Presentation Theme

A presentation theme defines the properties of design elements. When you select a presentation theme, you are essentially choosing a specific set of visual elements and their properties.

In PowerPoint, a theme comprises colors, fonts, background styles, and effects.

theme-constituents

Change Theme Color

A PowerPoint theme uses a specific set of colors for different elements on a slide. If you don’t like the colors, you change them colors by applying new colors for the theme. To allow you select a new theme color, Aspose.Slides provides values under the SchemeColor enumeration.

This Python code shows you how to change the accent color for a theme:

import aspose.pydrawing as draw
import aspose.slides as slides

with slides.Presentation() as pres:
    shape = pres.slides[0].shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 10, 100, 100)
    shape.fill_format.fill_type = slides.FillType.SOLID
    shape.fill_format.solid_fill_color.scheme_color = slides.SchemeColor.ACCENT4

You can determine the resulting color’s effective value this way:

fillEffective = shape.fill_format.get_effective()
print("{0} ({1})".format(fillEffective.solid_fill_color.name, fillEffective.solid_fill_color)) # ff8064a2 (Color [A=255, R=128, G=100, B=162])

To further demonstrate the color change operation, we create another element and assign the accent color (from the initial operation) to it. Then we change the color in the theme:

otherShape = pres.slides[0].shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 120, 100, 100)
otherShape.fill_format.fill_type = slides.FillType.SOLID
otherShape.fill_format.solid_fill_color.scheme_color = slides.SchemeColor.ACCENT4

pres.master_theme.color_scheme.accent4.color = draw.Color.red

The new color is applied automatically on both elements.

Set Theme Color from Additional Palette

When you apply luminance transformations to the main theme color(1), colors from the additional palette(2) are formed. You can then set and get those theme colors.

additional-palette-colors

1- Main theme colors

2 - Colors from the additional palette.

This Python code demonstrates an operation where additional palette colors are obtained from the main theme color and then used in shapes:

import aspose.slides as slides

with slides.Presentation() as presentation:
    slide = presentation.slides[0]

    # Accent 4
    shape1 = slide.shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 10, 50, 50)

    shape1.fill_format.fill_type = slides.FillType.SOLID
    shape1.fill_format.solid_fill_color.scheme_color = slides.SchemeColor.ACCENT4

    # Accent 4, Lighter 80%
    shape2 = slide.shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 70, 50, 50)

    shape2.fill_format.fill_type = slides.FillType.SOLID
    shape2.fill_format.solid_fill_color.scheme_color = slides.SchemeColor.ACCENT4
    shape2.fill_format.solid_fill_color.color_transform.add(slides.ColorTransformOperation.MULTIPLY_LUMINANCE, 0.2)
    shape2.fill_format.solid_fill_color.color_transform.add(slides.ColorTransformOperation.ADD_LUMINANCE, 0.8)

    # Accent 4, Lighter 60%
    shape3 = slide.shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 130, 50, 50)

    shape3.fill_format.fill_type = slides.FillType.SOLID
    shape3.fill_format.solid_fill_color.scheme_color = slides.SchemeColor.ACCENT4
    shape3.fill_format.solid_fill_color.color_transform.add(slides.ColorTransformOperation.MULTIPLY_LUMINANCE, 0.4)
    shape3.fill_format.solid_fill_color.color_transform.add(slides.ColorTransformOperation.ADD_LUMINANCE, 0.6)

    # Accent 4, Lighter 40%
    shape4 = slide.shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 190, 50, 50)

    shape4.fill_format.fill_type = slides.FillType.SOLID
    shape4.fill_format.solid_fill_color.scheme_color = slides.SchemeColor.ACCENT4
    shape4.fill_format.solid_fill_color.color_transform.add(slides.ColorTransformOperation.MULTIPLY_LUMINANCE, 0.6)
    shape4.fill_format.solid_fill_color.color_transform.add(slides.ColorTransformOperation.ADD_LUMINANCE, 0.4)

    # Accent 4, Darker 25%
    shape5 = slide.shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 250, 50, 50)

    shape5.fill_format.fill_type = slides.FillType.SOLID
    shape5.fill_format.solid_fill_color.scheme_color = slides.SchemeColor.ACCENT4
    shape5.fill_format.solid_fill_color.color_transform.add(slides.ColorTransformOperation.MULTIPLY_LUMINANCE, 0.75)

    # Accent 4, Darker 50%
    shape6 = slide.shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 310, 50, 50)

    shape6.fill_format.fill_type = slides.FillType.SOLID
    shape6.fill_format.solid_fill_color.scheme_color = slides.SchemeColor.ACCENT4
    shape6.fill_format.solid_fill_color.color_transform.add(slides.ColorTransformOperation.MULTIPLY_LUMINANCE, 0.5)

    presentation.save("example.pptx", slides.export.SaveFormat.PPTX)

Change Theme Font

To allow you select fonts for themes and other purposes, Aspose.Slides uses these special identifiers (similar to those used in PowerPoint):

+mn-lt - Body Font Latin (Minor Latin Font)
+mj-lt -Heading Font Latin (Major Latin Font)
+mn-ea - Body Font East Asian (Minor East Asian Font)
+mj-ea - Body Font East Asian (Major East Asian Font)

This Python code shows you how to assign the Latin font to a theme element:

shape = pres.slides[0].shapes.add_auto_shape(slides.ShapeType.RECTANGLE, 10, 10, 100, 100)

paragraph = slides.Paragraph()
portion = slides.Portion("Theme text format")
paragraph.portions.add(portion)
shape.text_frame.paragraphs.add(paragraph)
portion.portion_format.latin_font = slides.FontData("+mn-lt")

This Python code shows you how to change the presentation theme font:

pres.master_theme.font_scheme.minor.latin_font = slides.FontData("Arial")

The font in all text boxes will be updated.

TIP

You may want to see PowerPoint fonts.

Change Theme Background Style

By default, the PowerPoint app provides 12 predefined backgrounds but only 3 from those 12 backgrounds are saved in a typical presentation.

todo:image_alt_text

For example, after you save a presentation in the PowerPoint app, you can run this Python code to find out the number of predefined backgrounds in the presentation:

with slides.Presentation() as pres:
    numberOfBackgroundFills = len(pres.master_theme.format_scheme.background_fill_styles)
    print("Number of background fill styles for theme is {0}".format(numberOfBackgroundFills))

Using the BackgroundFillStyles property from the FormatScheme class, you can add or access the background style in a PowerPoint theme.

This Python code shows you how to set the background for a presentation:

pres.masters[0].background.style_index = 2

Index guide: 0 is used for no fill. The index starts from 1.

TIP

You may want to see PowerPoint Background.

Change Theme Effect

A PowerPoint theme usually contains 3 values for each style array. Those arrays are combined into these 3 effects: subtle, moderate, and intense. For example, this is the outcome when the effects are applied to a specific shape:

todo:image_alt_text

Using 3 properties (FillStyles, LineStyles, EffectStyles) from the FormatScheme class you can change the elements in a theme (even more flexibly than the options in PowerPoint).

This Python code shows you how to change a theme effect by altering parts of elements:

with slides.Presentation("combined_with_master.pptx") as pres:
    pres.master_theme.format_scheme.line_styles[0].fill_format.solid_fill_color.color = draw.Color.red
    pres.master_theme.format_scheme.fill_styles[2].fill_type = slides.FillType.SOLID
    pres.master_theme.format_scheme.fill_styles[2].solid_fill_color.color = draw.Color.forest_green
    pres.master_theme.format_scheme.effect_styles[2].effect_format.outer_shadow_effect.distance = 10

    pres.save("Design_04_Subtle_Moderate_Intense-out.pptx", slides.export.SaveFormat.PPTX)

The resulting changes in fill color, fill type, shadow effect, etc:

todo:image_alt_text

Presentation Background

Presentation Theme

Change Theme Color

Set Theme Color from Additional Palette

Change Theme Font

TIP

Change Theme Background Style

TIP

Change Theme Effect

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