feat: add justify, indent, alignment options

to MarkupText
fixes #34

Author: naveen521kk

manimpango/cmanimpango.pyx

@@ -1,6 +1,6 @@
 from xml.sax.saxutils import escape
 from .utils import *
-
+from .enums import Alignment
 class TextSetting:
     """Formatting for slices of a :class:`manim.mobject.svg.text_mobject.Text` object."""
     def __init__(
@@ -138,22 +138,28 @@ class MarkupUtils:
         slant: str,
         weight: str,
         size: int,
-        line_spacing: int,
+        _: int, # for some there was a keyword here.
         disable_liga: bool,
         file_name: str,
         START_X: int,
         START_Y: int,
         width: int,
         height: int,
+        *, # keyword only arguments below
+        justify: bool = None,
+        indent: float = None,
+        line_spacing: float = None,
+        alignment: Alignment = None
     ) -> int:
         """Render an SVG file from a :class:`manim.mobject.svg.text_mobject.MarkupText` object."""
         cdef cairo_surface_t* surface
         cdef cairo_t* context
         cdef PangoFontDescription* font_desc
         cdef PangoLayout* layout
         cdef cairo_status_t status
-        cdef double width_layout = width
+        cdef double width_layout = width - 50
         cdef double font_size = size
+        cdef int temp_int # a temporary C integer for conversion
 
         file_name_bytes = file_name.encode("utf-8")
 
@@ -182,8 +188,23 @@ class MarkupUtils:
             cairo_destroy(context)
             cairo_surface_destroy(surface)
             raise MemoryError("Pango.Layout can't be created from Cairo Context.")
+
         pango_layout_set_width(layout, pango_units_from_double(width_layout))
 
+        if justify:
+            pango_layout_set_justify(layout, justify)
+
+        if indent:
+            temp_int = pango_units_from_double(indent)
+            pango_layout_set_indent(layout, temp_int)
+
+        if line_spacing:
+            # Typical values are: 0, 1, 1.5, 2.
+            pango_layout_set_line_spacing(layout, line_spacing)
+
+        if alignment:
+            pango_layout_set_alignment(layout, alignment.value)
+
         font_desc = pango_font_description_new()
         if font_desc==NULL:
             cairo_destroy(context)

manimpango/enums.pyx

@@ -90,3 +90,21 @@ class Variant(Enum):
     """
     NORMAL = PANGO_VARIANT_NORMAL
     SMALL_CAPS = PANGO_VARIANT_SMALL_CAPS
+
+class Alignment(Enum):
+    """
+    An enumeration specifying alignment.
+
+    Attributes
+    ----------
+
+    NORMAL :
+        A normal font.
+
+    SMALL_CAPS :
+        A font with the lower case characters replaced by smaller variants
+        of the capital characters.
+    """
+    LEFT = PANGO_ALIGN_LEFT
+    CENTER = PANGO_ALIGN_CENTER
+    RIGHT = PANGO_ALIGN_RIGHT

manimpango/pango.pxd

@@ -37,6 +37,11 @@ cdef extern from "pango/pangocairo.h":
         PANGO_WRAP_WORD
         PANGO_WRAP_CHAR
         PANGO_WRAP_WORD_CHAR
+    ctypedef enum PangoAlignment:
+        PANGO_ALIGN_LEFT
+        PANGO_ALIGN_CENTER
+        PANGO_ALIGN_RIGHT
+
     PangoLayout* pango_cairo_create_layout(cairo_t* cr)
     void pango_cairo_show_layout(
         cairo_t* cr,
@@ -121,3 +126,19 @@ cdef extern from "pango/pangocairo.h":
     const char* pango_font_family_get_name(
         PangoFontFamily *family
     )
+    void pango_layout_set_justify(
+        PangoLayout *layout,
+        gboolean justify
+    )
+    void pango_layout_set_indent(
+        PangoLayout *layout,
+        int indent
+    )
+    void pango_layout_set_line_spacing(
+        PangoLayout *layout,
+        float factor
+    )
+    void pango_layout_set_alignment(
+        PangoLayout *layout,
+        PangoAlignment alignment
+    )

tests/_manim.py

@@ -0,0 +1,88 @@
+# -*- coding: utf-8 -*-
+"""This file contains helpers for the tests copied and modified
+from Manim.
+"""
+
+import os
+from pathlib import Path
+
+from manimpango import Alignment, MarkupUtils
+
+
+class MarkupText:
+    def __init__(
+        self,
+        text: str,
+        *,
+        size: int = 1,
+        line_spacing: int = -1,
+        font: str = None,
+        slant: str = "NORMAL",
+        weight: str = "NORMAL",
+        tab_width: int = 4,
+        disable_ligatures: bool = False,
+        justify: bool = None,
+        indent: float = None,
+        alignment: Alignment = None,
+        # for the tests
+        filename: str = "test.svg",
+        **kwargs,
+    ):
+        self.text = text
+        self.size = size
+        self.line_spacing = line_spacing
+        self.font = font
+        self.slant = slant
+        self.weight = weight
+        self.tab_width = tab_width
+        self.filename = filename
+        self.original_text = text
+        self.disable_ligatures = disable_ligatures
+
+        self.justify = justify
+        self.indent = indent
+        self.alignment = alignment
+        if not MarkupUtils.validate(self.text):
+            raise ValueError(
+                f"Pango cannot parse your markup in {self.text}. "
+                "Please check for typos, unmatched tags or unescaped "
+                "special chars like < and &."
+            )
+
+        if self.line_spacing == -1:
+            self.line_spacing = self.size + self.size * 0.3
+        else:
+            self.line_spacing = self.size + self.size * self.line_spacing
+
+        self.text2svg()
+
+    def text2svg(self):
+        """Convert the text to SVG using Pango."""
+        size = self.size * 10
+        line_spacing = self.line_spacing * 10
+        dir_name = Path(self.filename).parent
+        disable_liga = self.disable_ligatures
+        if not os.path.exists(dir_name):
+            os.makedirs(dir_name)
+        file_name = self.filename
+        return MarkupUtils.text2svg(
+            f"{self.text}",
+            self.font,
+            self.slant,
+            self.weight,
+            size,
+            line_spacing,
+            disable_liga,
+            file_name,
+            20,
+            20,
+            600,  # width
+            400,  # height
+            justify=self.justify,
+            indent=self.indent,
+            line_spacing=self.line_spacing,
+            alignment=self.alignment,
+        )
+
+    def __repr__(self):
+        return f"MarkupText({repr(self.original_text)})"

tests/test_markup.py

@@ -1,4 +1,18 @@
 # -*- coding: utf-8 -*-
+
+ipsum_text = (
+    "Lorem ipsum dolor sit amet, consectetur adipiscing elit,"
+    "sed do eiusmod tempor incididunt ut labore et dolore"
+    "magna aliqua. Ut enim ad minim veniam, quis nostrud"
+    "exercitation ullamco laboris nisi ut aliquip"
+    "ex ea commodo consequat. Duis aute irure dolor"
+    "in reprehenderit in voluptate velit esse cillum"
+    "dolore eu fugiat nulla pariatur. Excepteur sint"
+    "occaecat cupidatat non proident, sunt in culpa qui"
+    "officia deserunt mollit anim id est laborum."
+)
+
+
 def test_good_markup():
     import manimpango  # noqa: F401