{"id":2043,"date":"2014-01-20T07:00:00","date_gmt":"2014-01-20T07:00:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/2014\/01\/20\/how-do-i-get-a-high-resolution-icon-for-a-file\/"},"modified":"2024-06-05T11:58:36","modified_gmt":"2024-06-05T18:58:36","slug":"20140120-00","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20140120-00\/?p=2043","title":{"rendered":"How do I get a high resolution icon for a file?"},"content":{"rendered":"

Today’s Little Program obtains a high resolution icon for a file.<\/p>\n

Start with our scratch program<\/a> and make these changes. Remember, Little Programs do little or no error checking. This week’s smart pointer class is (rolls dice) _com_ptr_t<\/code>!<\/p>\n

...\r\n#include <shlwapi.h>\r\n#include <commoncontrols.h>                             <\/span>\r\n#include <comip.h>                                      <\/span>\r\n#include <comdef.h>                                     <\/span>\r\n\u00a0                                                       <\/span>\r\n_COM_SMARTPTR_TYPEDEF(IImageList, __uuidof(IImageList));<\/span>\r\n\r\nHICON g_hico;\r\n\r\nHINSTANCE g_hinst;                          \/* This application's HINSTANCE *\/\r\n...\r\n\r\nint GetIconIndex(PCTSTR pszFile)                                   <\/span>\r\n{                                                                  <\/span>\r\n  SHFILEINFO sfi;                                                  <\/span>\r\n  SHGetFileInfo(pszFile, 0, &sfi, sizeof(sfi), SHGFI_SYSICONINDEX);<\/span>\r\n  return sfi.iIcon;                                                <\/span>\r\n}                                                                  <\/span>\r\n\u00a0                                                                  <\/span>\r\nHICON GetJumboIcon(int iImage)                                     <\/span>\r\n{                                                                  <\/span>\r\n  IImageListPtr spiml;                                             <\/span>\r\n  SHGetImageList(SHIL_JUMBO, IID_PPV_ARGS(&spiml));                <\/span>\r\n\u00a0                                                                  <\/span>\r\n  HICON hico;                                                      <\/span>\r\n  spiml->GetIcon(iImage, ILD_TRANSPARENT, &hico);                  <\/span>\r\n  return hico;                                                     <\/span>\r\n}                                                                  <\/span>\r\n<\/pre>\n
The Get\u00adIcon\u00adIndex<\/code> function does nothing new. It simply retrieves the system image list icon index for a file’s icon.<\/p>\n
The Get\u00adJumbo\u00adIcon<\/code> retrieves an icon by its system image list index. First, it asks SHGet\u00adImage\u00adList<\/code> for the jumbo image list, then it asks the jumbo image list for the icon.<\/p>\n
Now all we have to do is hook the functions up.<\/p>\n
void\r\nPaintContent(HWND hwnd, PAINTSTRUCT *pps)\r\n{\r\n  DrawIconEx(pps->hdc, 50, 50, g_hico,    <\/span>\r\n             0, 0, 0, nullptr, DI_NORMAL);<\/span>\r\n}\r\n\r\n    ...\r\n    if (SUCCEEDED(CoInitialize(NULL))) {\/* In case we use COM *\/\r\n\r\n        g_hico = GetJumboIcon(GetIconIndex(lpCmdLine));<\/span>\r\n\r\n        ...\r\n        DestroyIcon(g_hico);<\/span>\r\n        CoUninitialize();\r\n    }\r\n    ...\r\n<\/pre>\n
Run this program and pass the full path to a file on the command line. (No quotation marks, even if it contains spaces!) Result: A gigantic icon for the file appears.<\/p>\n
Instead of converting the system imagelist index into an icon, we could just ask the jumbo imagelist to render it directly.<\/p>\n
int g_iImage;<\/span>\r\n\r\nvoid\r\nPaintContent(HWND hwnd, PAINTSTRUCT *pps)\r\n{\r\n  IImageListPtr spiml;                             <\/span>\r\n  SHGetImageList(SHIL_JUMBO, IID_PPV_ARGS(&spiml));<\/span>\r\n  \u00a0                                                <\/span>\r\n  IMAGELISTDRAWPARAMS ildp = { sizeof(ildp) };     <\/span>\r\n  ildp.himl = IImageListToHIMAGELIST(spiml);       <\/span>\r\n  ildp.i = g_iImage;                               <\/span>\r\n  ildp.hdcDst = pps->hdc;                          <\/span>\r\n  ildp.x = 50;                                     <\/span>\r\n  ildp.y = 50;                                     <\/span>\r\n  ildp.rgbBk = CLR_NONE;                           <\/span>\r\n  ildp.fStyle = ILD_TRANSPARENT;                   <\/span>\r\n  spiml->Draw(&ildp);                              <\/span>\r\n}\r\n\r\n    ...\r\n    if (SUCCEEDED(CoInitialize(NULL))) {\/* In case we use COM *\/\r\n\r\n        g_iImage = GetIconIndex(lpCmdLine);<\/span>\r\n\r\n        ...\r\n        \/\/ no cleanup necessary<\/span>\r\n        CoUninitialize();\r\n    }\r\n    ...\r\n<\/pre>\n
This is how Explorer deals with icons most of the time. It doesn’t create actual icons; it merely remembers indices into the system imagelist, and when it needs to draw an icon, it calls the Draw<\/code> method on the imagelist whose size corresponds to the image it wants.<\/p>\n
Bonus chatter<\/b>: The system imagelists come in four sizes (as of this writing). And yet large<\/i> is one of the smallest available ones. Why is that?<\/p>\n
The  system imagelist sizes<\/a> are<\/p>\n