/* * 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(Element* element) { if (!element) return "nullptr"; 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