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How to display the sort order in the listview columns

The way you can display the sort order in the column can change under different Windows versions. More exactly, it depends on the different common controls version you (implicitly) load: the 6.0 version (the latest one) or versions inferior to the 6.0. In fact, with commctrl version 6, displaying the column order is as easy as setting a flag. Under Windows 9x/ME/2000, instead, you need to manually set an image in the header. This tutorial's code works in both cases. Let's see how to do it.

Is the user using the latest common control version?

So, we need to check if the application is using the latest commctrl.dll version. Here's how to test it:


Let's dig into the code. All the common Windows DLLs exports a function called DllGetVersion, that gets the version of the DLL it was loaded from: in fact we can only load it dynamically. The DLLVERSIONINFO structure passed to it will then contain the version divided in three vars (major, minor and build version). The only thing that matters here is the major version, since all the old version are inferior to 6. Finally, since this function will be called many times, the result is stored in a static variable.

The function

As said before, the older versions of Windows needs an image to be set manually in the header: two images, actually, a down and an up arrow bitmaps. These two bitmaps are available in the download section of this page. It's your choice where to put them: i've included them in the executable and i use LoadImage and IDs to load those images. Change it if you put them elsewhere.

Here's the complete function code:

The function, explained

The function has this prototype: So, whenever you call this function, you must pass:

• the listview window handle
• the index of the column that is sorted
• whether or not the order is ascending (up arrow displayed) or descending (down arrow displayed)

The LVN_COLUMNCLICK notification handler should be the right place to put this function.

Inside the function now: The LVCOLUMN structure is useless, because it doesn't let you set all the header's features. So i'm going to use the header messages (HDM_X) sent to the header window, obtained through ListView_GetHeader. I store the BOOL that is TRUE or FALSE whether the application has commctrl version 6 loaded, to avoid unnecessary overhead by calling the function more than once inside this function.

The function doesn't store neither require from you the last ordered column index, so i need to iterate through all the existing columns to add the image to the correct column index and remove it from all the other column. And, since there are always few columns, this loop doesn't halt your program.

Here i retrieve the column props from the header through Header_GetItem. With commctrl 6, the only thing that changes is the format; without it i need to retrieve and set the bitmap too. So,

• version >= 6: HDI_FORMAT
• version < 6: HDI_FORMAT|HDI_BITMAP

The column index corresponds to the index you passed to the function, so this column is being sorted. As before, two ways:

• version >= 6
  • since i don't know which flag was set before, i remove the both of them
  • set the correct format flag for the order basing upon the value of isAscending: HDF_SORTUP or HDF_SORTDOWN. Windows will draw the order image in the header.
• version < 6
  • delete the old bitmap if it exists
  • append the format flags: HDF_BITMAP (again :) and HDF_BITMAP_ON_RIGHT (since the bitmap should be to the right of the text)
  • load and set the correct bitmap basing on the value of isAscending with LoadImage and the special flag LR_LOADMAP3DCOLORS. This flag replace the gray color ( RGB(192,192,192) ) with the corresponding system color (COLOR_3DFACE) that is also the background color of each column in the header.

All the other column indexex aren't being sorted, so i remove the image/flags from them (even if they don't have it).

Finally, i apply the changes through Header_SetItem and the modified HDITEM structure.

From the download section on this page you can download an example or a demo to test this function with your hands.

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