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https://github.com/python-pillow/Pillow.git
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implement text anchor for truetype fonts
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nulano
parent
5e271e2a6c
commit
bd693f7ecf
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@ -74,6 +74,61 @@ To load a OpenType/TrueType font, use the truetype function in the
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:py:mod:`~PIL.ImageFont` module. Note that this function depends on third-party
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libraries, and may not available in all PIL builds.
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Text anchors
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^^^^^^^^^^^^
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The ``anchor`` parameter determines the position of the ``xy`` coordinates relative to the text.
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It consists of two characters, the horizontal and vertical alignment.
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The default value is ``la`` for horizontal text and ``lt`` for vertical text.
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This parameter is ignored for legacy PIL fonts, where the anchor is always top-left.
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+---+-----------------------+-------------------------------------------------------+
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| Horizontal anchor alignment |
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+===+=======================+=======================================================+
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| l | left | Anchor is to the left of the text. |
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+---+-----------------------+-------------------------------------------------------+
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| m | middle | Anchor is horizontally centered with the text. |
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+---+-----------------------+-------------------------------------------------------+
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| r | right | Anchor is to the right of the text. |
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+---+-----------------------+-------------------------------------------------------+
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| s | baseline | **(vertical text only)** |
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| | | Anchor is at the baseline (middle) of the text. |
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| | | The exact alignment depends on the font. |
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+---+-----------------------+-------------------------------------------------------+
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+---+-----------------------+-------------------------------------------------------+
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| Vertical anchor alignment |
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+===+=======================+=======================================================+
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| a | ascender (top) | **(horizontal text only)** |
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| | | Anchor is at the ascender line (top) |
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| | | of the first line of text. |
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+---+-----------------------+-------------------------------------------------------+
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| t | top | **(single-line text only)** |
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| | | Anchor is at the top of the text. |
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+---+-----------------------+-------------------------------------------------------+
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| m | middle | Anchor is vertically centered with the text. |
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| | | For horizontal text this is the midpoint of the |
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| | | first ascender line and the last descender line. |
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+---+-----------------------+-------------------------------------------------------+
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| s | baseline | **(horizontal text only)** |
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| | | Anchor is at the baseline (bottom) |
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| | | of the first line of text, only |
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| | | descenders extend below the anchor. |
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+---+-----------------------+-------------------------------------------------------+
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| b | bottom | **(single-line text only)** |
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| | | Anchor is at the bottom of the text. |
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+---+-----------------------+-------------------------------------------------------+
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| d | descender (bottom) | **(horizontal text only)** |
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| | | Anchor is at the descender line (bottom) |
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| | | of the last line of text. |
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+---+-----------------------+-------------------------------------------------------+
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See `Font metrics on Wikipedia <https://en.wikipedia.org/wiki/Typeface#Font_metrics>`_
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for more information on the specific terms used.
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Example: Draw Partial Opacity Text
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----------------------------------
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@ -277,18 +332,27 @@ Methods
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Draws the string at the given position.
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:param xy: Top left corner of the text.
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:param xy: The anchor coordinates of the text.
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:param text: Text to be drawn. If it contains any newline characters,
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the text is passed on to
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:py:meth:`~PIL.ImageDraw.ImageDraw.multiline_text`.
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:param fill: Color to use for the text.
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:param font: An :py:class:`~PIL.ImageFont.ImageFont` instance.
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:param anchor: The text anchor alignment. Determines the relative location of
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the anchor to the text. The default alignment is top left.
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See :ref:`Text anchors` for valid values. This parameter is
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ignored for legacy PIL fonts.
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.. note:: This parameter was present in earlier versions
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of Pillow, but implemented only in version 7.2.0.
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:param spacing: If the text is passed on to
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:py:meth:`~PIL.ImageDraw.ImageDraw.multiline_text`,
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the number of pixels between lines.
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:param align: If the text is passed on to
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:py:meth:`~PIL.ImageDraw.ImageDraw.multiline_text`,
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``"left"``, ``"center"`` or ``"right"``.
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``"left"``, ``"center"`` or ``"right"``. Determines the relative alignment of lines.
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Use the ``anchor`` parameter to specify the alignment to ``xy``.
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:param direction: Direction of the text. It can be ``"rtl"`` (right to
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left), ``"ltr"`` (left to right) or ``"ttb"`` (top to bottom).
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Requires libraqm.
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@ -329,12 +393,22 @@ Methods
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Draws the string at the given position.
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:param xy: Top left corner of the text.
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:param xy: The anchor coordinates of the text.
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:param text: Text to be drawn.
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:param fill: Color to use for the text.
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:param font: An :py:class:`~PIL.ImageFont.ImageFont` instance.
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:param anchor: The text anchor alignment. Determines the relative location of
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the anchor to the text. The default alignment is top left.
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See :ref:`Text anchors` for valid values. This parameter is
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ignored for legacy PIL fonts.
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.. note:: This parameter was present in earlier versions
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of Pillow, but implemented only in version 7.2.0.
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:param spacing: The number of pixels between lines.
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:param align: ``"left"``, ``"center"`` or ``"right"``.
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:param align: ``"left"``, ``"center"`` or ``"right"``. Determines the relative alignment of lines.
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Use the ``anchor`` parameter to specify the alignment to ``xy``.
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:param direction: Direction of the text. It can be ``"rtl"`` (right to
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left), ``"ltr"`` (left to right) or ``"ttb"`` (top to bottom).
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Requires libraqm.
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@ -314,6 +314,7 @@ class ImageDraw:
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features=features,
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language=language,
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stroke_width=stroke_width,
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anchor=anchor,
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*args,
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**kwargs,
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)
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@ -327,6 +328,7 @@ class ImageDraw:
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features,
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language,
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stroke_width,
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anchor,
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*args,
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**kwargs,
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)
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@ -347,7 +349,7 @@ class ImageDraw:
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draw_text(stroke_ink, stroke_width)
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# Draw normal text
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draw_text(ink, 0, (stroke_width, stroke_width))
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draw_text(ink, 0)
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else:
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# Only draw normal text
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draw_text(ink)
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@ -367,6 +369,16 @@ class ImageDraw:
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stroke_width=0,
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stroke_fill=None,
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):
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if direction == "ttb":
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raise ValueError("ttb direction is unsupported for multiline text")
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if anchor is None:
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anchor = "la"
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elif len(anchor) != 2:
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raise ValueError("anchor must be a 2 character string")
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elif anchor[1] in "tb":
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raise ValueError("anchor not supported for multiline text")
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widths = []
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max_width = 0
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lines = self._multiline_split(text)
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@ -384,16 +396,33 @@ class ImageDraw:
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)
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widths.append(line_width)
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max_width = max(max_width, line_width)
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left, top = xy
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top = xy[1]
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if anchor[1] == 'm':
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top -= (len(lines) - 1) * line_spacing / 2.0
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elif anchor[1] == 'd':
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top -= (len(lines) - 1) * line_spacing
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for idx, line in enumerate(lines):
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left = xy[0]
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width_difference = max_width - widths[idx]
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# first align left by anchor
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if anchor[0] == 'm':
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left -= width_difference / 2.0
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elif anchor[0] == 'r':
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left -= width_difference
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# then align by align parameter
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if align == "left":
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pass # left = x
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pass
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elif align == "center":
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left += (max_width - widths[idx]) / 2.0
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left += width_difference / 2.0
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elif align == "right":
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left += max_width - widths[idx]
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left += width_difference
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else:
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raise ValueError('align must be "left", "center" or "right"')
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self.text(
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(left, top),
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line,
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@ -407,7 +436,6 @@ class ImageDraw:
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stroke_fill=stroke_fill,
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)
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top += line_spacing
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left = xy[0]
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def textsize(
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self,
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@ -345,6 +345,7 @@ class FreeTypeFont:
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features=None,
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language=None,
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stroke_width=0,
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anchor=None,
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):
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"""
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Create a bitmap for the text.
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@ -393,6 +394,12 @@ class FreeTypeFont:
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.. versionadded:: 6.2.0
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:param anchor: The text anchor alignment. Determines the relative location of
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the anchor to the text. The default alignment is top left.
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See :ref:`Text anchors` for valid values.
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.. versionadded:: 7.2.0
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:return: An internal PIL storage memory instance as defined by the
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:py:mod:`PIL.Image.core` interface module.
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"""
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@ -403,6 +410,7 @@ class FreeTypeFont:
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features=features,
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language=language,
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stroke_width=stroke_width,
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anchor=anchor,
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)[0]
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def getmask2(
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@ -414,6 +422,7 @@ class FreeTypeFont:
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features=None,
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language=None,
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stroke_width=0,
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anchor=None,
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*args,
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**kwargs
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):
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@ -464,14 +473,21 @@ class FreeTypeFont:
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.. versionadded:: 6.2.0
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:param anchor: The text anchor alignment. Determines the relative location of
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the anchor to the text. The default alignment is top left.
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See :ref:`Text anchors` for valid values.
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.. versionadded:: 7.2.0
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:return: A tuple of an internal PIL storage memory instance as defined by the
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:py:mod:`PIL.Image.core` interface module, and the text offset, the
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gap between the starting coordinate and the first marking
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"""
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size, offset = self.font.getsize(
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text, mode == "1", direction, features, language
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text, mode == "1", direction, features, language, anchor
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)
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size = size[0] + stroke_width * 2, size[1] + stroke_width * 2
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offset = offset[0] - stroke_width, offset[1] - stroke_width
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im = fill("L", size, 0)
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self.font.render(
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text, im.id, mode == "1", direction, features, language, stroke_width
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@ -612,12 +612,13 @@ font_getsize(FontObject* self, PyObject* args)
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int position, advanced;
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int x_max, x_min, y_max, y_min;
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FT_Face face;
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int xoffset, yoffset;
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int x_anchor, y_anchor;
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int horizontal_dir;
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int mask = 0;
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int load_flags;
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const char *dir = NULL;
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const char *lang = NULL;
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const char *anchor = NULL;
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size_t i, count;
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GlyphInfo *glyph_info = NULL;
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PyObject *features = Py_None;
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@ -625,10 +626,19 @@ font_getsize(FontObject* self, PyObject* args)
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/* calculate size and bearing for a given string */
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PyObject* string;
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if (!PyArg_ParseTuple(args, "O|izOz:getsize", &string, &mask, &dir, &features, &lang)) {
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if (!PyArg_ParseTuple(args, "O|izOzzz:getsize", &string, &mask, &dir, &features, &lang, &anchor)) {
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return NULL;
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}
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horizontal_dir = dir && strcmp(dir, "ttb") == 0 ? 0 : 1;
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if (anchor == NULL) {
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anchor = horizontal_dir ? "la" : "lt";
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}
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if (strlen(anchor) != 2) {
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goto bad_anchor;
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}
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count = text_layout(string, self, dir, features, lang, &glyph_info, mask);
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if (PyErr_Occurred()) {
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return NULL;
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@ -636,7 +646,6 @@ font_getsize(FontObject* self, PyObject* args)
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face = NULL;
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position = x_max = x_min = y_max = y_min = 0;
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horizontal_dir = dir && strcmp(dir, "ttb") == 0 ? 0 : 1;
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for (i = 0; i < count; i++) {
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int index, error, offset;
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FT_BBox bbox;
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@ -733,21 +742,90 @@ font_getsize(FontObject* self, PyObject* args)
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glyph_info = NULL;
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}
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x_anchor = y_anchor = 0;
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if (face) {
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if (horizontal_dir) {
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xoffset = 0;
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yoffset = self->face->size->metrics.ascender - y_max;
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switch (anchor[0]) {
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case 'l': // left
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x_anchor = 0;
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break;
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case 'm': // middle (left + right) / 2
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x_anchor = position / 2;
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break;
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case 'r': // right
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x_anchor = position;
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break;
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case 's': // vertical baseline
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default:
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goto bad_anchor;
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}
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switch (anchor[1]) {
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case 'a': // ascender
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y_anchor = self->face->size->metrics.ascender;
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break;
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case 't': // top
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y_anchor = y_max;
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break;
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case 'm': // middle (ascender + descender) / 2
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y_anchor = (self->face->size->metrics.ascender + self->face->size->metrics.descender) / 2;
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break;
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case 's': // horizontal baseline
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y_anchor = 0;
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break;
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case 'b': // bottom
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y_anchor = y_min;
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break;
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case 'd': // descender
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y_anchor = self->face->size->metrics.descender;
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break;
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default:
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goto bad_anchor;
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}
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} else {
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xoffset = 0;
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yoffset = -y_max;
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switch (anchor[0]) {
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case 'l': // left
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x_anchor = x_min;
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break;
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case 'm': // middle (left + right) / 2
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x_anchor = (x_min + x_max) / 2;
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break;
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case 'r': // right
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x_anchor = x_max;
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break;
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case 's': // vertical baseline
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x_anchor = 0;
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break;
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default:
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goto bad_anchor;
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}
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switch (anchor[1]) {
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case 't': // top
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y_anchor = 0;
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break;
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case 'm': // middle (top + bottom) / 2
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y_anchor = position / 2;
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break;
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case 'b': // bottom
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y_anchor = position;
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break;
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case 'a': // ascender
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case 's': // horizontal baseline
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case 'd': // descender
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default:
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goto bad_anchor;
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}
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}
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}
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return Py_BuildValue(
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"(ii)(ii)",
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PIXEL(x_max - x_min), PIXEL(y_max - y_min),
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PIXEL(xoffset), PIXEL(yoffset)
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);
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PIXEL(-x_anchor + x_min), PIXEL(y_anchor - y_max)
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);
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bad_anchor:
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PyErr_Format(PyExc_ValueError, "bad anchor specified: %s", anchor);
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return NULL;
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}
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static PyObject*
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