Icon can not be set as Finder's Folder

[akabekobeko]

Examine and fix the problem of #43 again.

[akabekobeko]

Safari's .icns file can be set in Finder's folder, so I will refer to this.

[akabekobeko]

Safari icon TOC is set. The type and length of the image are specified as TOC instead of individual headers, and then the images are connected.

byte	type	value
4	ascii	"icns"
4	number	Length (bytes) of file
4	ascii	"TOC " ...Trim is necessary
4	number	Length (bytes) of toc
4	ascii	Name of icon type (ex: "ic10")
4	number	Length (bytes) of icon image
...	...	...
*	binary	Image data (PNG, JPEG, ...etc)

[akabekobeko]

ICNS structure of app icon.

Firefox v52.0.2

OSType	Length (Bytes)
is32	635
s8mk	264
il32	2412
l8mk	1032
it32	27872
t8mk	16392
ic08	73381
ic09	183844
ic10	495671

Safari v10.1 (12603.1.30.0.34)

It has a TOC and defines the type and length there.

OSType	Length (Bytes)
is32	710
s8mk	264
il32	2440
l8mk	1032
ic07	24437
ic08	72437
ic09	223610
ic11	2726
ic12	8548
ic13	72437
ic14	223610
ic10	900891
is32	710

[akabekobeko]

Generate an icns file from the following image files with iconutil, the image file was renamed with icon-gen (svg2png) created.

Pixle	Name
1024	icon_512x512@2x.png
512	icon_512x512.png
512	icon_256x256@2x.png
256	icon_256x256.png
256	icon_128x128@2x.png
128	icon_128x128.png
64	icon_32x32@2x.png
32	icon_32x32.png
32	icon_16x16@2x.png
16	icon_16x16.png

Structure of generated ICNS file.

OSType	Length (Bytes)
ic09	43177
ic07	8988
ic12	4129
ic10	100541
ic14	43177
l8mk	1032
s8mk	264
ic08	19597
ic13	19597
ic11	1701
info	267
il32	1742
is32	615

TOC does not exist. However, types other than PNG are also stored.

[akabekobeko]

Reference documents when supporting formats other than PNG.

• OSX用アイコンファイルをWindows上で作る - てくにかるむ // multix.jp

[akabekobeko]

It was found that even if it does not correspond to PackBits, it can be corrected simply by skipping icp4, icp5, icp6.