dag: add diff tool option

cola/difftool.py

@@ -10,6 +10,7 @@
 from cola import qtutils
 from cola import gitcmds
 from cola.i18n import N_
+from cola.interaction import Interaction
 from cola.models import main
 from cola.models import selection
 from cola.widgets import completion
@@ -28,20 +29,40 @@ def run():
 
 
 def launch_with_head(filenames, staged, head):
-    args = []
-    if staged:
-        args.append('--cached')
-    if head != 'HEAD':
-        args.append(head)
-    args.append('--')
-    args.extend(filenames)
-    launch(args)
+    launch(left=head if head != 'HEAD' else None, staged=staged, paths=filenames)
 
 
-def launch(args):
-    """Launches 'git difftool' with args"""
+def launch(left=None, right=None, paths=None, left_take_parent=False, staged=False):
+    """Launches 'git difftool' with given parameters"""
     difftool_args = ['git', 'difftool', '--no-prompt']
-    difftool_args.extend(args)
+    if staged:
+        difftool_args.append('--cached')
+    if left:
+        if left_take_parent:
+            # Check root commit (no parents and thus cannot execute '~')
+            proc = core.start_command(['git', 'rev-list', '--parents', '-n', '1', left])
+            out, err = proc.communicate()
+            status = proc.returncode
+            Interaction.log_status(status, out, err)
+            if status:
+                raise Exception('git rev-list command failed')
+            line = out.splitlines()[0]
+            if len(line.split()) >= 2:
+                # Commit has a parent, so we can take its child as requested
+                left += '~'
+            else:
+                # No parent, assume it's the root commit, so we have to diff against an empty tree
+                left = '4b825dc642cb6eb9a060e54bf8d69288fbee4904'
+
+        difftool_args.append(left)
+    if right:
+        difftool_args.append(right)
+    if paths:
+        difftool_args.append('--')
+        if isinstance(paths, (tuple, list)):
+            difftool_args.extend(paths)
+        else:
+            difftool_args.append(paths) # paths is a string
     core.fork(difftool_args)
 
 
@@ -160,9 +181,13 @@ def tree_selection_changed(self):
 
     def tree_double_clicked(self, item, column):
         path = self.tree.filename_from_item(item)
-        launch(self.diff_arg + ['--', path])
+        launch(left=self.diff_arg[0] if self.diff_arg else None,
+               right=self.diff_arg[1] if len(self.diff_arg) > 1 else None,
+               paths=path)
 
     def diff(self):
         paths = self.tree.selected_filenames()
         for path in paths:
-            launch(self.diff_arg + ['--', ustr(path)])
+            launch(left=self.diff_arg[0] if self.diff_arg else None,
+                   right=self.diff_arg[1] if len(self.diff_arg) > 1 else None,
+                   paths=ustr(path))

cola/widgets/browse.py

@@ -366,7 +366,7 @@ def difftool_predecessor(self, paths):
         if not commits:
             return
         commit = commits[0]
-        difftool.launch([commit, '--'] + paths)
+        difftool.launch(left=commit, paths=paths)
 
 
 class BrowseModel(object):

cola/widgets/compare.py

@@ -250,7 +250,8 @@ def compare(self, *args):
     def compare_file(self, filename):
         """Initiates the difftool session"""
         if self.use_sandbox:
-            arg = self.diff_arg
+            left = self.diff_arg[0]
+            right = self.diff_arg[1] if len(self.diff_arg) > 1 else None
         else:
-            arg = (self.start, self.end)
-        difftool.launch(arg + ('--', filename))
+            left, right = self.start, self.end
+        difftool.launch(left=left, right=right, paths=filename)

cola/widgets/dag.py

@@ -12,6 +12,7 @@
 from PyQt4.QtCore import QRectF
 
 from cola import cmds
+from cola import core
 from cola import difftool
 from cola import observable
 from cola import qtutils
@@ -248,6 +249,12 @@ def goto(self, finder):
         if found:
             self.select([found.commit.sha1])
 
+    def selected_commit_range(self):
+        selected_items = self.selected_items()
+        if not selected_items:
+            return None, None
+        return selected_items[-1].commit.sha1, selected_items[0].commit.sha1
+
     def set_selecting(self, selecting):
         self.selecting = selecting
 
@@ -361,6 +368,8 @@ def __init__(self, model, ctx, parent=None, settings=None):
         self.notifier.add_observer(refs_updated, self.display)
         self.notifier.add_observer(filelist.HISTORIES_SELECTED,
                                    self.histories_selected)
+        self.notifier.add_observer(filelist.DIFFTOOL_SELECTED,
+                                   self.difftool_selected)
         self.notifier.add_observer(diff.COMMITS_SELECTED, self.commits_selected)
 
         self.treewidget = CommitTreeWidget(notifier, self)
@@ -591,7 +600,7 @@ def resize_to_desktop(self):
     def diff_commits(self, a, b):
         paths = self.ctx.paths()
         if paths:
-            difftool.launch([a, b, '--'] + paths)
+            difftool.launch(left=a, right=b, paths=paths)
         else:
             difftool.diff_commits(self, a, b)
 
@@ -612,6 +621,12 @@ def histories_selected(self, histories):
         self.revtext.setText(text)
         self.display()
 
+    def difftool_selected(self, files):
+        bottom, top = self.treewidget.selected_commit_range()
+        if not top:
+            return
+        difftool.launch(left=bottom, left_take_parent=True, right=top, paths=list(files))
+
 
 class ReaderThread(QtCore.QThread):
     begin = SIGNAL('begin')

cola/widgets/filelist.py

@@ -11,6 +11,7 @@
 from cola.widgets.diff import FILES_SELECTED
 
 HISTORIES_SELECTED = 'HISTORIES_SELECTED'
+DIFFTOOL_SELECTED = 'DIFFTOOL_SELECTED'
 
 class FileWidget(TreeWidget):
 
@@ -71,8 +72,16 @@ def contextMenuEvent(self, event):
         menu = QtGui.QMenu(self)
         menu.addAction(qtutils.add_action(self, N_('Show history'),
                                self.show_file_history))
+        menu.addAction(qtutils.add_action(self, N_('Launch Diff Tool'),
+                               self.show_file_diff, 'Ctrl+D'))
+
         menu.exec_(self.mapToGlobal(event.pos()))
 
+    def show_file_diff(self):
+        items = self.selected_items()
+        self.notifier.notify_observers(DIFFTOOL_SELECTED,
+                                       [i.file_name for i in items])
+
     def show_file_history(self):
         items = self.selected_items()
         self.notifier.notify_observers(HISTORIES_SELECTED,