WIP improve text positioning (not there yet)
This commit is contained in:
James R. Barlow
@@ -24,6 +24,7 @@ from ocrmypdf.hocrtransform.backends.reportlab import (
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ReportlabCanvas,
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black,
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cyan,
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green,
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inch,
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magenta,
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red,
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@@ -186,8 +187,11 @@ class HocrTransform:
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return float(matches.group(1)), int(matches.group(2))
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return (0.0, 0.0)
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def pt_from_pixel(self, pxl) -> Rect:
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def pt_from_pixel(self, pxl, topdown=False) -> Rect:
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"""Returns the quantity in PDF units (pt) given quantity in pixels."""
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if topdown:
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pxl.y1 = self.height - pxl.y1
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pxl.y2 = self.height - pxl.y2
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return Rect._make((c / self.dpi * inch) for c in pxl)
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def _child_xpath(self, html_tag: str, html_class: str | None = None) -> str:
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@@ -240,12 +244,6 @@ class HocrTransform:
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page_size=(self.width, self.height),
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)
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# draw bounding box for each paragraph
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# light blue for bounding box of paragraph
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pdf.set_stroke_color(cyan)
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# light blue for bounding box of paragraph
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pdf.set_fill_color(cyan)
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pdf.set_line_width(0) # no line for bounding box
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for elem in self.hocr.iterfind(self._child_xpath('p', 'ocr_par')):
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elemtxt = self._get_element_text(elem).rstrip()
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if len(elemtxt) == 0:
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@@ -253,11 +251,12 @@ class HocrTransform:
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pxl_coords = self.element_coordinates(elem)
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pt = self.pt_from_pixel(pxl_coords) # pylint: disable=invalid-name
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# draw the bbox border
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if show_bounding_boxes: # pragma: no cover
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# draw cyan box around paragraph
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if show_bounding_boxes and False: # pragma: no cover
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pdf.set_stroke_color(cyan)
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pdf.set_line_width(0.1) # no line for bounding box
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pdf.rect(
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pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1, fill=1
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pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1, fill=0
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)
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found_lines = False
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@@ -323,27 +322,34 @@ class HocrTransform:
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slope = 0.0
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angle = atan(slope)
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cos_a, sin_a = cos(angle), sin(angle)
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intercept = pxl_intercept / self.dpi * inch
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# Matrix it!
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# pdf._cs.push()
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# pdf._cs.cm(cos_a, -sin_a, sin_a, cos_a, 0, 0)
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# cos_a, sin_a = 1, 0
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# slope = 0
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# intercept = 0
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text = pdf.begin_text()
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intercept = pxl_intercept / self.dpi * inch
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# Don't allow the font to break out of the bounding box. Division by
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# cos_a accounts for extra clearance between the glyph's vertical axis
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# on a sloped baseline and the edge of the bounding box.
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fontsize = (line_height - abs(intercept)) / cos_a
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text.set_font(fontname, fontsize)
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if invisible_text:
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if invisible_text or True:
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text.set_render_mode(3) # Invisible (indicates OCR text)
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# Intercept is normally negative, so this places it above the bottom
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# of the line box
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baseline_y2 = self.height - (line_box.y2 + intercept)
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if show_bounding_boxes: # pragma: no cover
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if show_bounding_boxes and True: # pragma: no cover
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# draw the baseline in magenta, dashed
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pdf.set_dashes()
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pdf.set_stroke_color(magenta)
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pdf.set_line_width(0.5)
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pdf.set_line_width(0.25)
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# negate slope because it is defined as a rise/run in pixel
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# coordinates and page coordinates have the y axis flipped
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pdf.line(
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@@ -352,10 +358,6 @@ class HocrTransform:
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line_box.x2,
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self.polyval((-slope, baseline_y2), line_box.x2 - line_box.x1),
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)
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# light green for bounding box of word/line
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pdf.set_dashes(6, 3)
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pdf.set_stroke_color(red)
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text.set_text_transform(cos_a, -sin_a, sin_a, cos_a, line_box.x1, baseline_y2)
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pdf.set_fill_color(black) # text in black
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@@ -389,6 +391,18 @@ class HocrTransform:
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# draw the bbox border
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if show_bounding_boxes: # pragma: no cover
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pdf.set_dashes()
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pdf.set_stroke_color(red)
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pdf.set_line_width(0.1)
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# Draw a triangle that conveys word height and drawing direction
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if True:
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pdf.line(box.x1, box.y1, box.x2, box.y1) # across bottom
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pdf.line(box.x2, box.y1, box.x1, box.y2) # diagonal
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pdf.line(box.x1, box.y1, box.x1, box.y2) # rise
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pdf.set_dashes()
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pdf.set_stroke_color(green)
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pdf.set_line_width(0.1)
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pdf.rect(
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box.x1, self.height - line_box.y2, box_width, line_height, fill=0
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)
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@@ -405,10 +419,19 @@ class HocrTransform:
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# For skewed lines, in the text transform we set up a rotated
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# coordinate system, so we don't have to account for the
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# incremental offset. Surprisingly most PDF viewers can handle this.
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cursor = text.get_start_of_line()
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dx = box.x1 - cursor[0]
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dy = baseline_y2 - cursor[1]
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text.move_cursor(dx, dy)
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if 0:
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cursor = text.get_start_of_line()
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dx = box.x1 - cursor[0]
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dy = baseline_y2 - cursor[1]
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text.move_cursor(dx, dy)
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text.set_text_transform(
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cos_a,
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-sin_a,
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sin_a,
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cos_a,
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box.x1,
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self.height - line_box.y2,
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)
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# If reportlab tells us this word is 0 units wide, our best seems
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# to be to suppress this text
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@@ -416,6 +439,7 @@ class HocrTransform:
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text.set_horiz_scale(100 * box_width / font_width)
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text.show(elemtxt)
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pdf.draw_text(text)
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# pdf._cs.pop()
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if __name__ == "__main__":
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