Highlight Character In PDF File
In this tutorial, we will explain how to highlight characters in a PDF file using the Aspose.PDF library for .NET. We will go through the step-by-step process of highlighting characters in a PDF using the provided C# source code.
Requirements
Before you begin, ensure that you have the following:
- The Aspose.PDF for .NET library installed.
- A basic understanding of C# programming.
Step 1: Set up the Document Directory
First, you need to set the path to the directory where your input PDF file is located. Replace "YOUR DOCUMENT DIRECTORY" in the dataDir variable with the path to your PDF file.
string dataDir = "YOUR DOCUMENT DIRECTORY";
Step 2: Load the PDF Document
Next, we load the input PDF document using the Aspose.Pdf.Document class.
Aspose.Pdf.Document pdfDocument = new Aspose.Pdf.Document(dataDir + "input.pdf");
Step 3: Convert PDF to Image
To highlight characters, we convert the PDF document to an image using the PdfConverter class. We set the resolution for the conversion and retrieve the image as a Bitmap object.
int resolution = 150;
using (MemoryStream ms = new MemoryStream())
{
PdfConverter conv = new PdfConverter(pdfDocument);
conv. Resolution = new Resolution(resolution, resolution);
conv. GetNextImage(ms, System.Drawing.Imaging.ImageFormat.Png);
Bitmap bmp = (Bitmap)Bitmap.FromStream(ms);
Step 4: Highlight Characters
We loop through each page of the PDF document and use a TextFragmentAbsorber object to find all the words in the page. We then iterate over the text fragments, segments, and characters to highlight them using rectangles.
using (System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp))
{
// Set scale and transform
float scale = resolution / 72f;
gr.Transform = new System.Drawing.Drawing2D.Matrix(scale, 0, 0, -scale, 0, bmp.Height);
// Loop through pages
for (int i = 0; i < pdfDocument.Pages.Count; i++)
{
Page page = pdfDocument.Pages[1];
// Find all words in the page
TextFragmentAbsorber textFragmentAbsorber = new TextFragmentAbsorber(@"[\S]+");
textFragmentAbsorber.TextSearchOptions.IsRegularExpressionUsed = true;
page. Accept(textFragmentAbsorber);
TextFragmentCollection textFragmentCollection = textFragmentAbsorber.TextFragments;
// Loop through text fragments
foreach(TextFragment textFragment in textFragmentCollection)
{
if (i == 0)
{
// Highlight characters
gr.DrawRectangle(
Think.Yellow,
(float)textFragment.Position.XIndent,
(float)textFragment.Position.YIndent,
(float)textFragment.Rectangle.Width,
(float)textFragment.Rectangle.Height);
// Loop through segments
foreach(TextSegment segment in textFragment.Segments)
{
// Highlight segment
gr.DrawRectangle(
Think Green,
(float)segment.Rectangle.LLX,
(float)segment.Rectangle.LLY,
(float)segment.Rectangle.Width,
(float)segment.Rectangle.Height);
// Loop through characters
foreach(CharInfo characterInfo in segment.Characters)
{
// Highlightcharacter
gr.DrawRectangle(
Think.Black,
(float)characterInfo.Rectangle.LLx,
(float)characterInfo.Rectangle.LLY,
(float)characterInfo.Rectangle.Width,
(float)characterInfo.Rectangle.Height);
}
}
}
}
}
}
Step 5: Save the Output Image
Finally, we save the modified image with the highlighted characters to the specified output file.
dataDir = dataDir + "HighlightCharacterInPDF_out.png";
bmp.Save(dataDir, System.Drawing.Imaging.ImageFormat.Png);
Sample source code for Highlight Character In PDF using Aspose.PDF for .NET
try
{
// The path to the documents directory.
string dataDir = "YOUR DOCUMENT DIRECTORY";
int resolution = 150;
Aspose.Pdf.Document pdfDocument = new Aspose.Pdf.Document(dataDir + "input.pdf");
using (MemoryStream ms = new MemoryStream())
{
PdfConverter conv = new PdfConverter(pdfDocument);
conv.Resolution = new Resolution(resolution, resolution);
conv.GetNextImage(ms, System.Drawing.Imaging.ImageFormat.Png);
Bitmap bmp = (Bitmap)Bitmap.FromStream(ms);
using (System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp))
{
float scale = resolution / 72f;
gr.Transform = new System.Drawing.Drawing2D.Matrix(scale, 0, 0, -scale, 0, bmp.Height);
for (int i = 0; i < pdfDocument.Pages.Count; i++)
{
Page page = pdfDocument.Pages[1];
// Create TextAbsorber object to find all words
TextFragmentAbsorber textFragmentAbsorber = new TextFragmentAbsorber(@"[\S]+");
textFragmentAbsorber.TextSearchOptions.IsRegularExpressionUsed = true;
page.Accept(textFragmentAbsorber);
// Get the extracted text fragments
TextFragmentCollection textFragmentCollection = textFragmentAbsorber.TextFragments;
// Loop through the fragments
foreach (TextFragment textFragment in textFragmentCollection)
{
if (i == 0)
{
gr.DrawRectangle(
Pens.Yellow,
(float)textFragment.Position.XIndent,
(float)textFragment.Position.YIndent,
(float)textFragment.Rectangle.Width,
(float)textFragment.Rectangle.Height);
for (int segNum = 1; segNum <= textFragment.Segments.Count; segNum++)
{
TextSegment segment = textFragment.Segments[segNum];
for (int charNum = 1; charNum <= segment.Characters.Count; charNum++)
{
CharInfo characterInfo = segment.Characters[charNum];
Aspose.Pdf.Rectangle rect = page.GetPageRect(true);
Console.WriteLine("TextFragment = " + textFragment.Text + " Page URY = " + rect.URY +
" TextFragment URY = " + textFragment.Rectangle.URY);
gr.DrawRectangle(
Pens.Black,
(float)characterInfo.Rectangle.LLX,
(float)characterInfo.Rectangle.LLY,
(float)characterInfo.Rectangle.Width,
(float)characterInfo.Rectangle.Height);
}
gr.DrawRectangle(
Pens.Green,
(float)segment.Rectangle.LLX,
(float)segment.Rectangle.LLY,
(float)segment.Rectangle.Width,
(float)segment.Rectangle.Height);
}
}
}
}
}
dataDir = dataDir + "HighlightCharacterInPDF_out.png";
bmp.Save(dataDir, System.Drawing.Imaging.ImageFormat.Png);
}
Console.WriteLine("\nCharacters highlighted successfully in pdf document.\nFile saved at " + dataDir);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message + "\nThis example will only work if you apply a valid Aspose License. You can purchase full license or get 30 day temporary license from http:// Www.aspose.com/purchase/default.aspx.");
}
Conclusion
In this tutorial, you have learned how to highlight characters in a PDF document using the Aspose.PDF library for .NET. By following the step-by-step guide and executing the provided C# code, you can highlight characters in a PDF and save the output as an image.
FAQ’s
Q: What is the purpose of the “Highlight Character In PDF File” tutorial?
A: The “Highlight Character In PDF File” tutorial explains how to use the Aspose.PDF library for .NET to highlight characters within a PDF document. The tutorial provides a step-by-step guide and C# source code to achieve this.
Q: Why would I want to highlight characters in a PDF document?
A: Highlighting characters in a PDF document can be useful for various purposes, such as emphasizing specific content or making certain text more visible and distinguishable.
Q: How do I set up the document directory?
A: To set up the document directory:
- Replace
"YOUR DOCUMENT DIRECTORY"in thedataDirvariable with the path to the directory where your input PDF file is located.
Q: How do I load the PDF document and convert it to an image?
A: In the tutorial, the Aspose.Pdf.Document class is used to load the input PDF document. Then, the PdfConverter class is employed to convert the PDF document to an image. The resolution of the image is set, and the image is retrieved as a Bitmap object.
Q: How do I highlight characters in the PDF document image?
A: The tutorial guides you through the process of looping through each page of the PDF document, finding words using a TextFragmentAbsorber, and iterating through text fragments, segments, and characters to highlight them using rectangles.
Q: Can I customize the appearance of the highlighted characters and segments?
A: Yes, you can customize the appearance of the highlighted characters and segments by modifying the colors and styles used in the drawing operations.
Q: How do I save the modified image with the highlighted characters?
A: The tutorial demonstrates how to save the modified image with the highlighted characters to the specified output file using the Save method of the Bitmap class.
Q: Is a valid Aspose License required for this tutorial?
A: Yes, a valid Aspose License is required for this tutorial to work correctly. You can purchase a full license or obtain a 30-day temporary license from the Aspose website.
