PDF::Builder::Resource::XObject::Image::PNG(3)
                                           User Contributed Perl Documentation


NAME
       PDF::Builder::Resource::XObject::Image::PNG - support routines for PNG
       image library (using pure Perl code).  Inherits from
       PDF::Builder::Resource::XObject::Image

METHODS
   new
           $res = PDF::Builder::Resource::XObject::Image::PNG->new($pdf, $file, %opts)

           Returns a PNG-image object. $pdf is the PDF object being added to,
           $file is the input PNG file, and the optional $name of the new
           parent image object defaults to PxAAA.

           If the Image::PNG::Libpng package is installed, the PNG_IPL library
           will be used instead of the PNG library. In such a case, use of the
           PNG library may be forced via the "nouseIPL" flag (see Builder
           documentation for image_png()).

           opts:

           'notrans' => 1
               No transparency -- ignore tRNS chunk if provided, ignore Alpha
               channel if provided.

           'name' => 'string'
               This is the name you can give for the PNG image object. The
               default is Pxnnnn.

           Remember that you need to invoke the image_png method from
           Builder.pm in order to use this functionality.

   Supported PNG types
          (0) Gray scale of depth 1, 2, 4, or 8 bits per pixel (2, 4, 16, or 256
              gray levels). 16 bpp is not currently supported (a PNG with 16 bpp
              is a fatal error). Full transparency (of one 8-bit gray value) via
              the tRNS chunk is allowed, unless the notrans option specifies
              that it be ignored.

          (2) RGB 24-bit truecolor with 8 bits per sample (16.7 million colors).
              16 bps is not currently supported (a PNG with 16 bps is a fatal
              error). Full transparency (of one 3x8-bit RGB color value) via the
              tRNS chunk is allowed, unless the notrans option specifies that it
              be ignored.

          (3) Palette color with 1, 2, 4, or 8 bits per pixel (2, 4, 16, or 256
              color table/palette entries). 16 bpp is not currently supported by
              PNG or PDF. Partial transparency (8-bit Alpha) for each palette
              entry via the tRNS chunk is allowed, unless the notrans option
              specifies that it be ignored (all entries fully opaque).

          (4) Gray scale of depth 8 bits per pixel plus 8-bit Alpha channel (256
              gray levels and 256 levels of transparency). 16 bpp is not
              currently supported (a PNG with 16 bpp is a fatal error). The Alpha
              channel is ignored if the notrans option is given. The tRNS chunk
              is not permitted.

          (6) RGB 24-bit truecolor with 8 bits per sample (16.7 million colors)
              plus 8-bit Alpha channel (256 levels of transparency). 16 bps is not
              currently supported (a PNG with 16 bps is a fatal error). The Alpha
              channel is ignored if the notrans option is given. The tRNS chunk
              is not permitted.

       In all cases, 16 bits per sample are not implemented. A fatal error
       will be returned if a PNG image with 16-bps data is supplied. The code
       is assuming standard "network" bit ordering (Big Endian). Interlaced
       (progressive) display images are not supported. Use the PNG_IPL version
       if you need to support 16 bps or interlaced images.

       The transparency chunk (tRNS) will specify one gray level entry or one
       RGB entry to be treated as transparent (Alpha = 0). For palette color,
       up to 256 palette entry 8-bit Alpha values are specified (256 levels of
       transparency, from 0 = transparent to 255 = opaque).

       Only a limited number of chunks are handled: IHDR, IDAT (internally),
       PLTE, tRNS, and IEND (internally). All other chunks are ignored at this
       time. Certain filters and compressions applied to data will be handled,
       but there may be unsupported methods.

   usesLib
           $mode = $png->usesLib()

           Returns 1 if Image::PNG::Libpng installed and used, 0 if not
           installed, or -1 if installed but not used (nouseIPL option given
           to "image_png").

           Caution: this method can only be used after the image object has
           been created. It can't tell you whether Image::PNG::Libpng is
           available in advance of actually using it, in case you want to use
           some functionality available only in PNG_IPL. See the PDF::Builder
           LA_IPL() call if you need to know in advance.

perl v5.38.1                      2023-12-21
                                PDF::Builder::Resource::XObject::Image::PNG(3)