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ImageViewerInteractiveMode Class

Summary

Base class for the rich user experience features of the ImageViewer.

Syntax
C#
Objective-C
C++
public abstract class ImageViewerInteractiveMode 
@interface LTImageViewerInteractiveMode : NSObject //ABSTRACT 
vb[VB Syntax] 
Public MustInherit Class ImageViewerInteractiveMode 
public ref class ImageViewerInteractiveMode abstract 
Remarks

ImageViewerInteractiveMode works with the InteractiveService object of the ImageViewer to provide rich user interface experiences when the user interacts with the viewer using mouse or touch.

ImageViewerInteractiveMode is a base abstract class: from it you can derive your own class to handle custom interaction with the viewer. For more information and for a list of the out-of-the-box modes provided by LEADTOOLS, refer to Image Viewer Interactive Modes.

ImageViewerInteractiveMode has the following functionality:

Member Description

WorkingCursor, IdleCursor and HitTestStateCursor

Cursor to use when the interactive mode is in an idle, working or hit-test state (for desktop browsers).

MouseButtons

The mouse button attached to this mode (for desktop browsers)

To use an interactive mode, you create an instance of any of the derived classes and assign it to the viewer using one of the following methods:

Within the derived class, attach listeners to the events of InteractiveService to perform actions based on user input. Set InteractiveEventArgs.IsHandled to true to mark the events as handled so that other interactive modes will not also respond to the events, if desired.

You can use multiple interactive modes at the same time. For example, use the following code to support panning/zooming with the left mouse button and magnify glass with the right button:

Example

This example will create a custom ImageViewerInteractiveMode that will rotate the image when the user clicks or touches and drags on the viewer.

C#
using Leadtools; 
using Leadtools.Controls; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
 
private class TransformInteractiveMode : ImageViewerInteractiveMode 
{ 
   public TransformInteractiveMode() : 
      base() 
   { 
      this.AutoItemMode = ImageViewerAutoItemMode.AutoSet; 
   } 
 
   private Keys _scaleKeyModifier = Keys.Control; 
   public virtual Keys ScaleKeyModifier 
   { 
      get { return _scaleKeyModifier; } 
      set 
      { 
         // Supported is none and any modifiers 
         switch (value) 
         { 
            case Keys.None: 
            case Keys.Alt: 
            case Keys.Shift: 
            case Keys.Control: 
               _scaleKeyModifier = value; 
               break; 
 
            default: 
               throw new ArgumentException("Invalid value", "ScaleKeyModifier"); 
         } 
      } 
   } 
 
   private Keys _rotateKeyModifier = Keys.Alt; 
   public virtual Keys RotateKeyModifier 
   { 
      get { return _rotateKeyModifier; } 
      set 
      { 
         // Supported is none and any modifiers 
         switch (value) 
         { 
            case Keys.None: 
            case Keys.Alt: 
            case Keys.Shift: 
            case Keys.Control: 
               _rotateKeyModifier = value; 
               break; 
 
            default: 
               throw new ArgumentException("Invalid value", "PageKeyModifier"); 
         } 
      } 
   } 
 
   public override string Name 
   { 
      get { return "Transform"; } 
   } 
 
   public override int Id 
   { 
      get { return ImageViewerInteractiveMode.UserModeId + 3; } 
   } 
 
   public override void Start(ImageViewer imageViewer) 
   { 
      base.Start(imageViewer); 
      var service = base.InteractiveService; 
 
      // Pan required events 
      service.DragStarted += new EventHandler<InteractiveDragStartedEventArgs>(service_DragStarted); 
      service.DragDelta += new EventHandler<InteractiveDragDeltaEventArgs>(service_DragDelta); 
      service.DragCompleted += new EventHandler<InteractiveDragCompletedEventArgs>(service_DragCompleted); 
      service.DoubleTap += new EventHandler<InteractiveEventArgs>(service_DoubleTap); 
   } 
 
   public override void Stop(ImageViewer imageViewer) 
   { 
      if (IsStarted) 
      { 
         var service = base.InteractiveService; 
 
         service.DragStarted -= new EventHandler<InteractiveDragStartedEventArgs>(service_DragStarted); 
         service.DragDelta -= new EventHandler<InteractiveDragDeltaEventArgs>(service_DragDelta); 
         service.DragCompleted -= new EventHandler<InteractiveDragCompletedEventArgs>(service_DragCompleted); 
         service.DoubleTap -= new EventHandler<InteractiveEventArgs>(service_DoubleTap); 
 
         base.Stop(imageViewer); 
      } 
   } 
 
   private void service_DragStarted(object sender, InteractiveDragStartedEventArgs e) 
   { 
      // Make sure pinch is not working, otherwise, ignore pan 
      if (!this.CanStartWork(e)) 
         return; 
 
      // Make sure we are on an item 
      if (this.Item == null) 
         return; 
 
      e.IsHandled = true; 
      this.OnWorkStarted(EventArgs.Empty); 
   } 
 
   private void service_DragDelta(object sender, InteractiveDragDeltaEventArgs e) 
   { 
      if (!this.IsWorking) 
         return; 
 
      var item = this.Item; 
      if (item == null) 
         return; 
 
      // Find out what to do 
      var dx = e.Change.X; 
      var dy = e.Change.Y; 
 
      if (dx == 0 && dy == 0) 
         return; 
 
      var scaleKeyModifier = this.ScaleKeyModifier; 
      var rotateKeyModifier = this.RotateKeyModifier; 
      var scale = (Control.ModifierKeys & scaleKeyModifier) == scaleKeyModifier; 
      var rotate = (Control.ModifierKeys & rotateKeyModifier) == rotateKeyModifier; 
 
      var imageViewer = this.ImageViewer; 
 
      if (scale) 
      { 
         Scale(imageViewer, item, dy, e.Origin); 
      } 
      else if (rotate) 
      { 
         Rotate(imageViewer, item, dx, e.Origin); 
      } 
      else 
      { 
         Translate(imageViewer, item, dx, dy); 
      } 
 
      e.IsHandled = true; 
   } 
 
   private void service_DragCompleted(object sender, InteractiveDragCompletedEventArgs e) 
   { 
      if (!this.IsWorking) 
         return; 
 
      e.IsHandled = true; 
      OnWorkCompleted(EventArgs.Empty); 
   } 
 
   private void service_DoubleTap(object sender, InteractiveEventArgs e) 
   { 
      // Make sure we not working already 
      if (this.IsWorking || !this.CanStartWork(e)) 
         return; 
 
      // Make sure we have an item 
      var item = this.Item; 
      if (item == null) 
         return; 
 
      e.IsHandled = true; 
 
      this.OnWorkStarted(EventArgs.Empty); 
      Identity(this.ImageViewer, item); 
      this.OnWorkCompleted(EventArgs.Empty); 
   } 
 
   private void Identity(ImageViewer imageViewer, ImageViewerItem item) 
   { 
      item.Transform = LeadMatrix.Identity; 
   } 
 
   private void Scale(ImageViewer imageViewer, ImageViewerItem item, int dy, LeadPoint position) 
   { 
      // ... 
      // set scale code 
      // ... 
   } 
 
   private void Rotate(ImageViewer imageViewer, ImageViewerItem item, int dx, LeadPoint position) 
   { 
      // ... 
      // set rotate code 
      // ... 
   } 
 
   private void Translate(ImageViewer imageViewer, ImageViewerItem item, int dx, int dy) 
   { 
      // ... 
      // set translate code 
      // ... 
   } 
} 
 
public void ImageViewerInteractiveMode_Example() 
{ 
   _imageViewer.InteractiveModes.BeginUpdate(); 
   _imageViewer.InteractiveModes.Add(new TransformInteractiveMode { IsEnabled = false }); 
   //... 
   //... 
   //... 
   _imageViewer.InteractiveModes.EndUpdate(); 
} 
Requirements

Target Platforms

Help Version 22.0.2022.4.4
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Leadtools.Controls Assembly

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© 1991-2022 LEAD Technologies, Inc. All Rights Reserved.