Setting the transparency of images in PDF documents is crucial for achieving professional-grade output, which allows for layering images without hard edges and creating a seamless integration with the background or underlying content. This not only enhances the visual appeal but also creates a polished and cohesive look, especially in graphics-intensive documents. This article will demonstrate how to effectively set the transparency of PDF images using Spire.PDF for Python in Python programs.

• Add Images with Specified Transparency to PDF
• Adjust the Transparency of Existing Images in PDF

Install Spire.PDF for Python

This scenario requires Spire.PDF for Python and plum-dispatch v1.7.4. They can be easily installed in your Windows through the following pip command.

pip install Spire.PDF

If you are unsure how to install, please refer to: How to Install Spire.PDF for Python on Windows

Add Images with Specified Transparency to PDF

Developers can utilize the PdfPageBase.Canvas.DrawImage() method in Spire.PDF for Python to draw an image at a specified location on a PDF page. Before drawing, developers can set the transparency of the canvas using PdfPageBase.Canvas.SetTransparency() method, which in turn sets the transparency level of the image being drawn. Below are the detailed steps:

• Create an object of PdfDocument class and load a PDF document using PdfDocument.LoadFromFile() method.
• Get a page in the document using PdfDocument.Pages.get_Item() method.
• Load an image using PdfImage.FromFile() method.
• Set the transparency of the canvas using PdfPageBase.Canvas.SetTransparency() method.
• Draw the image on the page using PdfPageBase.Canvas.DrawImage() method.
• Save the document using PdfDocument.SaveToFile() method.

from spire.pdf import *

# Create a PdfDocument instance
pdf = PdfDocument()

# Load a PDF file
pdf.LoadFromFile("Sample.pdf")

# Get the first page
page = pdf.Pages.get_Item(0)

# Load an image
image = PdfImage.FromFile("Screen.jpg")

# Set the transparency of the canvas
page.Canvas.SetTransparency(0.2)

# Draw the image at the specified location
page.Canvas.DrawImage(image, PointF(80.0, 80.0))

# Save the document
pdf.SaveToFile("output/AddTranslucentPicture.pdf")
pdf.Close()

Adjust the Transparency of Existing Images in PDF

To adjust the transparency of an existing image on a PDF page, developers can retrieve the image along with its bounds, delete the image, and finally redraw the image in the same location with the specified transparency. This process allows for the adjustment of the image's opacity while maintaining its original placement. The detailed steps are as follows:

• Create an object of PdfDocument class and load a PDF document using PdfDocument.LoadFromFile() method.
• Get a page in the document using PdfDocument.Pages.get_Item() method.
• Get an image on the page as a stream through PdfPageBase.ImagesInfo[].Image property and get the bounds of the image through PdfPageBase.ImagesInfo[].Bounds property.
• Remove the image from the page using PdfPageBase.DeleteImage() method.
• Create a PdfImage instance with the stream using PdfImage.FromStream() method.
• Set the transparency of the canvas using PdfPageBase.Canvas.SetTransparency() method.
• Redraw the image in the same location with the specified transparency using PdfPageBase.Canvas.DrawImage() method.
• Save the document using PdfDocument.SaveToFile() method.

from spire.pdf import *

# Create a PdfDocument instance
pdf = PdfDocument()

# Load a PDF file
pdf.LoadFromFile("Sample1.pdf")

# Get the first page
page = pdf.Pages.get_Item(0)

# Get the first image on the page as a stream and the bounds of the image
imageHelper = PdfImageHelper()
imageInformation = imageHelper.GetImagesInfo(page)
bounds = imageInformation[0].Bounds
imageStream =imageInformation[0].Image

# Delete the original image
imageHelper.DeleteImage(imageInformation[0])

# Create a PdfImage instance using the image stream
image = PdfImage.FromStream(imageStream)

# Create a PdfImage instance using the image stream
image = PdfImage.FromStream(imageStream)

# Set the transparency of the canvas
page.Canvas.SetTransparency(0.3)

# Draw the new image at the same location using the canvas
page.Canvas.DrawImage(image, bounds)

# Save the document
pdf.SaveToFile("output/SetExistingImageTransparency.pdf")
pdf.Close()

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Data Bars in Excel is a feature within the Conditional Formatting tool that allows you to visually represent numerical data through a series of bars. This feature is particularly useful for comparing values at a glance, as the length of the bar corresponds to the magnitude of the value it represents. In this article, you will learn how to add data bars in an Excel cell range in Python using Spire.XLS for Python.

Install Spire.XLS for Python

This scenario requires Spire.XLS for Python and plum-dispatch v1.7.4. They can be easily installed in your Windows through the following pip command.

pip install Spire.XLS

If you are unsure how to install, please refer to this tutorial: How to Install Spire.XLS for Python on Windows

Add Data Bars in Excel in Python

With Spire.XLS for Python, you are allowed to add a data bar to a specified data range and also set its format. The following are the detailed steps.

• Create a Workbook instance.
• Load a sample Excel document using Workbook.LoadFromFile() method.
• Get a specified worksheet using Workbook.Worsheets[index] property.
• Add a conditional formatting to the worksheet using Worksheet.ConditionalFormats.Add() method and return an object of XlsConditionalFormats class.
• Set the cell range where the conditional formatting will be applied using XlsConditionalFormats.AddRange() method.
• Add a condition using XlsConditionalFormats.AddCondition() method, and then set its format type to DataBar using IConditionalFormat.FormatType property.
• Set the fill effect and color of the data bars using IConditionalFormat.DataBar.BarFillType and IConditionalFormat.DataBar.BarColor properties.
• Save the result document using Workbook.SaveToFile() method.

from spire.xls import *
from spire.xls.common import *

# Create a Workbook instance
workbook = Workbook()

# Load a sample Excel document
workbook.LoadFromFile("sample.xlsx")

# Get the first worksheet
sheet = workbook.Worksheets[0]

# Add a conditional format to the worksheet
xcfs = sheet.ConditionalFormats.Add()

# Set the range where the conditional format will be applied
xcfs.AddRange(sheet.Range["C2:C13"])

# Add a condition and set its format type to DataBar
format = xcfs.AddCondition()
format.FormatType = ConditionalFormatType.DataBar

# Set the fill effect and color of the data bars
format.DataBar.BarFillType = DataBarFillType.DataBarFillGradient
format.DataBar.BarColor = Color.get_Red()

# Save the result document
workbook.SaveToFile("ApplyDataBarsToCellRange.xlsx", ExcelVersion.Version2016)
workbook.Dispose()

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If you'd like to remove the evaluation message from the generated documents, or to get rid of the function limitations, please request a 30-day trial license for yourself.

Handling PDF documents using bytes and bytearray provides an efficient and flexible approach within applications. By processing PDFs directly as byte streams, developers can manage documents in memory or transfer them over networks without the need for temporary file storage, optimizing space and improving overall application performance. This method also facilitates seamless integration with web services and APIs. Additionally, using bytearray allows developers to make precise byte-level modifications to PDF documents.

This article will demonstrate how to save PDFs as bytes and bytearray and load PDFs from bytes and bytearray using Spire.PDF for Python, offering practical examples for Python developers.

• Create a PDF Document and Save It to Bytes
• Load a PDF Document from Bytes

Install Spire.PDF for Python

This scenario requires Spire.PDF for Python and plum-dispatch v1.7.4. They can be easily installed in your Windows through the following pip command.

pip install Spire.PDF

If you are unsure how to install, please refer to: How to Install Spire.PDF for Python on Windows

Create a PDF Document and Save It to Bytes and Bytearray

Developers can create PDF documents using the classes and methods provided by Spire.PDF for Python, save them to a Stream object, and then convert it to an immutable bytes object or a mutable bytearray object. The Stream object can also be used to perform byte-level operations.

The detailed steps are as follows:

• Create an object of PdfDocument class to create a PDF document.
• Add a page to the document and draw text on the page.
• Save the document to a Stream object using PdfDocument.SaveToStream() method.
• Convert the Stream object to a bytes object using Stream.ToArray() method.
• The bytes object can be directly converted to a bytearray object.
• Afterward, the byte streams can be used for further operations, such as writing them to a file using the BinaryIO.write() method.

from spire.pdf import *

# Create an instance of PdfDocument class
pdf = PdfDocument()

# Set the page size and margins of the document
pageSettings = pdf.PageSettings
pageSettings.Size = PdfPageSize.A4()
pageSettings.Margins.Top = 50
pageSettings.Margins.Bottom = 50
pageSettings.Margins.Left = 40
pageSettings.Margins.Right = 40

# Add a new page to the document
page = pdf.Pages.Add()

# Create fonts and brushes for the document content
titleFont = PdfTrueTypeFont("HarmonyOS Sans SC", 16.0, PdfFontStyle.Bold, True)
titleBrush = PdfBrushes.get_Brown()
contentFont = PdfTrueTypeFont("HarmonyOS Sans SC", 13.0, PdfFontStyle.Regular, True)
contentBrush = PdfBrushes.get_Black()

# Draw the title on the page
titleText = "Brief Introduction to Cloud Services"
titleSize = titleFont.MeasureString(titleText)
page.Canvas.DrawString(titleText, titleFont, titleBrush, PointF(0.0, 30.0))

# Draw the body text on the page
contentText = ("Cloud computing is a service model where computing resources are provided over the internet on a pay-as-you-go basis. "
               "It is a type of infrastructure-as-a-service (IaaS), platform-as-a-service (PaaS), and software-as-a-service (SaaS) model. "
               "Cloud computing is typically offered througha subscription-based model, where users pay for access to the cloud resources on a monthly, yearly, or other basis.")
# Set the string format of the body text
contentFormat = PdfStringFormat()
contentFormat.Alignment = PdfTextAlignment.Justify
contentFormat.LineSpacing = 20.0
# Create a TextWidget object with the body text and apply the string format
textWidget = PdfTextWidget(contentText, contentFont, contentBrush)
textWidget.StringFormat = contentFormat
# Create a TextLayout object and set the layout options
textLayout = PdfTextLayout()
textLayout.Layout = PdfLayoutType.Paginate
textLayout.Break = PdfLayoutBreakType.FitPage
# Draw the TextWidget on the page
rect = RectangleF(PointF(0.0, titleSize.Height + 50.0), page.Canvas.ClientSize)
textWidget.Draw(page, rect, textLayout)

# Save the PDF document to a Stream object
pdfStream = Stream()
pdf.SaveToStream(pdfStream)

# Convert the Stream object to a bytes object
pdfBytes = pdfStream.ToArray()

# Convert the Stream object to a bytearray object
pdfBytearray = bytearray(pdfStream.ToArray())

# Write the byte stream to a file
with open("output/PDFBytearray.pdf", "wb") as f:
    f.write(pdfBytearray)

Load a PDF Document from Byte Streams

Developers can use a bytes object of a PDF file to create a stream and load it using the PdfDocument.LoadFromStream() method. Once the PDF document is loaded, various operations such as reading, modifying, and converting the PDF can be performed. The following is an example of the steps:

• Create a bytes object with a PDF file.
• Create a Stream object using the bytes object.
• Load the Stream object as a PDF document using PdfDocument.LoadFromStream() method.
• Extract the text from the first page of the document and print the text.

from spire.pdf import *

# Create a byte array from a PDF file
with open("Sample.pdf", "rb") as f:
    byteData = f.read()

# Create a Stream object from the byte array
stream = Stream(byteData)

# Load the Stream object as a PDF document
pdf = PdfDocument(stream)

# Get the text from the first page
page = pdf.Pages.get_Item(0)
textExtractor = PdfTextExtractor(page)
extractOptions = PdfTextExtractOptions()
extractOptions.IsExtractAllText = True
text = textExtractor.ExtractText(extractOptions)

# Print the text
print(text)

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Adding page numbers to a PDF enhances its organization and readability, making it easier for readers to navigate the document. Whether for reports, manuals, or e-books, page numbers provide a professional touch and help maintain the flow of information. This process involves determining the placement, alignment, and style of the numbers within the footer or header.

In this article, you will learn how to add page numbers to the PDF footer using Spire.PDF for Python.

• Add Left-Aligned Page Numbers to PDF Footer
• Add Center-Aligned Page Numbers to PDF Footer
• Add Right-Aligned Page Numbers to PDF Footer

Install Spire.PDF for Python

This scenario requires Spire.PDF for Python and plum-dispatch v1.7.4. They can be easily installed in your Windows through the following pip command.

pip install Spire.PDF

If you are unsure how to install, please refer to this tutorial: How to Install Spire.PDF for Python on Windows

Coordinate System in PDF

When using Spire.PDF for Python to modify a PDF document, the coordinate system's origin is at the top-left corner of the page. The x-axis extends to the right, while the y-axis extends downward.

Page numbers are usually positioned in the header or footer. Thus, it's important to consider the page size and margins when determining the placement of the page numbers.

Classes and Methods for Creating Page Numbers

Spire.PDF for Python provides the PdfPageNumberField and PdfPageCountField classes to retrieve the current page number and total page count. These can be merged into a single PdfCompositeField that formats the output as "Page X of Y", where X represents the current page number and Y indicates the total number of pages.

To position the PdfCompositeField on the page, use the Location property, and render it with the Draw() method.

Add Left-Aligned Page Numbers to PDF Footer

To add left-aligned page numbers in the footer, you need to consider the left and bottom page margins as well as the page height. For example, you can use coordinates such as (LeftMargin, PageHeight – BottomMargin + SmallNumber). This ensures that the page numbers align with the left side of the text while keeping a comfortable distance from both the content and the edges of the page.

The steps to add left-aligned page numbers to PDF footer are as follows:

• Create a PdfDocument object.
• Load a PDF file from a specified path.
• Create a PdfPageNumberField object and a PdfPageCountField object.
• Create a PdfCompositeField object to combine page count field and page number field in a single string.
• Set the position of the composite field through PdfCompositeField.Location property to ensure the page number aligns with the left side of the text.
• Iterate through the pages in the document, and draw the composite field on each page at the specified location.
• Save the document to a different PDF file.

from spire.pdf.common import *
from spire.pdf import *

# Create a PdfDocument object
doc = PdfDocument()

# Load a PDF file
doc.LoadFromFile("C:\\Users\\Administrator\\Desktop\\Privacy Policy.pdf")

# Create font, brush and pen
font = PdfTrueTypeFont("Times New Roman", 12.0, PdfFontStyle.Regular, True)
brush = PdfBrushes.get_Black()
pen = PdfPen(brush, 1.0)

# Create a PdfPageNumberField object and a PdfPageCountField object
pageNumberField = PdfPageNumberField()
pageCountField = PdfPageCountField()

# Create a PdfCompositeField object to combine page count field and page number field in a single string
compositeField = PdfCompositeField(font, brush, "Page {0} of {1}", [pageNumberField, pageCountField])

# Get the page size
pageSize = doc.Pages.get_Item(0).Size

# Specify the blank areas around the page
leftMargin = 54.0
rightMargin = 54.0
bottomMargin = 72.0

# Set the location of the composite field
compositeField.Location = PointF(leftMargin, pageSize.Height - bottomMargin + 18.0)

# Iterate through the pages in the document
for i in range(doc.Pages.Count):

    # Get a specific page
    page = doc.Pages.get_Item(i)

    # Draw a line at the specified position
    page.Canvas.DrawLine(pen, leftMargin, pageSize.Height - bottomMargin + 15.0, pageSize.Width - rightMargin, pageSize.Height - bottomMargin + 15.0)

    # Draw the composite field on the page
    compositeField.Draw(page.Canvas, 0.0, 0.0)

# Save to a different PDF file
doc.SaveToFile("Output/LeftAlignedPageNumbers.pdf")

# Dispose resources
doc.Dispose()

Add Center-Aligned Page Numbers to PDF Footer

To position the page number in the center of the footer, you first need to measure the width of the page number itself. Once you have this measurement, you can calculate the appropriate X coordinate by using the formula (PageWidth - PageNumberWidth) / 2. This ensures the page number is horizontally centered within the footer.

The steps to add center-aligned page numbers to PDF footer are as follows:

• Create a PdfDocument object.
• Load a PDF file from a specified path.
• Create a PdfPageNumberField object and a PdfPageCountField object.
• Create a PdfCompositeField object to combine page count field and page number field in a single string.
• Set the position of the composite field through PdfCompositeField.Location property to ensure the page number is perfectly centered in the footer.
• Iterate through the pages in the document, and draw the composite field on each page at the specified location.
• Save the document to a different PDF file.

from spire.pdf.common import *
from spire.pdf import *

# Create a PdfDocument object
doc = PdfDocument()

# Load a PDF file
doc.LoadFromFile("C:\\Users\\Administrator\\Desktop\\Privacy Policy.pdf")

# Create font, brush and pen
font = PdfTrueTypeFont("Times New Roman", 12.0, PdfFontStyle.Regular, True)
brush = PdfBrushes.get_Black()
pen = PdfPen(brush, 1.0)

# Specify the blank margins around the page
leftMargin = 54.0
rightMargin = 54.0
bottomMargin = 72.0

# Create a PdfPageNumberField object and a PdfPageCountField object
pageNumberField = PdfPageNumberField()
pageCountField = PdfPageCountField()

# Create a PdfCompositeField object to combine page count field and page number field in a single field
compositeField = PdfCompositeField(font, brush, "Page {0} of {1}", [pageNumberField, pageCountField])

# Iterate through the pages in the document
for i in range(doc.Pages.Count):

    # Get a specific page
    page = doc.Pages.get_Item(i)

    # Get the page size
    pageSize = doc.Pages.get_Item(i).Size

    # Draw a line at the specified position
    page.Canvas.DrawLine(pen, leftMargin, pageSize.Height - bottomMargin + 15.0, pageSize.Width - rightMargin, pageSize.Height - bottomMargin + 15.0)

    # Measure the size the "Page X of Y"
    pageNumberSize = font.MeasureString("Page {} of {}".format(i + 1, doc.Pages.Count))

    # Set the location of the composite field
    compositeField.Location = PointF((pageSize.Width - pageNumberSize.Width)/2, pageSize.Height - bottomMargin + 18.0)

    # Draw the composite field on the page
    compositeField.Draw(page.Canvas, 0.0, 0.0)

# Save to a different PDF file
doc.SaveToFile("Output/CenterAlignedPageNumbers.pdf")

# Dispose resources
doc.Dispose()

Add Right-Aligned Page Numbers to PDF Footer

To add a right-aligned page number in the footer, measure the width of the page number. Then, calculate the X coordinate using the formula PageWidth - PageNumberWidth - RightMargin. This ensures that the page number aligns with the right side of the text.

The following are the steps to add right-aligned page numbers to PDF footer:

• Create a PdfDocument object.
• Load a PDF file from a specified path.
• Create a PdfPageNumberField object and a PdfPageCountField object.
• Create a PdfCompositeField object to combine page count field and page number field in a single string.
• Set the position of the composite field through PdfCompositeField.Location property to ensure the page number aligns with the right side of the text.
• Iterate through the pages in the document, and draw the composite field on each page at the specified location.
• Save the document to a different PDF file.

from spire.pdf.common import *
from spire.pdf import *

# Create a PdfDocument object
doc = PdfDocument()

# Load a PDF file
doc.LoadFromFile("C:\\Users\\Administrator\\Desktop\\Privacy Policy.pdf")

# Create font, brush and pen
font = PdfTrueTypeFont("Times New Roman", 12.0, PdfFontStyle.Regular, True)
brush = PdfBrushes.get_Black()
pen = PdfPen(brush, 1.0)

# Specify the blank margins around the page
leftMargin = 54.0
rightMargin = 54.0
bottomMargin = 72.0

# Create a PdfPageNumberField object and a PdfPageCountField object
pageNumberField = PdfPageNumberField()
pageCountField = PdfPageCountField()

# Create a PdfCompositeField object to combine page count field and page number field in a single string
compositeField = PdfCompositeField(font, brush, "Page {0} of {1}", [pageNumberField, pageCountField])

# Iterate through the pages in the document
for i in range(doc.Pages.Count):

    # Get a specific page
    page = doc.Pages.get_Item(i)

    # Get the page size
    pageSize = doc.Pages.get_Item(i).Size

    # Draw a line at the specified position
    page.Canvas.DrawLine(pen, leftMargin, pageSize.Height - bottomMargin + 15.0, pageSize.Width - rightMargin, pageSize.Height - bottomMargin + 15.0)

    # Measure the size the "Page X of Y"
    pageNumberSize = font.MeasureString("Page {} of {}".format(i + 1, doc.Pages.Count))

    # Set the location of the composite field
    compositeField.Location = PointF(pageSize.Width - pageNumberSize.Width - rightMargin, pageSize.Height - bottomMargin + 18.0)

    # Draw the composite field on the page
    compositeField.Draw(page.Canvas, 0.0, 0.0)

# Save to a different PDF file
doc.SaveToFile("Output/RightAlignedPageNumbers.pdf")

# Dispose resources
doc.Dispose()

Apply for a Temporary License

If you'd like to remove the evaluation message from the generated documents, or to get rid of the function limitations, please request a 30-day trial license for yourself.