Presentation Locking
Presentation Locking
A common use for Aspose.Slides is to create, update and save Microsoft PowerPoint 2007 (PPTX) presentations as part of an automated workflow. Users of the application that uses Aspose.Slides this way get access to the output presentations. Protecting them from editing is a common concern. It is important that auto-generated presentations retain their original formatting and content.
This explains how presentations and slides are constructed and how Aspose.Slides for .NET can apply protection to, and then remove it from a presentation. This feature is unique to Aspose.Slides and, at the time of writing, is not available in Microsoft PowerPoint. It gives developers a way of controlling how the presentations their applications create are used.
Composition of a Slide
A PPTX slide is composed of a number of components like auto shapes, tables, OLE objects, grouped shapes, picture frames, video frames, connectors and the various other elements available to build up a presentation.
In Aspose.Slides for .NET, each element on a slide is turned into a Shape object. In other words, each element on the slide is either a Shape object or an object derived from the Shape object.
The structure of PPTX is complex so unlike PPT, where a generic lock can be used for all type of shapes, there are different types of locks for different shape type. The BaseShapeLock class is the generic PPTX locking class. The following types of locks are supported in Aspose.Slides for .NET for PPTX.
- AutoShapeLock locks auto shapes.
- ConnectorLock locks connecter shapes.
- GraphicalObjectLock locks graphical objects.
- GroupshapeLock locks group shapes.
- PictureFrameLock locks picture frames.
Any action performed on all Shape objects in a Presentation object is applied to the whole presentation.
Apply and Remove Protection
Applying protection ensures that a presentation cannot be edited. It is a useful technique for protecting a presentation’s content.
Applying Protection to PPTX Shapes
Aspose.Slides for .NET provides the Shape class to handle a shape on the slide.
As mentioned earlier, each shape class has an associated shape lock class for protection. This article focuses on the NoSelect, NoMove and NoResize locks. These locks ensure that shapes cannot be selected (through mouse clicks or other selection methods), and it cannot be moved or resized.
The code samples that follow apply protection to all shapes types in a presentation.
using Aspose.Slides;
//Instatiate Presentation class that represents a PPTX file
using (Presentation pTemplate = new Presentation("Applying Protection.pptx"))
{
//Traversing through all the slides in the presentation
foreach (ISlide slide in pTemplate.Slides)
{
//Travesing through all the shapes in the slides
foreach (IShape shape in slide.Shapes)
{
//if shape is autoshape
if (shape is IAutoShape)
{
//Type casting to Auto shape and getting auto shape lock
IAutoShape Ashp = (IAutoShape)shape;
IAutoShapeLock AutoShapeLock = Ashp.ShapeLock;
//Applying shapes locks
AutoShapeLock.PositionLocked = true;
AutoShapeLock.SelectLocked = true;
AutoShapeLock.SizeLocked = true;
}
//if shape is group shape
else if (shape is IGroupShape)
{
//Type casting to group shape and getting group shape lock
IGroupShape Group = (IGroupShape)shape;
IGroupShapeLock groupShapeLock = Group.ShapeLock;
//Applying shapes locks
groupShapeLock.GroupingLocked = true;
groupShapeLock.PositionLocked = true;
groupShapeLock.SelectLocked = true;
groupShapeLock.SizeLocked = true;
}
//if shape is a connector
else if (shape is IConnector)
{
//Type casting to connector shape and getting connector shape lock
IConnector Conn = (IConnector)shape;
IConnectorLock ConnLock = Conn.ShapeLock;
//Applying shapes locks
ConnLock.PositionMove = true;
ConnLock.SelectLocked = true;
ConnLock.SizeLocked = true;
}
//if shape is picture frame
else if (shape is IPictureFrame)
{
//Type casting to picture frame shape and getting picture frame shape lock
IPictureFrame Pic = (IPictureFrame)shape;
IPictureFrameLock PicLock = Pic.ShapeLock;
//Applying shapes locks
PicLock.PositionLocked = true;
PicLock.SelectLocked = true;
PicLock.SizeLocked = true;
}
//if shape is a graphical object: table, chart, OLE object frame
else if (shape is IGraphicalObject)
{
//Type casting to graphical object and getting graphical object lock
IGraphicalObject Gobj = (IGraphicalObject)shape;
IGraphicalObjectLock GobjLock = Gobj.ShapeLock;
//Applying shapes locks
GobjLock.PositionLocked = true;
GobjLock.SelectLocked = true;
GobjLock.SizeLocked = true;
}
}
}
//Saving the presentation file
pTemplate.Save("ProtectedSample.pptx", Aspose.Slides.Export.SaveFormat.Pptx);
}
Removing Protection
Protection applied using Aspose.Slides for .NET can only be removed with Aspose.Slides for .NET. To unlock a shape, set the value of the applied lock to false. The code sample that follows shows how to unlock shapes in a locked presentation.
using Aspose.Slides;
//Open the desired presentation
using (Presentation pTemplate = new Presentation("ProtectedSample.pptx"))
{
//Traversing through all the slides in presentation
foreach (ISlide slide in pTemplate.Slides)
{
//Travesing through all the shapes in the slides
foreach (IShape shape in slide.Shapes)
{
//if shape is autoshape
if (shape is IAutoShape)
{
//Type casting to Auto shape and getting auto shape lock
IAutoShape Ashp = (IAutoShape)shape;
IAutoShapeLock AutoShapeLock = Ashp.ShapeLock;
//Applying shapes locks
AutoShapeLock.PositionLocked = false;
AutoShapeLock.SelectLocked = false;
AutoShapeLock.SizeLocked = false;
}
//if shape is group shape
else if (shape is IGroupShape)
{
//Type casting to group shape and getting group shape lock
IGroupShape Group = (IGroupShape)shape;
IGroupShapeLock groupShapeLock = Group.ShapeLock;
//Applying shapes locks
groupShapeLock.GroupingLocked = false;
groupShapeLock.PositionLocked = false;
groupShapeLock.SelectLocked = false;
groupShapeLock.SizeLocked = false;
}
//if shape is Connector shape
else if (shape is IConnector)
{
//Type casting to connector shape and getting connector shape lock
IConnector Conn = (IConnector)shape;
IConnectorLock ConnLock = Conn.ShapeLock;
//Applying shapes locks
ConnLock.PositionMove = false;
ConnLock.SelectLocked = false;
ConnLock.SizeLocked = false;
}
//if shape is picture frame
else if (shape is IPictureFrame)
{
//Type casting to pitcture frame shape and getting picture frame shape lock
IPictureFrame Pic = (IPictureFrame)shape;
IPictureFrameLock PicLock = Pic.ShapeLock;
//Applying shapes locks
PicLock.PositionLocked = false;
PicLock.SelectLocked = false;
PicLock.SizeLocked = false;
}
//if shape is a graphical object: table, chart, OLE object frame
else if (shape is IGraphicalObject)
{
//Type casting to graphical object and getting graphical object lock
IGraphicalObject Gobj = (IGraphicalObject)shape;
IGraphicalObjectLock GobjLock = Gobj.ShapeLock;
//Applying shapes locks
GobjLock.PositionLocked = false;
GobjLock.SelectLocked = false;
GobjLock.SizeLocked = false;
}
}
}
//Saving the presentation file
pTemplate.Save("RemoveProtectionSample.pptx", Aspose.Slides.Export.SaveFormat.Pptx);
}