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ImageListPopup, a C# class which pops up a window to select an image from an image list

, 23 Feb 2003
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Have you ever wanted to display an image list which looks like the MSN Messenger emoticon chooser...
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Sample Image - ImageListPopup.jpg

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Introduction

The ImageListPopup is a quite easy to use Class that inherits from System.Windows.Forms.Form and allows to show a popup displaying the content of a specified Image List. When you click over an image, an event is fired and you get the index of the clicked image in the imagelist.

Features

The ImageListPopup class supports:
  • Custom colors for the grid, background color and selection color
  • Adjustable horizontal and vertical spaces between images

Compatibility

This class is stand alone and doesn't need any particular Libraries except .NET default ones. It runs in managed code and hence should be portable.

How to use the Class

  • First of all, copy ImageListPopup.cs in your project directory.
  • Add on the top of your source code the directive using CustomUIControls;
  • add a member variable in your class:
    ImageListPopup imageListPopup;
  • In your constructor add the following lines:
    imageListPopup = new ImageListPopup();
    
    // facultative properties
    imageListPopup.BackgroundColor = Color.FromArgb(241,241,241);
    imageListPopup.BackgroundOverColor = Color.FromArgb(102,154,204);
    imageListPopup.HLinesColor = Color.FromArgb(182,189,210);
    imageListPopup.VLinesColor = Color.FromArgb(182,189,210);
    imageListPopup.BorderColor = Color.FromArgb(0,0,0);
    imageListPopup.EnableDragDrop = true;
    
    imageListPopup.Init(imageList,8,8,5,4);
    imageListPopup.ItemClick += new ImageListPopupEventHandler(OnItemClicked);
    

Details

imageListPopup.BackgroundColor = Color.FromArgb(241,241,241);
imageListPopup.BackgroundOverColor = Color.FromArgb(102,154,204);
imageListPopup.HLinesColor = Color.FromArgb(182,189,210);
imageListPopup.VLinesColor = Color.FromArgb(182,189,210);
imageListPopup.BorderColor = Color.FromArgb(0,0,0);

These properties allow us to customize the different colors of the ImageList Popup (see the picture below for details):

Sample popup


The properties must be set before calling Init(), otherwise they won't be taken into account.

imageListPopup.EnableDragDrop = true;

This property allows to Enable Drag'n'Drop support (default is false). You can drag a bitmap from the popup to any Drop target. A Bitmap object and a string containing the Id of the dropped image in the imagelist are available to the target.

imageListPopup.Init(imageList,8,8,5,4);

This line sets the image list, the horizontal and vertical pixel spaces between 2 images, and the rows and columns number (must be present).

imageListPopup.ItemClick += new ImageListPopupEventHandler(OnItemClicked);

This is the Event that is fired when an image is selected. The delegate should look like this:

private void OnItemClicked(object sender, ImageListPopupEventArgs e)
{
 label1.Text = "Selected Image: " + e.SelectedItem;
}

When you want to show the ImageListPopup, you just have to call:

imageListPopup.Show(x,y);

Technical issues

When Init is called, a pre-calculated bitmap is generated with all the static drawing (the background Color, the grid, and all the images)

public bool Init(ImageList imageList, int nHSpace, int nVSpace,<BR>                 int nColumns, int nRows)
{
    _imageList = imageList;
    _nColumns = nColumns;
    _nRows = nRows;
    _nHSpace = nHSpace;
    _nVSpace = nVSpace;
    _nItemWidth = _imageList.ImageSize.Width + nHSpace;
    _nItemHeight = _imageList.ImageSize.Height + nVSpace;
    _nBitmapWidth = _nColumns * _nItemWidth + 1;
    _nBitmapHeight = _nRows * _nItemHeight + 1;
    this.Width = _nBitmapWidth;
    this.Height = _nBitmapHeight;


    _Bitmap = new Bitmap(_nBitmapWidth,_nBitmapHeight);
    Graphics grfx = Graphics.FromImage(_Bitmap);
    grfx.FillRectangle(new SolidBrush(BackgroundColor), 0, 0,<BR>                                      _nBitmapWidth, _nBitmapHeight);
    for (int i=0;i<_nColumns;i++)
        grfx.DrawLine(new Pen(VLinesColor), i*_nItemWidth, 0,<BR>                              i*_nItemWidth, _nBitmapHeight-1);
    for (int i=0;i<_nRows;i++)
        grfx.DrawLine(new Pen(HLinesColor), 0, <BR>                        i*_nItemHeight, _nBitmapWidth-1, i*_nItemHeight);
    
    grfx.DrawRectangle(new Pen(BorderColor), 0 ,0 , <BR>                               _nBitmapWidth-1, _nBitmapHeight-1);

    for (int i=0;i<_nColumns;i++)
        for (int j=0;j<_nRows ;j++)
            if ((j*_nColumns+i) < imageList.Images.Count)
                imageList.Draw(grfx,
                        i*_nItemWidth+_nHSpace/2,
                        j*_nItemHeight+nVSpace/2,
                        imageList.ImageSize.Width,
                        imageList.ImageSize.Height,
                        j*_nColumns+i);

    return true;
}

In the PaintBackground method, we blit the previously generated bitmap onto a hidden bitmap, then we draw the selection rectangle, and finally we blit everything to the screen with a basic double buffering technique.

protected override void OnPaintBackground(PaintEventArgs pea)
{
    Graphics grfx = pea.Graphics;
    grfx.PageUnit = GraphicsUnit.Pixel;
    
    // Basic double buffering technique
    Bitmap offscreenBitmap = new Bitmap(_nBitmapWidth, _nBitmapHeight);
    Graphics offscreenGrfx = Graphics.FromImage(offscreenBitmap);
    // We blit the precalculated bitmap on the offscreen Graphics
    offscreenGrfx.DrawImage(_Bitmap, 0, 0);

    if (_nCoordX!=-1 && _nCoordY!=-1 && <BR>       (_nCoordY*_nColumns+_nCoordX)<_imageList.Images.Count)
    {
        // We draw the selection rectangle
        offscreenGrfx.FillRectangle(new SolidBrush(BackgroundOverColor),
                                    _nCoordX*_nItemWidth + 1,
                                    _nCoordY*_nItemHeight + 1,
                                    _nItemWidth-1, _nItemHeight-1);
        if (_bIsMouseDown)
        {
            // Mouse Down aspect for the image
            _imageList.Draw(offscreenGrfx,
                _nCoordX*_nItemWidth + _nHSpace/2 + 1,
                _nCoordY*_nItemHeight + _nVSpace/2 + 1,
                _imageList.ImageSize.Width,
                _imageList.ImageSize.Height,
                _nCoordY*_nColumns + _nCoordX);
        }
        else
        {
            // Normal aspect for the image
            _imageList.Draw(offscreenGrfx,
                _nCoordX*_nItemWidth + _nHSpace/2,
                _nCoordY*_nItemHeight + _nVSpace/2,
                _imageList.ImageSize.Width,
                _imageList.ImageSize.Height,
                _nCoordY*_nColumns + _nCoordX);
        }
        // Border selection Rectangle
        offscreenGrfx.DrawRectangle(new Pen(BorderColor),
                                    _nCoordX*_nItemWidth, <BR>                                    _nCoordY*_nItemHeight,
                                    _nItemWidth, _nItemHeight);
    }

    // We blit the offscreen image on the screen
    grfx.DrawImage(offscreenBitmap, 0, 0);
}

Conclusion

I hope this code will be useful to you. If you have suggestions to enhance this class functionalities, please post a comment.

Updates

  • 24/02/2003 : Initial Release
  • 25/02/2003 : Added Keyboard support, Added Drag'n'Drop Support (disabled by default) - The selected Image and its Id are available to the drop target

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

John O'Byrne
Web Developer
United States United States
I live in Santa Clara CA and work as a software engineer for SAP Business Objects.
 
My areas of expertise are user interface developments in Eclipse RCP / SWT / Draw 2D and C#

Comments and Discussions

 
QuestionSelecting multiple images? Pinmemberlorecaster14-Jan-13 23:49 
GeneralMy vote of 5 Pinmembermanoj kumar choubey21-Feb-12 1:19 
QuestionAnyone have this working under 2008? PinmemberlittleGreenDude30-Dec-10 10:07 
AnswerRe: Anyone have this working under 2008? PinmemberlittleGreenDude3-Jan-11 9:26 
GeneralMy vote of 4 PinmemberToli Cuturicu14-Aug-10 6:45 
QuestionLicense Pinmemberclaudiogmi9-Jun-10 8:40 
GeneralScroll Bars PinmemberMember 434709223-Sep-08 0:40 
GeneralShowDialog problem PinmemberAlwik7-Dec-06 23:22 
GeneralLicense on source code and icons Pinmembermaihuaz30-Nov-06 14:24 
QuestionCould Embedded and chip lavel programming Possible in C#? Pinmemberrup_rj24-Sep-06 9:30 
GeneralNIce control Pinmemberdotnetfireball16-Mar-06 13:00 
GeneralDemo project is not downloading Pinmembersuresh_unique18-Aug-05 6:35 
GeneralRe: Demo project is not downloading PinmemberJohn O'Byrne18-Aug-05 6:49 
Questionanimated gif support? PinmemberUnruled Boy4-Jul-05 17:46 
GeneralToolTip PinmemberBluetears8-Oct-03 23:07 
GeneralYou forgot to release Graphics resource !! PinmemberJusin6-Apr-03 16:14 
GeneralRe: You forgot to release Graphics resource !! PinmemberJohn O'Byrne7-Apr-03 7:41 
GeneralRe: You forgot to release Graphics resource !! PinmemberJusin7-Apr-03 15:51 
GeneralRe: You forgot to release Graphics resource !! PinmemberTimDet5-May-04 14:56 
QuestionHow could i add those images to a richtextbox? PinmemberAcme31-Mar-03 4:48 
AnswerRe: How could i add those images to a richtextbox? PinmemberJohn O'Byrne31-Mar-03 5:33 
GeneralOne word PinsussAnonymous5-Mar-03 7:39 
GeneralGreat job. PinmemberRyan Farley4-Mar-03 6:43 
GeneralRe: Great job. PinmemberJohn O'Byrne4-Mar-03 11:31 
GeneralSlick PinmemberChopper25-Feb-03 1:15 

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