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ImageViewerViewLayout Class

Summary

Defines an ImageViewer layout controller.

Syntax
C#
C++/CLI
public abstract class ImageViewerViewLayout 
public ref class ImageViewerViewLayout abstract 
Remarks

ImageViewerViewLayout is the main class responsible for setting up the image viewer layout.

Derived classes must implement the following:

The layout must perform the following actions when UpdateTransform is called. All the values calculation must use the scale factor passed to the method and the viewer will update for view alignment after the method returns:

  • Update the itemBounds property: This is an array of rectangles that must be filled with the location and size of each item. Each value must be calculated based on the item size and its transformations. The items must be arranged in any way desired usually creating rows and columns or stacked on top of each other.

  • Update the values of ImageViewerItem.RowIndex and ImageViewerItem.ColumnIndex for each item: These values must be set to the 0-based index of the item row and column in the view grid (if any). The value will be used by code that requires finding the item to the left, top, right or bottom of another item such as ImageViewerSelectItemsInteractiveMode when using the arrow keys.

  • Set the value of SizeModeWidth: This is the width of the layout in pixels. The viewer will use this value to control how much to zoom when FitWidth> is used for example. Typically this should be the width of largest column.

  • Set the value of SizeModeWidthItemCount: The number of items in the largest column.

  • Set the value of SizeModeHeight: This is the height of the layout in pixels. The viewer will use this value to control how much to zoom when FitHeight is used for example. Typically this should be the height of the largest row.

  • Set the value of SizeModeHeightItemCount: The number of items in the largest row.

The following methods are available to help with the calculations of these values:

  • AlignHeights: Align the heights of the items and return the largest value.

  • AlignWidths: Align the widths of the items and return the largest value.

  • AlignRow: Align the items to even distances in a row.

  • AlignColumn: Align the items to even distances in a column.

For more information, refer to Image Viewer Layouts, Image Viewer Items, Image Viewer Transformation and Image Viewer Bounds and Transform.

Example
C#
using Leadtools; 
using Leadtools.Controls; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
 
 
public ImageViewerForm _form = new ImageViewerForm(); 
public ComboBox comboBox = new ComboBox(); 
public ImageViewer _imageViewer; 
 
public void ImageViewerViewLayoutExample() 
{ 
 
   // Get the ImageViewer control from the form 
   _imageViewer = _form.ImageViewer; 
 
   // Clear all the images already the viewer 
   _imageViewer.Items.Clear(); 
   // Use vertical view layout 
   _imageViewer.ViewLayout = new ImageViewerVerticalViewLayout(); 
   // Item Border 
   _imageViewer.ItemBorderThickness = 1; 
   // Make sure the item size is larger than the image size (thumbnails mode) 
   _imageViewer.ItemSize = LeadSize.Create(200, 200); 
 
   // Add 4 items to the viewer 
   using (var codecs = new RasterCodecs()) 
   { 
      for (var page = 1; page <= 4; page++) 
      { 
         ImageViewerItem item = new ImageViewerItem(); 
         var fileName = Path.Combine(LEAD_VARS.ImagesDir, string.Format("ocr{0}.tif", page)); 
 
         // Create a thumbnail from the image 
         using (var image = codecs.Load(fileName, page)) 
         { 
            item.Image = image.CreateThumbnail(180, 180, 24, RasterViewPerspective.TopLeft, RasterSizeFlags.Resample); 
         } 
         _imageViewer.Items.Add(item); 
      } 
   } 
 
   // Add a combo box control to show the view layout modes 
   comboBox.Top = _form.ClientRectangle.Top; 
   _form.Controls.Add(comboBox); 
 
   // Add an entry for each view mode to the combo box 
   comboBox.Items.Add("Single view layout"); 
   comboBox.Items.Add("Vertical view layout"); 
   comboBox.Items.Add("Horizontal view layout"); 
   comboBox.Items.Add("Vertical view layout - 2 Columns"); 
   comboBox.Items.Add("Horizontal view layout - 2 Rows"); 
 
   comboBox.BringToFront(); 
 
   // When the user selects a view layout mode from the combo box 
   comboBox.SelectedIndexChanged += ComboBox_SelectedIndexChanged; 
} 
 
private void ComboBox_SelectedIndexChanged(object sender, EventArgs e) 
{ 
   ComboBox comboBox = sender as ComboBox; 
   ImageViewerViewLayout layout; 
 
   switch (comboBox.SelectedItem.ToString()) 
   { 
      case "Single view layout": 
         layout = new ImageViewerSingleViewLayout(); 
         break; 
      case "Vertical view layout": 
      default: 
         layout = new ImageViewerVerticalViewLayout(); 
         break; 
      case "Horizontal view layout": 
         layout = new ImageViewerHorizontalViewLayout(); 
         break; 
      case "Vertical view layout - 2 Columns": 
         layout = new ImageViewerVerticalViewLayout() { Columns = 2 }; 
         break; 
      case "Horizontal view layout - 2 Rows": 
         layout = new ImageViewerHorizontalViewLayout() { Rows = 2 }; 
         break; 
   } 
 
   _imageViewer.ViewLayout = layout; 
   _imageViewer.UpdateTransform(); 
   // Call Zoom with current values to update ImageViewer.ViewLayout values 
   _imageViewer.Zoom(_imageViewer.SizeMode, _imageViewer.ScaleFactor, _imageViewer.DefaultZoomOrigin);  
 
   string msg = string.Format("Layout.Name = {0}\nLayout.SizeModeHeight = {1}\nLayout.SizeModeHeightItemCount = {2}\nLayout.SizeModeWidth = {3}\nLayout.SizeModeWidthItemCount = {4}\n", 
      _imageViewer.ViewLayout.Name, 
      _imageViewer.ViewLayout.SizeModeHeight, 
      _imageViewer.ViewLayout.SizeModeHeightItemCount, 
      _imageViewer.ViewLayout.SizeModeWidth, 
      _imageViewer.ViewLayout.SizeModeWidthItemCount); 
   Debug.WriteLine(msg, "ImageViewerLayout Information"); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS23\Resources\Images"; 
} 
Requirements

Target Platforms

Help Version 23.0.2024.2.29
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Leadtools.Controls Assembly
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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.