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LibGUI: Rewrite layout system in terms of min and max sizes

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This patch removes size policies and preferred sizes, and replaces them
with min-size and max-size for each widget.

Box layout now works in 3 passes:

    1) Set all items (widgets/spacers) to their min-size
    2) Distribute remaining space evenly, respecting max-size
    3) Place widgets one after the other, adding spacing in between

I've also added convenience helpers for setting a fixed size (which is
the same as setting min-size and max-size to the same value.)

This significantly reduces the verbosity of widget layout and makes GML
a bit more pleasant to write, too. :^)
This commit is contained in:
Andreas Kling 2020-12-30 01:23:32 +01:00
parent b2bba5ce5c
commit 7dc5a3ead8
83 changed files with 444 additions and 957 deletions
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223
Libraries/LibGUI/BoxLayout.cpp
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@ -43,169 +43,124 @@ BoxLayout::BoxLayout(Orientation orientation)
void BoxLayout::run(Widget& widget)
{
bool should_log = false;
#ifdef GBOXLAYOUT_DEBUG
should_log = true;
#endif
if (should_log)
dbgprintf("BoxLayout: running layout on %s{%p}, entry count: %zu\n", widget.class_name(), &widget, m_entries.size());
if (m_entries.is_empty())
return;
Gfx::IntSize available_size = widget.size();
int number_of_entries_with_fixed_size = 0;
struct Item {
Widget* widget { nullptr };
int min_size { -1 };
int max_size { -1 };
int size { 0 };
bool final { false };
};
int number_of_visible_entries = 0;
if (should_log)
dbgprintf("BoxLayout: Starting with available size: %s\n", available_size.to_string().characters());
Vector<Item, 32> items;
for (size_t i = 0; i < m_entries.size(); ++i) {
auto& entry = m_entries[i];
if (entry.type == Entry::Type::Spacer) {
++number_of_visible_entries;
items.append(Item { nullptr, -1, -1 });
continue;
}
if (!entry.widget)
continue;
if (!entry.widget->is_visible())
continue;
++number_of_visible_entries;
if (entry.widget && entry.widget->size_policy(orientation()) == SizePolicy::Fixed) {
if (should_log) {
dbgprintf("BoxLayout: Subtracting for fixed %s{%p}, size: %s\n", entry.widget->class_name(), entry.widget.ptr(), entry.widget->preferred_size().to_string().characters());
dbgprintf("BoxLayout: Available size before: %s\n", available_size.to_string().characters());
auto min_size = entry.widget->min_size();
auto max_size = entry.widget->max_size();
items.append(Item { entry.widget.ptr(), min_size.primary_size_for_orientation(orientation()), max_size.primary_size_for_orientation(orientation()) });
}
if (items.is_empty())
return;
int available_size = widget.size().primary_size_for_orientation(orientation()) - spacing() * (items.size() - 1);
int unfinished_items = items.size();
if (orientation() == Gfx::Orientation::Horizontal)
available_size -= margins().left() + margins().right();
else
available_size -= margins().top() + margins().bottom();
// Pass 1: Set all items to their minimum size.
for (auto& item : items) {
item.size = 0;
if (item.min_size >= 0)
item.size = item.min_size;
available_size -= item.size;
if (item.min_size >= 0 && item.max_size >= 0 && item.min_size == item.max_size) {
// Fixed-size items finish immediately in the first pass.
item.final = true;
--unfinished_items;
}
}
// Pass 2: Distribute remaining available size evenly, respecting each item's maximum size.
while (unfinished_items && available_size > 0) {
int slice = available_size / unfinished_items;
available_size = 0;
for (auto& item : items) {
if (item.final)
continue;
int item_size_with_full_slice = item.size + slice;
item.size = item_size_with_full_slice;
if (item.max_size >= 0)
item.size = min(item.max_size, item_size_with_full_slice);
// If the slice was more than we needed, return remained to available_size.
int remainder_to_give_back = item_size_with_full_slice - item.size;
available_size += remainder_to_give_back;
if (item.max_size >= 0 && item.size == item.max_size) {
// We've hit the item's max size. Don't give it any more space.
item.final = true;
--unfinished_items;
}
available_size -= entry.widget->preferred_size();
if (should_log)
dbgprintf("BoxLayout: Available size after: %s\n", available_size.to_string().characters());
++number_of_entries_with_fixed_size;
}
available_size -= { spacing(), spacing() };
}
available_size += { spacing(), spacing() };
available_size -= { margins().left() + margins().right(), margins().top() + margins().bottom() };
if (should_log)
dbgprintf("BoxLayout: Number of visible: %d/%zu\n", number_of_visible_entries, m_entries.size());
int number_of_entries_with_automatic_size = number_of_visible_entries - number_of_entries_with_fixed_size;
if (should_log)
dbgprintf("BoxLayout: available_size=%s, fixed=%d, fill=%d\n", available_size.to_string().characters(), number_of_entries_with_fixed_size, number_of_entries_with_automatic_size);
Gfx::IntSize automatic_size;
int remaining_size = 0;
int number_of_entries_with_automatic_size_remaining = number_of_entries_with_automatic_size;
if (number_of_entries_with_automatic_size) {
if (m_orientation == Orientation::Horizontal) {
automatic_size.set_width(available_size.width() / number_of_entries_with_automatic_size);
automatic_size.set_height(widget.height());
remaining_size = available_size.width();
} else {
automatic_size.set_width(widget.width());
automatic_size.set_height(available_size.height() / number_of_entries_with_automatic_size);
remaining_size = available_size.height();
}
}
if (should_log)
dbgprintf("BoxLayout: automatic_size=%s\n", automatic_size.to_string().characters());
// Pass 3: Place the widgets.
int current_x = margins().left();
int current_y = margins().top();
for (size_t i = 0; i < m_entries.size(); ++i) {
auto& entry = m_entries[i];
if (entry.type == Entry::Type::Spacer) {
current_x += automatic_size.width();
current_y += automatic_size.height();
continue;
}
for (auto& item : items) {
Gfx::IntRect rect { current_x, current_y, 0, 0 };
if (!entry.widget)
continue;
if (!entry.widget->is_visible())
continue;
Gfx::IntRect rect(current_x, current_y, 0, 0);
if (entry.layout) {
// FIXME: Implement recursive layout.
ASSERT_NOT_REACHED();
}
ASSERT(entry.widget);
rect.set_primary_size_for_orientation(orientation(), item.size);
if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fixed) {
rect.set_width(widget.width());
rect.set_height(entry.widget->preferred_size().height());
} else {
if (orientation() == Orientation::Horizontal)
rect.set_height(widget.height());
if (item.widget) {
int secondary = widget.size().secondary_size_for_orientation(orientation());
if (orientation() == Gfx::Orientation::Horizontal)
secondary -= margins().top() + margins().bottom();
else
rect.set_height(remaining_size / number_of_entries_with_automatic_size_remaining);
}
secondary -= margins().left() + margins().right();
if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fixed) {
rect.set_width(entry.widget->preferred_size().width());
rect.set_height(widget.height());
} else {
if (orientation() == Orientation::Horizontal)
rect.set_width(remaining_size / number_of_entries_with_automatic_size_remaining);
int min_secondary = item.widget->min_size().secondary_size_for_orientation(orientation());
int max_secondary = item.widget->max_size().secondary_size_for_orientation(orientation());
if (min_secondary >= 0)
secondary = max(secondary, min_secondary);
if (max_secondary >= 0)
secondary = min(secondary, max_secondary);
rect.set_secondary_size_for_orientation(orientation(), secondary);
if (orientation() == Gfx::Orientation::Horizontal)
rect.center_vertically_within(widget.rect());
else
rect.set_width(widget.width());
rect.center_horizontally_within(widget.rect());
item.widget->set_relative_rect(rect);
}
if (orientation() == Orientation::Horizontal) {
if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fill)
rect.set_height(widget.height() - margins().top() - margins().bottom());
} else {
if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fill)
rect.set_width(widget.width() - margins().left() - margins().right());
}
// Apply min/max constraints to filled widgets.
if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fill) {
if (entry.widget->min_size().width() >= 0)
rect.set_width(max(entry.widget->min_size().width(), rect.width()));
if (entry.widget->max_size().width() >= 0)
rect.set_width(min(entry.widget->max_size().width(), rect.width()));
}
if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fill) {
if (entry.widget->min_size().height() >= 0)
rect.set_height(max(entry.widget->min_size().height(), rect.height()));
if (entry.widget->max_size().height() >= 0)
rect.set_height(min(entry.widget->max_size().height(), rect.height()));
}
if (orientation() == Orientation::Horizontal)
rect.center_vertically_within(widget.rect());
else
rect.center_horizontally_within(widget.rect());
if (should_log)
dbgprintf("BoxLayout: apply, %s{%p} <- %s\n", entry.widget->class_name(), entry.widget.ptr(), rect.to_string().characters());
entry.widget->set_relative_rect(rect);
if (orientation() == Orientation::Horizontal) {
if (entry.widget->size_policy(Orientation::Horizontal) == SizePolicy::Fill) {
remaining_size -= rect.width();
--number_of_entries_with_automatic_size_remaining;
}
if (orientation() == Gfx::Orientation::Horizontal)
current_x += rect.width() + spacing();
} else {
if (entry.widget->size_policy(Orientation::Vertical) == SizePolicy::Fill) {
remaining_size -= rect.height();
--number_of_entries_with_automatic_size_remaining;
}
else
current_y += rect.height() + spacing();
}
}
}
}