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

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

       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

          No transparency -- ignore tRNS chunk if provided, ignore Alpha channel
          if provided.

   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.

       $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 v5.34.0                                2022-PDF::Builder::Resource::XObject::Image::PNG(3pm)