[meld] Improve blank line ignoring behaviour (closes bgo#505087 and bgo#392640)

[Kai Willadsen <kaiw src gnome org>]

commit 0d25f92958a49d5be6618ff63c04ffe1415849a1
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sat Jun 27 08:59:08 2009 +1000

    Improve blank line ignoring behaviour (closes bgo#505087 and bgo#392640)
    
    Blank lines were not ignored when drawing areas in the textview or when
    drawing regions in the diffmap, and blank regions were being incorrectly
    skipped when navigating between diff chunks. This commit factors out the
    correct logic (adapted from on_linkmap_expose_event()) and adapts it to
    work with chunks returned by Differ.single_changes().
    
    This commit fixes bgo#505087 and bgo#392640, as well as an unreported bug
    with blank changes being shown in the diffmap.

 filediff.py |   53 ++++++++++++++++++++++++++++++-----------------------
 1 files changed, 30 insertions(+), 23 deletions(-)
---
diff --git a/filediff.py b/filediff.py
index 478ac6a..f5617bb 100644
--- a/filediff.py
+++ b/filediff.py
@@ -680,6 +680,9 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
 
         last_change = None
         for change in self.linediffer.single_changes(pane, self._get_texts()):
+            change, skip = self._consume_blank_lines(change, pane, change[5])
+            if skip:
+                continue
             if change[2] < start_line: continue
             if change[1] > end_line: break
             if last_change and change[1] <= last_change[2]:
@@ -989,8 +992,9 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
                 "delete":solid_green}
         for c in self.linediffer.single_changes(textindex, self._get_texts()):
             assert c[0] != "equal"
-            if self.prefs.ignore_blank_lines:
-                self._consume_blank_lines( self._get_texts()[textindex][c[1]:c[2]] )
+            c, skip = self._consume_blank_lines(c, textindex, c[5])
+            if skip:
+                continue
             rect(context, ctab[c[0]], scale*c[1], scale*c[2])
 
     def on_diffmap_button_press_event(self, area, event):
@@ -1052,18 +1056,16 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
         if direction == gdk.SCROLL_DOWN:
             for c in self.linediffer.single_changes(1, self._get_texts()):
                 assert c[0] != "equal"
-                if self.prefs.ignore_blank_lines:
-                    c1, c2 = self._consume_blank_lines(self._get_texts()[1][c[1]:c[2]])
-                    if (c1 or c2) and c[1] + c1 == c[2] - c2:
-                        continue
+                c, skip = self._consume_blank_lines(c, 1, c[5])
+                if skip:
+                    continue
                 if c[1] > curline:
                     break
         else: #direction == gdk.SCROLL_UP
             for chunk in self.linediffer.single_changes(1, self._get_texts()):
-                if self.prefs.ignore_blank_lines:
-                    c1, c2 = self._consume_blank_lines(self._get_texts()[1][chunk[1]:chunk[2]])
-                    if (c1 or c2) and chunk[1] + c1 == chunk[2] - c2:
-                        continue
+                chunk, skip = self._consume_blank_lines(chunk, 1, chunk[5])
+                if skip:
+                    continue
                 if chunk[2] < curline:
                     c = chunk
                 elif c:
@@ -1084,7 +1086,18 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
             buf = self._get_focused_textview().get_buffer()
             buf.place_cursor(buf.get_iter_at_line(l0))
 
-    def _consume_blank_lines(self, txt):
+    def _consume_blank_lines(self, c, pane1, pane2):
+        if not self.prefs.ignore_blank_lines:
+            return c, False
+        c1, c2 = self._find_blank_lines(self._get_texts()[pane1][c[1]:c[2]])
+        c3, c4 = self._find_blank_lines(self._get_texts()[pane2][c[3]:c[4]])
+        new_c = (c[0], c[1] + c1, c[2] - c2, c[3] + c3, c[4] - c4)
+        if len(c) == 6:
+            new_c += (c[5],)
+        nothing_left = new_c[1] == new_c[2] and new_c[3] == new_c[4]
+        return new_c, nothing_left
+
+    def _find_blank_lines(self, txt):
         lo, hi = 0, 0
         for l in txt:
             if len(l)==0:
@@ -1137,12 +1150,9 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
             context.identity_matrix()
 
         for c in self.linediffer.pair_changes(which, which+1, self._get_texts()):
-            if self.prefs.ignore_blank_lines:
-                c1,c2 = self._consume_blank_lines( self._get_texts()[which  ][c[1]:c[2]] )
-                c3,c4 = self._consume_blank_lines( self._get_texts()[which+1][c[3]:c[4]] )
-                c = c[0], c[1]+c1,c[2]-c2, c[3]+c3,c[4]-c4
-                if c[1]==c[2] and c[3]==c[4]:
-                    continue
+            c, skip = self._consume_blank_lines(c, which, which + 1)
+            if skip:
+                continue
 
             assert c[0] != "equal"
             if c[2] < visible[1] and c[4] < visible[3]: # find first visible chunk
@@ -1222,12 +1232,9 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
             adj = self.scrolledwindow[src].get_vadjustment()
 
             for c in self.linediffer.pair_changes(src, dst, self._get_texts()):
-                if self.prefs.ignore_blank_lines:
-                    c1,c2 = self._consume_blank_lines( self._get_texts()[src][c[1]:c[2]] )
-                    c3,c4 = self._consume_blank_lines( self._get_texts()[dst][c[3]:c[4]] )
-                    c = c[0], c[1]+c1,c[2]-c2, c[3]+c3,c[4]-c4
-                    if c[1]==c[2] and c[3]==c[4]:
-                        continue
+                c, skip = self._consume_blank_lines(c, src, dst)
+                if skip:
+                    continue
                 if c[0] == "insert":
                     continue
                 h = self._line_to_pixel(src, c[1]) - adj.value