foresight_png

foresight_png, PNG images as base64 data, for raster plots (gnuplot with image) in SVG.

8-bit RGBA, no interlace, every row unfiltered and the zlib stream made of stored (uncompressed) deflate blocks: no compression to write, a file a few bytes per pixel, the same bytes for the same image (golden tests). CRC-32 and Adler-32 as the PNG and zlib specifications; base64 by BeFoR64.

Source: src/lib/foresight_png.F90

Contents

• png_base64
• stored
• chunk
• crc32
• adler32
• be32
• byte

Functions

png_base64

Base64 of the PNG of the image rgba(channel, column, row): red, green, blue, alpha (0..255) of each pixel, columns left to right, rows top to bottom.

Returns: character(len=:)

function png_base64(rgba) result(code)

Arguments

Name	Type	Intent	Attributes	Description
rgba	integer(kind=I4P)	in		Pixels.

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stored

zlib stream of data in stored deflate blocks of at most 65535 bytes, with its Adler-32.

Attributes: pure

Returns: integer(kind=I1P)

function stored(data) result(stream)

Arguments

Name	Type	Intent	Attributes	Description
data	integer(kind=I1P)	in		Data.

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chunk

PNG chunk: length, type, data, CRC-32 of type and data.

Attributes: pure

Returns: integer(kind=I1P)

function chunk(kind, data) result(bytes)

Arguments

Name	Type	Intent	Attributes	Description
kind	character(len=4)	in		Chunk type.
data	integer(kind=I1P)	in		Chunk data.

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crc32

CRC-32 (ISO 3309, as PNG) of data, as a signed 32-bit integer.

Attributes: pure

Returns: integer(kind=I4P)

function crc32(data) result(crc)

Arguments

Name	Type	Intent	Attributes	Description
data	integer(kind=I1P)	in		Data.

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adler32

Adler-32 of data, as a signed 32-bit integer.

Attributes: pure

Returns: integer(kind=I4P)

function adler32(data) result(sum)

Arguments

Name	Type	Intent	Attributes	Description
data	integer(kind=I1P)	in		Data.

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be32

Big-endian bytes of the 32-bit integer v (two's complement).

Attributes: pure

Returns: integer(kind=I1P)

function be32(v) result(bytes)

Arguments

Name	Type	Intent	Attributes	Description
v	integer(kind=I4P)	in		Value.

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byte

Byte of the unsigned value v (0..255), stored two's complement.

Attributes: elemental

Returns: integer(kind=I1P)

function byte(v) result(b)

Arguments

Name	Type	Intent	Attributes	Description
v	integer(kind=I4P)	in		Value.

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