Add line numbers to the diff view

src/calibre/gui2/tweak_book/diff.py

@@ -9,10 +9,12 @@ __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 import sys
 from functools import partial
 
-from PyQt4.Qt import (QSplitter, QApplication, QPlainTextDocumentLayout, QTextDocument, QTextCursor, QTextCharFormat)
+from PyQt4.Qt import (
+    QSplitter, QApplication, QPlainTextDocumentLayout, QTextDocument,
+    QTextCursor, QTextCharFormat, Qt, QRect, QPainter, QPalette)
 
 from calibre.gui2.tweak_book import tprefs
-from calibre.gui2.tweak_book.editor.text import PlainTextEdit, get_highlighter, default_font_family
+from calibre.gui2.tweak_book.editor.text import PlainTextEdit, get_highlighter, default_font_family, LineNumbers
 from calibre.gui2.tweak_book.editor.themes import THEMES, default_theme, theme_color
 from calibre.utils.diff import get_sequence_matcher
 
@@ -22,12 +24,13 @@ def get_theme():
         theme = THEMES[default_theme()]
     return theme
 
-class TextBrowser(PlainTextEdit):
+class TextBrowser(PlainTextEdit):  # {{{
 
     def __init__(self, parent=None):
         PlainTextEdit.__init__(self, parent)
         self.setReadOnly(True)
         w = self.fontMetrics()
+        self.number_width = max(map(lambda x:w.width(str(x)), xrange(10)))
         self.space_width = w.width(' ')
         self.setLineWrapMode(self.WidgetWidth if tprefs['editor_line_wrap'] else self.NoWrap)
         self.setTabStopWidth(tprefs['editor_tab_stop_width'] * self.space_width)
@@ -46,8 +49,62 @@ class TextBrowser(PlainTextEdit):
         pal.setColor(pal.Highlight, theme_color(theme, 'Visual', 'bg'))
         pal.setColor(pal.HighlightedText, theme_color(theme, 'Visual', 'fg'))
         self.setPalette(pal)
+        self.viewport().setCursor(Qt.ArrowCursor)
+        self.line_number_area = LineNumbers(self)
+        self.blockCountChanged[int].connect(self.update_line_number_area_width)
+        self.updateRequest.connect(self.update_line_number_area)
+        self.line_number_palette = pal = QPalette()
+        pal.setColor(pal.Base, theme_color(theme, 'LineNr', 'bg'))
+        pal.setColor(pal.Text, theme_color(theme, 'LineNr', 'fg'))
+        pal.setColor(pal.BrightText, theme_color(theme, 'LineNrC', 'fg'))
+        self.line_number_map = {}
 
-class Highlight(QTextDocument):
+    def update_line_number_area_width(self, block_count=0):
+        self.setViewportMargins(self.line_number_area_width(), 0, 0, 0)
+
+    def line_number_area_width(self):
+        digits = 1
+        limit = max(1, self.blockCount())
+        while limit >= 10:
+            limit /= 10
+            digits += 1
+
+        return 8 + self.number_width * digits
+
+    def update_line_number_area(self, rect, dy):
+        if dy:
+            self.line_number_area.scroll(0, dy)
+        else:
+            self.line_number_area.update(0, rect.y(), self.line_number_area.width(), rect.height())
+        if rect.contains(self.viewport().rect()):
+            self.update_line_number_area_width()
+
+    def resizeEvent(self, ev):
+        PlainTextEdit.resizeEvent(self, ev)
+        cr = self.contentsRect()
+        self.line_number_area.setGeometry(QRect(cr.left(), cr.top(), self.line_number_area_width(), cr.height()))
+
+    def paint_line_numbers(self, ev):
+        painter = QPainter(self.line_number_area)
+        painter.fillRect(ev.rect(), self.line_number_palette.color(QPalette.Base))
+
+        block = self.firstVisibleBlock()
+        num = block.blockNumber()
+        top = int(self.blockBoundingGeometry(block).translated(self.contentOffset()).top())
+        bottom = top + int(self.blockBoundingRect(block).height())
+        painter.setPen(self.line_number_palette.color(QPalette.Text))
+
+        while block.isValid() and top <= ev.rect().bottom():
+            if block.isVisible() and bottom >= ev.rect().top():
+                painter.drawText(0, top, self.line_number_area.width() - 5, self.fontMetrics().height(),
+                              Qt.AlignRight, unicode(self.line_number_map.get(num, '')))
+            block = block.next()
+            top = bottom
+            bottom = top + int(self.blockBoundingRect(block).height())
+            num += 1
+# }}}
+
+class Highlight(QTextDocument):  # {{{
 
     def __init__(self, parent, text, syntax):
         QTextDocument.__init__(self, parent)
@@ -77,6 +134,7 @@ class Highlight(QTextDocument):
                 cursor.insertBlock()
                 cursor.setCharFormat(QTextCharFormat())
                 block = block.next()
+# }}}
 
 class TextDiffView(QSplitter):
 
@@ -92,8 +150,8 @@ class TextDiffView(QSplitter):
         self.left_highlight, self.right_highlight = Highlight(self, left_text, syntax), Highlight(self, right_text, syntax)
         self.context = context
 
-        self.left_insert = partial(self.do_insert, self.left.textCursor(), self.left_highlight)
+        self.left_insert = partial(self.do_insert, self.left.textCursor(), self.left_highlight, self.left.line_number_map)
-        self.right_insert = partial(self.do_insert, self.right.textCursor(), self.right_highlight)
+        self.right_insert = partial(self.do_insert, self.right.textCursor(), self.right_highlight, self.right.line_number_map)
         self.cruncher = get_sequence_matcher()(None, left_lines, right_lines)
         self.do_layout(context)
 
@@ -102,6 +160,7 @@ class TextDiffView(QSplitter):
 
     def do_layout(self, context=None):
         self.left.clear(), self.right.clear()
+        self.left.line_number_map.clear(), self.right.line_number_map.clear()
         if context is None:
             for tag, alo, ahi, blo, bhi in self.cruncher.get_opcodes():
                 getattr(self, tag)(alo, ahi, blo, bhi)
@@ -115,9 +174,11 @@ class TextDiffView(QSplitter):
             c.movePosition(c.Start)
             v.setTextCursor(c)
 
-    def do_insert(self, cursor, highlighter, lo, hi):
+    def do_insert(self, cursor, highlighter, line_number_map, lo, hi):
         start_block = cursor.blockNumber()
         highlighter.copy_lines(lo, hi, cursor)
+        for num, i in enumerate(xrange(start_block, cursor.blockNumber())):
+            line_number_map[i] = lo + num + 1
         return start_block, cursor.blockNumber()
 
     def equal(self, alo, ahi, blo, bhi):