/*
* 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 "LayoutDetails.h"
#include "../../../Include/RmlUi/Core/ComputedValues.h"
#include "../../../Include/RmlUi/Core/Element.h"
#include "../../../Include/RmlUi/Core/ElementScroll.h"
#include "../../../Include/RmlUi/Core/ElementText.h"
#include "../../../Include/RmlUi/Core/Math.h"
#include "../../../Include/RmlUi/Core/Profiling.h"
#include "ContainerBox.h"
#include "FormattingContext.h"
#include "LayoutEngine.h"
#include
namespace Rml {
// Convert width or height of a border box to the width or height of its corresponding content box.
static inline float BorderSizeToContentSize(float border_size, float border_padding_edges_size)
{
if (border_size < 0.0f || border_size >= FLT_MAX)
return border_size;
return Math::Max(0.0f, border_size - border_padding_edges_size);
}
void LayoutDetails::BuildBox(Box& box, Vector2f containing_block, Element* element, BuildBoxMode box_context)
{
if (!element)
{
box.SetContent(containing_block);
return;
}
const ComputedValues& computed = element->GetComputedValues();
// Calculate the padding area.
box.SetEdge(BoxArea::Padding, BoxEdge::Top, Math::Max(0.0f, ResolveValue(computed.padding_top(), containing_block.x)));
box.SetEdge(BoxArea::Padding, BoxEdge::Right, Math::Max(0.0f, ResolveValue(computed.padding_right(), containing_block.x)));
box.SetEdge(BoxArea::Padding, BoxEdge::Bottom, Math::Max(0.0f, ResolveValue(computed.padding_bottom(), containing_block.x)));
box.SetEdge(BoxArea::Padding, BoxEdge::Left, Math::Max(0.0f, ResolveValue(computed.padding_left(), containing_block.x)));
// Calculate the border area.
box.SetEdge(BoxArea::Border, BoxEdge::Top, Math::Max(0.0f, computed.border_top_width()));
box.SetEdge(BoxArea::Border, BoxEdge::Right, Math::Max(0.0f, computed.border_right_width()));
box.SetEdge(BoxArea::Border, BoxEdge::Bottom, Math::Max(0.0f, computed.border_bottom_width()));
box.SetEdge(BoxArea::Border, BoxEdge::Left, Math::Max(0.0f, computed.border_left_width()));
// Prepare sizing of the content area.
Vector2f content_area(-1, -1);
Vector2f min_size = Vector2f(0, 0);
Vector2f max_size = Vector2f(FLT_MAX, FLT_MAX);
// Intrinsic size for replaced elements.
Vector2f intrinsic_size(-1, -1);
float intrinsic_ratio = -1;
const bool replaced_element = element->GetIntrinsicDimensions(intrinsic_size, intrinsic_ratio);
// Calculate the content area and constraints. 'auto' width and height are handled later.
// For inline non-replaced elements, width and height are ignored, so we can skip the calculations.
if (box_context == BuildBoxMode::Block || box_context == BuildBoxMode::UnalignedBlock || replaced_element)
{
content_area.x = ResolveValueOr(computed.width(), containing_block.x, -1.f);
content_area.y = ResolveValueOr(computed.height(), containing_block.y, -1.f);
min_size = Vector2f{
ResolveValueOr(computed.min_width(), containing_block.x, 0.f),
ResolveValueOr(computed.min_height(), containing_block.y, 0.f),
};
max_size = Vector2f{
ResolveValueOr(computed.max_width(), containing_block.x, FLT_MAX),
ResolveValueOr(computed.max_height(), containing_block.y, FLT_MAX),
};
// Adjust sizes for the given box sizing model.
if (computed.box_sizing() == Style::BoxSizing::BorderBox)
{
const float border_padding_width = box.GetSizeAcross(BoxDirection::Horizontal, BoxArea::Border, BoxArea::Padding);
const float border_padding_height = box.GetSizeAcross(BoxDirection::Vertical, BoxArea::Border, BoxArea::Padding);
min_size.x = BorderSizeToContentSize(min_size.x, border_padding_width);
max_size.x = BorderSizeToContentSize(max_size.x, border_padding_width);
content_area.x = BorderSizeToContentSize(content_area.x, border_padding_width);
min_size.y = BorderSizeToContentSize(min_size.y, border_padding_height);
max_size.y = BorderSizeToContentSize(max_size.y, border_padding_height);
content_area.y = BorderSizeToContentSize(content_area.y, border_padding_height);
}
if (content_area.x >= 0)
content_area.x = Math::Clamp(content_area.x, min_size.x, max_size.x);
if (content_area.y >= 0)
content_area.y = Math::Clamp(content_area.y, min_size.y, max_size.y);
if (replaced_element)
content_area = CalculateSizeForReplacedElement(content_area, min_size, max_size, intrinsic_size, intrinsic_ratio);
}
box.SetContent(content_area);
// Evaluate the margins, and width and height if they are auto.
BuildBoxSizeAndMargins(box, min_size, max_size, containing_block, element, box_context, replaced_element);
}
void LayoutDetails::GetMinMaxWidth(float& min_width, float& max_width, const ComputedValues& computed, const Box& box, float containing_block_width)
{
min_width = ResolveValueOr(computed.min_width(), containing_block_width, 0.f);
max_width = ResolveValueOr(computed.max_width(), containing_block_width, FLT_MAX);
if (computed.box_sizing() == Style::BoxSizing::BorderBox)
{
const float border_padding_width = box.GetSizeAcross(BoxDirection::Horizontal, BoxArea::Border, BoxArea::Padding);
min_width = BorderSizeToContentSize(min_width, border_padding_width);
max_width = BorderSizeToContentSize(max_width, border_padding_width);
}
}
void LayoutDetails::GetMinMaxHeight(float& min_height, float& max_height, const ComputedValues& computed, const Box& box,
float containing_block_height)
{
min_height = ResolveValueOr(computed.min_height(), containing_block_height, 0.f);
max_height = ResolveValueOr(computed.max_height(), containing_block_height, FLT_MAX);
if (computed.box_sizing() == Style::BoxSizing::BorderBox)
{
const float border_padding_height = box.GetSizeAcross(BoxDirection::Vertical, BoxArea::Border, BoxArea::Padding);
min_height = BorderSizeToContentSize(min_height, border_padding_height);
max_height = BorderSizeToContentSize(max_height, border_padding_height);
}
}
void LayoutDetails::GetDefiniteMinMaxHeight(float& min_height, float& max_height, const ComputedValues& computed, const Box& box,
float containing_block_height)
{
const float box_height = box.GetSize().y;
if (box_height < 0)
{
GetMinMaxHeight(min_height, max_height, computed, box, containing_block_height);
}
else
{
min_height = box_height;
max_height = box_height;
}
}
ContainingBlock LayoutDetails::GetContainingBlock(ContainerBox* parent_container, const Style::Position position)
{
RMLUI_ASSERT(parent_container);
using Style::Position;
ContainerBox* container = parent_container;
BoxArea area = BoxArea::Content;
// For absolutely positioned boxes we look for the first positioned ancestor. We deviate from the CSS specs by using
// the same rules for fixed boxes, as that is particularly helpful on handles and other widgets that should not
// scroll with the window. This is a common design pattern in target applications for this library, although this
// behavior may be reconsidered in the future.
if (position == Position::Absolute || position == Position::Fixed)
{
area = BoxArea::Padding;
while (container->GetParent() && !container->IsAbsolutePositioningContainingBlock())
container = container->GetParent();
}
const Box* box = container->GetIfBox();
if (!box)
{
RMLUI_ERROR;
return {container, {}};
}
Vector2f containing_block = box->GetSize(area);
if (position == Position::Static || position == Position::Relative)
{
// For static elements we subtract the scrollbar size so that elements normally don't overlap their parent's
// scrollbars. In CSS, this would also be done for absolutely positioned elements, we might want to copy that
// behavior in the future. If so, we would also need to change the element offset behavior, and ideally also
// make positioned boxes contribute to the scrollable area.
if (Element* element = container->GetElement())
{
ElementScroll* element_scroll = element->GetElementScroll();
if (containing_block.x >= 0.f)
containing_block.x = Math::Max(containing_block.x - element_scroll->GetScrollbarSize(ElementScroll::VERTICAL), 0.f);
if (containing_block.y >= 0.f)
containing_block.y = Math::Max(containing_block.y - element_scroll->GetScrollbarSize(ElementScroll::HORIZONTAL), 0.f);
}
}
return {container, containing_block};
}
void LayoutDetails::BuildBoxSizeAndMargins(Box& box, Vector2f min_size, Vector2f max_size, Vector2f containing_block, Element* element,
BuildBoxMode box_context, bool replaced_element)
{
const ComputedValues& computed = element->GetComputedValues();
if (box_context == BuildBoxMode::Inline || box_context == BuildBoxMode::UnalignedBlock)
{
// For inline elements, their calculations are straightforward. No worrying about auto margins and dimensions, etc.
// Evaluate the margins. Any declared as 'auto' will resolve to 0.
box.SetEdge(BoxArea::Margin, BoxEdge::Top, ResolveValue(computed.margin_top(), containing_block.x));
box.SetEdge(BoxArea::Margin, BoxEdge::Right, ResolveValue(computed.margin_right(), containing_block.x));
box.SetEdge(BoxArea::Margin, BoxEdge::Bottom, ResolveValue(computed.margin_bottom(), containing_block.x));
box.SetEdge(BoxArea::Margin, BoxEdge::Left, ResolveValue(computed.margin_left(), containing_block.x));
}
else
{
// The element is block, so we need to run the box through the ringer to potentially evaluate auto margins and dimensions.
BuildBoxWidth(box, computed, min_size.x, max_size.x, containing_block, element, replaced_element);
BuildBoxHeight(box, computed, min_size.y, max_size.y, containing_block.y);
}
}
float LayoutDetails::GetShrinkToFitWidth(Element* element, Vector2f containing_block)
{
RMLUI_ASSERT(element);
// @performance Can we lay out the elements directly using a fit-content size mode, instead of fetching the
// shrink-to-fit width first? Use a non-definite placeholder for the box content width, and available width as a
// maximum constraint.
Box box;
float min_height, max_height;
LayoutDetails::BuildBox(box, containing_block, element, BuildBoxMode::UnalignedBlock);
LayoutDetails::GetDefiniteMinMaxHeight(min_height, max_height, element->GetComputedValues(), box, containing_block.y);
if (box.GetSize().x >= 0.f)
{
return box.GetSize().x;
}
// Currently we don't support shrink-to-fit width for tables. Just return a zero-sized width.
const Style::Display display = element->GetDisplay();
if (display == Style::Display::Table || display == Style::Display::InlineTable)
{
return 0.f;
}
// Use a large size for the box content width, so that it is practically unconstrained. This makes the formatting
// procedure act as if under a maximum content constraint. Children with percentage sizing values may be scaled
// based on this width (such as 'width' or 'margin'), if so, the layout is considered undefined like in CSS 2.
const float max_content_constraint_width = containing_block.x + 10000.f;
box.SetContent({max_content_constraint_width, box.GetSize().y});
// First, format the element under the above generated box. Then we ask the resulting box for its shrink-to-fit
// width. For block containers, this is essentially its largest line or child box.
// @performance. Some formatting can be simplified, e.g. absolute elements do not contribute to the shrink-to-fit
// width. Also, children of elements with a fixed width and height don't need to be formatted further.
RootBox root(Math::Max(containing_block, Vector2f(0.f)));
UniquePtr layout_box = FormattingContext::FormatIndependent(&root, element, &box, FormattingContextType::Block);
float shrink_to_fit_width = layout_box->GetShrinkToFitWidth();
if (containing_block.x >= 0)
{
const float available_width =
Math::Max(0.f, containing_block.x - box.GetSizeAcross(BoxDirection::Horizontal, BoxArea::Margin, BoxArea::Padding));
shrink_to_fit_width = Math::Min(shrink_to_fit_width, available_width);
}
return shrink_to_fit_width;
}
ComputedAxisSize LayoutDetails::BuildComputedHorizontalSize(const ComputedValues& computed)
{
return ComputedAxisSize{computed.width(), computed.min_width(), computed.max_width(), computed.padding_left(), computed.padding_right(),
computed.margin_left(), computed.margin_right(), computed.border_left_width(), computed.border_right_width(), computed.box_sizing()};
}
ComputedAxisSize LayoutDetails::BuildComputedVerticalSize(const ComputedValues& computed)
{
return ComputedAxisSize{computed.height(), computed.min_height(), computed.max_height(), computed.padding_top(), computed.padding_bottom(),
computed.margin_top(), computed.margin_bottom(), computed.border_top_width(), computed.border_bottom_width(), computed.box_sizing()};
}
void LayoutDetails::GetEdgeSizes(float& margin_a, float& margin_b, float& padding_border_a, float& padding_border_b,
const ComputedAxisSize& computed_size, const float base_value)
{
margin_a = ResolveValue(computed_size.margin_a, base_value);
margin_b = ResolveValue(computed_size.margin_b, base_value);
padding_border_a = Math::Max(0.0f, ResolveValue(computed_size.padding_a, base_value)) + Math::Max(0.0f, computed_size.border_a);
padding_border_b = Math::Max(0.0f, ResolveValue(computed_size.padding_b, base_value)) + Math::Max(0.0f, computed_size.border_b);
}
String LayoutDetails::GetDebugElementName(Node* node)
{
if (!node)
return "nullptr";
if (AsIf(node))
return "#text";
Element* element = As(node);
if (!element->GetId().empty())
return '#' + element->GetId();
if (auto element_text = rmlui_dynamic_cast(element))
return '\"' + StringUtilities::StripWhitespace(element_text->GetText()).substr(0, 20) + '\"';
return element->GetAddress(false, false);
}
Vector2f LayoutDetails::CalculateSizeForReplacedElement(const Vector2f specified_content_size, const Vector2f min_size, const Vector2f max_size,
const Vector2f intrinsic_size, const float intrinsic_ratio)
{
// Start with the element's specified width and height. If any of them are auto, use the element's intrinsic
// dimensions and ratio to find a suitable content size.
Vector2f content_size = specified_content_size;
const bool auto_width = (content_size.x < 0);
const bool auto_height = (content_size.y < 0);
if (auto_width)
content_size.x = intrinsic_size.x;
if (auto_height)
content_size.y = intrinsic_size.y;
// Use a fallback size if we still couldn't determine the size.
if (content_size.x < 0)
content_size.x = 300;
if (content_size.y < 0)
content_size.y = 150;
// Resolve the size constraints.
const float min_width = min_size.x;
const float max_width = max_size.x;
const float min_height = min_size.y;
const float max_height = max_size.y;
// If we have an intrinsic ratio and one of the dimensions is 'auto', then scale it such that the ratio is preserved.
if (intrinsic_ratio > 0)
{
if (auto_width && !auto_height)
{
content_size.x = content_size.y * intrinsic_ratio;
}
else if (auto_height && !auto_width)
{
content_size.y = content_size.x / intrinsic_ratio;
}
else if (auto_width && auto_height)
{
// If both width and height are auto, try to preserve the ratio under the respective min/max constraints.
const float w = content_size.x;
const float h = content_size.y;
if ((w < min_width && h > max_height) || (w > max_width && h < min_height))
{
// Cannot preserve aspect ratio, let it be clamped.
}
else if (w < min_width && h < min_height)
{
// Increase the size such that both min-constraints are respected. The non-scaled axis will
// be clamped below, preserving the aspect ratio.
if (min_width <= min_height * intrinsic_ratio)
content_size.x = min_height * intrinsic_ratio;
else
content_size.y = min_width / intrinsic_ratio;
}
else if (w > max_width && h > max_height)
{
// Shrink the size such that both max-constraints are respected. The non-scaled axis will
// be clamped below, preserving the aspect ratio.
if (max_width <= max_height * intrinsic_ratio)
content_size.y = max_width / intrinsic_ratio;
else
content_size.x = max_height * intrinsic_ratio;
}
else
{
// Single constraint violations.
if (w < min_width)
content_size.y = min_width / intrinsic_ratio;
else if (w > max_width)
content_size.y = max_width / intrinsic_ratio;
else if (h < min_height)
content_size.x = min_height * intrinsic_ratio;
else if (h > max_height)
content_size.x = max_height * intrinsic_ratio;
}
}
}
content_size.x = Math::Clamp(content_size.x, min_width, max_width);
content_size.y = Math::Clamp(content_size.y, min_height, max_height);
return content_size;
}
void LayoutDetails::BuildBoxWidth(Box& box, const ComputedValues& computed, float min_width, float max_width, Vector2f containing_block,
Element* element, bool replaced_element, float override_shrink_to_fit_width)
{
RMLUI_ZoneScoped;
Vector2f content_area = box.GetSize();
// Determine if the element has automatic margins.
bool margins_auto[2];
int num_auto_margins = 0;
for (int i = 0; i < 2; ++i)
{
const Style::Margin margin_value = (i == 0 ? computed.margin_left() : computed.margin_right());
if (margin_value.type == Style::Margin::Auto)
{
margins_auto[i] = true;
num_auto_margins++;
box.SetEdge(BoxArea::Margin, i == 0 ? BoxEdge::Left : BoxEdge::Right, 0);
}
else
{
margins_auto[i] = false;
box.SetEdge(BoxArea::Margin, i == 0 ? BoxEdge::Left : BoxEdge::Right, ResolveValue(margin_value, containing_block.x));
}
}
const bool absolutely_positioned = (computed.position() == Style::Position::Absolute || computed.position() == Style::Position::Fixed);
const bool inset_auto = (computed.left().type == Style::Left::Auto || computed.right().type == Style::Right::Auto);
const bool width_auto = (content_area.x < 0);
auto GetInsetWidth = [&] {
// For absolutely positioned elements (and only those), the 'left' and 'right' values are part of the box's width constraint.
if (absolutely_positioned)
return ResolveValue(computed.left(), containing_block.x) + ResolveValue(computed.right(), containing_block.x);
return 0.f;
};
// If the width is set to auto, we need to calculate the width.
if (width_auto)
{
// Apply the shrink-to-fit algorithm here to find the width of the element.
// See CSS 2.1 section 10.3.7 for when this should be applied.
const bool shrink_to_fit = !replaced_element &&
((computed.float_() != Style::Float::None) || (absolutely_positioned && inset_auto) ||
(computed.display() == Style::Display::InlineBlock || computed.display() == Style::Display::InlineFlex));
if (!shrink_to_fit)
{
// The width is set to whatever remains of the containing block.
content_area.x = containing_block.x - (GetInsetWidth() + box.GetSizeAcross(BoxDirection::Horizontal, BoxArea::Margin, BoxArea::Padding));
content_area.x = Math::Max(0.0f, content_area.x);
}
else if (override_shrink_to_fit_width >= 0)
{
content_area.x = override_shrink_to_fit_width;
}
else
{
content_area.x = GetShrinkToFitWidth(element, containing_block);
override_shrink_to_fit_width = content_area.x;
}
}
// Otherwise, the margins that are set to auto will pick up the remaining width of the containing block.
else if (num_auto_margins > 0)
{
const float margin =
(containing_block.x - (GetInsetWidth() + box.GetSizeAcross(BoxDirection::Horizontal, BoxArea::Margin))) / float(num_auto_margins);
if (margins_auto[0])
box.SetEdge(BoxArea::Margin, BoxEdge::Left, margin);
if (margins_auto[1])
box.SetEdge(BoxArea::Margin, BoxEdge::Right, margin);
}
// Clamp the calculated width; if the width is changed by the clamp, then the margins need to be recalculated if
// they were set to auto.
const float clamped_width = Math::Clamp(content_area.x, min_width, max_width);
if (clamped_width != content_area.x)
{
content_area.x = clamped_width;
box.SetContent(content_area);
if (num_auto_margins > 0)
BuildBoxWidth(box, computed, min_width, max_width, containing_block, element, replaced_element, clamped_width);
}
else
box.SetContent(content_area);
}
void LayoutDetails::BuildBoxHeight(Box& box, const ComputedValues& computed, float min_height, float max_height, float containing_block_height)
{
RMLUI_ZoneScoped;
Vector2f content_area = box.GetSize();
// Determine if the element has automatic margins.
bool margins_auto[2];
int num_auto_margins = 0;
for (int i = 0; i < 2; ++i)
{
const Style::Margin margin_value = (i == 0 ? computed.margin_top() : computed.margin_bottom());
if (margin_value.type == Style::Margin::Auto)
{
margins_auto[i] = true;
num_auto_margins++;
box.SetEdge(BoxArea::Margin, i == 0 ? BoxEdge::Top : BoxEdge::Bottom, 0);
}
else
{
margins_auto[i] = false;
box.SetEdge(BoxArea::Margin, i == 0 ? BoxEdge::Top : BoxEdge::Bottom, ResolveValue(margin_value, containing_block_height));
}
}
const bool absolutely_positioned = (computed.position() == Style::Position::Absolute || computed.position() == Style::Position::Fixed);
const bool inset_auto = (computed.top().type == Style::Top::Auto || computed.bottom().type == Style::Bottom::Auto);
const bool height_auto = (content_area.y < 0);
auto GetInsetHeight = [&] {
// For absolutely positioned elements (and only those), the 'top' and 'bottom' values are part of the box's height constraint.
if (absolutely_positioned)
return ResolveValue(computed.top(), containing_block_height) + ResolveValue(computed.bottom(), containing_block_height);
return 0.f;
};
// If the height is set to auto, we need to calculate the height.
if (height_auto)
{
// If the height is set to auto for a box in normal flow, the height is set to -1, representing indefinite height.
content_area.y = -1;
// But if we are dealing with an absolutely positioned element we need to consider if the top and bottom
// properties are set, since the height can be affected.
if (absolutely_positioned && !inset_auto)
{
// The height is set to whatever remains of the containing block.
content_area.y =
containing_block_height - (GetInsetHeight() + box.GetSizeAcross(BoxDirection::Vertical, BoxArea::Margin, BoxArea::Padding));
content_area.y = Math::Max(0.0f, content_area.y);
}
}
// Otherwise, the margins that are set to auto will pick up the remaining height of the containing block.
else if (num_auto_margins > 0)
{
const float margin =
(containing_block_height - (GetInsetHeight() + box.GetSizeAcross(BoxDirection::Vertical, BoxArea::Margin))) / float(num_auto_margins);
if (margins_auto[0])
box.SetEdge(BoxArea::Margin, BoxEdge::Top, margin);
if (margins_auto[1])
box.SetEdge(BoxArea::Margin, BoxEdge::Bottom, margin);
}
if (content_area.y >= 0)
{
// Clamp the calculated height; if the height is changed by the clamp, then the margins need to be recalculated if
// they were set to auto.
float clamped_height = Math::Clamp(content_area.y, min_height, max_height);
if (clamped_height != content_area.y)
{
content_area.y = clamped_height;
box.SetContent(content_area);
if (num_auto_margins > 0)
BuildBoxHeight(box, computed, min_height, max_height, containing_block_height);
return;
}
}
box.SetContent(content_area);
}
} // namespace Rml