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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/ui/views/tabs/z_orderable_tab_container_element.h"
#include <bit>
#include <cstdint>
#include "chrome/browser/ui/views/tabs/tab.h"
#include "chrome/browser/ui/views/tabs/tab_group_header.h"
#include "chrome/browser/ui/views/tabs/tab_group_highlight.h"
#include "chrome/browser/ui/views/tabs/tab_group_underline.h"
#include "chrome/browser/ui/views/tabs/tab_style_views.h"
#include "ui/views/view_utils.h"
// static
bool ZOrderableTabContainerElement::CanOrderView(views::View* view) {
return views::IsViewClass<Tab>(view) ||
views::IsViewClass<TabGroupHeader>(view) ||
views::IsViewClass<TabGroupUnderline>(view) ||
views::IsViewClass<TabGroupHighlight>(view);
}
// static
float ZOrderableTabContainerElement::CalculateZValue(views::View* child) {
Tab* tab = views::AsViewClass<Tab>(child);
TabGroupHeader* header = views::AsViewClass<TabGroupHeader>(child);
TabGroupUnderline* underline = views::AsViewClass<TabGroupUnderline>(child);
TabGroupHighlight* highlight = views::AsViewClass<TabGroupHighlight>(child);
DCHECK_EQ(1, !!tab + !!header + !!underline + !!highlight);
// Construct a bitfield that encodes `child`'s z-value. Higher-order bits
// encode more important properties - see usage below for details on each.
// The lowest-order `num_bits_reserved_for_tab_style_z_value` bits are
// reserved for the factors considered by TabStyle, e.g. selection and hover
// state.
constexpr int num_bits_reserved_for_tab_style_z_value =
std::bit_width<uint32_t>(TabStyle::kMaximumZValue);
enum ZValue {
kActiveTab = (1u << (num_bits_reserved_for_tab_style_z_value + 1)),
kGroupView = (1u << num_bits_reserved_for_tab_style_z_value)
};
// Group highlights will keep this z-value and be drawn below everything.
unsigned int z_value = 0;
// The active tab is always on top.
if (tab && tab->IsActive()) {
z_value |= kActiveTab;
}
// Group headers and underlines are painted above non-active tabs.
if (header || underline) {
z_value |= kGroupView;
}
// The non-active tabs are painted next. They are ordered by their selected
// or hovered state, which is animated and thus real-valued.
const float tab_style_z_value =
tab ? tab->tab_style_views()->GetZValue() + 1.0f : 0.0f;
return z_value + tab_style_z_value;
}
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