gdPngInfo Struct Reference

Basic information read from a PNG stream. More...

#include <gd.h>

Data Fields
int	width
int	height
int	bit_depth
int	color_type
int	has_alpha
int	has_transparency
int	palette_entries
int	interlace_method
int	x_pixels_per_unit
int	y_pixels_per_unit
int	physical_unit
gdImageMetadata *	metadata
int	decoded_truecolor
int	resolution_x
int	resolution_y

Detailed Description

Basic information read from a PNG stream.

PNG stores physical pixel density in the pHYs chunk as two raw pixels-per-unit values plus a unit flag. When physical_unit is PNG_RESOLUTION_METER, x_pixels_per_unit and y_pixels_per_unit are pixels per meter and resolution_x/resolution_y contain the converted DPI values. When physical_unit is PNG_RESOLUTION_UNKNOWN, the raw values describe pixel aspect ratio only and resolution_x/resolution_y remain -1.

Field Documentation

bit_depth

int gdPngInfo::bit_depth

PNG bit depth from the IHDR chunk.

color_type

int gdPngInfo::color_type

PNG color type from the IHDR chunk.

decoded_truecolor

int gdPngInfo::decoded_truecolor

Non-zero if gd decodes this PNG as truecolor.

has_alpha

int gdPngInfo::has_alpha

Non-zero if the PNG color type includes alpha.

has_transparency

int gdPngInfo::has_transparency

Non-zero if a tRNS transparency chunk is present.

height

int gdPngInfo::height

Image height in pixels.

interlace_method

int gdPngInfo::interlace_method

PNG interlace method from the IHDR chunk.

metadata

gdImageMetadata* gdPngInfo::metadata

Optional metadata object populated while probing.

palette_entries

int gdPngInfo::palette_entries

Number of palette entries, or -1 if no PLTE chunk was read.

physical_unit

int gdPngInfo::physical_unit

pHYs unit flag: PNG_RESOLUTION_UNKNOWN, PNG_RESOLUTION_METER, or -1.

resolution_x

int gdPngInfo::resolution_x

Horizontal DPI converted from meter pHYs, or -1 if not available.

resolution_y

int gdPngInfo::resolution_y

Vertical DPI converted from meter pHYs, or -1 if not available.

width

int gdPngInfo::width

Image width in pixels.

x_pixels_per_unit

int gdPngInfo::x_pixels_per_unit

Raw pHYs horizontal pixels per unit, or -1 if not available.

y_pixels_per_unit

int gdPngInfo::y_pixels_per_unit

Raw pHYs vertical pixels per unit, or -1 if not available.

---

The documentation for this struct was generated from the following file:

• src/gd.h