View source for ANI (file format)

{{Short description|File format for animated mouse cursors}}
{{about|the file format||Ani (disambiguation)}}
{{More sources needed|date=April 2024}}
{{Infobox file format
| name = ANI
| extension = {{mono|.ani}}
| mime = 
| magic ={{code|ACON}} (4 bytes, ASCII)
| owner = [[Microsoft]]
| genre = [[Computer animation|animated]] [[raster graphics|raster]] [[image format]] for [[cursor (computers)#Mouse cursor|mouse cursors]]<ref>{{cite web|url=https://www.nationalarchives.gov.uk/pronom/fmt/386|access-date=April 1, 2025|title=Details for: Microsoft Animated Cursor Format|website=The National Archives}}</ref>
| containerfor = 
| containedby = 
| extendedfrom = 
| extendedto = 
}}
The '''ANI file format''' is a [[graphics file format]] used for [[animation|animated]] [[cursor (computers)|mouse cursors]] on the [[Microsoft Windows]] [[operating system]].<ref>{{Cite web |title=ANI File - What is an .ani file and how do I open it? |url=https://fileinfo.com/extension/ani |access-date=2024-04-27 |website=fileinfo.com}}</ref>

The format is based on the Microsoft [[Resource Interchange File Format]], which is used as a [[container format (digital)|container]] for storing the individual frames (which are standard [[ICO (icon image file format)|Windows icons]]) of the animation.

== File structure ==
The [[Resource Interchange File Format|RIFF]] file structure description:

<pre>
#define AF_ICON 0x1                // Frames are in Windows ICO format.
#define AF_SEQUENCE 0x2            // Animation is sequenced.

typedef struct {                   
    DWORD cbSizeof;                // Should be sizeof(ANIHEADER) = 36 bytes.
    DWORD cFrames;                 // Number of frames in the frame list.
    DWORD cSteps;                  // Number of steps in the animation loop.
    DWORD cx, cy;                  // Not used.
    DWORD cBitCount, cPlanes;      // Not used.
    DWORD jifRate;                 // Default display rate, in jiffies (1/60s).
    DWORD fl;                      // AF_ICON should be set. AF_SEQUENCE is optional.
} ANIHEADER;                       

RIFF('ACON'                        
    [LIST('INFO'                   
        [INAM(<ZSTR>)]             // Title. Optional.
        [IART(<ZSTR>)]             // Author. Optional.
    )]                             
    'anih'(<ANIHEADER>)            // ANI file header.
    ['rate'(<DWORD...>)]           // Rate table (array of jiffies).
                                   // If the AF_SEQUENCE flag is set
                                   // then the count is ANIHEADER.cSteps,
                                   // otherwise ANIHEADER.cFrames.
    ['seq '(<DWORD...>)]           // Sequence table (array of frame index values).
                                   // Should be present when AF_SEQUENCE flag is set.
                                   // Count is ANIHEADER.cSteps.
    LIST('fram'                    // List of frames data. Count is ANIHEADER.cFrames.
       'icon'(<icon_data_1>)       // Frame 1
       'icon'(<icon_data_2>)       // Frame 2
       ...
    )
)</pre>

Individual frames are in [[ICO (icon image file format)|ICO format]].

Frame rates are measured in [[Jiffy (time)|jiffies]], with one jiffy equal to 1/60 of a second, or 16.666 ms.

Sequence information present in the file determines the sequence of frames, and allows frames to be played more than once, or in a different order than that in which they appear in the file. For example, if the animation contains three different images numbered 1, 2 and 3, and the sequence is 1-2-3-2-1, (five frames) then only three icons need to be stored in the file, thereby saving storage space.

If an ANI file is used as [[Windows]] cursor, the sequence will loop. There is no way of influencing that behavior.<ref>{{Cite web |title=file-format-ani |url=https://www.daubnet.com/en/file-format-ani |access-date=2025-05-03 |website=www.daubnet.com}}</ref>

Animated Cursor Editor for Windows NT (ANIEDIT) source code from MSDN October 2001 Library is a good source of knowledge about ANI file format structure.<ref>{{Cite web |title=MSDN Library October 2001 - Internet Archive |url=https://archive.org/details/MSDN_Library_October_2001 |access-date=2025-05-03 |website=archive.org}}</ref>

== See also ==
*[[Pointer (user interface)]]
*[[ICO (file format)]]

==References==
{{reflist}}

== External links ==
*[http://www.gdgsoft.com/anituner/help/aniformat.htm Description of the ani file format]
*[https://www.informit.com/articles/article.aspx?p=1189080 Introduce Animated Cursors to Java GUIs, Part 2]
*[https://isc.sans.edu/diary/Windows+Animated+Cursor+Handling+vulnerability+-+CVE-2007-0038/2534 Vulnerability in Windows Animated Cursor Handling]

{{Graphics file formats}}
[[Category:Graphics file formats]]
[[Category:Windows architecture]]

{{windows-stub}}