Text#

This section is about drawing text on slides.

Text is drawn on a box (or slide) by calling the .text() method. It creates a new box containing a text.

@deck.slide()
def text_demo(slide):
    slide.text("Hello world!")

Note for Elsie users

Calling .text() creates a new box; this is a different behavior than in Elsie, where calling .text() does not create a new box, which very often leads to code like .box().text() to create a wrapping box. This is not necessary in Nelsie.

Text styles#

The drawing of a text is configured by TextStyle instances. One of the uses is to set it as the second argument of the .text() method.

from nelsie import TextStyle

@deck.slide()
def text_style_demo(slide):
    style = TextStyle(size=100, color="green")
    slide.text("Hello world!", style)

The TextStyle constructor has the following parameters; each parameter can be `None', which means that the parameter will not be overridden by this style.

font_family: str - Name of the font or a generic family: sans-serif, monospace, serif
color: str - Color of the text
size: float - Size of the font
line_spacing: float - Line spacing relative to size
italics: bool - Enable italic mode
weight: int - Weight of the font; values 1-1000
- 400 = Normal
- 700 = Bold
bold: bool - Shortcut that sets weight=700
underline: bool - Draws a line under the text
overline: bool - Draws a line over the text
line_through: bool - Draws a line through a text
stroke: Stroke | None - If not None, font is drawn in stroked mode (see Paths for documentation of Stroke class)
stretch: FontStretch:
- FontStretch.UltraCondensed
- FontStretch.ExtraCondensed
- FontStretch.Condensed
- FontStretch.SemiCondensed
- FontStretch.Normal
- FontStretch.SemiExpanded
- FontStretch.Expanded
- FontStretch.ExtraExpanded
- FontStretch.UltraExpanded

Named styles#

Each box can have a set of named fonts defined. When a new box is created it inherits all named styles from its parent.

@deck.slide()
def text_style_demo(slide):
    slide.set_style("my-style", TextStyle(size=100, color="red"))
    slide.text("Hello world!", "my-style")

Slide deck may also defines a font that is inherited by all slides.

deck.set_slide("my-style", TextStyle(size=100, color="red"))

Build-in styles#

There are three predefined text styles:

"default"
"monospace"
"code"

Style "default" is special and is used as a source of default values for drawing fonts when values are not overridden by more specific fonts:

@deck.slide()
def default_style_demo(slide):

    # Set default style
    slide.set_style("default", TextStyle(color="blue"))

    # Draw text with overriden style, color is taken from the default style
    slide.text("Hello world!", TextStyle(size=100))

Style "monospace" sets the font family to a monospace font.

Style "code" is used as a default style in .code() method. See Code for more details. By default is have the same effect as style "monospace".

Inline styles#

Named styles are particularly useful for modifying individual blocks of text within a single string passed to the .text() method. To style a block of text, use the following syntax ~STYLE{TEXT} where STYLE is a style name and TEXT is the styled text.

@deck.slide()
def inline_style_demo(slide):

    slide.set_style("red", TextStyle(color="red"))
    slide.set_style("big", TextStyle(size=64))

    slide.text("~red{Hello} world!\n~monospace{github.com/spirali/~big{nelsie}}")

Fonts#

A font can be specified by the font_family parameter of TextStyle. All system fonts are available by default. You can add more fonts via Resources.

Nelsie is not shipped with a built-in font and tries to automatically detect a sans-serif font as font_family for the "default" style and a monospace font for the "monospace" style.

You can override this behavior by setting

deck = SlideDeck(default_font="Helvetica", default_monospace_font="Ubuntu Mono")

Robust slide rendering across systems

For robust cross-platform slide rendering, it is recommended to include all used fonts along with the slide source code.

Text alignment#

A text can be aligned to the left, center, and right by setting .text(align="...") to "start", "center", or "end". The value "start" is the default.

@deck.slide()
def text_align_demo(slide):

    TEXT = "Line 1\nLooooong line\nThird line"

    box = slide.box(gap=(0, 50))
    box.text(TEXT, align="start")
    box.text(TEXT, align="center")
    box.text(TEXT, align="end")

Text box#

Calling .text() creates a box for the text; the method takes the same arguments as .box() to configure the underlying box.

@deck.slide()
def text_box_demo(slide):
    box = slide.box(bg_color="gray")
    box.text("Hello world!", bg_color="orange", m_x=50, m_y=30)

Updating style#

The .set_style() method overrides the whole style over given name:

deck.set_style("my-style", TextStyle(color="green"))

@deck.slide()
def text_style_demo(slide):
    slide.set_style("default", TextStyle(size=80))

    # "my-style" now forgets the color, as we fully redefining what "my-style" is
    slide.set_style("my-style", TextStyle(italic=True))
    slide.text("Hello world!", "my-style")

There is method .update_style(), if we want to "update" style, and change only some properties and keep others.

deck.set_style("my-style", TextStyle(color="green"))

@deck.slide()
def text_style_demo(slide):
    slide.set_style("default", TextStyle(size=80))

    # "my-style" now contains both color change to green and italic style
    slide.update_style("my-style", TextStyle(italic=True))
    slide.text("Hello world!", "my-style")

Setting a default style

There is an exception for style "default" as it always needs to define all attributes. Hence .set_style() for "default" style always behaves as .update_style().

Text and `InSteps`#

You may use InSteps in .text():

@deck.slide()
def text_style_demo(slide):
    slide.set_style("default", TextStyle(size=80))
    slide.text(InSteps({1: "Hello world!", 2: "Hello Nelsie!"}))

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You can also provide an array of strings and InSteps. String in the array is concatenated for each step:

@deck.slide()
def text_style_demo(slide):
    slide.set_style("default", TextStyle(size=80))
    slide.text(["Hello ", InSteps({1: "world", 2: "Nelsie"}), "!"])

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Text styles and `InSteps`#

When a style is set through set_style an instance of InSteps can be used:

@deck.slide()
def text_style_demo(slide):
    slide.set_style("default", TextStyle(size=80))
    slide.set_style("my-style",
                    InSteps({1: TextStyle(color="red"), 2: TextStyle(color="green")}))
    slide.text("Hello world!", "my-style")

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Automatic text stripping#

The .text() method automatically strips whitespace from the beginning and end of the text. This can be disabled by setting .text(..., strip=False).