question is:

      1.) Is that pdf spec compliant? (I did a quick search however couldn't find anything about it)

      2.) Is that PDF/A-1 compliant (if that makes a difference)?

       

      Thanks,

      ToM

        • 1. Re: PDF form field rectangle out of page coordinates
          lrosenth Adobe Employee

          I'd like to see the PDF in question…

           

          But in general, the coordinates of fields DO NOT need to lie within page boundaries.  It is perfectly valid to have a field that it outside of the coordinates – in fact, it's a quite common way to show/hide fields by simply shifting the rect "offscreen".

           

          And there is nothing in PDF/A-1 (or 2 or 3) that would prohibit it.

          • 2. Re: PDF form field rectangle out of page coordinates
            ToM_1st Community Member

            Unfortunatly it is a customer document and i am not allowed to publish it...

             

            To your answer:

            Interessting. But then there should be some rules in the spec for the "viewer" so to speak?

            I mean in the case half of the field is in the pdf and the other half is not - like in my case - what should a reader do?

            And incase the field is outside then a viewer should not display the field at all?

            What happens if you "jump" into the field with the Tab key? Or, in that case, that is forbidden?

             

            Regards,

            ToM

            • 3. Re: PDF form field rectangle out of page coordinates
              lrosenth Adobe Employee

              There probably should be, but there aren't (AFAIK).  Right now, all such behaviors are up to the reader.

               

              Here is a PDF (<http://drops.pdfsages.com/UcC7>) that has some fields partially as well as completely offscreen.  See what happens…

               

              This issue is certainly something we can certainly raise in committee.

              • 4. Re: PDF form field rectangle out of page coordinates
                ToM_1st Community Member

                I just got another pdf in, which has negative coordinates for some of its fields.

                 

                E.g. (shortened for readability)

                <</Type/Annot/F 6/T(1)/Ff 8388608/Rect[-240.608 26.5735 -64.9627 45.9284]/Subtype/Widget/FT/Tx>>

                or

                <</Type/Annot/T(2)/Ff 393216/Rect[-135.442 -118.175 -33.3329 -100.756]/FT/Ch>>

                 

                The Reader/Acrobat however puts the field inside the document. So are negative coordinates of a rectangle spec compliant, also?

                I searched the spec however didn't find anything about negative rectangle coordinates...

                Do I just take the absolut value?

                 

                Thanks

                ToM

                • 5. Re: PDF form field rectangle out of page coordinates
                  lrosenth Adobe Employee

                  Yes, negative coords are perfectly valid.   Remember those are relative to the MediaBox, which doesn't have to be origined at (0,0)

                  • 6. Re: PDF form field rectangle out of page coordinates
                    ToM_1st Community Member

                    You are right, I found the page dictionary of that page:

                    (shortened for readability)

                    <</Type/Page/CropBox[-295.667 -765.0 296.333 74.9995]/ArtBox[-269.467 -811.0 464.877 51.8296]/MediaBox[-295.667 -765.0 296.333 74.9995]>>

                     

                    So form fields are placed on the media box (and not on on the other boxes)?

                     

                    Thanks,

                    ToM

                    • 7. Re: PDF form field rectangle out of page coordinates
                      lrosenth Adobe Employee

                      Only MediaBox.

                      • 8. Re: PDF form field rectangle out of page coordinates
                        olafdruemmer Community Member

                        If CropBox is present it takes precedence in terms of which portion of the page description is shown (everything outside the CropBox is clipped). Only if the CopBox is not present,  the MediaBox will also act as the CropBox. The  perceived position of the form fields and annotations on the page is a result of their position in relationship to the area defined by the CropBox (or MediaBox, if no CropBox  is present).

                        • 9. Re: PDF form field rectangle out of page coordinates
                          lrosenth Adobe Employee

                          Olaf – you are correct that what is VISIBLE is defined by the CropBox (if present).  However, ALL PAGE COORDINATES (both content and annotations/fields) are ALWAYS relative to the MediaBox.

                          • 10. Re: PDF form field rectangle out of page coordinates
                            olafdruemmer Community Member

                            No, I think this is incorrect - all page coordinates are relative to the coordinate system:

                             

                            From ISO 32000-1, Table 164:

                             

                            Rect

                            rectangle

                            (Required) The annotation rectangle, defining the location of the annotation on the page in default user space units.

                             

                             

                            Default user space is not relative to MediaBox or any other box.

                             

                            From ISO 32000-1, Table 30:

                             

                            MediaBox

                            rectangle

                            (Required; inheritable) A rectangle (see 7.9.5, "Rectangles"), expressed in default user space units, that shall define the boundaries of the physical medium on which the page shall be displayed or printed (see 14.11.2, "Page Boundaries").

                             

                             

                            From ISO 32000-1, 8.3.2.3, User Space:

                             

                            The CropBox entry in the page dictionary shall specify the rectangle of user space corresponding to the visible area of the intended output medium (display window or printed page).

                             

                             

                            Otherwise annotations and form fields would move just because someone is changing the MediaBox or CropBox values...

                             

                            Olaf

                            • 11. Re: PDF form field rectangle out of page coordinates
                              lrosenth Adobe Employee

                              Annotations DO move if you change the MediaBox, but will NOT move if you change the CropBox.   Try it

                              • 12. Re: PDF form field rectangle out of page coordinates
                                Test Screen Name CommunityMVP

                                Ah, but if you change the MediaBox bottom left, then you are changing the effective co-ordinates of the page, so the annotations will move relative to that. Indeed, if annotations were relative to the media box bottom left, then changing the media box bottom left would leave the annotations in place. And it doesn't.

                                 

                                I think I'd say:

                                Annotations, MediaBox, CropBox, other boxes are all measured relative to the same origin, which may be within, at the edge of, or outside the visible page. This is also the origin of the co-ordinate system used in page content. Measurements are not relative to the visible page, but will coincide if the visible page bottom left is at the origin.

                                 

                                The term " in default user space units" is a bit unhelpful. The units clearly defines the size of a unit square, but does it define the origin?

                                • 13. Re: PDF form field rectangle out of page coordinates
                                  lrosenth Adobe Employee

                                  No they won't, because the coordinates of the fields are RELATIVE to the MediaBox origin – NOT absolute.   And yes, changing the origin (bottom/left) of the MediaBox will keep the annotations visually at the same place (relative to content).

                                  • 14. Re: PDF form field rectangle out of page coordinates
                                    ToM_1st Community Member

                                    Sorry for this slightly unrelated question:

                                    Where can i see the cropbox and mediabox values in acrobat?

                                    • 15. Re: PDF form field rectangle out of page coordinates
                                      Test Screen Name CommunityMVP

                                      Acrobat doesn't have low level tools for inspecting things like this (there are add-ons). However, the Crop Pages dialog shows you what it calls the CropBox. This is defined by margins rather than being a rectangle. In fact it isn't always the same as the actual stored value, since the page Rotate value is applied first. However, for the ordinary user (rather than the PDF developer) what it does is the correct and intuitive thing.

                                       

                                      To find out the media box, set the crop values all to zero. The crop and media box will be the same.