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#include "linear_layout.h"
namespace cru::ui::controls
{
LinearLayout::LinearLayout(const Orientation orientation)
: Control(true), orientation_(orientation)
{
}
inline float AtLeast0(const float value)
{
return value < 0 ? 0 : value;
}
inline Size AtLeast0(const Size& size)
{
return Size(AtLeast0(size.width), AtLeast0(size.height));
}
Size LinearLayout::OnMeasure(const Size& available_size)
{
const auto layout_params = GetLayoutParams();
if (!layout_params->Validate())
throw std::runtime_error("LayoutParams is not valid. Please check it.");
auto&& get_available_length_for_child = [](const LayoutLength& layout_length, const float available_length) -> float
{
switch (layout_length.mode)
{
case MeasureMode::Exactly:
{
return std::min(layout_length.length, available_length);
}
case MeasureMode::Stretch:
case MeasureMode::Content:
{
return available_length;
}
default:
UnreachableCode();
}
};
Size total_available_size_for_children(
get_available_length_for_child(layout_params->width, available_size.width),
get_available_length_for_child(layout_params->height, available_size.height)
);
auto rest_available_size_for_children = total_available_size_for_children;
float secondary_side_child_max_length = 0;
std::list<Control*> stretch_control_list;
// First measure Content and Exactly and count Stretch.
if (orientation_ == Orientation::Horizontal)
ForeachChild([&](Control* const control)
{
const auto mode = control->GetLayoutParams()->width.mode;
if (mode == MeasureMode::Content || mode == MeasureMode::Exactly)
{
control->Measure(AtLeast0(rest_available_size_for_children));
const auto size = control->GetDesiredSize();
rest_available_size_for_children.width -= size.width;
secondary_side_child_max_length = std::max(size.height, secondary_side_child_max_length);
}
else
stretch_control_list.push_back(control);
});
else
ForeachChild([&](Control* const control)
{
const auto mode = control->GetLayoutParams()->height.mode;
if (mode == MeasureMode::Content || mode == MeasureMode::Exactly)
{
control->Measure(AtLeast0(rest_available_size_for_children));
const auto size = control->GetDesiredSize();
rest_available_size_for_children.height -= size.height;
secondary_side_child_max_length = std::max(size.width, secondary_side_child_max_length);
}
else
stretch_control_list.push_back(control);
});
if (orientation_ == Orientation::Horizontal)
{
const auto available_width = rest_available_size_for_children.width / stretch_control_list.size();
for (const auto control : stretch_control_list)
{
control->Measure(Size(available_width, AtLeast0(rest_available_size_for_children.height)));
const auto size = control->GetDesiredSize();
rest_available_size_for_children.width -= size.width;
secondary_side_child_max_length = std::max(size.height, secondary_side_child_max_length);
}
}
else
{
const auto available_height = rest_available_size_for_children.height / stretch_control_list.size();
for (const auto control : stretch_control_list)
{
control->Measure(Size(AtLeast0(rest_available_size_for_children.width), available_height));
const auto size = control->GetDesiredSize();
rest_available_size_for_children.height -= size.height;
secondary_side_child_max_length = std::max(size.width, secondary_side_child_max_length);
}
}
auto actual_size_for_children = total_available_size_for_children;
if (orientation_ == Orientation::Horizontal)
{
actual_size_for_children.width -= rest_available_size_for_children.width;
actual_size_for_children.height = secondary_side_child_max_length;
}
else
{
actual_size_for_children.width = secondary_side_child_max_length;
actual_size_for_children.height -= rest_available_size_for_children.height;
}
auto&& calculate_final_length = [](const LayoutLength& layout_length, const float length_for_children, const float max_child_length) -> float
{
switch (layout_length.mode)
{
case MeasureMode::Exactly:
case MeasureMode::Stretch:
return length_for_children;
case MeasureMode::Content:
return max_child_length;
default:
UnreachableCode();
}
};
return Size(
calculate_final_length(layout_params->width, total_available_size_for_children.width, actual_size_for_children.width),
calculate_final_length(layout_params->height, total_available_size_for_children.height, actual_size_for_children.height)
);
}
void LinearLayout::OnLayout(const Rect& rect)
{
float current_anchor_length = 0;
ForeachChild([this, ¤t_anchor_length, rect](Control* control)
{
const auto layout_params = control->GetLayoutParams();
const auto size = control->GetDesiredSize();
const auto alignment = orientation_ == Orientation::Horizontal ? layout_params->height.alignment : layout_params->width.alignment;
auto&& calculate_anchor = [alignment](const float layout_length, const float control_length) -> float
{
switch (alignment)
{
case Alignment::Center:
return (layout_length - control_length) / 2;
case Alignment::Start:
return 0;
case Alignment::End:
return layout_length - control_length;
default:
UnreachableCode();
}
};
if (orientation_ == Orientation::Horizontal)
{
control->Layout(Rect(Point(current_anchor_length, calculate_anchor(rect.height, size.height)), size));
current_anchor_length += size.width;
}
else
{
control->Layout(Rect(Point(calculate_anchor(rect.width, size.width), current_anchor_length), size));
current_anchor_length += size.height;
}
});
}
}
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