Thursday, November 10, 2011

C# - ListView Item Spacing (Padding)

I'm perplexed at the reasoning that the ListView control, has no direct spacing/padding property. I am utilizing the ListView in the capacity of images, using the View state, View.LargeIcon. There is a method to modify the spacing/padding between the ListViewItem(s).

Initially, you'll need to add:
using System.Runtime.InteropServices;
Next, you'll need to import the DLL, so that you can utilize SendMessage, to modify the ListView parameters.
[DllImport("user32.dll")]
public static extern int SendMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam); 
Once completed, create the following two functions/methods:
public int MakeLong(short lowPart, short highPart)
{
     return (int)(((ushort)lowPart) | (uint)(highPart << 16));
}
 
public void ListViewItem_SetSpacing(ListView listview, short leftPadding, short topPadding) 
{     
    const int LVM_FIRST = 0x1000;     
    const int LVM_SETICONSPACING = LVM_FIRST + 53;     
    SendMessage(listview.Handle, LVM_SETICONSPACING, IntPtr.Zero, (IntPtr)MakeLong(leftPadding, topPadding));      
}
Then to use the function, just pass in your ListView, and set the values. In the example, 64 pixels is the image width, and 32 pixels is my horizontal spacing/padding, 100 pixels is the image height, and 16 pixels is my vertical spacing/padding, and both parameters require a minimum of 4 pixels.
ListViewItem_SetSpacing(this.listView, 64 + 32, 100 + 16);
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