html: layout: Split out common helpers

2 files changed, 599 insertions, 527 deletions

diff --git a/content/handlers/html/layout.c b/content/handlers/html/layout.c
index cb5be5dde..99e9bcf19 100644
--- a/content/handlers/html/layout.c
+++ b/content/handlers/html/layout.c
@@ -67,13 +67,9 @@
 #include "html/font.h"
 #include "html/form_internal.h"
 #include "html/layout.h"
+#include "html/layout_internal.h"
 #include "html/table.h"
 
-#define AUTO INT_MIN
-
-/* Fixed point percentage (a) of an integer (b), to an integer */
-#define FPCT_OF_INT_TOINT(a, b) (FIXTOINT(FDIV((a * b), F_100)))
-
 typedef uint8_t (*css_len_func)(
 		const css_computed_style *style,
 		css_fixed *length, css_unit *unit);
@@ -84,7 +80,7 @@ typedef uint8_t (*css_border_color_func)(
 		css_color *color);
 
 /** Array of per-side access functions for computed style margins. */
-static const css_len_func margin_funcs[4] = {
+const css_len_func margin_funcs[4] = {
 	[TOP]    = css_computed_margin_top,
 	[RIGHT]  = css_computed_margin_right,
 	[BOTTOM] = css_computed_margin_bottom,
@@ -92,7 +88,7 @@ static const css_len_func margin_funcs[4] = {
 };
 
 /** Array of per-side access functions for computed style paddings. */
-static const css_len_func padding_funcs[4] = {
+const css_len_func padding_funcs[4] = {
 	[TOP]    = css_computed_padding_top,
 	[RIGHT]  = css_computed_padding_right,
 	[BOTTOM] = css_computed_padding_bottom,
@@ -100,7 +96,7 @@ static const css_len_func padding_funcs[4] = {
 };
 
 /** Array of per-side access functions for computed style border_widths. */
-static const css_len_func border_width_funcs[4] = {
+const css_len_func border_width_funcs[4] = {
 	[TOP]    = css_computed_border_top_width,
 	[RIGHT]  = css_computed_border_right_width,
 	[BOTTOM] = css_computed_border_bottom_width,
@@ -108,67 +104,15 @@ static const css_len_func border_width_funcs[4] = {
 };
 
 /** Array of per-side access functions for computed style border styles. */
-static const css_border_style_func border_style_funcs[4] = {
+const css_border_style_func border_style_funcs[4] = {
 	[TOP]    = css_computed_border_top_style,
 	[RIGHT]  = css_computed_border_right_style,
 	[BOTTOM] = css_computed_border_bottom_style,
 	[LEFT]   = css_computed_border_left_style,
 };
 
-/** Layout helper: Check for CSS border on given side. */
-static inline bool lh__have_border(
-		enum box_side side,
-		const css_computed_style *style)
-{
-	return border_style_funcs[side](style) != CSS_BORDER_STYLE_NONE;
-}
-
-/** Layout helper: Check whether box is a float. */
-static inline bool lh__box_is_float_box(const struct box *b)
-{
-	return b->type == BOX_FLOAT_LEFT ||
-	       b->type == BOX_FLOAT_RIGHT;
-}
-
-/** Layout helper: Check whether box takes part in inline flow. */
-static inline bool lh__box_is_inline_flow(const struct box *b)
-{
-	return b->type == BOX_INLINE ||
-	       b->type == BOX_INLINE_BLOCK ||
-	       b->type == BOX_TEXT ||
-	       b->type == BOX_INLINE_END;
-}
-
-/** Layout helper: Check whether box is inline level. (Includes BR.) */
-static inline bool lh__box_is_inline_level(const struct box *b)
-{
-	return lh__box_is_inline_flow(b) ||
-	       b->type == BOX_BR;
-}
-
-/** Layout helper: Check whether box is inline level. (Includes BR, floats.) */
-static inline bool lh__box_is_inline_content(const struct box *b)
-{
-	return lh__box_is_float_box(b) ||
-	       lh__box_is_inline_level(b);
-}
-
-/** Layout helper: Check whether box is an object. */
-static inline bool lh__box_is_object(const struct box *b)
-{
-	return b->object ||
-	       (b->flags & (IFRAME | REPLACE_DIM));
-}
-
-/** Layout helper: Check whether box is replaced. */
-static inline bool lh__box_is_replace(const struct box *b)
-{
-	return b->gadget ||
-	       lh__box_is_object(b);
-}
-
 /** Array of per-side access functions for computed style border colors. */
-static const css_border_color_func border_color_funcs[4] = {
+const css_border_color_func border_color_funcs[4] = {
 	[TOP]    = css_computed_border_top_color,
 	[RIGHT]  = css_computed_border_right_color,
 	[BOTTOM] = css_computed_border_bottom_color,
@@ -176,10 +120,6 @@ static const css_border_color_func border_color_funcs[4] = {
 };
 
 /* forward declaration to break cycles */
-static bool layout_block_context(
-		struct box *block,
-		int viewport_height,
-		html_content *content);
 static void layout_minmax_block(
 		struct box *block,
 		const struct gui_layout_table *font_func,
@@ -315,74 +255,6 @@ static int layout_text_indent(
 
 
 /**
- * Determine width of margin, borders, and padding on one side of a box.
- *
- * \param unit_len_ctx  CSS length conversion context for document
- * \param style    style to measure
- * \param side     side of box to measure
- * \param margin   whether margin width is required
- * \param border   whether border width is required
- * \param padding  whether padding width is required
- * \param fixed    increased by sum of fixed margin, border, and padding
- * \param frac     increased by sum of fractional margin and padding
- */
-static void
-calculate_mbp_width(const css_unit_ctx *unit_len_ctx,
-		    const css_computed_style *style,
-		    unsigned int side,
-		    bool margin,
-		    bool border,
-		    bool padding,
-		    int *fixed,
-		    float *frac)
-{
-	css_fixed value = 0;
-	css_unit unit = CSS_UNIT_PX;
-
-	assert(style);
-
-	/* margin */
-	if (margin) {
-		enum css_margin_e type;
-
-		type = margin_funcs[side](style, &value, &unit);
-		if (type == CSS_MARGIN_SET) {
-			if (unit == CSS_UNIT_PCT) {
-				*frac += FIXTOINT(FDIV(value, F_100));
-			} else {
-				*fixed += FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-			}
-		}
-	}
-
-	/* border */
-	if (border) {
-		if (lh__have_border(side, style)) {
-			border_width_funcs[side](style, &value, &unit);
-
-			*fixed += FIXTOINT(css_unit_len2device_px(
-					style, unit_len_ctx,
-					value, unit));
-		}
-	}
-
-	/* padding */
-	if (padding) {
-		padding_funcs[side](style, &value, &unit);
-		if (unit == CSS_UNIT_PCT) {
-			*frac += FIXTOINT(FDIV(value, F_100));
-		} else {
-			*fixed += FIXTOINT(css_unit_len2device_px(
-					style, unit_len_ctx,
-					value, unit));
-		}
-	}
-}
-
-
-/**
  * Calculate minimum and maximum width of a table.
  *
  * \param table box of type TABLE
@@ -1227,375 +1099,6 @@ static void layout_minmax_block(
 
 
 /**
- * Adjust a specified width or height for the box-sizing property.
- *
- * This turns the specified dimension into a content-box dimension.
- *
- * \param  unit_len_ctx          Length conversion context
- * \param  box		    gadget to adjust dimensions of
- * \param  available_width  width of containing block
- * \param  setwidth	    set true if the dimension to be tweaked is a width,
- *				else set false for a height
- * \param  dimension	    current value for given width/height dimension.
- *				updated to new value after consideration of
- *				gadget properties.
- */
-static void layout_handle_box_sizing(
-		const css_unit_ctx *unit_len_ctx,
-		const struct box *box,
-		int available_width,
-		bool setwidth,
-		int *dimension)
-{
-	enum css_box_sizing_e bs;
-
-	assert(box && box->style);
-
-	bs = css_computed_box_sizing(box->style);
-
-	if (bs == CSS_BOX_SIZING_BORDER_BOX) {
-		int orig = *dimension;
-		int fixed = 0;
-		float frac = 0;
-
-		calculate_mbp_width(unit_len_ctx, box->style,
-				setwidth ? LEFT : TOP,
-				false, true, true, &fixed, &frac);
-		calculate_mbp_width(unit_len_ctx, box->style,
-				setwidth ? RIGHT : BOTTOM,
-				false, true, true, &fixed, &frac);
-		orig -= frac * available_width + fixed;
-		*dimension = orig > 0 ? orig : 0;
-	}
-}
-
-
-/**
- * Calculate width, height, and thickness of margins, paddings, and borders.
- *
- * \param  unit_len_ctx          Length conversion context
- * \param  available_width  width of containing block
- * \param  viewport_height  height of viewport in pixels or -ve if unknown
- * \param  box		    current box
- * \param  style	    style giving width, height, margins, paddings,
- *                          and borders
- * \param  width            updated to width, may be NULL
- * \param  height           updated to height, may be NULL
- * \param  max_width        updated to max-width, may be NULL
- * \param  min_width        updated to min-width, may be NULL
- * \param  max_height       updated to max-height, may be NULL
- * \param  min_height       updated to min-height, may be NULL
- * \param  margin	    filled with margins, may be NULL
- * \param  padding	    filled with paddings, may be NULL
- * \param  border	    filled with border widths, may be NULL
- */
-static void
-layout_find_dimensions(const css_unit_ctx *unit_len_ctx,
-		       int available_width,
-		       int viewport_height,
-		       const struct box *box,
-		       const css_computed_style *style,
-		       int *width,
-		       int *height,
-		       int *max_width,
-		       int *min_width,
-		       int *max_height,
-		       int *min_height,
-		       int margin[4],
-		       int padding[4],
-		       struct box_border border[4])
-{
-	struct box *containing_block = NULL;
-	unsigned int i;
-
-	if (width) {
-		enum css_width_e wtype;
-		css_fixed value = 0;
-		css_unit unit = CSS_UNIT_PX;
-
-		wtype = css_computed_width(style, &value, &unit);
-
-		if (wtype == CSS_WIDTH_SET) {
-			if (unit == CSS_UNIT_PCT) {
-				*width = FPCT_OF_INT_TOINT(
-						value, available_width);
-			} else {
-				*width = FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-			}
-		} else {
-			*width = AUTO;
-		}
-
-		if (*width != AUTO) {
-			layout_handle_box_sizing(unit_len_ctx, box, available_width,
-					true, width);
-		}
-	}
-
-	if (height) {
-		enum css_height_e htype;
-		css_fixed value = 0;
-		css_unit unit = CSS_UNIT_PX;
-
-		htype = css_computed_height(style, &value, &unit);
-
-		if (htype == CSS_HEIGHT_SET) {
-			if (unit == CSS_UNIT_PCT) {
-				enum css_height_e cbhtype;
-
-				if (css_computed_position(box->style) ==
-						CSS_POSITION_ABSOLUTE &&
-						box->parent) {
-					/* Box is absolutely positioned */
-					assert(box->float_container);
-					containing_block = box->float_container;
-				} else if (box->float_container &&
-					css_computed_position(box->style) !=
-						CSS_POSITION_ABSOLUTE &&
-					(css_computed_float(box->style) ==
-						CSS_FLOAT_LEFT ||
-					 css_computed_float(box->style) ==
-						CSS_FLOAT_RIGHT)) {
-					/* Box is a float */
-					assert(box->parent &&
-						box->parent->parent &&
-						box->parent->parent->parent);
-
-					containing_block =
-						box->parent->parent->parent;
-				} else if (box->parent && box->parent->type !=
-						BOX_INLINE_CONTAINER) {
-					/* Box is a block level element */
-					containing_block = box->parent;
-				} else if (box->parent && box->parent->type ==
-						BOX_INLINE_CONTAINER) {
-					/* Box is an inline block */
-					assert(box->parent->parent);
-					containing_block = box->parent->parent;
-				}
-
-				if (containing_block) {
-					css_fixed f = 0;
-					css_unit u = CSS_UNIT_PX;
-
-					cbhtype = css_computed_height(
-							containing_block->style,
-							&f, &u);
-				}
-
-				if (containing_block &&
-					containing_block->height != AUTO &&
-					(css_computed_position(box->style) ==
-							CSS_POSITION_ABSOLUTE ||
-						cbhtype == CSS_HEIGHT_SET)) {
-					/* Box is absolutely positioned or its
-					 * containing block has a valid
-					 * specified height.
-					 * (CSS 2.1 Section 10.5) */
-					*height = FPCT_OF_INT_TOINT(value,
-						containing_block->height);
-				} else if ((!box->parent ||
-						!box->parent->parent) &&
-						viewport_height >= 0) {
-					/* If root element or it's child
-					 * (HTML or BODY) */
-					*height = FPCT_OF_INT_TOINT(value,
-							viewport_height);
-				} else {
-					/* precentage height not permissible
-					 * treat height as auto */
-					*height = AUTO;
-				}
-			} else {
-				*height = FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-			}
-		} else {
-			*height = AUTO;
-		}
-
-		if (*height != AUTO) {
-			layout_handle_box_sizing(unit_len_ctx, box, available_width,
-					false, height);
-		}
-	}
-
-	if (max_width) {
-		enum css_max_width_e type;
-		css_fixed value = 0;
-		css_unit unit = CSS_UNIT_PX;
-
-		type = css_computed_max_width(style, &value, &unit);
-
-		if (type == CSS_MAX_WIDTH_SET) {
-			if (unit == CSS_UNIT_PCT) {
-				*max_width = FPCT_OF_INT_TOINT(value,
-						available_width);
-			} else {
-				*max_width = FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-			}
-		} else {
-			/* Inadmissible */
-			*max_width = -1;
-		}
-
-		if (*max_width != -1) {
-			layout_handle_box_sizing(unit_len_ctx, box, available_width,
-					true, max_width);
-		}
-	}
-
-	if (min_width) {
-		enum css_min_width_e type;
-		css_fixed value = 0;
-		css_unit unit = CSS_UNIT_PX;
-
-		type = ns_computed_min_width(style, &value, &unit);
-
-		if (type == CSS_MIN_WIDTH_SET) {
-			if (unit == CSS_UNIT_PCT) {
-				*min_width = FPCT_OF_INT_TOINT(value,
-						available_width);
-			} else {
-				*min_width = FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-			}
-		} else {
-			/* Inadmissible */
-			*min_width = 0;
-		}
-
-		if (*min_width != 0) {
-			layout_handle_box_sizing(unit_len_ctx, box, available_width,
-					true, min_width);
-		}
-	}
-
-	if (max_height) {
-		enum css_max_height_e type;
-		css_fixed value = 0;
-		css_unit unit = CSS_UNIT_PX;
-
-		type = css_computed_max_height(style, &value, &unit);
-
-		if (type == CSS_MAX_HEIGHT_SET) {
-			if (unit == CSS_UNIT_PCT) {
-				/* TODO: handle percentage */
-				*max_height = -1;
-			} else {
-				*max_height = FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-			}
-		} else {
-			/* Inadmissible */
-			*max_height = -1;
-		}
-	}
-
-	if (min_height) {
-		enum css_min_height_e type;
-		css_fixed value = 0;
-		css_unit unit = CSS_UNIT_PX;
-
-		type = ns_computed_min_height(style, &value, &unit);
-
-		if (type == CSS_MIN_HEIGHT_SET) {
-			if (unit == CSS_UNIT_PCT) {
-				/* TODO: handle percentage */
-				*min_height = 0;
-			} else {
-				*min_height = FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-			}
-		} else {
-			/* Inadmissible */
-			*min_height = 0;
-		}
-	}
-
-	for (i = 0; i != 4; i++) {
-		if (margin) {
-			enum css_margin_e type = CSS_MARGIN_AUTO;
-			css_fixed value = 0;
-			css_unit unit = CSS_UNIT_PX;
-
-			type = margin_funcs[i](style, &value, &unit);
-
-			if (type == CSS_MARGIN_SET) {
-				if (unit == CSS_UNIT_PCT) {
-					margin[i] = FPCT_OF_INT_TOINT(value,
-							available_width);
-				} else {
-					margin[i] = FIXTOINT(css_unit_len2device_px(
-							style, unit_len_ctx,
-							value, unit));
-				}
-			} else {
-				margin[i] = AUTO;
-			}
-		}
-
-		if (padding) {
-			css_fixed value = 0;
-			css_unit unit = CSS_UNIT_PX;
-
-			padding_funcs[i](style, &value, &unit);
-
-			if (unit == CSS_UNIT_PCT) {
-				padding[i] = FPCT_OF_INT_TOINT(value,
-						available_width);
-			} else {
-				padding[i] = FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-			}
-		}
-
-		/* Table cell borders are populated in table.c */
-		if (border && box->type != BOX_TABLE_CELL) {
-			enum css_border_style_e bstyle = CSS_BORDER_STYLE_NONE;
-			css_color color = 0;
-			css_fixed value = 0;
-			css_unit unit = CSS_UNIT_PX;
-
-			border_width_funcs[i](style, &value, &unit);
-			bstyle = border_style_funcs[i](style);
-			border_color_funcs[i](style, &color);
-
-			border[i].style = bstyle;
-			border[i].c = color;
-
-			if (bstyle == CSS_BORDER_STYLE_HIDDEN ||
-					bstyle == CSS_BORDER_STYLE_NONE)
-				/* spec unclear: following Mozilla */
-				border[i].width = 0;
-			else
-				border[i].width = FIXTOINT(css_unit_len2device_px(
-						style, unit_len_ctx,
-						value, unit));
-
-			/* Special case for border-collapse: make all borders
-			 * on table/table-row-group/table-row zero width. */
-			if (css_computed_border_collapse(style) ==
-					CSS_BORDER_COLLAPSE_COLLAPSE &&
-					(box->type == BOX_TABLE ||
-					 box->type == BOX_TABLE_ROW_GROUP ||
-					 box->type == BOX_TABLE_ROW))
-				border[i].width = 0;
-		}
-	}
-}
-
-
-/**
  * Find next block that current margin collapses to.
  *
  * \param  unit_len_ctx  Length conversion context
@@ -2058,15 +1561,10 @@ static void layout_move_children(struct box *box, int x, int y)
 }
 
 
-/**
- * Layout a table.
- *
- * \param  table	    table to layout
- * \param  available_width  width of containing block
- * \param  content	   memory pool for any new boxes
- * \return  true on success, false on memory exhaustion
- */
-static bool layout_table(struct box *table, int available_width,
+/* Documented in layout_internal.h */
+bool layout_table(
+		struct box *table,
+		int available_width,
 		html_content *content)
 {
 	unsigned int columns = table->columns;  /* total columns */
@@ -3977,21 +3475,11 @@ static bool layout_inline_container(struct box *inline_container, int width,
 }
 
 
-/**
- * Layout a block formatting context.
- *
- * \param  block	    BLOCK, INLINE_BLOCK, or TABLE_CELL to layout
- * \param  viewport_height  Height of viewport in pixels or -ve if unknown
- * \param  content	    Memory pool for any new boxes
- * \return  true on success, false on memory exhaustion
- *
- * This function carries out layout of a block and its children, as described
- * in CSS 2.1 9.4.1.
- */
-static bool
-layout_block_context(struct box *block,
-		     int viewport_height,
-		     html_content *content)
+/* Documented in layout_intertnal.h */
+bool layout_block_context(
+		struct box *block,
+		int viewport_height,
+		html_content *content)
 {
 	struct box *box;
 	int cx, cy;  /**< current coordinates */
diff --git a/content/handlers/html/layout_internal.h b/content/handlers/html/layout_internal.h
new file mode 100644
index 000000000..0c171ef44
--- /dev/null
+++ b/content/handlers/html/layout_internal.h
@@ -0,0 +1,584 @@
+/*
+ * Copyright 2003 James Bursa <bursa@users.sourceforge.net>
+ *
+ * This file is part of NetSurf, http://www.netsurf-browser.org/
+ *
+ * NetSurf is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * NetSurf is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * \file
+ * HTML layout private interface.
+ */
+
+#ifndef NETSURF_HTML_LAYOUT_INTERNAL_H
+#define NETSURF_HTML_LAYOUT_INTERNAL_H
+
+#define AUTO INT_MIN
+
+/* Fixed point percentage (a) of an integer (b), to an integer */
+#define FPCT_OF_INT_TOINT(a, b) (FIXTOINT(FDIV((a * b), F_100)))
+
+/**
+ * Layout a block formatting context.
+ *
+ * \param  block            BLOCK, INLINE_BLOCK, or TABLE_CELL to layout
+ * \param  viewport_height  Height of viewport in pixels or -ve if unknown
+ * \param  content          Memory pool for any new boxes
+ * \return  true on success, false on memory exhaustion
+ *
+ * This function carries out layout of a block and its children, as described
+ * in CSS 2.1 9.4.1.
+ */
+bool layout_block_context(
+		struct box *block,
+		int viewport_height,
+		html_content *content);
+
+/**
+ * Layout a table.
+ *
+ * \param  table            table to layout
+ * \param  available_width  width of containing block
+ * \param  content          memory pool for any new boxes
+ * \return  true on success, false on memory exhaustion
+ */
+bool layout_table(
+		struct box *table,
+		int available_width,
+		html_content *content);
+
+/**
+ * Layout a flex container.
+ *
+ * \param[in] flex             table to layout
+ * \param[in] available_width  width of containing block
+ * \param[in] content          memory pool for any new boxes
+ * \return  true on success, false on memory exhaustion
+ */
+bool layout_flex(
+		struct box *flex,
+		int available_width,
+		html_content *content);
+
+typedef uint8_t (*css_len_func)(
+		const css_computed_style *style,
+		css_fixed *length, css_unit *unit);
+typedef uint8_t (*css_border_style_func)(
+		const css_computed_style *style);
+typedef uint8_t (*css_border_color_func)(
+		const css_computed_style *style,
+		css_color *color);
+
+/** Array of per-side access functions for computed style margins. */
+extern const css_len_func margin_funcs[4];
+
+/** Array of per-side access functions for computed style paddings. */
+extern const css_len_func padding_funcs[4];
+
+/** Array of per-side access functions for computed style border_widths. */
+extern const css_len_func border_width_funcs[4];
+
+/** Array of per-side access functions for computed style border styles. */
+extern const css_border_style_func border_style_funcs[4];
+
+/** Array of per-side access functions for computed style border colors. */
+extern const css_border_color_func border_color_funcs[4];
+
+/** Layout helper: Check whether box is a float. */
+static inline bool lh__box_is_float_box(const struct box *b)
+{
+	return b->type == BOX_FLOAT_LEFT ||
+	       b->type == BOX_FLOAT_RIGHT;
+}
+
+/** Layout helper: Check whether box takes part in inline flow. */
+static inline bool lh__box_is_inline_flow(const struct box *b)
+{
+	return b->type == BOX_INLINE ||
+	       b->type == BOX_INLINE_BLOCK ||
+	       b->type == BOX_TEXT ||
+	       b->type == BOX_INLINE_END;
+}
+
+/** Layout helper: Check whether box is inline level. (Includes BR.) */
+static inline bool lh__box_is_inline_level(const struct box *b)
+{
+	return lh__box_is_inline_flow(b) ||
+	       b->type == BOX_BR;
+}
+
+/** Layout helper: Check whether box is inline level. (Includes BR, floats.) */
+static inline bool lh__box_is_inline_content(const struct box *b)
+{
+	return lh__box_is_float_box(b) ||
+	       lh__box_is_inline_level(b);
+}
+
+/** Layout helper: Check whether box is an object. */
+static inline bool lh__box_is_object(const struct box *b)
+{
+	return b->object ||
+	       (b->flags & (IFRAME | REPLACE_DIM));
+}
+
+/** Layout helper: Check whether box is replaced. */
+static inline bool lh__box_is_replace(const struct box *b)
+{
+	return b->gadget ||
+	       lh__box_is_object(b);
+}
+
+/** Layout helper: Check for CSS border on given side. */
+static inline bool lh__have_border(
+		enum box_side side,
+		const css_computed_style *style)
+{
+	return border_style_funcs[side](style) != CSS_BORDER_STYLE_NONE;
+}
+
+/**
+ * Determine width of margin, borders, and padding on one side of a box.
+ *
+ * \param unit_len_ctx  CSS length conversion context for document
+ * \param style    style to measure
+ * \param side     side of box to measure
+ * \param margin   whether margin width is required
+ * \param border   whether border width is required
+ * \param padding  whether padding width is required
+ * \param fixed    increased by sum of fixed margin, border, and padding
+ * \param frac     increased by sum of fractional margin and padding
+ */
+static inline void calculate_mbp_width(
+		const css_unit_ctx *unit_len_ctx,
+		const css_computed_style *style,
+		unsigned int side,
+		bool margin,
+		bool border,
+		bool padding,
+		int *fixed,
+		float *frac)
+{
+	css_fixed value = 0;
+	css_unit unit = CSS_UNIT_PX;
+
+	assert(style);
+
+	/* margin */
+	if (margin) {
+		enum css_margin_e type;
+
+		type = margin_funcs[side](style, &value, &unit);
+		if (type == CSS_MARGIN_SET) {
+			if (unit == CSS_UNIT_PCT) {
+				*frac += FIXTOINT(FDIV(value, F_100));
+			} else {
+				*fixed += FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+			}
+		}
+	}
+
+	/* border */
+	if (border) {
+		if (lh__have_border(side, style)) {
+			border_width_funcs[side](style, &value, &unit);
+
+			*fixed += FIXTOINT(css_unit_len2device_px(
+					style, unit_len_ctx,
+					value, unit));
+		}
+	}
+
+	/* padding */
+	if (padding) {
+		padding_funcs[side](style, &value, &unit);
+		if (unit == CSS_UNIT_PCT) {
+			*frac += FIXTOINT(FDIV(value, F_100));
+		} else {
+			*fixed += FIXTOINT(css_unit_len2device_px(
+					style, unit_len_ctx,
+					value, unit));
+		}
+	}
+}
+
+/**
+ * Adjust a specified width or height for the box-sizing property.
+ *
+ * This turns the specified dimension into a content-box dimension.
+ *
+ * \param  unit_len_ctx          Length conversion context
+ * \param  box		    gadget to adjust dimensions of
+ * \param  available_width  width of containing block
+ * \param  setwidth	    set true if the dimension to be tweaked is a width,
+ *				else set false for a height
+ * \param  dimension	    current value for given width/height dimension.
+ *				updated to new value after consideration of
+ *				gadget properties.
+ */
+static inline void layout_handle_box_sizing(
+		const css_unit_ctx *unit_len_ctx,
+		const struct box *box,
+		int available_width,
+		bool setwidth,
+		int *dimension)
+{
+	enum css_box_sizing_e bs;
+
+	assert(box && box->style);
+
+	bs = css_computed_box_sizing(box->style);
+
+	if (bs == CSS_BOX_SIZING_BORDER_BOX) {
+		int orig = *dimension;
+		int fixed = 0;
+		float frac = 0;
+
+		calculate_mbp_width(unit_len_ctx, box->style,
+				setwidth ? LEFT : TOP,
+				false, true, true, &fixed, &frac);
+		calculate_mbp_width(unit_len_ctx, box->style,
+				setwidth ? RIGHT : BOTTOM,
+				false, true, true, &fixed, &frac);
+		orig -= frac * available_width + fixed;
+		*dimension = orig > 0 ? orig : 0;
+	}
+}
+
+/**
+ * Calculate width, height, and thickness of margins, paddings, and borders.
+ *
+ * \param  unit_len_ctx     Length conversion context
+ * \param  available_width  width of containing block
+ * \param  viewport_height  height of viewport in pixels or -ve if unknown
+ * \param  box              current box
+ * \param  style            style giving width, height, margins, paddings,
+ *                          and borders
+ * \param  width            updated to width, may be NULL
+ * \param  height           updated to height, may be NULL
+ * \param  max_width        updated to max-width, may be NULL
+ * \param  min_width        updated to min-width, may be NULL
+ * \param  max_height       updated to max-height, may be NULL
+ * \param  min_height       updated to min-height, may be NULL
+ * \param  margin           filled with margins, may be NULL
+ * \param  padding          filled with paddings, may be NULL
+ * \param  border           filled with border widths, may be NULL
+ */
+static inline void layout_find_dimensions(
+		const css_unit_ctx *unit_len_ctx,
+		int available_width,
+		int viewport_height,
+		const struct box *box,
+		const css_computed_style *style,
+		int *width,
+		int *height,
+		int *max_width,
+		int *min_width,
+		int *max_height,
+		int *min_height,
+		int margin[4],
+		int padding[4],
+		struct box_border border[4])
+{
+	struct box *containing_block = NULL;
+	unsigned int i;
+
+	if (width) {
+		enum css_width_e wtype;
+		css_fixed value = 0;
+		css_unit unit = CSS_UNIT_PX;
+
+		wtype = css_computed_width(style, &value, &unit);
+
+		if (wtype == CSS_WIDTH_SET) {
+			if (unit == CSS_UNIT_PCT) {
+				*width = FPCT_OF_INT_TOINT(
+						value, available_width);
+			} else {
+				*width = FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+			}
+		} else {
+			*width = AUTO;
+		}
+
+		if (*width != AUTO) {
+			layout_handle_box_sizing(unit_len_ctx, box,
+					available_width, true, width);
+		}
+	}
+
+	if (height) {
+		enum css_height_e htype;
+		css_fixed value = 0;
+		css_unit unit = CSS_UNIT_PX;
+
+		htype = css_computed_height(style, &value, &unit);
+
+		if (htype == CSS_HEIGHT_SET) {
+			if (unit == CSS_UNIT_PCT) {
+				enum css_height_e cbhtype;
+
+				if (css_computed_position(box->style) ==
+						CSS_POSITION_ABSOLUTE &&
+						box->parent) {
+					/* Box is absolutely positioned */
+					assert(box->float_container);
+					containing_block = box->float_container;
+				} else if (box->float_container &&
+					css_computed_position(box->style) !=
+						CSS_POSITION_ABSOLUTE &&
+					(css_computed_float(box->style) ==
+						CSS_FLOAT_LEFT ||
+					 css_computed_float(box->style) ==
+						CSS_FLOAT_RIGHT)) {
+					/* Box is a float */
+					assert(box->parent &&
+						box->parent->parent &&
+						box->parent->parent->parent);
+
+					containing_block =
+						box->parent->parent->parent;
+				} else if (box->parent && box->parent->type !=
+						BOX_INLINE_CONTAINER) {
+					/* Box is a block level element */
+					containing_block = box->parent;
+				} else if (box->parent && box->parent->type ==
+						BOX_INLINE_CONTAINER) {
+					/* Box is an inline block */
+					assert(box->parent->parent);
+					containing_block = box->parent->parent;
+				}
+
+				if (containing_block) {
+					css_fixed f = 0;
+					css_unit u = CSS_UNIT_PX;
+
+					cbhtype = css_computed_height(
+							containing_block->style,
+							&f, &u);
+				}
+
+				if (containing_block &&
+					containing_block->height != AUTO &&
+					(css_computed_position(box->style) ==
+							CSS_POSITION_ABSOLUTE ||
+						cbhtype == CSS_HEIGHT_SET)) {
+					/* Box is absolutely positioned or its
+					 * containing block has a valid
+					 * specified height.
+					 * (CSS 2.1 Section 10.5) */
+					*height = FPCT_OF_INT_TOINT(value,
+						containing_block->height);
+				} else if ((!box->parent ||
+						!box->parent->parent) &&
+						viewport_height >= 0) {
+					/* If root element or it's child
+					 * (HTML or BODY) */
+					*height = FPCT_OF_INT_TOINT(value,
+							viewport_height);
+				} else {
+					/* precentage height not permissible
+					 * treat height as auto */
+					*height = AUTO;
+				}
+			} else {
+				*height = FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+			}
+		} else {
+			*height = AUTO;
+		}
+
+		if (*height != AUTO) {
+			layout_handle_box_sizing(unit_len_ctx, box,
+					available_width, false, height);
+		}
+	}
+
+	if (max_width) {
+		enum css_max_width_e type;
+		css_fixed value = 0;
+		css_unit unit = CSS_UNIT_PX;
+
+		type = css_computed_max_width(style, &value, &unit);
+
+		if (type == CSS_MAX_WIDTH_SET) {
+			if (unit == CSS_UNIT_PCT) {
+				*max_width = FPCT_OF_INT_TOINT(value,
+						available_width);
+			} else {
+				*max_width = FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+			}
+		} else {
+			/* Inadmissible */
+			*max_width = -1;
+		}
+
+		if (*max_width != -1) {
+			layout_handle_box_sizing(unit_len_ctx, box,
+					available_width, true, max_width);
+		}
+	}
+
+	if (min_width) {
+		enum css_min_width_e type;
+		css_fixed value = 0;
+		css_unit unit = CSS_UNIT_PX;
+
+		type = ns_computed_min_width(style, &value, &unit);
+
+		if (type == CSS_MIN_WIDTH_SET) {
+			if (unit == CSS_UNIT_PCT) {
+				*min_width = FPCT_OF_INT_TOINT(value,
+						available_width);
+			} else {
+				*min_width = FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+			}
+		} else {
+			/* Inadmissible */
+			*min_width = 0;
+		}
+
+		if (*min_width != 0) {
+			layout_handle_box_sizing(unit_len_ctx, box,
+					available_width, true, min_width);
+		}
+	}
+
+	if (max_height) {
+		enum css_max_height_e type;
+		css_fixed value = 0;
+		css_unit unit = CSS_UNIT_PX;
+
+		type = css_computed_max_height(style, &value, &unit);
+
+		if (type == CSS_MAX_HEIGHT_SET) {
+			if (unit == CSS_UNIT_PCT) {
+				/* TODO: handle percentage */
+				*max_height = -1;
+			} else {
+				*max_height = FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+			}
+		} else {
+			/* Inadmissible */
+			*max_height = -1;
+		}
+	}
+
+	if (min_height) {
+		enum css_min_height_e type;
+		css_fixed value = 0;
+		css_unit unit = CSS_UNIT_PX;
+
+		type = ns_computed_min_height(style, &value, &unit);
+
+		if (type == CSS_MIN_HEIGHT_SET) {
+			if (unit == CSS_UNIT_PCT) {
+				/* TODO: handle percentage */
+				*min_height = 0;
+			} else {
+				*min_height = FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+			}
+		} else {
+			/* Inadmissible */
+			*min_height = 0;
+		}
+	}
+
+	for (i = 0; i != 4; i++) {
+		if (margin) {
+			enum css_margin_e type = CSS_MARGIN_AUTO;
+			css_fixed value = 0;
+			css_unit unit = CSS_UNIT_PX;
+
+			type = margin_funcs[i](style, &value, &unit);
+
+			if (type == CSS_MARGIN_SET) {
+				if (unit == CSS_UNIT_PCT) {
+					margin[i] = FPCT_OF_INT_TOINT(value,
+							available_width);
+				} else {
+					margin[i] = FIXTOINT(css_unit_len2device_px(
+							style, unit_len_ctx,
+							value, unit));
+				}
+			} else {
+				margin[i] = AUTO;
+			}
+		}
+
+		if (padding) {
+			css_fixed value = 0;
+			css_unit unit = CSS_UNIT_PX;
+
+			padding_funcs[i](style, &value, &unit);
+
+			if (unit == CSS_UNIT_PCT) {
+				padding[i] = FPCT_OF_INT_TOINT(value,
+						available_width);
+			} else {
+				padding[i] = FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+			}
+		}
+
+		/* Table cell borders are populated in table.c */
+		if (border && box->type != BOX_TABLE_CELL) {
+			enum css_border_style_e bstyle = CSS_BORDER_STYLE_NONE;
+			css_color color = 0;
+			css_fixed value = 0;
+			css_unit unit = CSS_UNIT_PX;
+
+			border_width_funcs[i](style, &value, &unit);
+			bstyle = border_style_funcs[i](style);
+			border_color_funcs[i](style, &color);
+
+			border[i].style = bstyle;
+			border[i].c = color;
+
+			if (bstyle == CSS_BORDER_STYLE_HIDDEN ||
+					bstyle == CSS_BORDER_STYLE_NONE)
+				/* spec unclear: following Mozilla */
+				border[i].width = 0;
+			else
+				border[i].width = FIXTOINT(css_unit_len2device_px(
+						style, unit_len_ctx,
+						value, unit));
+
+			/* Special case for border-collapse: make all borders
+			 * on table/table-row-group/table-row zero width. */
+			if (css_computed_border_collapse(style) ==
+					CSS_BORDER_COLLAPSE_COLLAPSE &&
+					(box->type == BOX_TABLE ||
+					 box->type == BOX_TABLE_ROW_GROUP ||
+					 box->type == BOX_TABLE_ROW))
+				border[i].width = 0;
+		}
+	}
+}
+
+#endif