Render Presentations with Fallback Fonts in Python via Java

Overview

Aspose.Slides allows you to render presentations using fallback font rules. This article shows how to create a fallback font rules collection, modify its rules by removing or adding fallback fonts, and assign the collection using the FontsManager.setFontFallBackRulesCollection method.

Once the fallback font rules collection is assigned to the presentation’s FontsManager, the rules are applied during operations such as saving, rendering, and converting the presentation. The example demonstrates how to use the configured rules when rendering a slide thumbnail and saving it as a JPEG image.

Render a Slide Using Fallback Font Rules

The following example includes these steps:

  1. Create a fallback font rules collection.
  2. Remove a fallback font from a rule and add fallback fonts to another rule.
  3. Assign the rules collection using setFontFallBackRulesCollection on the font manager returned by getFontsManager.
  4. Use the Presentation.save method to save the presentation in the same format or another format. After the fallback font rules collection is assigned to FontsManager, these rules are applied during operations on the presentation: saving, rendering, converting, and so on.
import jpype
import asposeslides

if not jpype.isJVMStarted():
    jpype.startJVM()

from asposeslides.api import FontFallBackRule, FontFallBackRulesCollection, ImageFormat, Presentation

# Create a new rules collection.
fallback_rules = FontFallBackRulesCollection()

# Create several rules.
cyrillic_rule = FontFallBackRule(0x400, 0x4FF, "Times New Roman")
fallback_rules.add(cyrillic_rule)
arabic_rule = FontFallBackRule(0x600, 0x6FF, "Tahoma, Arial")
fallback_rules.add(arabic_rule)

for fallback_rule in fallback_rules:
    # Try to remove the fallback font "Tahoma" from the rules.
    fallback_rule.remove("Tahoma")

    # Update the rules for the specified range.
    if fallback_rule.getRangeEndIndex() >= 0x400 and fallback_rule.getRangeStartIndex() < 0x500:
        fallback_rule.addFallBackFonts("Verdana")

# Remove an existing rule, keeping at least one rule for rendering.
if fallback_rules.size() > 1:
    rule_to_remove = fallback_rules.get_Item(1)
    fallback_rules.remove(rule_to_remove)

presentation = Presentation("input.pptx")
try:
    # Assign the prepared rules collection.
    presentation.getFontsManager().setFontFallBackRulesCollection(fallback_rules)

    # Render a thumbnail using the configured rules collection.
    slide_image = presentation.getSlides().get_Item(0).getImage(1.0, 1.0)
    try:
        # Save the image to disk in JPEG format.
        slide_image.save("Slide_0.jpg", ImageFormat.Jpeg)
    finally:
        slide_image.dispose()
finally:
    presentation.dispose()
Configure Fallback Font Collections in Python via Java