PNGT_UNION

PNGT_UNION: OP_PNGTRANSCODE

The PNGT_UNION structure supplies parameters to the OP_PNGTRANSCODE opcode used for optimizing input PNG files to minimally sized output PNG files.

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typedef struct { DWORD Reserved0; BYTE PICHUGE* Reserved1; BYTE PICHUGE* Reserved2; BYTE PICHUGE* Reserved3; BYTE PICHUGE* Reserved4; BYTE PICHUGE* Reserved5; BYTE PICHUGE* Reserved6; BYTE PICHUGE* Reserved7; BYTE PICHUGE* Reserved8; PICFLAGS PicFlags; PICFLAGS PicFlags2; REGION2 Region; DWORD AlphaBpp; BYTE BitDepth; WORD ResolutionUnit; DWORD XResolution; DWORD YResolution; BYTE Interlace; } PNGT_UNION;

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typedef struct {  
   DWORD                           Reserved0;
   BYTE PICHUGE*                   Reserved1;
   BYTE PICHUGE*                   Reserved2;
   BYTE PICHUGE*                   Reserved3;
   BYTE PICHUGE*                   Reserved4;
   BYTE PICHUGE*                   Reserved5;
   BYTE PICHUGE*                   Reserved6;
   BYTE PICHUGE*                   Reserved7;
   BYTE PICHUGE*                   Reserved8;
   PICFLAGS                        PicFlags;
   PICFLAGS                        PicFlags2;  
   REGION2                         Region;  
   DWORD                           AlphaBpp;  
   BYTE                            BitDepth;  
   WORD                            ResolutionUnit;
   DWORD                           XResolution;  
   DWORD                           YResolution;
   BYTE                            Interlace;
} PNGT_UNION;

Fields:

Name

Description

Reserved0

This field is not currently used and must be set to 0.

Reserved1

Reserved2

Reserved3

Reserved4

Reserved5

Reserved6

Reserved7

Reserved8

These fields are not used and must be set to NULL.

PicFlags

Flags that control or report on the operation.

Value	Meaning
PF_HaveTransparency	A Transparency chunk is present in the input image. This flag is set by the tRNS chunk in the input PNG file and is returned to the user.
PF_IsColorMapped	Set if the original image was color mapped.
PF_IsGray	Set if the original image was gray or was color-mapped with a gray palette.

PicFlags2

Flags that control or report on the OP_PNGTRANSCODE operation.

Value	Meaning
PF2_HaveAlpha	Set if the original image had alpha or transparency information.

AlphaBpp

Set during REQ_INIT. The number of bits per pixel, after being adjusted for the presence of an alpha channel of the input PNG image.

BitDepth

This is the number of bits per component of the input PNG image.

ResolutionUnit

ResolutionUnit = 0 specifies that units are unknown, otherwise ResolutionUnit = 1 means that non-zero XResolution/YResolution are pixels per meter. X/Y also specifies the aspect ratio.

XResolution

Horizontal Pixels / Resolution Unit

YResolution

Vertical Pixels / Resolution Unit

Interlace

Set during REQ_INIT to report the interlace method that was used to compress the input PNG file. 0 indicates no interlacing, and 1 indicates Adam7 interlacing.