First stab at MD text buttons

ui/views/controls/button/md_text_button.cc

+// Copyright 2015 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/button/md_text_button.h"
+
+#include "base/i18n/case_conversion.h"
+#include "ui/gfx/render_text.h"
+#include "ui/native_theme/native_theme.h"
+
+namespace views {
+
+namespace {
+
+// Inset between clickable region border and button contents (text).
+const int kHorizontalPadding = 12;
+const int kVerticalPadding = 6;
+
+// Minimum size to reserve for the button contents.
+const int kMinWidth = 48;
+
+const gfx::FontList& GetFontList() {
+  static base::LazyInstance<gfx::FontList>::Leaky font_list =
+      LAZY_INSTANCE_INITIALIZER;
+  return font_list.Get();
+}
+
+}  // namespace
+
+MdTextButton::MdTextButton(ButtonListener* listener, const base::string16& text)
+    : CustomButton(listener),
+      render_text_(gfx::RenderText::CreateInstance()) {
+  render_text_->SetFontList(GetFontList());
+  render_text_->SetCursorEnabled(false);
+  render_text_->SetText(base::i18n::ToUpper(text));
+  render_text_->SetColor(SK_ColorBLUE);
+
+  SetFocusable(true);
+}
+
+MdTextButton::~MdTextButton() {}
+
+void MdTextButton::OnPaint(gfx::Canvas* canvas) {
+  UpdateColor();

[bruthig, 2015/12/22 15:56:19]

The material design ripple is supposed to be drawn behind the text.  In order to
do that the text will need to be rendered to it's own layer so that the z-order
of the text and ripple can be controlled.
In other words, we won't be able to draw the text in this OnPaint() method.  The
MdTextButton should have a Label label_ instance instead so that the label_ can
be painted to it's own layer.

[Evan Stade, 2015/12/29 18:14:04]

If we need another layer, wouldn't we just create a new layer and call
layer()->Add(new_layer) and make this class a LayerDelegate?

Even if the best way to get a new layer is to create a child view, I would not
want to use Label for that. Label has all kinds of special behavior we don't
want and RenderText gives us all the functionality we need for drawing text.

+  gfx::Rect rect = GetLocalBounds();
+  rect.Inset(kHorizontalPadding, kVerticalPadding);
+  render_text_->SetDisplayRect(rect);
+  render_text_->Draw(canvas);
+}
+
+gfx::Size MdTextButton::GetPreferredSize() const {
+  gfx::Size size = render_text_->GetStringSize();
+  size.SetToMax(gfx::Size(kMinWidth, 0));
+  size.Enlarge(kHorizontalPadding * 2, kVerticalPadding * 2);
+  return size;
+}
+
+void MdTextButton::UpdateColor() {
+  // TODO(estade): handle call to action theming and other things that can
+  // affect the text color.
+  render_text_->SetColor(GetNativeTheme()->GetSystemColor(
+      enabled() ? ui::NativeTheme::kColorId_MdTextButtonEnabledColor
+                : ui::NativeTheme::kColorId_MdTextButtonDisabledColor));
+}
+
+}  // namespace views