ListView Watermark in VB.NET

Download source code - 172 KB

lvwBackground1

Windows Vista Screenshot

Windows XP Screenshot

Introduction

This code uses the LVBKIF_TYPE_WATERMARK flag of LVBKIMAGE to put a watermark in the lower right corner of a ListView control.

Using the code

The zip file above includes a class that inherits the ListView. Add the class to your solution, and build the solution. In the control's toolbox, you'll see the cListView added. Drag one onto the form and set its WatermarkImage property to the desired image you want. Also, set the WatermarkAlpha property to the desired translucency. It will support any image file that VB.NET can open. It will automatically convert the image to the needed bitmap.

Points of interest

It took me about 4+ months to figure out how to make the flag work. All I could find were C++ demonstrations for the flag. Finally I came through.

"I strived for a goal, and I succeeded". In other words I tried and tried again.

History

I don't plan on any updates, but you will be the first to know if I do.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

clwprogrammer

United States

Member

Self Taught. I started with vba in excel writing a few templates for my daddy's job. I then went from there to Visual Basic 6. Just played around with it a lot. I saw something I wanted to try to reproduce, and I worked at it until it worked(mostly). Now I am into vb.net. I am currently working on a few different things at the moment, but my time is limited, because I have to work for a living.

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Listviewitem backcolor ignored...

MCS_Erik

0:18 14 Nov '11

Hi. First of all, great work! I noticed that the backcolor of a listviewitem is ignored when you use a watermark. For example. Dim MyItem as new listviewitem("Some text") MyItem.backcolor = color.Blue MyListview.Items.add(MyItem) Mylisview.Watermark = MyImage 'AFTER THIS LINE, THE LISTVIEWITEM IS NO LONGER BLUE.... :( Any solutions to this? Thanks. Erik.
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Re: Listviewitem backcolor ignored...

clwprogrammer

21:28 14 Nov '11

I remember reading somewhere that when using the Watermark Code, that the item's backcolor property is either ignored or overridden.
It is automatically set to transparent or something. I haven't really looked into it yet. There may be a way to circumvent this through owner drawing. I'll play around with it later, I've got a busy week ahead of me. If I come up with something, I'll let you know.

CLWPROGRAMMER

My vote of 5

swdev.bali

18:27 6 Nov '11

I need this type of functionality badly! Thanks for this
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On Windows 2003

juansossa

3:28 29 Oct '09

Hi, The watermark doesn't work on a computer with Windows server 2003 R2. Why? Thanks.
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Re: On Windows 2003

clwprogrammer

10:41 29 Oct '09

Not sure, I don't have a computer with windows server 2003 R2 to test it on. CLWPROGRAMMER
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Similar, but for Textboxes?

Johnny J.

1:13 8 Oct '09

Does anyone know of any way to do somethings similar for a multiline textbox? Not necessarily using P-Invoke The watermark must be semi-transparent so it doesn't disturb the eye too much. TIA, Johnny J.
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Some Information

clwprogrammer

10:40 20 Sep '09

I wanted to let everyone know that I am working on an update. It may take a bit, because I work 8-10 hrs a day and off 2. Some plans are: renaming of some properties(watermarkimage to backgroundimage, WatermarkAlpha to BackgroundImageTransparency), adding some properties(BackgroundImageLayout{None,Stretch,Zoom...}, BackgroundImagePosition{TopLeft,TopCenter,TopRight,...}), Gonna try to fix the item background problem when setting a backgroundimage(microsoft automatically paints item's background color as transparent no matter which backgroundimage setting you use). That's all I can think of at the moment. I won't be updating the article until I get something more concrete to work with. Thanks for your patience.

CLWPROGRAMMER

[My vote of 2] good find

Donsw

16:24 12 Sep '09

good find but why not just add code to the article so I can read what you did, also since you said you took a long time in finding out how to do it why don't you say what the issues were in the article. cheers, Donsw My Recent Article : Backup of Data files - Full and Incremental
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wow ...

FidoDildo

1:03 31 Aug '09

respect, dude ... Thanks for sharing. Just what I was looking for. Any idea how to mak it centered in the listview? And zooming i.s.o. static size? Regards ... ... Dennis
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Re: wow ...

clwprogrammer

8:56 31 Aug '09

This link may help you to get what you need.
http://msdn.microsoft.com/en-us/library/bb774742(VS.85).aspx[^]

the way microsoft's article reads, you have to use lvbkif_style_normal in the ulFlag to be able to move the background image to center, I don't think you can use lvbkif_type_watermark along with lvbkif_style_normal and have the background image to stay stationary. I may be wrong, because I haven't messed around with the other settings for the ulFlag property. I was only trying to get the watermark in the lower right corner to work. I will work on the control a little more to see what I can come up with. Maybe another added property to set the background style and position.

I may be showing my dumb streak, but I'm not too sure what you mean by 'zooming i.s.o static size'.
After all, I'm a self learner. I don't exactly have the time for school at the moment. I just mess around with programming on my free time.

CLWPROGRAMMER

Re: wow ...

FidoDildo

20:24 31 Aug '09

Thanks for the quick reply! If I can find some extra time, I will also play with some of the setting and publish my findings here. >> I'm not too sure what you mean by 'zooming i.s.o static size' I mean that the watermark image can grow and shrink with the control Greetz ... ... Dennis
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Re: wow ...

clwprogrammer

6:17 1 Sep '09

>>image can grow and shrink with the control in the extended control's code, edit the getbmp code to redraw the image to the size you want. because that's really what I do to get the alphablended effect. CLWPROGRAMMER
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A change in the GetBMP Function in the extended control's code.

clwprogrammer

23:00 14 Aug '09

The following is the GetBMP Function currently in the zipped code.

	Private Function GetBMP(ByVal FromImage As Image) As IntPtr
        Dim bmp As Bitmap = New Bitmap(FromImage.Width, FromImage.Height)
        Dim g As Graphics = Graphics.FromImage(bmp)
        g.Clear(Me.BackColor)
        g.DrawImage(FromImage, 0, 0, bmp.Width, bmp.Height)
        g.FillRectangle(New SolidBrush(Color.FromArgb(WatermarkAlpha, Me.BackColor.R, Me.BackColor.G, Me.BackColor.B)), New RectangleF(0, 0, bmp.Width, bmp.Height))
        g.Dispose()
        Return bmp.GetHbitmap
        bmp.Dispose
    End Function

The above will need to be changed to the following, just to make sure the temporary bitmap gets destroyed:

	Private Function GetBMP(ByVal FromImage As Image) As IntPtr
        Dim bmp As Bitmap = New Bitmap(FromImage.Width, FromImage.Height)
        Dim g As Graphics = Graphics.FromImage(bmp)
        g.Clear(Me.BackColor)
        g.DrawImage(FromImage, 0, 0, bmp.Width, bmp.Height)
        g.FillRectangle(New SolidBrush(Color.FromArgb(WatermarkAlpha, Me.BackColor.R, Me.BackColor.G, Me.BackColor.B)), New RectangleF(0, 0, bmp.Width, bmp.Height))
        g.Dispose()
        Dim hBM as IntPtr = bmp.GetHbitmap
        bmp.Dispose
        Return hBM
    End Function

CLWPROGRAMMER

About the BMP.Dispose

clwprogrammer

9:18 6 Aug '09

thank you for the information on the bmp.dispose. I had saw people using the keyword 'Using' in c# but had never seen it being used in vb.NET. I as a self-learner, meaning I have never been to school for this stuff, and learn by examples. Again, Thank You. CLWPROGRAMMER
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bmp.dispose not called in GetMBP

d_camillo

19:03 5 Aug '09

Hi

thx for sharing! I always wanted to know how this is done.

One thing: In GetBMP the bmp.Dispose is afaik not called. The return statement prevents this. I added two using statements.

	

Private Function GetBMP(ByVal FromImage As Image) As IntPtr

  Using bmp = New Bitmap(FromImage.Width, FromImage.Height)

    Using g As Graphics = Graphics.FromImage(bmp)

      ...

    End Using

    Return bmp.GetHbitmap

  End Using

End Function

have a great day
Daniel

Re: bmp.dispose not called in GetMBP

tgrt

2:40 9 Aug '09

Daniel, You are incorrect. The using pattern creates a try..finally block that is functionally the same as the following code Try ... End Try Finally bmp.Dispose() End Finally Even with a return statement the CLR will ensure that the Finally block is called.
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