How to make report viewer on WPF with FastReport Open Source. Part 2.

In the first part of the article, we have implemented the report loading into the Image object. This was done by exporting the report to png format. As a result of exporting the report, an image file is generated, and if there are several pages in the report, then several files will be created. We should delete the export files before opening another report.

Add a method to delete export files:

public void DeleteTempFiles()

{

FileInfo[] path = new DirectoryInfo(Directory.GetCurrentDirectory()).GetFiles("test*", SearchOption.AllDirectories);

foreach (FileInfo file in path)

{

File.Delete(file.FullName);

}

pages.Clear();

}

Here we look for files with the name containing “test” and delete them in a loop. And also clear the list of files pages.

Recall the SetContent method, which exports the report to png and sets an image in the Image object:

private void SetContent(Report report)

{

ex.ImageFormat = ImageExportFormat.Png;

ex.ResolutionX = 96;

ex.ResolutionY = 96;

ex.Export(report, Directory.GetCurrentDirectory() + "/test.png");

foreach (string file in ex.GeneratedFiles)

{

pages.Add(new BitmapImage(new Uri(file)));

}

im.Source = pages[0];

}

We will add a call to the function to delete temporary files. But this is not the main addition to this method. The fact is that we cannot delete files so easily. With the current method of reading files for adding to the list, the files are not released. Therefore, we will save them to the list of cache image files.

But there is a pitfall. If you generate files with the same names each time you open another report, the cache will play a cruel joke, and you will receive images that are cached firstly. Therefore, we add a random number to the name of the temporary files. This is how the SetContent method will transform:

private void SetContent(Report report)

{

DeleteTempFiles();

ex.ImageFormat = ImageExportFormat.Png;

ex.ResolutionX = 96;

ex.ResolutionY = 96;

Random rnd = new Random();

ex.Export(report, Directory.GetCurrentDirectory() + "/test." + rnd.Next(100) + ".png");

foreach (string file in ex.GeneratedFiles)

{

BitmapImage image = new BitmapImage();

image.BeginInit();

image.CacheOption = BitmapCacheOption.OnLoad;

image.UriSource = new Uri(file);

image.EndInit();

pages.Add(image);

}

CurrentPage = 0;

im.Source = pages[0];

}

As you can see, inside the loop we now create an image cache and add it to the list. We also set the CurrentPage variable to 0. This variable will allow you to track the currently selected page. It will be useful to us in the future. Let's declare it:

private int currentPage = 0;

public int CurrentPage

{

get { return currentPage; }

set {

if (value >= 0 && value < pages.Count())

currentPage = value;

}

When assigning a value, we check that the page number is not less than the number of report pages and is greater than or equal to 0. In the page list there is a zero element, but in reality it is the first page.

It's time to implement switching between pages. For these actions, we have as many as 4 buttons and a text field. Let's start with the first button that returns to the first page of the report. Create an OnClick event for it:

private void First_Click(object sender, RoutedEventArgs e)

{

CurrentPage = 0;

SetImage();

}

The current page is the first item in the list of pages. The SetImage method allows you to load a picture into an Image object:

public void SetImage()

{

im.Source = pages[CurrentPage];

}

Here we simply assign an image from the list to the Image object. By the way, since we have such a method, let's replace the string im.Source = pages [0] in the SetContent method; on SetImage ();

The second button will allow you to move one page back:

private void Back_Click(object sender, RoutedEventArgs e)

{

CurrentPage--;

SetImage();

}

The third button allows you to move to the next page:

private void Next_Click(object sender, RoutedEventArgs e)

{

CurrentPage++;

SetImage();

}

And the fourth - accordingly displays the last page of the report:

private void Last_Click(object sender, RoutedEventArgs e)

{

CurrentPage = pages.Count() - 1;

SetImage();

}

In addition to the navigation buttons between pages, we have a text field in which we can enter the page number or display the current page number. To display the current page number, add a line to the SetImage () method:

PageNumber.Text = (CurrentPage + 1).ToString();

Create an OnClick event handler for the text field:

private void PageNumber_KeyDown(object sender, KeyEventArgs e)

{

if (e.Key == Key.Enter)

{

if (int.Parse(PageNumber.Text) > 0)

{

CurrentPage = int.Parse(PageNumber.Text) - 1;

SetImage();

}

By pressing the Enter key, the specified report page will be selected.

And now let's implement report scaling. First for the zoom button:

private void Zoom_in_Click(object sender, RoutedEventArgs e)

{

using (MemoryStream stream = new MemoryStream())

{

if (ex != null)

{

ex.ImageFormat = ImageExportFormat.Png;

ex.Resolution += 25;

ex.PageNumbers = (CurrentPage + 1).ToString();

Report.Export(ex, stream);

if (CurrentPage >= 0 && CurrentPage < pages.Count())

im.Source = LoadImage(stream);

PageNumber.Text = (CurrentPage + 1).ToString();

}

im.Width += 50;

im.Height += 50;

}

This time we will save the report export in the stream, not in the file. In the export settings, specify the type of export png. And also we increase the image resolution using the Resolution parameter. In the export property PageNumbers specify the number of pages to be exported. In our case, this is the current page. And at the end we increase the width and height of the image. If we didn’t increase the resolution of the image at each approximation, we would get a blurry image.

And to reduce the scale, we will not reduce the resolution:

private void Zoom_out_Click(object sender, RoutedEventArgs e)

{

using (MemoryStream stream = new MemoryStream())

{

if (ex != null)

{

ex.ImageFormat = ImageExportFormat.Png;

ex.PageNumbers = (CurrentPage + 1).ToString(); Report.Export(ex, stream);

if (CurrentPage >= 0 && CurrentPage < pages.Count())

im.Source = LoadImage(stream);

PageNumber.Text = (CurrentPage + 1).ToString();

}

im.Width -= 50;

im.Height -= 50;

}

In order to go back to the original image scale when moving between report pages, we will save the height and width during form initialization and set these parameters every time when the SetImage () function is called:

private double imHeight;

private double imWidth;

public MainWindow()

{

InitializeComponent();

imHeight = im.Height;

imWidth = im.Width;

}

Add the function of the image installation:

public void SetImage()

{

im.Source = pages[CurrentPage];

im.Height = imHeight;

im.Width = imWidth;

PageNumber.Text = (CurrentPage + 1).ToString();

}

Now it is time to run the application:

Let's load the report. Click on the file open icon. And select a report.

Here is the first report page:

Enter the page number in the text field and press Enter. And we can see the selected page:

When you switch between pages using buttons, you see the number of the current page in the text box. And now let's bring the page closer by pressing the "+" button several times: