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# This file is part of ReText
# Copyright: 2016-2023 Maurice van der Pot
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from PyQt6.QtCore import QPoint
class SyncScroll:
def __init__(self, previewFrame,
editorPositionToSourceLineFunc,
sourceLineToEditorPositionFunc):
self.posmap = {}
self.frame = previewFrame
self.editorPositionToSourceLine = editorPositionToSourceLineFunc
self.sourceLineToEditorPosition = sourceLineToEditorPositionFunc
self.previewPositionBeforeLoad = QPoint()
self.contentIsLoading = False
self.editorViewportHeight = 0
self.editorViewportOffset = 0
self.editorCursorPosition = 0
self.frame.contentsSizeChanged.connect(self._handlePreviewResized)
self.frame.loadStarted.connect(self._handleLoadStarted)
self.frame.loadFinished.connect(self._handleLoadFinished)
def isActive(self):
return bool(self.posmap)
def handleEditorResized(self, editorViewportHeight):
self.editorViewportHeight = editorViewportHeight
self._updatePreviewScrollPosition()
def handleEditorScrolled(self, editorViewportOffset):
self.editorViewportOffset = editorViewportOffset
return self._updatePreviewScrollPosition()
def handleCursorPositionChanged(self, editorCursorPosition):
self.editorCursorPosition = editorCursorPosition
return self._updatePreviewScrollPosition()
def _handleLoadStarted(self):
# Store the current scroll position so it can be restored when the new
# content is presented
self.previewPositionBeforeLoad = self.frame.scrollPosition()
self.contentIsLoading = True
def _handleLoadFinished(self):
self.frame.setScrollPosition(self.previewPositionBeforeLoad)
self.contentIsLoading = False
self.frame.getPositionMap(self._setPositionMap)
def _handlePreviewResized(self):
self.frame.getPositionMap(self._setPositionMap)
self._updatePreviewScrollPosition()
if not self.posmap and self.frame.scrollPosition().y() == 0:
self.frame.setScrollPosition(self.previewPositionBeforeLoad)
def _linearScale(self, fromValue, fromMin, fromMax, toMin, toMax):
fromRange = fromMax - fromMin
toRange = toMax - toMin
toValue = toMin
if fromRange:
toValue += ((fromValue - fromMin) * toRange) / float(fromRange)
return toValue
def _updatePreviewScrollPosition(self):
if not self.posmap:
# Loading new content resets the scroll position to the top. If we
# don't have a posmap to calculate the new best position, then
# restore the position stored at the beginning of the load.
if self.contentIsLoading:
self.frame.setScrollPosition(self.previewPositionBeforeLoad)
return
textedit_pixel_to_scroll_to = self.editorCursorPosition
if textedit_pixel_to_scroll_to < self.editorViewportOffset:
textedit_pixel_to_scroll_to = self.editorViewportOffset
last_viewport_pixel = self.editorViewportOffset + self.editorViewportHeight
if textedit_pixel_to_scroll_to > last_viewport_pixel:
textedit_pixel_to_scroll_to = last_viewport_pixel
line_to_scroll_to = self.editorPositionToSourceLine(textedit_pixel_to_scroll_to)
# Do a binary search through the posmap to find the nearest line above
# and below the line to scroll to for which the rendered position is
# known.
posmap_lines = [0] + sorted(self.posmap.keys())
min_index = 0
max_index = len(posmap_lines) - 1
while max_index - min_index > 1:
current_index = int((min_index + max_index) / 2)
if posmap_lines[current_index] > line_to_scroll_to:
max_index = current_index
else:
min_index = current_index
# number of nearest line above and below for which we have a position
min_line = posmap_lines[min_index]
max_line = posmap_lines[max_index]
min_textedit_pos = self.sourceLineToEditorPosition(min_line)
max_textedit_pos = self.sourceLineToEditorPosition(max_line)
# rendered pixel position of nearest line above and below
min_preview_pos = self.posmap[min_line]
max_preview_pos = self.posmap[max_line]
# calculate rendered pixel position of line corresponding to cursor
# (0 == top of document)
preview_pixel_to_scroll_to = self._linearScale(textedit_pixel_to_scroll_to,
min_textedit_pos, max_textedit_pos,
min_preview_pos, max_preview_pos)
distance_to_top_of_viewport_editor = textedit_pixel_to_scroll_to - self.editorViewportOffset
distance_to_top_of_viewport_preview = distance_to_top_of_viewport_editor / self.frame.zoomFactor()
preview_scroll_offset = preview_pixel_to_scroll_to - distance_to_top_of_viewport_preview
pos = self.frame.scrollPosition()
pos.setY(preview_scroll_offset)
self.frame.setScrollPosition(pos)
def _setPositionMap(self, posmap):
self.posmap = posmap
if posmap:
self.posmap[0] = 0
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