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ThumbnailSizeFlags Property

Summary

Controls the quality of the thumbnail images created by the control.

Syntax

C++/CLI

C++

public RasterSizeFlags ThumbnailSizeFlags { get; set; }

public: 
property RasterSizeFlags ThumbnailSizeFlags { 
   RasterSizeFlags get(); 
   void set (    RasterSizeFlags ); 
}

public:  
   property RasterSizeFlags^ ThumbnailSizeFlags 
   { 
      RasterSizeFlags^ get() 
      void set(RasterSizeFlags^ value) 
   }

Property Value

A Leadtools.RasterSizeFlags enumeration that controls quality of the thumbnail images created by the control.

Remarks

The RasterThumbnailBrowser control creates thumbnail for the images found as a result of calling the LoadThumbnails(String,String,RasterThumbnailBrowserLoadFlags) method. Some of these images might be larger than the ItemImageSize value, so the control will create a thumbnail of these images. You can control the speed and quality of the thumbnail creation operation by changing the ThumbnailSizeFlags property. For example, RasterSizeFlags.Normal will result in the fastest thumbnail creation operation but with lower quality. RasterSizeFlags.Bicubic will result in very high quality thumbnails, but the process of creating these thumbnails is much slower. Several other options are available, for more information, refer to the Leadtools.RasterSizeFlags enumeration.

Important note: RasterSizeFlags.FavorBlack is not supported in loading image thumbnails. If this flag is set, the RasterThumbnailBrowser control will use RasterSizeFlags.Bicubic instead.

Example

using Leadtools.WinForms; 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
 
class MyForm : Form 
{ 
   public RasterThumbnailBrowser theBrowser; 
   public bool cancelOperation;        // Informs us if the user canceled the operation 
   public Button buttonCancel;         // Cancel browse loading 
   public Button buttonBrowse;         // Diplays the browse control 
   public ProgressBar progressBar;     // shows progress of loading browse images 
 
   void buttonBrowse_Click(object sender, EventArgs e) 
   { 
      // If we are already loading thumbails, cancel 
      // this operation 
      if (theBrowser.IsLoadingThumbnails) 
         theBrowser.CancelLoadingThumbnails(); 
 
      // Clean all the items 
      theBrowser.Items.Clear(); 
 
      // Update the application state 
      buttonCancel.Enabled = true; 
      progressBar.Value = 0; 
 
      // And load the new thumbnails 
      cancelOperation = false; 
 
      string folderPath = LEAD_VARS.ImagesDir; 
      theBrowser.LoadStamp = true; 
      theBrowser.LoadThumbnails(folderPath, "*.*", RasterThumbnailBrowserLoadFlags.Block); 
 
      theBrowser.Refresh(); 
 
      theBrowser.EnableBrowserWatcher = true; 
   } 
 
   private void thumbnailBrowser_LoadThumbnail(object sender, RasterThumbnailBrowserLoadThumbnailEventArgs e) 
   { 
      // If this is the first iteration, update the progress bar minimum and maximum values 
      if (e.Index == 0) 
      { 
         progressBar.Minimum = 0; 
         progressBar.Maximum = e.Total - 1; 
      } 
 
      // Update where we are in the loading operation 
      progressBar.Value = e.Index; 
 
      // Check if we need to cancel (due to the user clicking the Cancel button) 
      if (cancelOperation) 
         e.Cancel = true; 
   } 
 
   private void thumbnailBrowser_AddFile(object sender, RasterThumbnailBrowserAddFileEventArgs e) 
   { 
      Console.WriteLine("AddFile: {0}    Add: {1}", e.FileName, e.Add); 
   } 
 
   private void thumbnailBrowser_FinishedLoadingThumbnails(object sender, EventArgs e) 
   { 
      buttonCancel.Enabled = false; 
   } 
 
   private void buttonCancel_Click(object sender, EventArgs e) 
   { 
      // The user has clicked the cancel button 
      this.cancelOperation = true; 
   } 
 
   // Create  custom images to use as the "error" and "loading" thumbnails. 
   void CreateErrorThumbnail() 
   { 
      // Get the image size 
      Size imageSize = theBrowser.ItemImageSize; 
 
      // No "loading" thumbnail 
      theBrowser.LoadingThumbnail = null; 
 
      // For the "error" thumbnail, create a red X image 
      RasterColor[] palette = new RasterColor[0]; 
      RasterImage image = new RasterImage( 
         RasterMemoryFlags.Conventional, 
         imageSize.Width, 
         imageSize.Height, 
         24, 
         RasterByteOrder.Bgr, 
         RasterViewPerspective.TopLeft, 
      palette, 
      IntPtr.Zero, 
      0 
      ); 
 
      IntPtr hdc = RasterImagePainter.CreateLeadDC(image); 
      Graphics g = Graphics.FromHdc(hdc); 
 
      g.FillRectangle(Brushes.Magenta, 0, 0, imageSize.Width, imageSize.Height); 
 
      g.DrawLine(Pens.Red, 0, 0, imageSize.Width, imageSize.Height); 
      g.DrawLine(Pens.Red, imageSize.Width, 0, 0, imageSize.Height); 
 
      g.Dispose(); 
      RasterImagePainter.DeleteLeadDC(hdc); 
 
      // Make this image transparent 
      image.Transparent = true; 
      image.TransparentColor = RasterColor.FromKnownColor(RasterKnownColor.Magenta); 
 
      theBrowser.ErrorThumbnail = image; 
   } 
 
   public void Cleanup() 
   { 
      buttonBrowse.Click -= new EventHandler(buttonBrowse_Click); 
      buttonCancel.Click -= new EventHandler(buttonCancel_Click); 
      theBrowser.LoadThumbnail -= new EventHandler<RasterThumbnailBrowserLoadThumbnailEventArgs>(thumbnailBrowser_LoadThumbnail); 
      theBrowser.FinishedLoadingThumbnails -= new EventHandler(thumbnailBrowser_FinishedLoadingThumbnails); 
   } 
 
   public MyForm() 
   { 
      Size = new Size(300, 200); 
 
      // create the browser 
      theBrowser = new RasterThumbnailBrowser(); 
      theBrowser.Codecs = new RasterCodecs(); 
      theBrowser.Dock = DockStyle.Fill; 
      theBrowser.ItemSpacingSize = new Size(10, 10); 
      theBrowser.ThumbnailSizeFlags = RasterSizeFlags.Bicubic; 
      theBrowser.LoadThumbnail += new EventHandler<RasterThumbnailBrowserLoadThumbnailEventArgs>(thumbnailBrowser_LoadThumbnail); 
      theBrowser.FinishedLoadingThumbnails += new EventHandler(thumbnailBrowser_FinishedLoadingThumbnails); 
      theBrowser.AddFile += new EventHandler<RasterThumbnailBrowserAddFileEventArgs>(thumbnailBrowser_AddFile); 
 
      // Create a thumbnail image to be displayed on error 
      CreateErrorThumbnail(); 
 
      // add a panel 
      Panel panel = new Panel(); 
      panel.Dock = DockStyle.Left; 
      panel.Width = 100; 
      Controls.Add(panel); 
      panel.BringToFront(); 
 
      // add a "browse" button 
      buttonBrowse = new Button(); 
      buttonBrowse.Text = "Browse"; 
      buttonBrowse.Dock = DockStyle.Top; 
      panel.Controls.Add(buttonBrowse); 
      buttonBrowse.Click += new EventHandler(buttonBrowse_Click); 
 
      // add a "cancel" button 
      buttonCancel = new Button(); 
      buttonCancel.Text = "Cancel"; 
      buttonBrowse.Dock = DockStyle.Bottom; 
      panel.Controls.Add(buttonCancel); 
      buttonCancel.Click += new EventHandler(buttonCancel_Click); 
 
      // add a progress bar 
      progressBar = new ProgressBar(); 
      progressBar.Dock = DockStyle.Bottom; 
      Controls.Add(progressBar); 
 
      Controls.Add(theBrowser); 
      theBrowser.BringToFront(); 
   } 
 
   private void InitializeComponent() 
   { 
      this.SuspendLayout(); 
      //  
      // MyForm 
      //  
      this.ClientSize = new System.Drawing.Size(315, 273); 
      this.Name = "MyForm"; 
      this.ResumeLayout(false); 
 
   } 
} 
public void RasterThumbnailBrowser_RasterThumbnailBrowser() 
{ 
   MyForm form = new MyForm(); 
   form.ShowDialog(); 
   form.Cleanup(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms