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IShellItemImageFactory::GetImage method

Gets an HBITMAP that represents an IShellItem. The default behavior is to load a thumbnail. If there is no thumbnail for the current IShellItem, it retrieves an HBITMAP for the icon of the item. The thumbnail or icon is extracted if it is not currently cached.

Syntax


HRESULT GetImage(
  [in]   SIZE size,
  [in]   SIIGBF flags,
  [out]  HBITMAP *phbm
);

Parameters

size [in]

Type: SIZE

A structure that specifies the size of the image to be received.

flags [in]

Type: SIIGBF

One or more of the following:

SIIGBF_RESIZETOFIT (0x00000000)

Shrink the bitmap as necessary to fit, preserving its aspect ratio.

SIIGBF_BIGGERSIZEOK (0x00000001)

Passed by callers if they want to stretch the returned image themselves. For example, if the caller passes an icon size of 80x80, a 96x96 thumbnail could be returned. This action can be used as a performance optimization if the caller expects that they will need to stretch the image. Note that the Shell implementation of IShellItemImageFactory performs a GDI stretch blit. If the caller wants a higher quality image stretch than provided through that mechanism, they should pass this flag and perform the stretch themselves.

SIIGBF_MEMORYONLY (0x00000002)

Return the item only if it is already in memory. Do not access the disk even if the item is cached. Note that this only returns an already-cached icon and can fall back to a per-class icon if an item has a per-instance icon that has not been cached. Retrieving a thumbnail, even if it is cached, always requires the disk to be accessed, so GetImage should not be called from the UI thread without passing SIIGBF_MEMORYONLY.

SIIGBF_ICONONLY (0x00000004)

Return only the icon, never the thumbnail.

SIIGBF_THUMBNAILONLY (0x00000008)

Return only the thumbnail, never the icon. Note that not all items have thumbnails, so SIIGBF_THUMBNAILONLY will cause the method to fail in these cases.

SIIGBF_INCACHEONLY (0x00000010)

Allows access to the disk, but only to retrieve a cached item. This returns a cached thumbnail if it is available. If no cached thumbnail is available, it returns a cached per-instance icon but does not extract a thumbnail or icon.

SIIGBF_CROPTOSQUARE (0x00000020)

Introduced in Windows 8. If necessary, crop the bitmap to a square.

SIIGBF_WIDETHUMBNAILS (0x00000040)

Introduced in Windows 8. Stretch and crop the bitmap to a 0.7 aspect ratio.

SIIGBF_ICONBACKGROUND (0x00000080)

Introduced in Windows 8. If returning an icon, paint a background using the associated app's registered background color.

SIIGBF_SCALEUP (0x00000100)

Introduced in Windows 8. If necessary, stretch the bitmap so that the height and width fit the given size.

phbm [out]

Type: HBITMAP*

Pointer to a value that, when this method returns successfully, receives the handle of the retrieved bitmap. It is the responsibility of the caller to free this retrieved resource through DeleteObject when it is no longer needed.

Return value

Type: HRESULT

If this method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

Icon extraction can be time consuming. This method generally should not be called from a UI thread to avoid causing that thread to become unresponsive. You can call IShellItemImageFactory::GetImage on a UI thread if you set the SIIGBF_INCACHEONLY flag. However, if the image is not found in the cache, the calling application should be prepared to launch a background thread to extract the image. An extraction should never be done on a UI thread.

See the Using Image Factory sample for a full example of how to use this method.

Requirements

Minimum supported client

Windows Vista [desktop apps only]

Minimum supported server

Windows Server 2008 [desktop apps only]

Header

Shobjidl.h

IDL

Shobjidl.idl

 

 

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