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ViewTransform Property


Current transformation matrix of the view.

public LeadMatrix ViewTransform { get; } 
   property LeadMatrix^ ViewTransform 
      LeadMatrix^ get() 

Property Value

The current transformation matrix of the view.


The view consists of all current the items in the viewer plus any padding (set in ViewPadding). This is the area that the viewer use to determine whether horizontal and vertical scrollbars are needed and to calculate their size and position.

The view area is calculated during UpdateTransform. The current ViewLayout determines where each item is placed and calculates their sizes. The total of these sizes is calculated and multiplied by any scale factor (XScaleFactor and YScaleFactor) set by the Zoom method. The final size is the view area.

During the calculations, the viewer will calculate the transformation matrix used when rendering the view. This matrix contains the current padding, scroll offset and scale factors and stored in ViewTransform. For example, to render the view border, the viewer simply draws the value of GetViewBounds transformed with ViewTransform.

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

using Leadtools; 
using Leadtools.Controls; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
public ImageViewerForm _form = new ImageViewerForm(); 
public ImageViewer _imageViewer; 
public PictureBox redirectRenderControl; 
public void ImageViewerRedirectRenderExample() 
   // Get the ImageViewer control from the form 
   _imageViewer = _form.ImageViewer; 
   // Load an image 
   using (var codecs = new RasterCodecs()) 
      _imageViewer.Image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "cannon.jpg")); 
   // PanZoom Interactive Mode 
   _imageViewer.DefaultInteractiveMode = new ImageViewerPanZoomInteractiveMode(); 
   // Separate Form with PictureBox control 
   Form redirectRenderForm = new Form(); 
   redirectRenderControl = new PictureBox(); 
   redirectRenderControl.Width = 400; 
   redirectRenderControl.Dock = DockStyle.Fill; 
   // Invalidate on double-click 
   bool renderView = false; 
   redirectRenderControl.DoubleClick += (sender, e) => 
      renderView = !renderView; 
   redirectRenderControl.Paint += (sender, e) => 
      if (_imageViewer.Image == null) 
      // Get PictureBox Graphics object 
      Graphics graphics = e.Graphics; 
      // Destination rectangle in PictureBox 
      int margin = 20; 
      LeadRect destRect = LeadRect.Create(margin, margin, redirectRenderControl.ClientSize.Width - margin * 2, redirectRenderControl.ClientSize.Height - margin * 2); 
      LeadRect clipRect = destRect; 
      // Source rectangle 
      // RenderRedirect Options 
      ImageViewerRenderRedirectOptions options = new ImageViewerRenderRedirectOptions(); 
      options.BackgroundColor = Color.Transparent; 
      // Try to get item from the viewer 
      ImageViewerItem item = null; 
      if (!renderView) 
         item = _imageViewer.Items[0]; 
      LeadRectD sourceRect = LeadRectD.Empty; 
      if (item == null) 
         sourceRect = _imageViewer.GetViewBounds(true, false); 
         sourceRect = _imageViewer.GetItemViewBounds(item, ImageViewerItemPart.Image, false); 
         options.RenderBackgrounds = false; 
         options.RenderBorders = false; 
         options.RenderItemStates = false; 
         options.RenderShadows = false; 
         options.RenderText = false; 
      // Transformation Matrix (represents rotation, zooming...etc)  
      options.CreateTransform(_imageViewer, destRect, sourceRect, ControlSizeMode.FitAlways, ControlAlignment.Center, ControlAlignment.Center); 
      clipRect = options.Transform.TransformRect(sourceRect).ToLeadRect(); 
      // Redirect rendering to the PictureBox Graphics object (Outlined with a black rectangle) 
      _imageViewer.RenderRedirect(graphics, options, clipRect); 
      graphics.DrawRectangle(Pens.Black, destRect.X, destRect.Y, destRect.Width + 1, destRect.Height + 1); 
      // Calculate visible view 
      LeadRectD rect; 
      if (item == null) 
         rect = _imageViewer.GetViewBounds(true, true); 
         rect = _imageViewer.GetItemViewBounds(item, ImageViewerItemPart.Image, true); 
      LeadPointD[] points = 
            LeadPointD.Create(rect.Left, rect.Top), 
            LeadPointD.Create(rect.Right, rect.Bottom) 
      double xmin = points[0].X; 
      double ymin = points[0].Y; 
      double xmax = xmin; 
      double ymax = ymin; 
      for (int i = 1; i < points.Length; i++) 
         if (points[i].X < xmin) xmin = points[i].X; 
         if (points[i].X > xmax) xmax = points[i].X; 
         if (points[i].Y < ymin) ymin = points[i].Y; 
         if (points[i].Y > ymax) ymax = points[i].Y; 
      // Draw yellow rectangle showing visible part of the view 
      LeadRectD bounds = LeadRectD.FromLTRB(xmin, ymin, xmax, ymax); 
      RectangleF rc = new RectangleF((float)bounds.X, (float)bounds.Y, (float)bounds.Width, (float)bounds.Height); 
      graphics.DrawRectangle(Pens.Yellow, rc.X, rc.Y, rc.Width - 1, rc.Height - 1); 
   _imageViewer.RedirectRender += (sender, e) => 
static class LEAD_VARS 
   public const string ImagesDir = @"C:\LEADTOOLS23\Resources\Images"; 

Target Platforms

Help Version 23.0.2024.2.29
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Leadtools.Controls Assembly

Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.