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Change how blocks are positioned vertically (esp. margin handling). 

svn path=/trunk/netsurf/; revision=12235
This commit is contained in:
Michael Drake 2011-04-22 21:57:18 +00:00
parent 9fef803d1a
commit 8d2bb4bd3a
2 changed files with 219 additions and 61 deletions
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3
render/box.h
View File

@ -124,7 +124,8 @@ typedef enum {
PRE_STRIP = 1 << 3, /* PRE tag needing leading newline stripped */
CLONE = 1 << 4, /* continuation of previous box from wrapping */
MEASURED = 1 << 5, /* text box width has been measured */
HAS_HEIGHT = 1 << 6 /* box has height */
HAS_HEIGHT = 1 << 6, /* box has height (perhaps due to children) */
MAKE_HEIGHT = 1 << 7 /* box causes its own height */
} box_flags;
/* Sides of a box */

277
render/layout.c
View File

@ -69,6 +69,8 @@ static bool layout_block_context(struct box *block, int viewport_height,
struct content *content);
static void layout_minmax_block(struct box *block,
const struct font_functions *font_func);
static struct box* layout_next_margin_block(struct box *box, struct box *block,
int viewport_height, int *max_pos_margin, int *max_neg_margin);
static bool layout_block_object(struct box *block);
static void layout_get_object_dimensions(struct box *box,
int *width, int *height,
@ -208,7 +210,8 @@ bool layout_block_context(struct box *block, int viewport_height,
int max_neg_margin = 0;
int y = 0;
int lm, rm;
struct box *margin_box;
struct box *margin_collapse = NULL;
bool in_margin = false;
css_fixed gadget_size;
css_unit gadget_unit; /* Checkbox / radio buttons */
@ -281,7 +284,7 @@ bool layout_block_context(struct box *block, int viewport_height,
gadget_unit, block->style));
}
box = margin_box = block->children;
box = block->children;
/* set current coordinates to top-left of the block */
cx = 0;
y = cy = block->padding[TOP];
@ -314,7 +317,6 @@ bool layout_block_context(struct box *block, int viewport_height,
while (box) {
assert(box->type == BOX_BLOCK || box->type == BOX_TABLE ||
box->type == BOX_INLINE_CONTAINER);
assert(margin_box);
/* Tables are laid out before being positioned, because the
* position depends on the width which is calculated in
@ -336,6 +338,16 @@ bool layout_block_context(struct box *block, int viewport_height,
goto advance_to_next_box;
}
/* If we don't know which box the current margin collapses
* through to, find out. Update the pos/neg margin values. */
if (margin_collapse == NULL) {
margin_collapse = layout_next_margin_block(box, block,
viewport_height,
&max_pos_margin, &max_neg_margin);
/* We have a margin that has not yet been applied. */
in_margin = true;
}
/* Clearance. */
y = 0;
if (box->style && css_computed_clear(box->style) !=
@ -343,19 +355,6 @@ bool layout_block_context(struct box *block, int viewport_height,
y = layout_clear(block->float_children,
css_computed_clear(box->style));
/* Get top margin */
if (box->style) {
layout_find_dimensions(box->parent->width,
viewport_height, box, box->style,
NULL, NULL, NULL, NULL,
box->margin, NULL, NULL);
}
if (max_pos_margin < box->margin[TOP])
max_pos_margin = box->margin[TOP];
else if (max_neg_margin < -box->margin[TOP])
max_neg_margin = -box->margin[TOP];
/* Blocks establishing a block formatting context get minimum
* left and right margins to avoid any floats. */
lm = rm = 0;
@ -405,8 +404,9 @@ bool layout_block_context(struct box *block, int viewport_height,
* diminished due to floats. */
int x0, x1, top;
struct box *left, *right;
top = cy > y ? cy : y;
top += max_pos_margin - max_neg_margin;
top = cy + max_pos_margin -
max_neg_margin;
top = (top > y) ? top : y;
x0 = cx;
x1 = cx + box->parent->width -
box->parent->padding[LEFT] -
@ -436,18 +436,34 @@ bool layout_block_context(struct box *block, int viewport_height,
cx += box->x;
/* Position box: vertical. */
if (box->type != BOX_BLOCK || y ||
box->border[TOP].width || box->padding[TOP]) {
margin_box->y += max_pos_margin - max_neg_margin;
cy += max_pos_margin - max_neg_margin;
max_pos_margin = max_neg_margin = 0;
margin_box = 0;
if (box->border[TOP].width) {
box->y += box->border[TOP].width;
cy += box->border[TOP].width;
if (cy < y) {
box->y += y - cy;
cy = y;
}
}
/* Vertical margin */
if (((box->type == BOX_BLOCK &&
(box->flags & HAS_HEIGHT)) ||
box->type == BOX_TABLE ||
(box->type == BOX_INLINE_CONTAINER &&
box != box->parent->children) ||
margin_collapse == box) &&
in_margin == true) {
/* Margin goes above this box. */
cy += max_pos_margin - max_neg_margin;
box->y += max_pos_margin - max_neg_margin;
/* Current margin has been applied. */
in_margin = false;
max_pos_margin = max_neg_margin = 0;
}
/* Handle clearance */
if (box->type != BOX_INLINE_CONTAINER &&
(y > 0) && (cy < y)) {
/* box clears something*/
box->y += y - cy;
cy = y;
}
/* Unless the box has an overflow style of visible, the box
@ -455,15 +471,12 @@ bool layout_block_context(struct box *block, int viewport_height,
if (box->type == BOX_BLOCK && box->style &&
css_computed_overflow(box->style) !=
CSS_OVERFLOW_VISIBLE) {
cy += max_pos_margin - max_neg_margin;
box->y += max_pos_margin - max_neg_margin;
layout_block_context(box, viewport_height, content);
if (box->type == BOX_BLOCK || box->object)
cy += box->padding[TOP];
cy += box->padding[TOP];
if (box->type == BOX_BLOCK && box->height == AUTO) {
if (box->height == AUTO) {
box->height = 0;
layout_block_add_scrollbar(box, BOTTOM);
}
@ -471,23 +484,13 @@ bool layout_block_context(struct box *block, int viewport_height,
cx -= box->x;
cy += box->height + box->padding[BOTTOM] +
box->border[BOTTOM].width;
max_pos_margin = max_neg_margin = 0;
if (max_pos_margin < box->margin[BOTTOM])
max_pos_margin = box->margin[BOTTOM];
else if (max_neg_margin < -box->margin[BOTTOM])
max_neg_margin = -box->margin[BOTTOM];
y = box->y + box->padding[TOP] + box->height +
box->padding[BOTTOM] +
box->border[BOTTOM].width;
/* Skip children, because they are done in the new
* block context */
goto advance_to_next_box;
} else if (box->type == BOX_BLOCK && (box->flags & HAS_HEIGHT)) {
/* This block doesn't establish a new block formatting
* context */
cy += max_pos_margin - max_neg_margin;
box->y += max_pos_margin - max_neg_margin;
max_pos_margin = max_neg_margin = 0;
}
#ifdef LAYOUT_DEBUG
@ -546,14 +549,17 @@ bool layout_block_context(struct box *block, int viewport_height,
/* Advance to next box. */
if (box->type == BOX_BLOCK && !box->object && box->children) {
/* Down into children. */
if (box == margin_collapse) {
/* Current margin collapsed though to this box.
* Unset margin_collapse. */
margin_collapse = NULL;
}
y = box->padding[TOP];
box = box->children;
box->y = y;
cy += y;
if (!margin_box) {
max_pos_margin = max_neg_margin = 0;
margin_box = box;
}
continue;
} else if (box->type == BOX_BLOCK || box->object)
cy += box->padding[TOP];
@ -565,23 +571,42 @@ bool layout_block_context(struct box *block, int viewport_height,
cy += box->height + box->padding[BOTTOM] +
box->border[BOTTOM].width;
max_pos_margin = max_neg_margin = 0;
if (max_pos_margin < box->margin[BOTTOM])
max_pos_margin = box->margin[BOTTOM];
else if (max_neg_margin < -box->margin[BOTTOM])
max_neg_margin = -box->margin[BOTTOM];
cx -= box->x;
y = box->y + box->padding[TOP] + box->height +
box->padding[BOTTOM] +
box->border[BOTTOM].width;
advance_to_next_box:
if (!box->next) {
/* No more siblings:
* up to first ancestor with a sibling. */
do {
if (box == margin_collapse) {
/* Current margin collapsed though to
* this box. Unset margin_collapse. */
margin_collapse = NULL;
}
/* Apply bottom margin */
if (max_pos_margin < box->margin[BOTTOM])
max_pos_margin = box->margin[BOTTOM];
else if (max_neg_margin < -box->margin[BOTTOM])
max_neg_margin = -box->margin[BOTTOM];
box = box->parent;
if (box == block)
break;
/* Margin is invalidated if this is a box
* margins can't collapse through. */
if (box->type == BOX_BLOCK &&
box->flags & MAKE_HEIGHT) {
margin_collapse = NULL;
in_margin = false;
max_pos_margin = max_neg_margin = 0;
}
if (box->height == AUTO) {
box->height = y - box->padding[TOP];
@ -607,22 +632,31 @@ bool layout_block_context(struct box *block, int viewport_height,
cy += box->padding[BOTTOM] +
box->border[BOTTOM].width;
if (max_pos_margin < box->margin[BOTTOM])
max_pos_margin = box->margin[BOTTOM];
else if (max_neg_margin < -box->margin[BOTTOM])
max_neg_margin = -box->margin[BOTTOM];
cx -= box->x;
y = box->y + box->padding[TOP] + box->height +
box->padding[BOTTOM] +
box->border[BOTTOM].width;
} while (box != block && !box->next);
} while (box->next == NULL);
if (box == block)
break;
}
/* To next sibling. */
if (box == margin_collapse) {
/* Current margin collapsed though to this box.
* Unset margin_collapse. */
margin_collapse = NULL;
}
if (max_pos_margin < box->margin[BOTTOM])
max_pos_margin = box->margin[BOTTOM];
else if (max_neg_margin < -box->margin[BOTTOM])
max_neg_margin = -box->margin[BOTTOM];
box = box->next;
box->y = y;
margin_box = box;
}
/* Account for bottom margin of last contained block */
@ -737,11 +771,17 @@ void layout_minmax_block(struct box *block,
case BOX_INLINE_CONTAINER:
layout_minmax_inline_container(child,
&child_has_height, font_func);
if (child_has_height &&
child ==
child->parent->children) {
block->flags |= MAKE_HEIGHT;
}
break;
case BOX_TABLE:
layout_minmax_table(child, font_func);
/* todo: fix for zero height tables */
child_has_height = true;
child->flags |= MAKE_HEIGHT;
break;
default:
assert(0);
@ -779,8 +819,10 @@ void layout_minmax_block(struct box *block,
min = max = FIXTOINT(nscss_len2px(width, wunit, block->style));
}
if (height > 0 && hunit != CSS_UNIT_PCT)
if (height > 0 && hunit != CSS_UNIT_PCT) {
block->flags |= MAKE_HEIGHT;
block->flags |= HAS_HEIGHT;
}
/* add margins, border, padding to min, max widths */
/* Note: we don't know available width here so percentage margin
@ -823,6 +865,121 @@ void layout_minmax_block(struct box *block,
}
/**
* Find next block that current margin collapses to.
*
* \param box box to start tree-order search from (top margin is included)
* \param block box responsible for current block fromatting context
* \param viewport_height height of viewport in px
* \param max_pos_margin updated to to maximum positive margin encountered
* \param max_neg_margin updated to to maximum negative margin encountered
* \return next box that current margin collapses to, or NULL if none.
*/
struct box* layout_next_margin_block(struct box *box, struct box *block,
int viewport_height, int *max_pos_margin, int *max_neg_margin)
{
assert(block != NULL);
while (box != NULL) {
if (box->type == BOX_INLINE_CONTAINER || (box->style &&
(css_computed_position(box->style) !=
CSS_POSITION_ABSOLUTE &&
css_computed_position(box->style) !=
CSS_POSITION_FIXED))) {
/* Not positioned */
/* Get margins */
if (box->style) {
layout_find_dimensions(box->parent->width,
viewport_height, box,
box->style,
NULL, NULL, NULL, NULL,
box->margin, box->padding,
box->border);
/* Apply top margin */
if (*max_pos_margin < box->margin[TOP])
*max_pos_margin = box->margin[TOP];
else if (*max_neg_margin < -box->margin[TOP])
*max_neg_margin = -box->margin[TOP];
}
/* Check whether box is the box current margin collapses
* to */
if (box->flags & MAKE_HEIGHT ||
box->border[TOP].width ||
box->padding[TOP] ||
(box->style &&
css_computed_overflow(box->style) !=
CSS_OVERFLOW_VISIBLE) ||
(box->type == BOX_INLINE_CONTAINER &&
box != box->parent->children)) {
/* Collapse to this box; return it */
return box;
}
}
/* Find next box */
if (box->type == BOX_BLOCK && !box->object && box->children &&
box->style &&
css_computed_overflow(box->style) ==
CSS_OVERFLOW_VISIBLE) {
/* Down into children. */
box = box->children;
} else {
if (!box->next) {
/* No more siblings:
* Go up to first ancestor with a sibling. */
do {
/* Apply bottom margin */
if (*max_pos_margin <
box->margin[BOTTOM])
*max_pos_margin =
box->margin[BOTTOM];
else if (*max_neg_margin <
-box->margin[BOTTOM])
*max_neg_margin =
-box->margin[BOTTOM];
box = box->parent;
} while (box != block && !box->next);
if (box == block) {
/* Margins don't collapse with stuff
* outside the block formatting context
*/
return block;
}
}
/* Apply bottom margin */
if (*max_pos_margin < box->margin[BOTTOM])
*max_pos_margin = box->margin[BOTTOM];
else if (*max_neg_margin < -box->margin[BOTTOM])
*max_neg_margin = -box->margin[BOTTOM];
/* To next sibling. */
box = box->next;
/* Get margins */
if (box->style) {
layout_find_dimensions(box->parent->width,
viewport_height, box,
box->style,
NULL, NULL, NULL, NULL,
box->margin, box->padding,
box->border);
}
}
}
return NULL;
}
/**
* Layout a block which contains an object.
*