RmlUi/Source/Core/Layout/BlockFormattingContext.cpp

/*
 * This source file is part of RmlUi, the HTML/CSS Interface Middleware
 *
 * For the latest information, see http://github.com/mikke89/RmlUi
 *
 * Copyright (c) 2008-2010 CodePoint Ltd, Shift Technology Ltd
 * Copyright (c) 2019-2023 The RmlUi Team, and contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

#include "BlockFormattingContext.h"
#include "../../../Include/RmlUi/Core/ComputedValues.h"
#include "../../../Include/RmlUi/Core/Element.h"
#include "../../../Include/RmlUi/Core/Profiling.h"
#include "../../../Include/RmlUi/Core/PropertyDefinition.h"
#include "../../../Include/RmlUi/Core/StyleSheetSpecification.h"
#include "../../../Include/RmlUi/Core/SystemInterface.h"
#include "BlockContainer.h"
#include "FloatedBoxSpace.h"
#include "LayoutDetails.h"

namespace Rml {

// Table elements should be handled within FormatElementTable, log a warning when it seems like we're encountering table parts in the wild.
static void LogUnexpectedFlowElement(Element* element, Style::Display display)
{
	RMLUI_ASSERT(element);
	String value = "*unknown";
	StyleSheetSpecification::GetPropertySpecification().GetProperty(PropertyId::Display)->GetValue(value, Property(display));

	Log::Message(Log::LT_WARNING, "Element has a display type '%s' which cannot be located in normal flow layout. Element will not be formatted: %s",
		value.c_str(), element->GetAddress().c_str());
}

#ifdef RMLUI_DEBUG
static bool g_debug_dumping_layout_tree = false;
struct DebugDumpLayoutTree {
	Element* element;
	BlockContainer* block_box;
	bool is_printing_tree_root = false;

	DebugDumpLayoutTree(Element* element, BlockContainer* block_box) : element(element), block_box(block_box)
	{
		// When an element with this ID is encountered, dump the formatted layout tree (including for all descendant formatting contexts).
		static const String debug_trigger_id = "rmlui-debug-layout";
		is_printing_tree_root = element->HasAttribute(debug_trigger_id);
		if (is_printing_tree_root)
			g_debug_dumping_layout_tree = true;
	}
	~DebugDumpLayoutTree()
	{
		if (g_debug_dumping_layout_tree)
		{
			const String header = ":: " + LayoutDetails::GetDebugElementName(element) + " ::\n";
			const String layout_tree = header + block_box->DumpLayoutTree();
			if (SystemInterface* system_interface = GetSystemInterface())
				system_interface->LogMessage(Log::LT_INFO, layout_tree);

			if (is_printing_tree_root)
				g_debug_dumping_layout_tree = false;
		}
	}
};
#else
struct DebugDumpLayoutTree {
	DebugDumpLayoutTree(Element* /*element*/, BlockContainer* /*block_box*/) {}
};
#endif

enum class OuterDisplayType { BlockLevel, InlineLevel, Invalid };

static OuterDisplayType GetOuterDisplayType(Style::Display display)
{
	switch (display)
	{
	case Style::Display::Block:
	case Style::Display::FlowRoot:
	case Style::Display::Flex:
	case Style::Display::Table: return OuterDisplayType::BlockLevel;

	case Style::Display::Inline:
	case Style::Display::InlineBlock:
	case Style::Display::InlineFlex:
	case Style::Display::InlineTable: return OuterDisplayType::InlineLevel;

	case Style::Display::TableRow:
	case Style::Display::TableRowGroup:
	case Style::Display::TableColumn:
	case Style::Display::TableColumnGroup:
	case Style::Display::TableCell:
	case Style::Display::None: break;
	}

	return OuterDisplayType::Invalid;
}

UniquePtr<LayoutBox> BlockFormattingContext::Format(ContainerBox* parent_container, Element* element, Vector2f containing_block, const Box& box)
{
	RMLUI_ASSERT(parent_container && element);
	RMLUI_ZoneScopedC(0xB22222);
	RMLUI_ZoneName(CreateString("%s %x", element->GetAddress(false, false).c_str(), element));

	float min_height, max_height;
	LayoutDetails::GetDefiniteMinMaxHeight(min_height, max_height, element->GetComputedValues(), box, containing_block.y);

	UniquePtr<BlockContainer> container = MakeUnique<BlockContainer>(parent_container, nullptr, element, box, min_height, max_height);

	DebugDumpLayoutTree debug_dump_tree(element, container.get());

	container->ResetScrollbars(box);

	// Format the element's children. In rare cases, it is possible that we need three iterations: Once to enable the
	// horizontal scrollbar, then to enable the vertical scrollbar, and finally to format with both scrollbars enabled.
	for (int layout_iteration = 0; layout_iteration < 3; layout_iteration++)
	{
		bool all_children_formatted = true;
		for (int i = 0; i < element->GetNumChildren() && all_children_formatted; i++)
		{
			if (!FormatBlockContainerChild(container.get(), element->GetChild(i)))
				all_children_formatted = false;
		}

		if (all_children_formatted && container->Close(nullptr))
			// Success, break out of the loop.
			break;

		// Otherwise, restart formatting now that one or both scrollbars have been enabled.
		container->ResetContents();
	}

	return container;
}

float BlockFormattingContext::DetermineMaxContentWidth(Element* element, const Box& initial_box, const FormattingMode& formatting_mode)
{
	RMLUI_ASSERT(formatting_mode.constraint == FormattingMode::Constraint::MaxContent);
	const Vector2f containing_block(-1.f);
	RootBox root(Box(containing_block), formatting_mode);

	UniquePtr<LayoutBox> layout_box = BlockFormattingContext::Format(&root, element, containing_block, initial_box);

	return layout_box->GetShrinkToFitWidth();
}

bool BlockFormattingContext::FormatBlockBox(BlockContainer* parent_container, Element* element)
{
	RMLUI_ZoneScopedC(0x2F4F4F);
	const Vector2f containing_block = parent_container->GetContainingBlockSize(element->GetPosition());

	Box box;
	LayoutDetails::BuildBox(box, containing_block, element, BuildBoxMode::StretchFit);
	float min_height, max_height;
	LayoutDetails::GetDefiniteMinMaxHeight(min_height, max_height, element->GetComputedValues(), box, containing_block.y);

	BlockContainer* container = parent_container->OpenBlockBox(element, box, min_height, max_height);
	if (!container)
		return false;

	// Format our children. This may result in scrollbars being added to our formatting context root, then we need to
	// bail out and restart formatting for the current block formatting context.
	for (int i = 0; i < element->GetNumChildren(); i++)
	{
		if (!FormatBlockContainerChild(container, element->GetChild(i)))
			return false;
	}

	if (!container->Close(parent_container))
		return false;

	return true;
}

bool BlockFormattingContext::FormatInlineBox(BlockContainer* parent_container, Element* element)
{
	RMLUI_ZoneScopedC(0x3F6F6F);
	const Vector2f containing_block = parent_container->GetContainingBlockSize(element->GetPosition());

	Box box;
	LayoutDetails::BuildBox(box, containing_block, element, BuildBoxMode::Inline);
	auto inline_box_handle = parent_container->AddInlineElement(element, box);

	// Format the element's children.
	for (int i = 0; i < element->GetNumChildren(); i++)
	{
		if (!FormatBlockContainerChild(parent_container, element->GetChild(i)))
			return false;
	}

	parent_container->CloseInlineElement(inline_box_handle);

	return true;
}

bool BlockFormattingContext::FormatBlockContainerChild(BlockContainer* parent_container, Element* element)
{
	RMLUI_ZoneScoped;
	RMLUI_ZoneName(CreateString(">%s %x", element->GetAddress(false, false).c_str(), element));

	// Check for special formatting tags.
	if (element->GetTagName() == "br")
	{
		parent_container->AddBreak();
		return true;
	}

	auto& computed = element->GetComputedValues();
	const Style::Display display = computed.display();

	// Don't lay this element out if it is set to a display type of none.
	if (display == Style::Display::None)
		return true;

	// Check for absolutely positioned elements: they are removed from the flow and added to the box representing their
	// containing block, to be layed out and positioned once that box has been closed and sized.
	const Style::Position position_property = computed.position();
	if (position_property == Style::Position::Absolute || position_property == Style::Position::Fixed)
	{
		// TODO: When laying out an absolutely positioned element independently, we need to do the equivalent of this,
		// and the following `ContainerBox::ClosePositionedElements`. Do we need to store the static position and parent
		// container element? Hmm, I guess we can assume that the static position stays the same, since otherwise we
		// would have had an update occur in our parent, thereby closing it in the formatting context of the static
		// element. ... Looking more closely at it, looks like all we need is to call
		// `UpdateRelativeOffsetFromInsetConstraints`?
		// TODO Part 2: UpdateRelativeOffsetFromInsetConstraints alone solves some problems, but not all. Another issue
		// is when the box on the absolute element is changed, particularly margin edges. Then `ClosePositionedElements`
		// would change the submitted offset. Should we store this in the layout cache? Should we store the static
		// position and element, directly on the element? Maybe either/or that we are using the element's margin. Hmm,
		// don't really like that. Can we know that we are in a block formatting context? No, shouldn't depend directly
		// on that. Hacky solution: If absolutely positioned element layed out separately, check changed margin edges,
		// and apply the diff to SetOffset with otherwise the same as existing.
		// Can we set the static position directly on the element (here basically), and just call a function to update
		// everything at the end?
		const Vector2f static_position = parent_container->GetOpenStaticPosition(display) - parent_container->GetPosition();
		parent_container->AddAbsoluteElement(element, static_position, parent_container->GetElement());
		return true;
	}

	const OuterDisplayType outer_display = GetOuterDisplayType(display);
	if (outer_display == OuterDisplayType::Invalid)
	{
		LogUnexpectedFlowElement(element, display);
		return true;
	}

	// If the element creates an independent formatting context, then format it accordingly.
	if (UniquePtr<LayoutBox> layout_box = FormattingContext::FormatIndependent(parent_container, element, nullptr, FormattingContextType::None))
	{
		// If the element is floating, we remove it from the flow.
		if (computed.float_() != Style::Float::None)
		{
			parent_container->AddFloatElement(element, layout_box->GetVisibleOverflowSize());
		}
		// Otherwise, check if we have a sized block-level box.
		else if (layout_box && outer_display == OuterDisplayType::BlockLevel)
		{
			if (!parent_container->AddBlockLevelBox(std::move(layout_box), element, element->GetBox()))
				return false;
		}
		// Nope, then this must be an inline-level box.
		else
		{
			RMLUI_ASSERT(outer_display == OuterDisplayType::InlineLevel);
			auto inline_box_handle = parent_container->AddInlineElement(element, element->GetBox());
			parent_container->CloseInlineElement(inline_box_handle);
		}

		return true;
	}

	// The element is an in-flow box participating in this same block formatting context.
	switch (display)
	{
	case Style::Display::Block: return FormatBlockBox(parent_container, element);
	case Style::Display::Inline: return FormatInlineBox(parent_container, element);
	default:
		RMLUI_ERROR; // Should have been handled above.
		break;
	}

	return true;
}

} // namespace Rml