Hi all,
I have a directory full of images (most over 2MB in size) I was to show
each image as a thumbnail on a form, however in order to create a thumbnail I
have to open the complete image then scale it down. This is quite slow,
since there is a lot of file IO going on, what I want to be able to do is
open the image in the scaled down size so that I miss out the step of opening
the file then dowsizing it. I have not been able to find any way to do this
using .NET, possibly it is some Win32 API call, does anyone know?

If you look in Windows Explorer in thumbnail view it shows a thumbnail for
all the images in a directory lightening fast, there must be some Win32
method that can produce thumb size images without reading the whole file -
how can I be this fast using .Net?

Thanks
Mark

Mark,

In order to do this, you will want to use the IExtractImage interface on
the shell item (through COM interop). Here is a link to an old post on
google where I link to how to do this (watch for line wrap):

http://groups.google.com/group/micro...c571f730e13a25

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (E-Mail Removed)

"Mark R. Dawson" <(E-Mail Removed)> wrote in message
news:27522485-C463-411A-895B-(E-Mail Removed)...
> Hi all,
> I have a directory full of images (most over 2MB in size) I was to show
> each image as a thumbnail on a form, however in order to create a
> thumbnail I
> have to open the complete image then scale it down. This is quite slow,
> since there is a lot of file IO going on, what I want to be able to do is
> open the image in the scaled down size so that I miss out the step of
> opening
> the file then dowsizing it. I have not been able to find any way to do
> this
> using .NET, possibly it is some Win32 API call, does anyone know?
>
> If you look in Windows Explorer in thumbnail view it shows a thumbnail for
> all the images in a directory lightening fast, there must be some Win32
> method that can produce thumb size images without reading the whole file -
> how can I be this fast using .Net?
>
> Thanks
> Mark
>

Using IExtractImage will provide a speed advantage only if thumbnails are
already generated and cached.

If not, then it is not possible to generate a thumbnail without having to
read the whole image file.

----------------
-Atul, Sky Software http://www.ssware.com
Shell MegaPack For .Net & ActiveX
Windows Explorer GUI Controls
&
Quick-Launch Like Appbars, MSN/Office2003 Style Popups,
System Tray Icons and Shortcuts/Internet Shortcuts
----------------



"Nicholas Paldino [.NET/C# MVP]" <(E-Mail Removed)> wrote in
message news:%(E-Mail Removed)...
> Mark,
>
> In order to do this, you will want to use the IExtractImage interface
> on the shell item (through COM interop). Here is a link to an old post on
> google where I link to how to do this (watch for line wrap):
>
> http://groups.google.com/group/micro...c571f730e13a25
>
> Hope this helps.
>
>
> --
> - Nicholas Paldino [.NET/C# MVP]
> - (E-Mail Removed)
>
> "Mark R. Dawson" <(E-Mail Removed)> wrote in message
> news:27522485-C463-411A-895B-(E-Mail Removed)...
>> Hi all,
>> I have a directory full of images (most over 2MB in size) I was to
>> show
>> each image as a thumbnail on a form, however in order to create a
>> thumbnail I
>> have to open the complete image then scale it down. This is quite slow,
>> since there is a lot of file IO going on, what I want to be able to do is
>> open the image in the scaled down size so that I miss out the step of
>> opening
>> the file then dowsizing it. I have not been able to find any way to do
>> this
>> using .NET, possibly it is some Win32 API call, does anyone know?
>>
>> If you look in Windows Explorer in thumbnail view it shows a thumbnail
>> for
>> all the images in a directory lightening fast, there must be some Win32
>> method that can produce thumb size images without reading the whole
>> file -
>> how can I be this fast using .Net?
>>
>> Thanks
>> Mark
>>
>
>