Identify if the SfPdfViewer has values in the Undo, Redo collections
4 Jul 20241 minute to read
Syncfusion’s Blazor SfPdfViewer component allows you to identify if the SfPdfViewer has values in the Undo and Redo collections using the CanUndo and CanRedo APIs of the SfPdfViewer.
The following code example shows how to achieve this based on the Undo Redo actions.
@using Syncfusion.Blazor.SfPdfViewer
@using Syncfusion.Blazor.Buttons
@if (canUndo)
{
<button @onclick="undo">Undo</button>
}
else
{
<button @onclick="undo" disabled>Undo</button>
}
@if (canRedo)
{
<button @onclick="redo">Redo</button>
}
else
{
<button @onclick="redo" disabled>Redo</button>
}
<SfPdfViewer2 @ref="@viewer"
@bind-CanUndo="@canUndo"
@bind-CanRedo="@canRedo"
DocumentPath="@DocumentPath"
Height="100%"
Width="100%">
</SfPdfViewer2>
@code
{
SfPdfViewer2 viewer;
bool canUndo = true;
bool canRedo = true;
private string DocumentPath { get; set; } = "wwwroot/Data/PDF_Succinctly.pdf";
// Event triggers on Undo button click.
private async Task undo()
{
// API to perform Undo action.
await viewer.UndoAsync();
}
// Event triggers on Redo button click.
private async Task redo()
{
// API to perform Redo action.
await viewer.RedoAsync();
}
}