Implement drawing colored backgrounds for change blocks

src/calibre/gui2/tweak_book/diff.py

@@ -8,16 +8,19 @@ __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import sys
 from functools import partial
+from collections import namedtuple
 
 from PyQt4.Qt import (
     QSplitter, QApplication, QPlainTextDocumentLayout, QTextDocument,
-    QTextCursor, QTextCharFormat, Qt, QRect, QPainter, QPalette)
+    QTextCursor, QTextCharFormat, Qt, QRect, QPainter, QPalette, QPen)
 
 from calibre.gui2.tweak_book import tprefs
 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
 
+Change = namedtuple('Change', 'ltop lbot rtop rbot kind')
+
 def get_theme():
     theme = THEMES.get(tprefs['editor_theme'], None)
     if theme is None:
@@ -26,8 +29,9 @@ def get_theme():
 
 class TextBrowser(PlainTextEdit):  # {{{
 
-    def __init__(self, parent=None):
+    def __init__(self, right=False, parent=None):
         PlainTextEdit.__init__(self, parent)
+        self.right = right
         self.setReadOnly(True)
         w = self.fontMetrics()
         self.number_width = max(map(lambda x:w.width(str(x)), xrange(10)))
@@ -58,9 +62,29 @@ class TextBrowser(PlainTextEdit):  # {{{
         pal.setColor(pal.Text, theme_color(theme, 'LineNr', 'fg'))
         pal.setColor(pal.BrightText, theme_color(theme, 'LineNrC', 'fg'))
         self.line_number_map = {}
+        self.changes = []
+        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
+        self.diff_backgrounds = {
+            'replace' : theme_color(theme, 'DiffReplace', 'bg'),
+            'insert'  : theme_color(theme, 'DiffInsert', 'bg'),
+            'delete'  : theme_color(theme, 'DiffDelete', 'bg'),
+        }
+        self.diff_foregrounds = {
+            'replace' : theme_color(theme, 'DiffReplace', 'fg'),
+            'insert'  : theme_color(theme, 'DiffInsert', 'fg'),
+            'delete'  : theme_color(theme, 'DiffDelete', 'fg'),
+        }
+
+    def clear(self):
+        PlainTextEdit.clear(self)
+        self.line_number_map.clear()
+        del self.changes[:]
 
     def update_line_number_area_width(self, block_count=0):
-        self.setViewportMargins(self.line_number_area_width(), 0, 0, 0)
+        if self.right:
+            self.setViewportMargins(0, 0, self.line_number_area_width(), 0)
+        else:
+            self.setViewportMargins(self.line_number_area_width(), 0, 0, 0)
 
     def line_number_area_width(self):
         digits = 1
@@ -82,7 +106,10 @@ class TextBrowser(PlainTextEdit):  # {{{
     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()))
+        if self.right:
+            self.line_number_area.setGeometry(QRect(cr.right() - self.line_number_area_width(), cr.top(), cr.right(), cr.height()))
+        else:
+            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)
@@ -95,13 +122,45 @@ class TextBrowser(PlainTextEdit):  # {{{
         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():
+            r = ev.rect()
-                painter.drawText(0, top, self.line_number_area.width() - 5, self.fontMetrics().height(),
+            if block.isVisible() and bottom >= r.top():
+                if self.right:
+                    painter.drawText(r.left() + 3, top, r.right(), self.fontMetrics().height(),
+                              Qt.AlignLeft, unicode(self.line_number_map.get(num, '')))
+                else:
+                    painter.drawText(r.left(), top, r.right() - 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
+
+    def paintEvent(self, event):
+        w = self.width()
+        painter = QPainter(self.viewport())
+        painter.setClipRect(event.rect())
+        floor = event.rect().bottom()
+        ceiling = event.rect().top()
+        fv = self.firstVisibleBlock().blockNumber()
+        origin = self.contentOffset()
+        doc = self.document()
+
+        for top, bot, kind in self.changes:
+            if bot < fv:
+                continue
+            y_top = self.blockBoundingGeometry(doc.findBlockByNumber(top)).translated(origin).y() - 1
+            y_bot = self.blockBoundingGeometry(doc.findBlockByNumber(bot)).translated(origin).y() + 1
+            if max(y_top, y_bot) < ceiling:
+                continue
+            if min(y_top, y_bot) > floor:
+                break
+            painter.fillRect(0,  y_top, w, y_bot - y_top, self.diff_backgrounds[kind])
+            painter.setPen(QPen(self.diff_foregrounds[kind], 1))
+            painter.drawLine(0, y_top, w, y_top)
+            painter.drawLine(0, y_bot - 1, w, y_bot - 1)
+        painter.end()
+        PlainTextEdit.paintEvent(self, event)
+
 # }}}
 
 class Highlight(QTextDocument):  # {{{
@@ -141,7 +200,7 @@ class TextDiffView(QSplitter):
     def __init__(self, parent=None):
         QSplitter.__init__(self, parent)
 
-        self.left, self.right = TextBrowser(self), TextBrowser(self)
+        self.left, self.right = TextBrowser(parent=self), TextBrowser(right=True, parent=self)
         self.addWidget(self.left), self.addWidget(self.right)
 
     def __call__(self, left_text, right_text, context=None, syntax=None):
@@ -150,8 +209,6 @@ 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.line_number_map)
-        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)
 
@@ -160,7 +217,12 @@ 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()
+        cl, cr = self.left_cursor, self.right_cursor = self.left.textCursor(), self.right.textCursor()
+        cl.beginEditBlock(), cr.beginEditBlock()
+        self.changes = []
+        self.left_insert = partial(self.do_insert, cl, self.left_highlight, self.left.line_number_map)
+        self.right_insert = partial(self.do_insert, cr, self.right_highlight, self.right.line_number_map)
+
         if context is None:
             for tag, alo, ahi, blo, bhi in self.cruncher.get_opcodes():
                 getattr(self, tag)(alo, ahi, blo, bhi)
@@ -168,38 +230,55 @@ class TextDiffView(QSplitter):
             for group in self.cruncher.get_grouped_opcodes():
                 for tag, alo, ahi, blo, bhi in group:
                     getattr(self, tag)(alo, ahi, blo, bhi)
+        cl.endEditBlock(), cr.endEditBlock()
 
         for v in (self.left, self.right):
             c = v.textCursor()
             c.movePosition(c.Start)
             v.setTextCursor(c)
 
+        for ltop, lbot, rtop, rbot, kind in self.changes:
+            self.left.changes.append((ltop, lbot, kind))
+            self.right.changes.append((rtop, rbot, kind))
+
+        self.update()
+
     def do_insert(self, cursor, highlighter, line_number_map, lo, hi):
-        start_block = cursor.blockNumber()
+        start_block = cursor.block()
         highlighter.copy_lines(lo, hi, cursor)
-        for num, i in enumerate(xrange(start_block, cursor.blockNumber())):
+        for num, i in enumerate(xrange(start_block.blockNumber(), cursor.blockNumber())):
             line_number_map[i] = lo + num + 1
-        return start_block, cursor.blockNumber()
+        return start_block.blockNumber(), cursor.block().blockNumber()
 
     def equal(self, alo, ahi, blo, bhi):
         self.left_insert(alo, ahi), self.right_insert(blo, bhi)
 
     def delete(self, alo, ahi, blo, bhi):
-        self.left_insert(alo, ahi)
+        start_block, current_block = self.left_insert(alo, ahi)
+        r = self.right_cursor.block().blockNumber()
+        self.changes.append(Change(
+            ltop=start_block, lbot=current_block, rtop=r, rbot=r, kind='delete'))
 
     def insert(self, alo, ahi, blo, bhi):
-        self.right_insert(blo, bhi)
+        start_block, current_block = self.right_insert(blo, bhi)
+        l = self.left_cursor.block().blockNumber()
+        self.changes.append(Change(
+            rtop=start_block, rbot=current_block, ltop=l, lbot=l, kind='insert'))
 
     def replace(self, alo, ahi, blo, bhi):
-        self.left_insert(alo, ahi)
+        lsb, lcb = self.left_insert(alo, ahi)
-        self.right_insert(blo, bhi)
+        rsb, rcb = self.right_insert(blo, bhi)
+        self.changes.append(Change(
+            rtop=rsb, rbot=rcb, ltop=lsb, lbot=lcb, kind='replace'))
 
 if __name__ == '__main__':
     app = QApplication([])
     raw1 = open(sys.argv[-2], 'rb').read().decode('utf-8')
     raw2 = open(sys.argv[-1], 'rb').read().decode('utf-8')
     w = TextDiffView()
-    w(raw1, raw2, syntax='html', context=None)
     w.show()
+    w(raw1, raw2, syntax='html', context=None)
     app.exec_()
 
+# TODO: Add diff colors for other color schemes
+# TODO: Handle scroll wheel and key up/down events

src/calibre/gui2/tweak_book/editor/themes.py

@@ -137,6 +137,11 @@ THEMES = {
     SpecialCharacter bg={cursor_loc}
     Error        us=wave uc=red
 
+    DiffDelete   bg=rgb(255,160,180) fg=rgb(200,60,90)
+    DiffInsert   bg=rgb(180,255,180) fg=rgb(80,210,80)
+    DiffReplace  bg=rgb(206,226,250) fg=rgb(90,130,180)
+    DiffReplaceReplace bg=rgb(180,210,250)
+
     '''.format(
         cursor_loc='F8DE7E',
         identifier='7b5694',