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Implemented the binary chop algorithm to speed up 'word by word' rendering. 

bzr-revno: 1567
This commit is contained in:
Andreas Preikschat 2011-05-24 21:33:12 +02:00
parent 721def9b10 2377a5f5ff
commit 0db69c93ed
1 changed files with 49 additions and 16 deletions
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65
openlp/core/lib/renderer.py
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@ -335,7 +335,7 @@ class Renderer(object):
styled_text += styled_line
html = self.page_shell + styled_text + HTML_END
self.web.setHtml(html)
# Text too long so go to next page
# Text too long so go to next page.
if self.web_frame.contentsSize().height() > self.page_height:
if force_page and line_count > 0:
Receiver.send_message(u'theme_line_count', line_count)
@ -366,7 +366,7 @@ class Renderer(object):
"""
log.debug(u'_paginate_slide_words - Start')
line_end = u''
line_end = u' '
if line_break:
line_end = u'<br>'
formatted = []
@ -374,10 +374,11 @@ class Renderer(object):
previous_raw = u''
lines = text.split(u'\n')
for line in lines:
line = line.strip()
styled_line = expand_tags(line)
html = self.page_shell + previous_html + styled_line + HTML_END
self.web.setHtml(html)
# Text too long so go to next page
# Text too long so go to next page.
if self.web_frame.contentsSize().height() > self.page_height:
# Check if there was a verse before the current one and append
# it, when it fits on the page.
@ -401,24 +402,56 @@ class Renderer(object):
previous_html = styled_line + line_end
previous_raw = line + line_end
continue
words = self._words_split(line)
for word in words:
styled_word = expand_tags(word)
html = self.page_shell + previous_html + styled_word + \
HTML_END
# Figure out how many words of the line will fit on screen by
# using the algorithm known as "binary chop".
raw_words = self._words_split(line)
html_words = [expand_tags(word) for word in raw_words]
smallest_index = 0
highest_index = len(html_words) - 1
index = int(highest_index / 2)
while True:
html = self.page_shell + previous_html + \
u''.join(html_words[:index + 1]).strip() + HTML_END
self.web.setHtml(html)
# Text too long so go to next page
if self.web_frame.contentsSize().height() > \
self.page_height:
while previous_raw.endswith(u'<br>'):
previous_raw = previous_raw[:-4]
formatted.append(previous_raw)
# We know that it does not fit, so change/calculate the
# new index and highest_index accordingly.
highest_index = index
index = int(index - (index - smallest_index) / 2)
else:
smallest_index = index
index = int(index + (highest_index - index) / 2)
# We found the number of words which will fit.
if smallest_index == index or highest_index == index:
index = smallest_index
formatted.append(previous_raw.rstrip(u'<br>') +
u''.join(raw_words[:index + 1]))
previous_html = u''
previous_raw = u''
previous_html += styled_word
previous_raw += word
previous_html += line_end
previous_raw += line_end
else:
continue
# Check if the rest of the line fits on the slide. If it
# does we do not have to do the much more intensive "word by
# word" checking.
html = self.page_shell + \
u''.join(html_words[index + 1:]).strip() + HTML_END
self.web.setHtml(html)
if self.web_frame.contentsSize().height() <= \
self.page_height:
previous_html = \
u''.join(html_words[index + 1:]).strip() + line_end
previous_raw = \
u''.join(raw_words[index + 1:]).strip() + line_end
break
else:
# The other words do not fit, thus reset the indexes,
# create a new list and continue with "word by word".
raw_words = raw_words[index + 1:]
html_words = html_words[index + 1:]
smallest_index = 0
highest_index = len(html_words) - 1
index = int(highest_index / 2)
else:
previous_html += styled_line + line_end
previous_raw += line + line_end