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"""

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    Use of PIL to render the image formatting stuff

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"""

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from PIL import Image, ImageDraw, ImageFont

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from cStringIO import StringIO

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class PILImageFormatter (object) :

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    """

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        Mixin for LogFormatter that implements the basic image-rendering operations on top of format_txt

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    """

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    # the font we load

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    font = None

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    # line spacing in pixels

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    LINE_SPACING = 1

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    def _load_font (self) :

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        """

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            Use the configured img_ttf_path for a TrueType font, or a default one

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        """

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        if self.font :

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            pass

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        elif self.img_ttf_path :

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            # load truetype with configured size

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            self.font = ImageFont.truetype(self.img_ttf_path, self.img_font_size)

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        else :

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            # default

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            self.font = ImageFont.load_default()

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        return self.font

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    def format_png (self, lines, **kwargs) :

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        """

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            Build and return a PNG image of the given lines, using format_txt

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        """

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        # load font

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        font = self._load_font()

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        # build list of plain-text line data

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        lines = list(data for line, data in self.format_txt(lines, **kwargs))

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        # lines sizes

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        line_sizes = [font.getsize(line) for line in lines]

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        # figure out how wide/high the image will be

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        width = max(width for width, height in line_sizes)

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        height = sum(height + self.LINE_SPACING for width, height in line_sizes)

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        # create new B/W image

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        img = Image.new('L', (width, height), 0xff)

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        # drawer

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        draw = ImageDraw.Draw(img)

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        # starting offset

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        offset_y = 0

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        # draw the lines

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        for line, (width, height) in zip(lines, line_sizes) :

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            # draw

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            draw.text((0, offset_y), line, font=font)

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            # next offset

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            offset_y += height + self.LINE_SPACING

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        # output buffer

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        buf = StringIO()

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        # save

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        img.save(buf, 'png')

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        # return data

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        return buf.getvalue()

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