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

ui/views/controls/styled_label.cc

+// 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.
+
+#include "ui/views/controls/styled_label.h"
+
+#include <vector>
+
+#include "base/string_util.h"
+#include "ui/base/text/text_elider.h"
+#include "ui/views/controls/label.h"
+#include "ui/views/controls/link.h"
+#include "ui/views/controls/styled_label_listener.h"
+
+namespace views {
+
+namespace {
+
+// Calculates the height of a line of text. Currently returns the height of
+// a link.

[msw, 2013/03/15 08:38:02]

nit: comment says link, but code says label.

[Evan Stade, 2013/03/15 20:28:38]

Done.

+int CalculateLineHeight() {
+  Label label;

[msw, 2013/03/15 08:38:02]

nit: static int height = Label().GetPreferredSize().height(); return height;
or, static int height = 0; if (height == 0) { <init height> } return height;

[Evan Stade, 2013/03/15 20:28:38]

I specifically was worried that the default height of a label might change over
time (e.g. if the user changed default system font size or something). Computing
this every time is cheap (especially given that we're creating a bunch of labels
anyway, and this just adds one more).

+  return label.GetPreferredSize().height();
+}
+
+}  // namespace
+
+bool StyledLabel::LinkRange::operator<(
+    const StyledLabel::LinkRange& other) const {
+  // Intentionally reversed so the priority queue is sorted by smallest first.
+  return range.start() > other.range.start();
+}
+
+StyledLabel::StyledLabel(const string16& text, StyledLabelListener* listener)
+    : text_(text),
+      listener_(listener) {}
+
+StyledLabel::~StyledLabel() {}
+
+void StyledLabel::AddLink(const ui::Range& range) {
+  DCHECK(!range.is_reversed());
+  DCHECK(!range.is_empty());
+  DCHECK(ui::Range(0, text_.size()).Contains(range));
+  link_ranges_.push(LinkRange(range));
+  calculated_size_ = gfx::Size();
+  InvalidateLayout();
+}
+
+gfx::Insets StyledLabel::GetInsets() const {
+  gfx::Insets insets = View::GetInsets();
+  const gfx::Insets focus_border_padding(1, 1, 1, 1);
+  insets += focus_border_padding;
+  return insets;
+}
+
+int StyledLabel::GetHeightForWidth(int w) {
+  if (w != calculated_size_.width())
+    calculated_size_ = gfx::Size(w, CalculateAndDoLayout(w, true));
+
+  return calculated_size_.height();
+}
+
+void StyledLabel::Layout() {
+  CalculateAndDoLayout(GetLocalBounds().width(), false);
+}
+
+void StyledLabel::LinkClicked(Link* source, int event_flags) {
+  listener_->StyledLabelLinkClicked(link_targets_[source], event_flags);
+}
+
+int StyledLabel::CalculateAndDoLayout(int width, bool dry_run) {
+  if (!dry_run) {
+    RemoveAllChildViews(true);
+    link_targets_.clear();
+  }
+
+  width -= GetInsets().width();
+  if (width <= 0)
+    return 0;
+
+  const int line_height = CalculateLineHeight();
+  // The index of the line we're on.
+  int line = 0;
+  // The x position (in pixels) of the line we're on, relative to content
+  // bounds.
+  int x = 0;
+
+  string16 remaining_string = text_;
+  std::priority_queue<LinkRange> link_ranges = link_ranges_;
+
+  // Iterate over the text, creating a bunch of labels and links and laying them
+  // out in the appropriate positions.
+  while (!remaining_string.empty()) {
+    // Don't put whitespace at beginning of a line.
+    if (x == 0)
+      TrimWhitespace(remaining_string, TRIM_LEADING, &remaining_string);
+
+    ui::Range range(ui::Range::InvalidRange());
+    if (!link_ranges.empty())
+      range = link_ranges.top().range;
+
+    const gfx::Rect chunk_bounds(x, 0, width - x, 2 * line_height);
+    std::vector<string16> substrings;
+    ui::ElideRectangleText(remaining_string,
+                           gfx::Font(),
+                           chunk_bounds.width(),
+                           chunk_bounds.height(),
+                           ui::IGNORE_LONG_WORDS,
+                           &substrings);
+
+    string16 chunk = substrings[0];
+    if (chunk.empty()) {
+      // Nothing fit on this line. Start a new line. If x is 0, there's no room
+      // for anything. Just abort.
+      if (x == 0)
+        break;
+
+      x = 0;
+      line++;
+      continue;
+    }
+
+    scoped_ptr<View> view;
+    const size_t position = text_.size() - remaining_string.size();
+    if (position >= range.start()) {
+      // This chunk is a link.
+      if (chunk.size() < range.length() && x != 0) {
+        // Don't wrap links. Try to fit them entirely on one line.
+        x = 0;
+        line++;
+        continue;
+      }
+
+      chunk = chunk.substr(0, range.length());
+      Link* link = new Link(chunk);
+      link->set_listener(this);
+      if (!dry_run)
+        link_targets_[link] = range;
+      view.reset(link);
+      link_ranges.pop();
+    } else {
+      // This chunk is normal text.
+      if (position + chunk.size() > range.start())
+        chunk = chunk.substr(0, range.start() - position);
+
+      Label* label = new Label(chunk);
+      // Give the label a focus border so that its preferred size matches
+      // links' preferred sizes.
+      label->SetHasFocusBorder(true);
+      view.reset(label);
+    }
+
+    // Lay out the views to overlap by 1 pixel to compensate for their border
+    // spacing. Otherwise, "<a>link</a>," will render as "link ,".
+    const int overlap = 1;
+    const gfx::Size view_size = view->GetPreferredSize();
+    DCHECK_EQ(line_height, view_size.height() - 2 * overlap);
+    if (!dry_run) {
+      view->SetBoundsRect(gfx::Rect(
+          gfx::Point(GetInsets().left() + x - overlap,
+                     GetInsets().top() + line * line_height - overlap),
+          view_size));
+      AddChildView(view.release());
+    }
+    x += view_size.width() - 2 * overlap;
+
+    remaining_string = remaining_string.substr(chunk.size());
+  }
+
+  return (line + 1) * line_height + GetInsets().height();
+}
+
+}  // namespace views