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netsurf/render/layout.c
James Bursa 3c4148943a [project @ 2004-03-26 01:35:35 by bursa] 
Fix infinite loop in layout_line(), improve layout of inline blocks, break out layout_float().

svn path=/import/netsurf/; revision=669
2004-03-26 01:35:35 +00:00

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/*
* This file is part of NetSurf, http://netsurf.sourceforge.net/
* Licensed under the GNU General Public License,
* http://www.opensource.org/licenses/gpl-license
* Copyright 2004 James Bursa <bursa@users.sourceforge.net>
* Copyright 2003 Phil Mellor <monkeyson@users.sourceforge.net>
*/
/** \file
* HTML layout (implementation).
*
* Layout is carried out in a single pass through the box tree, except for
* precalculation of minimum / maximum box widths.
*/
#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "netsurf/css/css.h"
#ifdef riscos
#include "netsurf/desktop/gui.h"
#endif
#include "netsurf/render/box.h"
#include "netsurf/render/font.h"
#include "netsurf/render/layout.h"
#define NDEBUG
#include "netsurf/utils/log.h"
#include "netsurf/utils/utils.h"
#define AUTO INT_MIN
static void layout_node(struct box *box, int width, struct box *cont,
int cx, int cy);
static void layout_block_find_dimensions(int available_width,
struct css_style *style, struct box *box);
static void layout_float_find_dimensions(int available_width,
struct css_style *style, struct box *box);
static void layout_find_dimensions(int available_width,
struct css_style *style,
int margin[4], int padding[4], int border[4]);
static void layout_block_children(struct box *box, struct box *cont,
int cx, int cy);
static int layout_clear(struct box *fl, css_clear clear);
static void find_sides(struct box *fl, int y0, int y1,
int *x0, int *x1, struct box **left, struct box **right);
static void layout_inline_container(struct box *box, int width,
struct box *cont, int cx, int cy);
static int line_height(struct css_style *style);
static struct box * layout_line(struct box *first, int width, int *y,
int cx, int cy, struct box *cont, bool indent);
static int layout_text_indent(struct css_style *style, int width);
static void layout_float(struct box *b, int width);
static void place_float_below(struct box *c, int width, int y,
struct box *cont);
static void layout_table(struct box *box);
static void calculate_widths(struct box *box);
static void calculate_inline_container_widths(struct box *box);
static void calculate_table_widths(struct box *table);
/**
* Calculate positions of boxes in a document.
*
* \param doc root of document box tree
* \param width available page width
*/
void layout_document(struct box *doc, int width)
{
struct box *box;
doc->float_children = 0;
calculate_widths(doc);
layout_block_find_dimensions(width, doc->style, doc);
doc->x = doc->margin[LEFT] + doc->border[LEFT];
doc->y = doc->margin[TOP] + doc->border[TOP];
width -= doc->margin[LEFT] + doc->border[LEFT] +
doc->border[RIGHT] + doc->margin[RIGHT];
layout_node(doc, width, doc, 0, 0);
for (box = doc->float_children; box != 0; box = box->next_float)
if (doc->height < box->y + box->height)
doc->height = box->y + box->height;
}
/**
* Layout the children of a box.
*
* \param box box to layout
* \param width horizontal space available
* \param cont ancestor box which defines horizontal space, for floats
* \param cx box position relative to cont
* \param cy box position relative to cont
*/
void layout_node(struct box *box, int width, struct box *cont,
int cx, int cy)
{
int cy1, x0, x1, table_width;
struct box *left, *right;
LOG(("box %p, width %i, cont %p, cx %i, cy %i",
box, width, cont, cx, cy));
gui_multitask();
switch (box->type) {
case BOX_BLOCK:
case BOX_INLINE_BLOCK:
layout_block(box, cont, cx, cy);
break;
case BOX_INLINE_CONTAINER:
layout_inline_container(box, box->width, cont, cx, cy);
break;
case BOX_TABLE:
layout_table(box);
/* find sides and move table down if it doesn't fit
in available width */
cy1 = cy;
table_width = box->width;
while (1) {
x0 = cx;
x1 = cx + width;
find_sides(cont->float_children, cy1, cy1 + box->height,
&x0, &x1, &left, &right);
if (table_width <= x1 - x0)
break;
if (left == 0 && right == 0)
break;
/* move down to the next place where the space may increase */
if (left == 0)
cy1 = right->y + right->height + 1;
else if (right == 0)
cy1 = left->y + left->height + 1;
else if (left->y + left->height < right->y + right->height)
cy1 = left->y + left->height + 1;
else
cy1 = right->y + right->height + 1;
}
box->x = x0;
box->y += cy1 - cy;
break;
default:
assert(0);
}
}
/**
* Layout the children of a block box.
*
* \param box block box to layout
* \param cont ancestor box which defines horizontal space, for floats
* \param cx box position relative to cont
* \param cy box position relative to cont
*/
void layout_block(struct box *box, struct box *cont, int cx, int cy)
{
struct css_style *style = box->style;
assert(box->type == BOX_BLOCK || box->type == BOX_INLINE_BLOCK);
assert(style != 0);
LOG(("box %p, cont %p, cx %i, cy %i", box, cont, cx, cy));
layout_block_children(box, cont, cx, cy);
switch (style->height.height) {
case CSS_HEIGHT_LENGTH:
box->height = len(&style->height.length, style);
break;
case CSS_HEIGHT_AUTO:
default:
/* use the computed height */
break;
}
}
/**
* Compute dimensions of box, margins, paddings, and borders for a block-level
* element.
*/
void layout_block_find_dimensions(int available_width,
struct css_style *style, struct box *box)
{
int width;
int *margin = box->margin;
int *padding = box->padding;
int *border = box->border;
/* calculate box width */
switch (style->width.width) {
case CSS_WIDTH_LENGTH:
width = len(&style->width.value.length, style);
break;
case CSS_WIDTH_PERCENT:
width = available_width * style->width.value.percent / 100;
break;
case CSS_WIDTH_AUTO:
default:
width = AUTO;
break;
}
layout_find_dimensions(available_width, style, margin, padding, border);
/* solve the width constraint as given in CSS 2.1 section 10.3.3 */
if (width == AUTO) {
/* any other 'auto' become 0 */
if (margin[LEFT] == AUTO)
margin[LEFT] = 0;
if (margin[RIGHT] == AUTO)
margin[RIGHT] = 0;
width = available_width -
(margin[LEFT] + border[LEFT] + padding[LEFT] +
padding[RIGHT] + border[RIGHT] + margin[RIGHT]);
} else if (margin[LEFT] == AUTO && margin[RIGHT] == AUTO) {
/* make the margins equal, centering the element */
margin[LEFT] = margin[RIGHT] = (available_width -
(border[LEFT] + padding[LEFT] + width +
padding[RIGHT] + border[RIGHT])) / 2;
} else if (margin[LEFT] == AUTO) {
margin[LEFT] = available_width -
(border[LEFT] + padding[LEFT] + width +
padding[RIGHT] + border[RIGHT] + margin[RIGHT]);
} else {
/* margin-right auto or "over-constained" */
margin[RIGHT] = available_width -
(margin[LEFT] + border[LEFT] + padding[LEFT] +
width + padding[RIGHT] + border[RIGHT]);
}
if (margin[TOP] == AUTO)
margin[TOP] = 0;
if (margin[BOTTOM] == AUTO)
margin[BOTTOM] = 0;
box->width = width;
}
/**
* Compute dimensions of box, margins, paddings, and borders for a floating
* element.
*/
void layout_float_find_dimensions(int available_width,
struct css_style *style, struct box *box)
{
layout_find_dimensions(available_width, style,
box->margin, box->padding, box->border);
if (box->margin[LEFT] == AUTO)
box->margin[LEFT] = 0;
if (box->margin[RIGHT] == AUTO)
box->margin[RIGHT] = 0;
/* calculate box width */
switch (style->width.width) {
case CSS_WIDTH_LENGTH:
box->width = len(&style->width.value.length, style);
break;
case CSS_WIDTH_PERCENT:
box->width = available_width *
style->width.value.percent / 100;
break;
case CSS_WIDTH_AUTO:
default:
/* CSS 2.1 section 10.3.5 */
available_width -= box->margin[LEFT] + box->border[LEFT] +
box->padding[LEFT] + box->padding[RIGHT] +
box->border[RIGHT] + box->margin[RIGHT];
if (box->min_width < available_width)
box->width = available_width;
else
box->width = box->min_width;
if (box->max_width < box->width)
box->width = box->max_width;
break;
}
}
/**
* Calculate size of margins, paddings, and borders.
*/
void layout_find_dimensions(int available_width,
struct css_style *style,
int margin[4], int padding[4], int border[4])
{
unsigned int i;
for (i = 0; i != 4; i++) {
switch (style->margin[i].margin) {
case CSS_MARGIN_LENGTH:
margin[i] = len(&style->margin[i].value.length, style);
break;
case CSS_MARGIN_PERCENT:
margin[i] = available_width *
style->margin[i].value.percent / 100;
break;
case CSS_MARGIN_AUTO:
default:
margin[i] = AUTO;
break;
}
switch (style->padding[i].padding) {
case CSS_MARGIN_PERCENT:
padding[i] = available_width *
style->padding[i].value.percent / 100;
break;
case CSS_PADDING_LENGTH:
default:
padding[i] = len(&style->padding[i].value.length, style);
break;
}
if (style->border[i].style == CSS_BORDER_STYLE_NONE ||
style->border[i].style == CSS_BORDER_STYLE_HIDDEN)
/* spec unclear: following Mozilla */
border[i] = 0;
else
border[i] = len(&style->border[i].width.value, style);
}
}
/**
* Recursively layout block children.
*
* \param box block box to layout
* \param cont ancestor box which defines horizontal space, for floats
* \param cx box position relative to cont
* \param cy box position relative to cont
*
* box->width, box->margin, box->padding and box->border must be valid.
* box->height is filled in.
*/
void layout_block_children(struct box *box, struct box *cont,
int cx, int cy)
{
struct box *c;
int width = box->width;
int y = box->padding[TOP];
int y1;
int vert_margin = 0;
assert(box->type == BOX_BLOCK || box->type == BOX_INLINE_BLOCK ||
box->type == BOX_FLOAT_LEFT || box->type == BOX_FLOAT_RIGHT ||
box->type == BOX_TABLE_CELL);
LOG(("box %p, width %i, cont %p, cx %i, cy %i",
box, width, cont, cx, cy));
for (c = box->children; c != 0; c = c->next) {
if (c->style && c->style->clear != CSS_CLEAR_NONE) {
y1 = layout_clear(cont->float_children,
c->style->clear) - cy;
if (y < y1)
y = y1;
}
c->x = box->padding[LEFT];
c->y = y;
if (c->style) {
layout_block_find_dimensions(width, c->style, c);
c->x += c->margin[LEFT] + c->border[LEFT];
if (vert_margin < c->margin[TOP])
vert_margin = c->margin[TOP];
c->y += vert_margin + c->border[TOP];
} else {
c->width = box->width;
}
layout_node(c, width, cont, cx + c->x, cy + c->y);
y = c->y + c->height + c->padding[TOP] + c->padding[BOTTOM] +
c->border[BOTTOM];
if (box->width < c->width)
box->width = c->width;
vert_margin = c->margin[BOTTOM];
}
box->height = y - box->padding[TOP];
}
/**
* Find y coordinate which clears all floats on left and/or right.
*
* \param fl first float in float list
* \param clear type of clear
* \return y coordinate relative to ancestor box for floats
*/
int layout_clear(struct box *fl, css_clear clear)
{
int y = 0;
for (; fl; fl = fl->next_float) {
if ((clear == CSS_CLEAR_LEFT || clear == CSS_CLEAR_BOTH) &&
fl->type == BOX_FLOAT_LEFT)
if (y < fl->y + fl->height + 1)
y = fl->y + fl->height + 1;
if ((clear == CSS_CLEAR_RIGHT || clear == CSS_CLEAR_BOTH) &&
fl->type == BOX_FLOAT_RIGHT)
if (y < fl->y + fl->height + 1)
y = fl->y + fl->height + 1;
}
return y;
}
/**
* Find left and right edges in a vertical range.
*
* \param fl first float in float list
* \param y0 start of y range to search
* \param y1 end of y range to search
* \param x0 start left edge, updated to available left edge
* \param x1 start right edge, updated to available right edge
* \param left returns float on left if present
* \param right returns float on right if present
*/
void find_sides(struct box *fl, int y0, int y1,
int *x0, int *x1, struct box **left, struct box **right)
{
int fy0, fy1, fx0, fx1;
LOG(("y0 %i, y1 %i, x0 %i, x1 %i", y0, y1, *x0, *x1));
*left = *right = 0;
for (; fl; fl = fl->next_float) {
fy0 = fl->y;
fy1 = fl->y + fl->height;
if (y0 <= fy1 && fy0 <= y1) {
if (fl->type == BOX_FLOAT_LEFT) {
fx1 = fl->x + fl->width;
if (*x0 < fx1) {
*x0 = fx1;
*left = fl;
}
} else if (fl->type == BOX_FLOAT_RIGHT) {
fx0 = fl->x;
if (fx0 < *x1) {
*x1 = fx0;
*right = fl;
}
}
}
}
LOG(("x0 %i, x1 %i, left %p, right %p", *x0, *x1, *left, *right));
}
/**
* Layout lines of text or inline boxes with floats.
*
* \param box inline container
* \param width horizontal space available
* \param cont ancestor box which defines horizontal space, for floats
* \param cx box position relative to cont
* \param cy box position relative to cont
*/
void layout_inline_container(struct box *box, int width,
struct box *cont, int cx, int cy)
{
bool first_line = true;
struct box *c;
int y = 0;
assert(box->type == BOX_INLINE_CONTAINER);
LOG(("box %p, width %i, cont %p, cx %i, cy %i",
box, width, cont, cx, cy));
for (c = box->children; c; ) {
LOG(("c %p", c));
c = layout_line(c, width, &y, cx, cy + y, cont, first_line);
first_line = false;
}
box->width = width;
box->height = y;
}
/**
* Calculate line height from a style.
*/
int line_height(struct css_style *style)
{
assert(style);
assert(style->line_height.size == CSS_LINE_HEIGHT_LENGTH ||
style->line_height.size == CSS_LINE_HEIGHT_ABSOLUTE ||
style->line_height.size == CSS_LINE_HEIGHT_PERCENT);
switch (style->line_height.size) {
case CSS_LINE_HEIGHT_LENGTH:
return len(&style->line_height.value.length, style);
case CSS_LINE_HEIGHT_ABSOLUTE:
return style->line_height.value.absolute *
len(&style->font_size.value.length, 0);
case CSS_LINE_HEIGHT_PERCENT:
default:
return style->line_height.value.percent *
len(&style->font_size.value.length, 0)
/ 100.0;
}
}
/**
* Position a line of boxes in inline formatting context.
*
* \param first box at start of line
* \param width available width
* \param y coordinate of top of line, updated on exit to bottom
* \param cy coordinate of top of line relative to cont
* \param cont ancestor box which defines horizontal space, for floats
* \param indent apply any first-line indent
*/
struct box * layout_line(struct box *first, int width, int *y,
int cx, int cy, struct box *cont, bool indent)
{
int height, used_height;
int x0 = 0;
int x1 = width;
int x, h, x_previous;
struct box *left;
struct box *right;
struct box *b;
struct box *split_box = 0;
struct box *d;
int move_y = 0;
int space_before = 0, space_after = 0;
unsigned int inline_count = 0;
LOG(("first->text '%.*s', width %i, y %i, cy %i",
first->length, first->text, width, *y, cy));
/* find sides at top of line */
x0 += cx;
x1 += cx;
find_sides(cont->float_children, cy, cy, &x0, &x1, &left, &right);
x0 -= cx;
x1 -= cx;
/* get minimum line height from containing block */
used_height = height = line_height(first->parent->parent->style);
/* pass 1: find height of line assuming sides at top of line */
for (x = 0, b = first; x < x1 - x0 && b != 0; b = b->next) {
assert(b->type == BOX_INLINE || b->type == BOX_INLINE_BLOCK ||
b->type == BOX_FLOAT_LEFT ||
b->type == BOX_FLOAT_RIGHT);
if (b->type == BOX_INLINE_BLOCK) {
if (b->width == UNKNOWN_WIDTH)
layout_float(b, width);
/** \todo should margin be included? spec unclear */
h = b->border[TOP] + b->padding[TOP] + b->height +
b->padding[BOTTOM] + b->border[BOTTOM];
if (height < h)
height = h;
x += b->margin[LEFT] + b->border[LEFT] +
b->padding[LEFT] + b->width +
b->padding[RIGHT] + b->border[RIGHT] +
b->margin[RIGHT];
}
if (b->type != BOX_INLINE)
continue;
if ((b->object || b->gadget) && b->style &&
b->style->height.height == CSS_HEIGHT_LENGTH)
h = len(&b->style->height.length, b->style);
else
h = line_height(b->style ? b->style :
b->parent->parent->style);
b->height = h;
if (height < h)
height = h;
if ((b->object || b->gadget) && b->style &&
b->style->width.width == CSS_WIDTH_LENGTH)
b->width = len(&b->style->width.value.length, b->style);
else if ((b->object || b->gadget) && b->style &&
b->style->width.width == CSS_WIDTH_PERCENT)
b->width = width * b->style->width.value.percent / 100;
else if (b->text) {
if (b->width == UNKNOWN_WIDTH)
b->width = font_width(b->font, b->text,
b->length);
} else
b->width = 0;
if (b->text)
x += b->width + b->space ? b->font->space_width : 0;
else
x += b->width;
}
/* find new sides using this height */
x0 = cx;
x1 = cx + width;
find_sides(cont->float_children, cy, cy + height, &x0, &x1,
&left, &right);
x0 -= cx;
x1 -= cx;
if (indent)
x0 += layout_text_indent(first->parent->parent->style, width);
if (x1 < x0)
x1 = x0;
/* pass 2: place boxes in line: loop body executed at least once */
for (x = x_previous = 0, b = first; x <= x1 - x0 && b; b = b->next) {
if (b->type == BOX_INLINE || b->type == BOX_INLINE_BLOCK) {
x_previous = x;
x += space_after;
b->x = x;
if (b->type == BOX_INLINE_BLOCK) {
b->x += b->margin[LEFT] + b->border[LEFT];
x = b->x + b->padding[LEFT] + b->width +
b->padding[RIGHT] +
b->border[RIGHT] +
b->margin[RIGHT];
} else
x += b->width;
space_before = space_after;
if (b->object)
space_after = 0;
else if (b->text)
space_after = b->space ? b->font->space_width : 0;
else
space_after = 0;
split_box = b;
move_y = 1;
inline_count++;
/* fprintf(stderr, "layout_line: '%.*s' %li %li\n", b->length, b->text, xp, x); */
} else {
/* float */
d = b->children;
d->float_children = 0;
/* css_dump_style(b->style); */
layout_float(d, width);
d->x = d->margin[LEFT] + d->border[LEFT];
d->y = d->margin[TOP] + d->border[TOP];
b->width = d->margin[LEFT] + d->border[LEFT] +
d->padding[LEFT] + d->width +
d->padding[RIGHT] + d->border[RIGHT] +
d->margin[RIGHT];
b->height = d->margin[TOP] + d->border[TOP] +
d->padding[TOP] + d->height +
d->padding[BOTTOM] + d->border[BOTTOM] +
d->margin[BOTTOM];
if (b->width < (x1 - x0) - x || (left == 0 && right == 0 && x == 0)) {
/* fits next to this line, or this line is empty with no floats */
if (b->type == BOX_FLOAT_LEFT) {
b->x = x0;
x0 += b->width;
left = b;
} else {
b->x = x1 - b->width;
x1 -= b->width;
right = b;
}
b->y = cy;
/* fprintf(stderr, "layout_line: float fits %li %li, edges %li %li\n", */
/* b->x, b->y, x0, x1); */
} else {
/* doesn't fit: place below */
place_float_below(b, width, cy + height + 1, cont);
/* fprintf(stderr, "layout_line: float doesn't fit %li %li\n", b->x, b->y); */
}
assert(cont->float_children != b);
b->next_float = cont->float_children;
cont->float_children = b;
split_box = 0;
}
}
if (x1 - x0 < x && split_box) {
/* the last box went over the end */
unsigned int i;
unsigned int space = 0;
int w;
struct box * c2;
x = x_previous;
if (split_box->type == BOX_INLINE && !split_box->object &&
!split_box->gadget && split_box->text) {
for (i = 0; i != split_box->length &&
split_box->text[i] != ' '; i++)
;
if (i != split_box->length)
space = i;
}
/* space != 0 implies split_box->text != 0 */
if (space == 0)
w = split_box->width;
else
w = font_width(split_box->font, split_box->text, space);
LOG(("splitting: split_box %p, space %u, w %i, left %p, "
"right %p, inline_count %u",
split_box, space, w, left, right,
inline_count));
if ((space == 0 || x1 - x0 <= x + space_before + w) &&
!left && !right && inline_count == 1) {
/* first word doesn't fit, but no floats and first
on line so force in */
if (space == 0) {
/* only one word in this box or not text */
b = split_box->next;
} else {
/* cut off first word for this line */
/* \todo allocate from box_pool */
c2 = memcpy(xcalloc(1, sizeof (struct box)),
split_box, sizeof (struct box));
c2->text = xstrdup(split_box->text + space + 1);
c2->length = split_box->length - (space + 1);
c2->width = UNKNOWN_WIDTH;
c2->clone = 1;
split_box->length = space;
split_box->width = w;
split_box->space = 1;
c2->next = split_box->next;
split_box->next = c2;
c2->prev = split_box;
if (c2->next)
c2->next->prev = c2;
else
c2->parent->last = c2;
b = c2;
}
x += space_before + w;
/* fprintf(stderr, "layout_line: overflow, forcing\n"); */
} else if (space == 0 || x1 - x0 <= x + space_before + w) {
/* first word doesn't fit, but full width not
available so leave for later */
b = split_box;
/* fprintf(stderr, "layout_line: overflow, leaving\n"); */
} else {
/* fit as many words as possible */
assert(space != 0);
space = font_split(split_box->font, split_box->text,
split_box->length,
x1 - x0 - x - space_before, &w)
- split_box->text;
LOG(("'%.*s' %i %u %i", (int) split_box->length,
split_box->text, x1 - x0, space, w));
/* assert(space != split_box->text); */
if (space == 0)
space = 1;
/* \todo use box pool */
c2 = memcpy(xcalloc(1, sizeof (struct box)), split_box,
sizeof (struct box));
c2->text = xstrdup(split_box->text + space + 1);
c2->length = split_box->length - (space + 1);
c2->width = UNKNOWN_WIDTH;
c2->clone = 1;
split_box->length = space;
split_box->width = w;
split_box->space = 1;
c2->next = split_box->next;
split_box->next = c2;
c2->prev = split_box;
if (c2->next)
c2->next->prev = c2;
else
c2->parent->last = c2;
b = c2;
x += space_before + w;
/* fprintf(stderr, "layout_line: overflow, fit\n"); */
}
move_y = 1;
}
/* set positions */
switch (first->parent->parent->style->text_align) {
case CSS_TEXT_ALIGN_RIGHT: x0 = x1 - x; break;
case CSS_TEXT_ALIGN_CENTER: x0 = (x0 + (x1 - x)) / 2; break;
default: break; /* leave on left */
}
for (d = first; d != b; d = d->next) {
if (d->type == BOX_INLINE || d->type == BOX_INLINE_BLOCK) {
d->x += x0;
d->y = *y + d->border[TOP];
h = d->border[TOP] + d->padding[TOP] + d->height +
d->padding[BOTTOM] + d->border[BOTTOM];
if (used_height < h)
used_height = h;
}
}
assert(b != first || (move_y && 0 < used_height && (left || right)));
if (move_y) *y += used_height;
return b;
}
/**
* Calculate the text-indent length.
*
* \param style style of block
* \param width width of containing block
* \return length of indent
*/
int layout_text_indent(struct css_style *style, int width)
{
switch (style->text_indent.size) {
case CSS_TEXT_INDENT_LENGTH:
return len(&style->text_indent.value.length, style);
case CSS_TEXT_INDENT_PERCENT:
return width * style->text_indent.value.percent / 100;
default:
return 0;
}
}
/**
* Layout the contents of a float or inline block.
*
* \param b float or inline block box
* \param width available width
*/
void layout_float(struct box *b, int width)
{
struct box *fl;
layout_float_find_dimensions(width, b->style, b);
layout_node(b, b->width, b, 0, 0);
/* increase height to contain any floats inside */
for (fl = b->float_children; fl != 0; fl = fl->next_float)
if (b->height < fl->y + fl->height)
b->height = fl->y + fl->height;
}
/**
* Position a float in the first available space.
*
* \param c float box to position
* \param width available width
* \param y y coordinate relative to cont to place float below
* \param cont ancestor box which defines horizontal space, for floats
*/
void place_float_below(struct box *c, int width, int y,
struct box *cont)
{
int x0, x1, yy = y;
struct box * left;
struct box * right;
do {
y = yy;
x0 = 0;
x1 = width;
find_sides(cont->float_children, y, y, &x0, &x1, &left, &right);
if (left != 0 && right != 0) {
yy = (left->y + left->height < right->y + right->height ?
left->y + left->height : right->y + right->height) + 1;
} else if (left == 0 && right != 0) {
yy = right->y + right->height + 1;
} else if (left != 0 && right == 0) {
yy = left->y + left->height + 1;
}
} while (!((left == 0 && right == 0) || (c->width < x1 - x0)));
if (c->type == BOX_FLOAT_LEFT) {
c->x = x0;
} else {
c->x = x1 - c->width;
}
c->y = y;
}
/**
* layout a table
*/
void layout_table(struct box *table)
{
unsigned int columns = table->columns; /* total columns */
unsigned int i;
unsigned int *row_span;
int *excess_y;
int table_width, min_width = 0, max_width = 0;
int required_width = 0;
int x;
int table_height = 0;
int *xs; /* array of column x positions */
struct box *c;
struct box *row;
struct box *row_group;
struct box **row_span_cell;
struct box *fl;
struct column col[table->columns];
assert(table->type == BOX_TABLE);
assert(table->style != 0);
assert(table->children != 0 && table->children->children != 0);
assert(columns != 0);
LOG(("table %p", table));
memcpy(col, table->col, sizeof(col[0]) * columns);
table_width = table->width;
LOG(("width %i, min %i, max %i", table_width, table->min_width, table->max_width));
for (i = 0; i != columns; i++) {
if (col[i].type == COLUMN_WIDTH_FIXED)
required_width += col[i].width;
else if (col[i].type == COLUMN_WIDTH_PERCENT) {
int width = col[i].width * table_width / 100;
required_width += col[i].min < width ? width : col[i].min;
} else
required_width += col[i].min;
}
if (table_width < required_width) {
/* table narrower than required width for columns:
* treat percentage widths as maximums */
for (i = 0; i != columns; i++) {
if (col[i].type == COLUMN_WIDTH_PERCENT) {
col[i].max = table_width * col[i].width / 100;
if (col[i].max < col[i].min)
col[i].max = col[i].min;
}
min_width += col[i].min;
max_width += col[i].max;
}
} else {
/* take percentages exactly */
for (i = 0; i != columns; i++) {
if (col[i].type == COLUMN_WIDTH_PERCENT) {
int width = table_width * col[i].width / 100;
if (width < col[i].min)
width = col[i].min;
col[i].min = col[i].width = col[i].max = width;
col[i].type = COLUMN_WIDTH_FIXED;
}
min_width += col[i].min;
max_width += col[i].max;
}
}
if (table_width <= min_width) {
/* not enough space: minimise column widths */
for (i = 0; i < columns; i++) {
col[i].width = col[i].min;
}
table_width = min_width;
} else if (max_width <= table_width) {
/* more space than maximum width */
if (table->style->width.width == CSS_WIDTH_AUTO) {
/* for auto-width tables, make columns max width */
for (i = 0; i < columns; i++) {
col[i].width = col[i].max;
}
table_width = max_width;
} else {
/* for fixed-width tables, distribute the extra space too */
unsigned int flexible_columns = 0;
for (i = 0; i != columns; i++)
if (col[i].type != COLUMN_WIDTH_FIXED)
flexible_columns++;
if (flexible_columns == 0) {
int extra = (table_width - max_width) / columns;
for (i = 0; i != columns; i++)
col[i].width = col[i].max + extra;
} else {
int extra = (table_width - max_width) / flexible_columns;
for (i = 0; i != columns; i++)
if (col[i].type != COLUMN_WIDTH_FIXED)
col[i].width = col[i].max + extra;
}
}
} else {
/* space between min and max: fill it exactly */
float scale = (float) (table_width - min_width) /
(float) (max_width - min_width);
/* fprintf(stderr, "filling, scale %f\n", scale); */
for (i = 0; i < columns; i++) {
col[i].width = col[i].min +
(col[i].max - col[i].min) * scale;
}
}
xs = xcalloc(columns + 1, sizeof(*xs));
row_span = xcalloc(columns, sizeof(row_span[0]));
excess_y = xcalloc(columns, sizeof(excess_y[0]));
row_span_cell = xcalloc(columns, sizeof(row_span_cell[0]));
xs[0] = x = 0;
for (i = 0; i != columns; i++) {
x += col[i].width;
xs[i + 1] = x;
row_span[i] = 0;
excess_y[i] = 0;
row_span_cell[i] = 0;
}
/* position cells */
for (row_group = table->children; row_group != 0; row_group = row_group->next) {
int row_group_height = 0;
for (row = row_group->children; row != 0; row = row->next) {
int row_height = 0;
for (c = row->children; c != 0; c = c->next) {
assert(c->style != 0);
c->width = xs[c->start_column + c->columns] - xs[c->start_column];
c->float_children = 0;
layout_block_children(c, c, 0, 0);
if (c->style->height.height == CSS_HEIGHT_LENGTH) {
/* some sites use height="1" or similar to attempt
* to make cells as small as possible, so treat
* it as a minimum */
int h = len(&c->style->height.length, c->style);
if (c->height < h)
c->height = h;
}
/* increase height to contain any floats inside */
for (fl = c->float_children; fl != 0; fl = fl->next_float)
if (c->height < fl->y + fl->height)
c->height = fl->y + fl->height;
c->x = xs[c->start_column];
c->y = 0;
for (i = 0; i != c->columns; i++) {
row_span[c->start_column + i] = c->rows;
excess_y[c->start_column + i] = c->height;
row_span_cell[c->start_column + i] = 0;
}
row_span_cell[c->start_column] = c;
c->height = 0;
}
for (i = 0; i != columns; i++)
if (row_span[i] != 0)
row_span[i]--;
else
row_span_cell[i] = 0;
if (row->next || row_group->next) {
/* row height is greatest excess of a cell which ends in this row */
for (i = 0; i != columns; i++)
if (row_span[i] == 0 && row_height < excess_y[i])
row_height = excess_y[i];
} else {
/* except in the last row */
for (i = 0; i != columns; i++)
if (row_height < excess_y[i])
row_height = excess_y[i];
}
for (i = 0; i != columns; i++) {
if (row_height < excess_y[i])
excess_y[i] -= row_height;
else
excess_y[i] = 0;
if (row_span_cell[i] != 0)
row_span_cell[i]->height += row_height;
}
row->x = 0;
row->y = row_group_height;
row->width = table_width;
row->height = row_height;
row_group_height += row_height;
}
row_group->x = 0;
row_group->y = table_height;
row_group->width = table_width;
row_group->height = row_group_height;
table_height += row_group_height;
}
xfree(row_span_cell);
xfree(excess_y);
xfree(row_span);
xfree(xs);
table->width = table_width;
table->height = table_height;
}
/**
* Find min, max widths required by boxes.
*
* \param box top of tree of boxes
*
* The min_width and max_width fields of each box in the tree are computed.
*/
void calculate_widths(struct box *box)
{
struct box *child;
int min = 0, max = 0, width, extra_fixed = 0;
float extra_frac = 0;
unsigned int side;
struct css_style *style = box->style;
assert(box->type == BOX_TABLE_CELL ||
box->type == BOX_BLOCK || box->type == BOX_INLINE_BLOCK ||
box->type == BOX_FLOAT_LEFT || box->type == BOX_FLOAT_RIGHT);
/* check if the widths have already been calculated */
if (box->max_width != UNKNOWN_MAX_WIDTH)
return;
for (child = box->children; child != 0; child = child->next) {
switch (child->type) {
case BOX_BLOCK:
case BOX_TABLE:
if (child->type == BOX_TABLE)
calculate_table_widths(child);
else
calculate_widths(child);
if (child->style->width.width == CSS_WIDTH_LENGTH) {
width = len(&child->style->width.value.length,
child->style);
if (min < width) min = width;
if (max < width) max = width;
} else {
if (min < child->min_width) min = child->min_width;
if (max < child->max_width) max = child->max_width;
}
break;
case BOX_INLINE_CONTAINER:
calculate_inline_container_widths(child);
if (min < child->min_width) min = child->min_width;
if (max < child->max_width) max = child->max_width;
break;
default:
break;
}
}
/* add margins, border, padding to min, max widths */
if (style) {
for (side = 1; side != 5; side += 2) { /* RIGHT, LEFT */
if (style->padding[side].padding == CSS_PADDING_LENGTH)
extra_fixed += len(&style->padding[side].value.length,
style);
else if (style->padding[side].padding == CSS_PADDING_PERCENT)
extra_frac += style->padding[side].value.percent * 0.01;
if (style->border[side].style != CSS_BORDER_STYLE_NONE)
extra_fixed += len(&style->border[side].width.value,
style);
if (style->margin[side].margin == CSS_MARGIN_LENGTH)
extra_fixed += len(&style->margin[side].value.length,
style);
else if (style->margin[side].margin == CSS_MARGIN_PERCENT)
extra_frac += style->margin[side].value.percent * 0.01;
}
}
if (1.0 <= extra_frac)
extra_frac = 0.9;
box->min_width = (min + extra_fixed) / (1.0 - extra_frac);
box->max_width = (max + extra_fixed) / (1.0 - extra_frac);
}
void calculate_inline_container_widths(struct box *box)
{
struct box *child;
int min = 0, max = 0, width;
unsigned int i, j;
for (child = box->children; child != 0; child = child->next) {
switch (child->type) {
case BOX_INLINE:
if (child->object || child->gadget) {
if (child->style->width.width == CSS_WIDTH_LENGTH) {
child->width = len(&child->style->width.value.length,
child->style);
max += child->width;
if (min < child->width)
min = child->width;
}
} else if (child->text) {
/* max = all one line */
child->width = font_width(child->font,
child->text, child->length);
max += child->width;
if (child->next && child->space)
max += child->font->space_width;
/* min = widest word */
i = 0;
do {
for (j = i; j != child->length && child->text[j] != ' '; j++)
;
width = font_width(child->font, child->text + i, (j - i));
if (min < width) min = width;
i = j + 1;
} while (j != child->length);
}
break;
case BOX_INLINE_BLOCK:
calculate_widths(child);
if (child->style != 0 &&
child->style->width.width == CSS_WIDTH_LENGTH) {
width = len(&child->style->width.value.length,
child->style);
if (min < width) min = width;
max += width;
} else {
if (min < child->min_width) min = child->min_width;
max += child->max_width;
}
break;
case BOX_FLOAT_LEFT:
case BOX_FLOAT_RIGHT:
calculate_widths(child);
if (child->style != 0 &&
child->style->width.width == CSS_WIDTH_LENGTH) {
width = len(&child->style->width.value.length,
child->style);
if (min < width) min = width;
if (max < width) max = width;
} else {
if (min < child->min_width) min = child->min_width;
if (max < child->max_width) max = child->max_width;
}
break;
default:
assert(0);
}
}
if (box->parent && box->parent->style &&
(box->parent->style->white_space == CSS_WHITE_SPACE_PRE ||
box->parent->style->white_space == CSS_WHITE_SPACE_NOWRAP))
min = max;
assert(min <= max);
box->min_width = min;
box->max_width = max;
}
void calculate_table_widths(struct box *table)
{
unsigned int i, j;
struct box *row_group, *row, *cell;
int width, min_width = 0, max_width = 0;
struct column *col;
LOG(("table %p, columns %u", table, table->columns));
/* check if the widths have already been calculated */
if (table->max_width != UNKNOWN_MAX_WIDTH)
return;
free(table->col);
table->col = col = xcalloc(table->columns, sizeof(*col));
assert(table->children != 0 && table->children->children != 0);
/* 1st pass: consider cells with colspan 1 only */
for (row_group = table->children; row_group != 0; row_group = row_group->next) {
assert(row_group->type == BOX_TABLE_ROW_GROUP);
for (row = row_group->children; row != 0; row = row->next) {
assert(row->type == BOX_TABLE_ROW);
for (cell = row->children; cell != 0; cell = cell->next) {
assert(cell->type == BOX_TABLE_CELL);
assert(cell->style != 0);
if (cell->columns != 1)
continue;
calculate_widths(cell);
i = cell->start_column;
if (col[i].type == COLUMN_WIDTH_FIXED) {
if (col[i].width < cell->min_width)
col[i].min = col[i].width = col[i].max = cell->min_width;
continue;
}
/* update column min, max widths using cell widths */
if (col[i].min < cell->min_width)
col[i].min = cell->min_width;
if (col[i].max < cell->max_width)
col[i].max = cell->max_width;
if (col[i].type != COLUMN_WIDTH_FIXED &&
cell->style->width.width == CSS_WIDTH_LENGTH) {
/* fixed width cell => fixed width column */
col[i].type = COLUMN_WIDTH_FIXED;
width = len(&cell->style->width.value.length,
cell->style);
if (width < col[i].min)
/* if the given width is too small, give
* the column its minimum width */
width = col[i].min;
col[i].min = col[i].width = col[i].max = width;
} else if (col[i].type == COLUMN_WIDTH_UNKNOWN) {
if (cell->style->width.width == CSS_WIDTH_PERCENT) {
col[i].type = COLUMN_WIDTH_PERCENT;
col[i].width = cell->style->width.value.percent;
} else if (cell->style->width.width == CSS_WIDTH_AUTO) {
col[i].type = COLUMN_WIDTH_AUTO;
}
}
}
}
}
/* 2nd pass: cells which span multiple columns */
for (row_group = table->children; row_group != 0; row_group = row_group->next) {
for (row = row_group->children; row != 0; row = row->next) {
for (cell = row->children; cell != 0; cell = cell->next) {
unsigned int flexible_columns = 0;
int min = 0, max = 0, fixed_width = 0;
signed long extra;
if (cell->columns == 1)
continue;
calculate_widths(cell);
i = cell->start_column;
/* find min, max width so far of spanned columns */
for (j = 0; j != cell->columns; j++) {
min += col[i + j].min;
max += col[i + j].max;
if (col[i + j].type == COLUMN_WIDTH_FIXED)
fixed_width += col[i + j].width;
else
flexible_columns++;
}
if (cell->style->width.width == CSS_WIDTH_LENGTH &&
flexible_columns) {
/* cell is fixed width, and not all the spanned columns
* are fixed width, so split difference between spanned
* columns which aren't fixed width yet */
width = len(&cell->style->width.value.length,
cell->style);
if (width < cell->min_width)
width = cell->min_width;
extra = width - fixed_width;
for (j = 0; j != cell->columns; j++)
if (col[i + j].type != COLUMN_WIDTH_FIXED)
extra -= col[i + j].min;
if (0 < extra)
extra = 1 + extra / flexible_columns;
else
extra = 0;
for (j = 0; j != cell->columns; j++) {
if (col[i + j].type != COLUMN_WIDTH_FIXED) {
col[i + j].width = col[i + j].max =
col[i + j].min += extra;
col[i + j].type = COLUMN_WIDTH_FIXED;
}
}
continue;
}
/* distribute extra min, max to spanned columns */
if (min < cell->min_width) {
if (flexible_columns == 0) {
extra = 1 + (cell->min_width - min)
/ cell->columns;
for (j = 0; j != cell->columns; j++)
col[i + j].min = col[i + j].width =
col[i + j].max += extra;
} else {
extra = 1 + (cell->min_width - min)
/ flexible_columns;
max = 0;
for (j = 0; j != cell->columns; j++) {
if (col[i + j].type != COLUMN_WIDTH_FIXED) {
col[i + j].min += extra;
if (col[i + j].max < col[i + j].min)
col[i + j].max = col[i + j].min;
max += col[i + j].max;
}
}
}
}
if (max < cell->max_width && flexible_columns != 0) {
extra = 1 + (cell->max_width - max)
/ flexible_columns;
for (j = 0; j != cell->columns; j++)
if (col[i + j].type != COLUMN_WIDTH_FIXED)
col[i + j].max += extra;
}
}
}
}
for (i = 0; i < table->columns; i++) {
LOG(("col %u, type %i, min %i, max %i, width %i",
i, col[i].type, col[i].min, col[i].max, col[i].width));
assert(col[i].min <= col[i].max);
min_width += col[i].min;
max_width += col[i].max;
}
table->min_width = min_width;
table->max_width = max_width;
LOG(("min_width %i, max_width %i", min_width, max_width));
}
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