Rework somewhat how the folder menu window and main view sizes and positions ...

chrome/browser/cocoa/bookmark_bar_folder_controller.mm

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/cocoa/bookmark_bar_folder_controller.h"
 #include "base/mac_util.h"
 #include "base/nsimage_cache_mac.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/bookmarks/bookmark_model.h"
 #include "chrome/browser/bookmarks/bookmark_utils.h"
@@ skipping 359 matching lines @@
   [[self window] setLevel:NSPopUpMenuWindowLevel];
 }
 
 - (void)adjustWindowForHeight:(int)windowHeight {
   // Adjust all button widths to be consistent, determine the best size for
   // the window, and set the window frame.
   CGFloat windowWidth =
       [self adjustButtonWidths] + (2 * bookmarks::kBookmarkVerticalPadding) +
       bookmarks::kScrollViewContentWidthMargin;
   NSPoint newWindowTopLeft = [self windowTopLeftForWidth:windowWidth];
-  NSSize windowSize = [scrollView_ convertSize:NSMakeSize(windowWidth,
-                                                          windowHeight)
-                                        toView:nil];
-  newWindowTopLeft.y -= windowSize.height;
+  NSSize windowSize = NSMakeSize(windowWidth, windowHeight);
+  windowSize = [scrollView_ convertSize:windowSize toView:nil];
+  NSWindow* window = [self window];
+  // If the window is already visible then make sure its top remains stable.
+  BOOL windowAlreadyShowing = [window isVisible];
+  CGFloat deltaY = windowHeight - NSHeight([mainView_ frame]);
+  if (windowAlreadyShowing) {
+    NSRect oldFrame = [window frame];
+    newWindowTopLeft.y = oldFrame.origin.y + NSHeight(oldFrame);
+  }
   NSRect windowFrame = NSMakeRect(newWindowTopLeft.x,
-                                  newWindowTopLeft.y,
-                                  windowSize.width,
-                                  windowSize.height);
-
+      newWindowTopLeft.y - windowHeight, windowSize.width, windowHeight);
   // Make the scrolled content be the right size (full size).
-  NSRect mainViewFrame = NSMakeRect(0, 0,
-                                    windowWidth -
-                                    bookmarks::kScrollViewContentWidthMargin,
-                                    windowHeight);
+  NSRect mainViewFrame = NSMakeRect(0, 0, NSWidth(windowFrame) -
+      bookmarks::kScrollViewContentWidthMargin, NSHeight(windowFrame));
   [mainView_ setFrame:mainViewFrame];
-
   // Make sure the window fits on the screen.  If not, constrain.
   // We'll scroll to allow the user to see all the content.
   NSRect screenFrame = [[[self window] screen] frame];
   screenFrame = NSInsetRect(screenFrame, 0, kScrollWindowVerticalMargin);
   BOOL wasScrollable = scrollable_;
   if (!NSContainsRect(screenFrame, windowFrame)) {
     scrollable_ = YES;
     windowFrame = NSIntersectionRect(screenFrame, windowFrame);
   } else {
     scrollable_ = NO;
   }
-  NSWindow* window = [self window];
-  [window setFrame:windowFrame display:YES];
-  // If scrollable then offset the view and show the arrows.
+  [window setFrame:windowFrame display:NO];
   if (wasScrollable != scrollable_) {
-    NSSize windowLocalSize = [scrollView_ convertSize:windowFrame.size
-                                             fromView:nil];
-    [mainView_ scrollPoint:NSMakePoint(0, (NSHeight(mainViewFrame) -
-                                           windowLocalSize.height))];
+    // If scrollability changed then rework visibility of the scroll arrows
+    // and the scroll offset of the menu view.
+    NSSize windowLocalSize =
+        [scrollView_ convertSize:windowFrame.size fromView:nil];
+    CGFloat scrollPointY = NSHeight(mainViewFrame) - windowLocalSize.height +
+        bookmarks::kBookmarkVerticalPadding;
+    [mainView_ scrollPoint:NSMakePoint(0, scrollPointY)];
     [self showOrHideScrollArrows];
     [self addOrUpdateScrollTracking];
+  } else if (scrollable_ && windowAlreadyShowing) {
+    // If the window was already showing and is still scrollable then make
+    // sure the main view moves upward, not downward so that the content
+    // at the bottom of the menu, not the top, appears to move.
+    // The edge case is when the menu is scrolled all the way to top (hence
+    // the test of scrollDownArrowShown_) - don't scroll then.
+    NSView* superView = [mainView_ superview];
+    DCHECK([superView isKindOfClass:[NSClipView class]]);
+    NSClipView* clipView = static_cast<NSClipView*>(superView);
+    CGFloat scrollPointY = [clipView bounds].origin.y +
+        bookmarks::kBookmarkVerticalPadding;
+    if (scrollDownArrowShown_ || deltaY > 0.0)
+      scrollPointY += deltaY;
+    [mainView_ scrollPoint:NSMakePoint(0, scrollPointY)];
   }
+  [window display];
 }
 
 // Determine window size and position.
 // Create buttons for all our nodes.
 // TODO(jrg): break up into more and smaller routines for easier unit testing.
 - (void)configureWindow {
   const BookmarkNode* node = [parentButton_ bookmarkNode];
   DCHECK(node);
   int startingIndex = [[parentButton_ cell] startingChildIndex];
   DCHECK_LE(startingIndex, node->GetChildCount());
   // Must have at least 1 button (for "empty")
   int buttons = std::max(node->GetChildCount() - startingIndex, 1);
 
   // Prelim height of the window.  We'll trim later as needed.
-  int height = buttons * bookmarks::kBookmarkButtonHeight;
+  int height = buttons * bookmarks::kBookmarkButtonHeight +
+      bookmarks::kBookmarkVerticalPadding;
   // We'll need this soon...
   [self window];
 
   // TODO(jrg): combine with frame code in bookmark_bar_controller.mm
   // http://crbug.com/35966
   NSRect buttonsOuterFrame = NSMakeRect(
     bookmarks::kBookmarkHorizontalPadding,
     height - bookmarks::kBookmarkButtonHeight,
     bookmarks::kDefaultBookmarkWidth,
     bookmarks::kBookmarkButtonHeight);
@@ skipping 787 matching lines @@
     buttonFrame.origin.y -= bookmarks::kBookmarkBarHeight;
   BookmarkButton* newButton = [self makeButtonForNode:node
                                                 frame:buttonFrame];
   [buttons_ insertObject:newButton atIndex:buttonIndex];
   [mainView_ addSubview:newButton];
 
   // Close any child folder(s) which may still be open.
   [self closeBookmarkFolder:self];
 
   // Prelim height of the window.  We'll trim later as needed.
-  int height = [buttons_ count] * bookmarks::kBookmarkButtonHeight;
+  int height = [buttons_ count] * bookmarks::kBookmarkButtonHeight +
+      bookmarks::kBookmarkVerticalPadding;
   [self adjustWindowForHeight:height];
 }
 
 // More code which essentially duplicates that of BookmarkBarController.
 // TODO(mrossetti,jrg): http://crbug.com/35966
 - (BOOL)addURLs:(NSArray*)urls withTitles:(NSArray*)titles at:(NSPoint)point {
   DCHECK([urls count] == [titles count]);
   BOOL nodesWereAdded = NO;
   // Figure out where these new bookmarks nodes are to be added.
   BookmarkButton* button = [self buttonForDroppingOnAtPoint:point];
@@ skipping 112 matching lines @@
                                     (bookmarks::kBookmarkBarHeight -
                                      2 * bookmarks::kBookmarkVerticalPadding));
     BookmarkButton* button = [self makeButtonForNode:nil
                                                frame:buttonFrame];
     [buttons_ addObject:button];
     [mainView_ addSubview:button];
     buttonCount = 1;
   }
 
   // Propose a height for the window.  We'll trim later as needed.
-  int height = buttonCount * bookmarks::kBookmarkButtonHeight;
+  int height = buttonCount * bookmarks::kBookmarkButtonHeight +
+      bookmarks::kBookmarkVerticalPadding;
   [self adjustWindowForHeight:height];
 }
 
 - (id<BookmarkButtonControllerProtocol>)controllerForNode:
     (const BookmarkNode*)node {
   // See if we are holding this node, otherwise see if it is in our
   // hierarchy of visible folder menus.
   if ([parentButton_ bookmarkNode] == node)
     return self;
   return [folderController_ controllerForNode:node];
 }
 
 #pragma mark TestingAPI Only
 
 - (void)setIgnoreAnimations:(BOOL)ignore {
   ignoreAnimations_ = ignore;
 }
 
 @end  // BookmarkBarFolderController