libRocket/Source/Core/ElementUtilities.cpp

/*
 * This source file is part of libRocket, the HTML/CSS Interface Middleware
 *
 * For the latest information, see http://www.librocket.com
 *
 * Copyright (c) 2008-2010 CodePoint Ltd, Shift Technology Ltd
 *
 * 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 "precompiled.h"
#include <Rocket/Core/ElementUtilities.h>
#include <queue>
#include "FontFaceHandle.h"
#include "LayoutEngine.h"
#include <Rocket/Core.h>

namespace Rocket {
namespace Core {

// Builds and sets the box for an element.
static void SetBox(Element* element);
// Positions an element relative to an offset parent.
static void SetElementOffset(Element* element, const Vector2f& offset);

Element* ElementUtilities::GetElementById(Element* root_element, const String& id)
{
	// Breadth first search on elements for the corresponding id
	typedef std::queue<Element*> SearchQueue;
	SearchQueue search_queue;
	search_queue.push(root_element);

	while (!search_queue.empty())
	{
		Element* element = search_queue.front();
		search_queue.pop();
		
		if (element->GetId() == id)
		{
			return element;
		}
		
		// Add all children to search
		for (int i = 0; i < element->GetNumChildren(); i++)
			search_queue.push(element->GetChild(i));
	}

	return NULL;
}

void ElementUtilities::GetElementsByTagName(ElementList& elements, Element* root_element, const String& tag)
{
	// Breadth first search on elements for the corresponding id
	typedef std::queue< Element* > SearchQueue;
	SearchQueue search_queue;
	for (int i = 0; i < root_element->GetNumChildren(); ++i)
		search_queue.push(root_element->GetChild(i));

	while (!search_queue.empty())
	{
		Element* element = search_queue.front();
		search_queue.pop();

		if (element->GetTagName() == tag)
			elements.push_back(element);

		// Add all children to search.
		for (int i = 0; i < element->GetNumChildren(); i++)
			search_queue.push(element->GetChild(i));
	}
}

void ElementUtilities::GetElementsByClassName(ElementList& elements, Element* root_element, const String& class_name)
{
	// Breadth first search on elements for the corresponding id
	typedef std::queue< Element* > SearchQueue;
	SearchQueue search_queue;
	for (int i = 0; i < root_element->GetNumChildren(); ++i)
		search_queue.push(root_element->GetChild(i));

	while (!search_queue.empty())
	{
		Element* element = search_queue.front();
		search_queue.pop();

		if (element->IsClassSet(class_name))
			elements.push_back(element);

		// Add all children to search.
		for (int i = 0; i < element->GetNumChildren(); i++)
			search_queue.push(element->GetChild(i));
	}
}

// Returns the element's font face.
FontFaceHandle* ElementUtilities::GetFontFaceHandle(Element* element)
{
	// Fetch the new font face.
	String font_family = element->GetProperty(FONT_FAMILY)->value.Get< String >();
	String font_charset = element->GetProperty(FONT_CHARSET)->value.Get< String >();
	Font::Style font_style = (Font::Style) element->GetProperty(FONT_STYLE)->value.Get< int >();
	Font::Weight font_weight = (Font::Weight) element->GetProperty(FONT_WEIGHT)->value.Get< int >();
	int font_size = Math::RealToInteger(element->ResolveProperty(FONT_SIZE, 0));

	FontFaceHandle* font = FontDatabase::GetFontFaceHandle(font_family, font_charset, font_style, font_weight, font_size);
	return font;
}

// Returns an element's font size, if it has a font defined.
int ElementUtilities::GetFontSize(Element* element)
{
	FontFaceHandle* font_face_handle = element->GetFontFaceHandle();
	if (font_face_handle == NULL)
		return 0;
	
	return font_face_handle->GetSize();
}

// Returns an element's line height, if it has a font defined.
int ElementUtilities::GetLineHeight(Element* element)
{
	FontFaceHandle* font_face_handle = element->GetFontFaceHandle();
	if (font_face_handle == NULL)
		return 0;

	int line_height = font_face_handle->GetLineHeight();
	float inch = element->GetRenderInterface()->GetPixelsPerInch();
	const Property* line_height_property = element->GetLineHeightProperty();

	switch (line_height_property->unit)
	{
		case Property::REM:
		// If the property is a straight number or an em measurement, then it scales the line height of the parent.
		// Ref: Equal to the computed value of ‘font-size’ on the root element.
		// Ref URL: http://www.w3.org/TR/css3-values/#rem-unit
		{
			Rocket::Core::ElementDocument* owner_document = element->GetOwnerDocument();
			if (owner_document == NULL)
				return 0;

			/// @TODO In release mode, using REM on a body tag will result in an infinite recursion loop
			/// and eventually a stack overflow crash, this needs to be resolved.
			ROCKET_ASSERTMSG(owner_document != element, "REM unit is not allowed on document or body root.");

			float base_value = owner_document->ResolveProperty(FONT_SIZE, 0);

			return Math::Round(line_height_property->value.Get< float >() * base_value);
		}
		case Property::NUMBER:
		case Property::EM:
			// If the property is a straight number or an em measurement, then it scales the line height.
			return Math::Round(line_height_property->value.Get< float >() * line_height);
		case Property::PERCENT:
			// If the property is a percentage, then it scales the line height.
			return Math::Round(line_height_property->value.Get< float >() * line_height * 0.01f);
		case Property::PX:
			// A px measurement.
			return Math::Round(line_height_property->value.Get< float >());
		case Property::INCH:
			// Values based on pixels-per-inch.
			return Math::Round(line_height_property->value.Get< float >() * inch);
		case Property::CM:
			return Math::Round(line_height_property->value.Get< float >() * inch * (1.0f / 2.54f));
		case Property::MM:
			return Math::Round(line_height_property->value.Get< float >() * inch * (1.0f / 25.4f));
		case Property::PT:
			return Math::Round(line_height_property->value.Get< float >() * inch * (1.0f / 72.0f));
		case Property::PC:
			return Math::Round(line_height_property->value.Get< float >() * inch * (1.0f / 6.0f));
	}

	return 0;
}

// Returns the width of a string rendered within the context of the given element.
int ElementUtilities::GetStringWidth(Element* element, const WString& string)
{
	FontFaceHandle* font_face_handle = element->GetFontFaceHandle();
	if (font_face_handle == NULL)
		return 0;

	return font_face_handle->GetStringWidth(string);
}

void ElementUtilities::BindEventAttributes(Element* element)
{
	int index = 0;
	String name;
	String value;

	// Check for and instance the on* events
	while(element->IterateAttributes(index, name, value))
	{
		if (name.Substring(0, 2) == "on")
		{
			EventListener* listener = Factory::InstanceEventListener(value, element);
			if (listener)
				element->AddEventListener(&name[2], listener, false);
		}
	}
}
	
// Generates the clipping region for an element.
bool ElementUtilities::GetClippingRegion(Vector2i& clip_origin, Vector2i& clip_dimensions, Element* element)
{
	clip_origin = Vector2i(-1, -1);
	clip_dimensions = Vector2i(-1, -1);
	
	int num_ignored_clips = element->GetClippingIgnoreDepth();
	if (num_ignored_clips < 0)
		return false;

	// Search through the element's ancestors, finding all elements that clip their overflow and have overflow to clip.
	// For each that we find, we combine their clipping region with the existing clipping region, and so build up a
	// complete clipping region for the element.
	Element* clipping_element = element->GetParentNode();

	while (clipping_element != NULL)
	{
		// Merge the existing clip region with the current clip region if we aren't ignoring clip regions.
		if (num_ignored_clips == 0 && clipping_element->IsClippingEnabled())
		{
			// Ignore nodes that don't clip.
			if (clipping_element->GetClientWidth() < clipping_element->GetScrollWidth()
				|| clipping_element->GetClientHeight() < clipping_element->GetScrollHeight())
			{				
				Vector2f element_origin_f = clipping_element->GetAbsoluteOffset(Box::CONTENT);
				Vector2f element_dimensions_f = clipping_element->GetBox().GetSize(Box::CONTENT);
				
				Vector2i element_origin(Math::RealToInteger(element_origin_f.x), Math::RealToInteger(element_origin_f.y));
				Vector2i element_dimensions(Math::RealToInteger(element_dimensions_f.x), Math::RealToInteger(element_dimensions_f.y));
				
				if (clip_origin == Vector2i(-1, -1) && clip_dimensions == Vector2i(-1, -1))
				{
					clip_origin = element_origin;
					clip_dimensions = element_dimensions;
				}
				else
				{
					Vector2i top_left(Math::Max(clip_origin.x, element_origin.x),
									  Math::Max(clip_origin.y, element_origin.y));
					
					Vector2i bottom_right(Math::Min(clip_origin.x + clip_dimensions.x, element_origin.x + element_dimensions.x),
										  Math::Min(clip_origin.y + clip_dimensions.y, element_origin.y + element_dimensions.y));
					
					clip_origin = top_left;
					clip_dimensions.x = Math::Max(0, bottom_right.x - top_left.x);
					clip_dimensions.y = Math::Max(0, bottom_right.y - top_left.y);
				}
			}
		}

		// If this region is meant to clip and we're skipping regions, update the counter.
		if (num_ignored_clips > 0)
		{
			if (clipping_element->IsClippingEnabled())
				num_ignored_clips--;
		}

		// Determine how many clip regions this ancestor ignores, and inherit the value. If this region ignores all
		// clipping regions, then we do too.
		int clipping_element_ignore_clips = clipping_element->GetClippingIgnoreDepth();
		if (clipping_element_ignore_clips < 0)
			break;
		
		num_ignored_clips = Math::Max(num_ignored_clips, clipping_element_ignore_clips);

		// Climb the tree to this region's parent.
		clipping_element = clipping_element->GetParentNode();
	}
	
	return clip_dimensions.x >= 0 && clip_dimensions.y >= 0;
}

// Sets the clipping region from an element and its ancestors.
bool ElementUtilities::SetClippingRegion(Element* element, Context* context)
{	
	Rocket::Core::RenderInterface* render_interface = NULL;
	if (element)
	{
		render_interface = element->GetRenderInterface();
		if (!context)
			context = element->GetContext();
	}
	else if (context)
	{
		render_interface = context->GetRenderInterface();
		if (!render_interface)
			render_interface = GetRenderInterface();
	}

	if (!render_interface || !context)
		return false;
	
	Vector2i clip_origin, clip_dimensions;
	bool clip = element && GetClippingRegion(clip_origin, clip_dimensions, element);
	
	Vector2i current_origin;
	Vector2i current_dimensions;
	bool current_clip = context->GetActiveClipRegion(current_origin, current_dimensions);
	if (current_clip != clip || (clip && (clip_origin != current_origin || clip_dimensions != current_dimensions)))
	{
		context->SetActiveClipRegion(clip_origin, clip_dimensions);
		ApplyActiveClipRegion(context, render_interface);
	}

	return true;
}

void ElementUtilities::ApplyActiveClipRegion(Context* context, RenderInterface* render_interface)
{
	if (render_interface == NULL)
		return;
	
	Vector2i origin;
	Vector2i dimensions;
	bool clip_enabled = context->GetActiveClipRegion(origin, dimensions);

	render_interface->EnableScissorRegion(clip_enabled);
	if (clip_enabled)
	{
		render_interface->SetScissorRegion(origin.x, origin.y, dimensions.x, dimensions.y);
	}
}

// Formats the contents of an element.
bool ElementUtilities::FormatElement(Element* element, const Vector2f& containing_block)
{
	LayoutEngine layout_engine;
	return layout_engine.FormatElement(element, containing_block);
}

// Generates the box for an element.
void ElementUtilities::BuildBox(Box& box, const Vector2f& containing_block, Element* element, bool inline_element)
{
	LayoutEngine::BuildBox(box, containing_block, element, inline_element);
}

// Sizes and positions an element within its parent.
bool ElementUtilities::PositionElement(Element* element, const Vector2f& offset)
{
	Element* parent = element->GetParentNode();
	if (parent == NULL)
		return false;

	SetBox(element);
	SetElementOffset(element, offset);

	return true;
}

// Sizes an element, and positions it within its parent offset from the borders of its content area.
bool ElementUtilities::PositionElement(Element* element, const Vector2f& offset, PositionAnchor anchor)
{
	Element* parent = element->GetParentNode();
	if (parent == NULL)
		return false;

	SetBox(element);

	Vector2f containing_block = element->GetParentNode()->GetBox().GetSize(Box::CONTENT);
	Vector2f element_block = element->GetBox().GetSize(Box::MARGIN);

	Vector2f resolved_offset = offset;

	if (anchor & RIGHT)
		resolved_offset.x = containing_block.x - (element_block.x + offset.x);

	if (anchor & BOTTOM)
		resolved_offset.y = containing_block.y - (element_block.y + offset.y);

	SetElementOffset(element, resolved_offset);

	return true;
}
/*
// Returns true if the element is visible within the current clipping region (if any), false if not.
static bool IsElementVisible(const Element* ROCKET_UNUSED(element))
{
	// Fix this when text elements have their sizes correctly set!
	return true;

	if (clip_root == NULL)
		return true;

	Vector2f element_position = element->GetAbsoluteOffset(Box::BORDER);
	for (int i = 0; i < element->GetNumBoxes(); ++i)
	{
		Vector2f box_position = element_position + element->GetBox(i).GetPosition(Box::MARGIN);
		Vector2f box_size = element->GetBox(i).GetSize(Box::MARGIN);

		// If both the left and right edges of this box are to the left of the clipping region,
		// then this box can't intersect the clipping region.
		if (box_position.x < clipping_region.top_left.x &&
			box_position.x + box_size.x < clipping_region.top_left.x)
			continue;

		// If both the left and right edges of this box are to the right of the clipping region,
		// then this box can't intersect the clipping region.
		if (box_position.x > clipping_region.bottom_right.x &&
			box_position.x + box_size.x > clipping_region.bottom_right.x)
			continue;

		// If both the top and bottom edges of this box are to the top of the clipping region,
		// then this box can't intersect the clipping region.
		if (box_position.y < clipping_region.top_left.y &&
			box_position.y + box_size.y < clipping_region.top_left.y)
			continue;

		// If both the top and bottom edges of this box are to the bottom of the clipping region,
		// then this box can't intersect the clipping region.
		if (box_position.y > clipping_region.bottom_right.y &&
			box_position.y + box_size.y > clipping_region.bottom_right.y)
			continue;

		// We intersect!
		return true;
	}

	return false;
}
*/
// Builds and sets the box for an element.
static void SetBox(Element* element)
{
	Element* parent = element->GetParentNode();
	ROCKET_ASSERT(parent != NULL);

	Vector2f containing_block = parent->GetBox().GetSize();
	containing_block.x -= parent->GetElementScroll()->GetScrollbarSize(ElementScroll::VERTICAL);
	containing_block.y -= parent->GetElementScroll()->GetScrollbarSize(ElementScroll::HORIZONTAL);

	Box box;
	LayoutEngine::BuildBox(box, containing_block, element);

	const Property *local_height;
	element->GetLocalDimensionProperties(NULL, &local_height);
	if (local_height == NULL)
		box.SetContent(Vector2f(box.GetSize().x, containing_block.y));

	element->SetBox(box);
}

// Positions an element relative to an offset parent.
static void SetElementOffset(Element* element, const Vector2f& offset)
{
	Vector2f relative_offset = element->GetParentNode()->GetBox().GetPosition(Box::CONTENT);
	relative_offset += offset;
	relative_offset.x += element->GetBox().GetEdge(Box::MARGIN, Box::LEFT);
	relative_offset.y += element->GetBox().GetEdge(Box::MARGIN, Box::TOP);

	element->SetOffset(relative_offset, element->GetParentNode());
}

}
}