Better UI layout

[adriengivry]

Problem this feature should fix

Widgets do not properly use 100% of the available space they could use. This is especially an issue with properties in the inspector and the material editor.

Expected solution

We should find a way to let widget stretch to use 100% of the available space.

Example/draft:

Screenshots

OvEditor_B62VqGyRvV.mp4

[adriengivry]

From my early investigation, it seems like using this before drawing a widget partially solves the issue:

ImGui::SetNextItemWidth(-1.0f);

However it doesn't work in some cases:

We should also probably move away from using ImGui::Columns() in favor of the new ImGui::BeginTable() and ImGui::EndTable().

[adriengivry]

Potential implementation for OvUI::Widgets::Layout::Columns::_Draw_Impl() using the new table API instead of columns:

virtual void _Draw_Impl() override
{
	const auto table_flags =
		ImGuiTableFlags_Resizable |
		ImGuiTableFlags_NoSavedSettings |
		ImGuiTableFlags_NoBordersInBodyUntilResize;

	if (ImGui::BeginTable(("##table_" + m_widgetID).c_str(), static_cast<int>(_Size), table_flags))
	{
		// Setup columns with specified widths
		for (size_t i = 0; i < _Size; ++i)
		{
			ImGuiTableColumnFlags column_flags = ImGuiTableColumnFlags_None;
			if (widths[i] != -1.f)
			{
				column_flags |= ImGuiTableColumnFlags_WidthFixed;
				ImGui::TableSetupColumn(("##col_" + std::to_string(i)).c_str(), column_flags, widths[i]);
			}
			else
			{
				column_flags |= ImGuiTableColumnFlags_WidthStretch;
				ImGui::TableSetupColumn(("##col_" + std::to_string(i)).c_str(), column_flags);
			}
		}

		// Draw widgets in table cells
		CollectGarbages();
		bool first_widget = true;

		for (auto it = m_widgets.begin(); it != m_widgets.end(); ++it)
		{
			// Move to next column (except for first widget)
			if (!first_widget)
			{
				ImGui::TableNextColumn();
			}
			else
			{
				ImGui::TableNextRow();
				ImGui::TableNextColumn();
				first_widget = false;
			}

			// Draw the widget
			it->first->Draw();
		}

		ImGui::EndTable();
	}
}

[adriengivry]

We should also consider updating OvUI::Widgets::Layout::Group to behave like a horizontal layout, with option to expand the content to fit the available space.

We could investigate using:

ImGui::BeginGroup(); // <-- this?
DrawWidgets();
ImGui::EndGroup(); // <-- and that?