Add views::RichLabel, a class which creates multi-line text with mixed

ui/views/controls/styled_label.h

+// Copyright 2013 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.
+
+#ifndef UI_VIEWS_CONTROLS_STYLED_LABEL_H_
+#define UI_VIEWS_CONTROLS_STYLED_LABEL_H_
+
+#include <map>
+#include <queue>
+
+#include "base/string16.h"
+#include "ui/base/range/range.h"
+#include "ui/gfx/size.h"
+#include "ui/views/controls/link_listener.h"
+#include "ui/views/view.h"
+
+namespace views {
+
+class Link;
+class StyledLabelListener;
+
+// A class which can apply mixed styles to a block of text. Currently, text is
+// always multiline, and the only style that may be applied is linkifying ranges
+// of text.
+class VIEWS_EXPORT StyledLabel : public View,
+                                 public LinkListener {

[msw, 2013/03/13 03:22:07]

nit: fits on the line above.

[Evan Stade, 2013/03/14 00:30:46]

Done.

+ public:
+  explicit StyledLabel(const string16& text, StyledLabelListener* listener);

[msw, 2013/03/13 03:22:07]

Could you take a LinkListener instead and nix StyledLabelListener?

[Evan Stade, 2013/03/14 00:30:46]

no, see below.

+  virtual ~StyledLabel();
+
+  // Marks the given range within |text_| as a link.
+  void SetLink(const ui::Range& range);

[msw, 2013/03/13 03:22:07]

Shouldn't this let users supply the associated Link*?
Or perhaps take a GURL, etc. and return the newly associated Link*?

[Evan Stade, 2013/03/14 00:30:46]

No. The fact that this class uses a Link view is an implementation detail which
I am intentionally hiding. My understanding is that you and Scott want to
eventually change the implementation of this class while leaving the interface
the same.

[sky, 2013/03/14 14:43:58]

That is definitely the case, but making this class store the GURL and pass to
the listener seems reasonable to me. Otherwise the consumer has to track it
which seems a bit tedious.

[Evan Stade, 2013/03/14 19:07:40]

there's not always going to be a GURL associated with a link. Clicking might
initiate some non-navigation action in the browser (for example, the bookmark
bubble does that).

[msw, 2013/03/14 23:24:30]

Hmm, I see your point. I guess tracking links by range is ok.

+
+  // View implementation:
+  virtual int GetHeightForWidth(int w) OVERRIDE;
+  virtual void Layout() OVERRIDE;
+
+  // LinkListener implementation:
+  virtual void LinkClicked(Link* source, int event_flags) OVERRIDE;
+
+ private:
+  struct LinkRange {

[msw, 2013/03/13 03:22:07]

Try replacing LinkRange, link_ranges_, & link_targets_ w/ gfx::BreakList<Link*>.
I think BreakList is well suited to the ranged link-association you need.
(otherwise make sure these handle overlapping ranges, etc. well enough)

[Evan Stade, 2013/03/14 00:30:46]

I tried doing this, but it's not pretty because ui::Range is used as the
identifier for the link (see StyledLabelListener) so the type would be
gfx::BreakList<ui::Range>, which is confusing and awkward.

The current implementation does not attempt to handle overlapping ranges, but it
also does not crash. It effectively bumps the second range to right after the
first range if there's overlap.

+    LinkRange(const ui::Range& range) : range(range) {}
+    ~LinkRange() {}
+
+    bool operator<(const LinkRange& other) const;
+
+    ui::Range range;
+  };
+
+  // Calculates how to layout child views, creates them and sets their size
+  // and position. |width| is the horizontal space, in pixels, that the view
+  // has to work with. If |dry_run| is true, the view hierarchy is not touched.
+  // The return value is the height in pixels.
+  int CalculateAndDoLayout(int width, bool dry_run);

[msw, 2013/03/13 03:22:07]

nit: Maybe GetHeightForWidthAndLayout with s/dry_run/layout/?

[Evan Stade, 2013/03/14 00:30:46]

I prefer the current naming but can change it if you feel strongly.

+
+  // The text to display.
+  string16 text_;
+
+  // The listener that will be informed of link clicks.
+  StyledLabelListener* listener_;
+
+  // The ranges that should be linkified, sorted by start position.
+  std::priority_queue<LinkRange> link_ranges_;
+
+  // A mapping from Link* control to the range it corresponds to in |text_|.
+  std::map<Link*, ui::Range> link_targets_;
+
+  // This variable saves the result of the last GetHeightForWidth call in order
+  // to avoid repeated calculation.
+  gfx::Size calculated_size_;
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_CONTROLS_STYLED_LABEL_H_