cheng/libpng
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[devel] Correct png_get_current_row_number documentation

Browse Source
This commit is contained in:
John Bowler 2011-02-16 06:15:13 -06:00 committed by Glenn Randers-Pehrson
parent 9616ad9828
commit cd11345693
2 changed files with 32 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
libpng-manual.txt
View File

@ -1563,6 +1563,14 @@ supported if user transforms are supported, secondly they may well return
unexpected results unless the row is actually being processed at the moment they
are called.
With interlaced
images the value returned is the row in the input sub-image image. Use
PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
The discussion of interlace handling above contains more information on how to
use these values.
You can also set up a pointer to a user structure for use by your
callback function, and you can inform libpng that your transform
function will change the number of channels or bit depth with the
@ -2821,9 +2829,15 @@ libpng also supplies an information routine that may be called from
your callback:
png_get_current_row_number(png_ptr);
png_get_current_pass_number(png_ptr);
This returns the current row passed to the transform. Even with interlaced
images the value returned is the row in the final output image.
This returns the current row passed to the transform. With interlaced
images the value returned is the row in the input sub-image image. Use
PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
The discussion of interlace handling above contains more information on how to
use these values.
You can also set up a pointer to a user structure for use by your
callback function.

18
libpng.3
View File

@ -2490,6 +2490,14 @@ supported if user transforms are supported, secondly they may well return
unexpected results unless the row is actually being processed at the moment they
are called.
With interlaced
images the value returned is the row in the input sub-image image. Use
PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
The discussion of interlace handling above contains more information on how to
use these values.
You can also set up a pointer to a user structure for use by your
callback function, and you can inform libpng that your transform
function will change the number of channels or bit depth with the
@ -3748,9 +3756,15 @@ libpng also supplies an information routine that may be called from
your callback:
png_get_current_row_number(png_ptr);
png_get_current_pass_number(png_ptr);
This returns the current row passed to the transform. Even with interlaced
images the value returned is the row in the final output image.
This returns the current row passed to the transform. With interlaced
images the value returned is the row in the input sub-image image. Use
PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
The discussion of interlace handling above contains more information on how to
use these values.
You can also set up a pointer to a user structure for use by your
callback function.