{"id":14153,"date":"2010-05-05T07:00:00","date_gmt":"2010-05-05T07:00:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/2010\/05\/05\/how-the-shell-converts-an-icon-location-into-an-icon\/"},"modified":"2010-05-05T07:00:00","modified_gmt":"2010-05-05T07:00:00","slug":"how-the-shell-converts-an-icon-location-into-an-icon","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20100505-00\/?p=14153","title":{"rendered":"How the shell converts an icon location into an icon"},"content":{"rendered":"

\nA customer had trouble getting an icon to display for a registered\nfile type.\n<\/p>\n

\n

\nIn my resource file, I specify the icon like this:\n<\/p>\n

\n101 ICON awesome.ico\n<\/pre>\n
\nAnd when I register my file type, I set it like this:\n<\/p>\n
\n[HKEY_CLASSES_ROOT\\.xyz\\DefaultIcon]\n@=\"C:\\path\\to\\awesome.exe,101\"\n<\/pre>\n
\nHowever, when I view an .xyz<\/tt> file,\nmy awesome icon doesn’t appear.\nOn the other hand, if I change the 101<\/tt> to a 0<\/tt>,\nthen it works.\nWhy?\nIsn’t the number in the resource file the resource ID?\n<\/p>\n<\/blockquote>\n
\nWhy yes, in fact, the number in the resource file is indeed\nthe resource ID.\nBut the number after the comma in the Default­Icon<\/code>\nisn’t<\/i>.\n<\/p>\n
\nThe format of shell icon locations (used most visibly\nby Default­Icon<\/code>, but also used in other places)\nis «file»,«index»<\/code>,\nwhere the index is a zero-based index of the icon in your\nresources.\nIn other words,\nan index of zero means “Give me the first icon in the file.”\nThe resource compiler sorts icons numerically by resource ID,\nso the first icon in the file is the icon with the numerically\nlowest resource ID.\nIn the above example, apparently there are no icons with resource IDs\nless than 101;\nthat would explain why asking for icon index zero results in the awesome\nicon.\n<\/p>\n
\nThe function behind all this icon hunting is Extract­Icon<\/code>.\nThe icon location string is split up at the comma into a path and\nan integer, and that path and integer are passed to the\nExtract­Icon<\/code> function.\nSince the Extract­Icon<\/code>\nfunction interprets the integer\nas the icon index, that’s what the integer in your icon location\nstring means.\n<\/p>\n
\nIn Windows 95, the\nExtract­Icon<\/code> function was enhanced\nso that you could also specify an icon by its resource ID\nby passing its negative<\/i> as the icon index.\nIn other words, if you place a negative number after the comma,\nthen its absolute value is interpreted as the resource ID.\n<\/p>\n
\nWe learned some time ago that\nthere’s a hole in this model:\nIt doesn’t work if you want a resource ID of 1,\nbecause\n\nthe value −1\nhas a special meaning to Extract­Icon<\/code><\/a>:\nInstead of extracting an icon, it tells you how many icons there are.\n<\/p>\n
\nThe workaround for this is actually straightforward,\nand you should be able to figure it out on your own\nbased on information provided in this article.\nHow do you specify that you want the icon whose resource ID is 1?<\/p>\n","protected":false},"excerpt":{"rendered":"
A customer had trouble getting an icon to display for a registered file type. In my resource file, I specify the icon like this: 101 ICON awesome.ico And when I register my file type, I set it like this: [HKEY_CLASSES_ROOT\\.xyz\\DefaultIcon] @=”C:\\path\\to\\awesome.exe,101″ However, when I view an .xyz file, my awesome icon doesn’t appear. On the […]<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[26],"class_list":["post-14153","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-other"],"acf":[],"blog_post_summary":"
A customer had trouble getting an icon to display for a registered file type. In my resource file, I specify the icon like this: 101 ICON awesome.ico And when I register my file type, I set it like this: [HKEY_CLASSES_ROOT\\.xyz\\DefaultIcon] @=”C:\\path\\to\\awesome.exe,101″ However, when I view an .xyz file, my awesome icon doesn’t appear. On the […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/14153","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=14153"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/14153\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=14153"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=14153"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=14153"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}