Reduce number of page reflows and viewport

redraws as images are fetched:
+ Flag known-sized boxes generated by images.
+ Treat them as replaced all through layout.
+ Only reflow the document for fetched images
  if we don't already have the box at the
  right size.

svn path=/trunk/netsurf/; revision=12243

5 files changed, 85 insertions, 28 deletions

diff --git a/render/box.h b/render/box.h
index 0703c6da5..e7c19ad6d 100644
--- a/render/box.h
+++ b/render/box.h
@@ -126,7 +126,8 @@ typedef enum {
 	MEASURED    = 1 << 5,	/* text box width has been measured */
 	HAS_HEIGHT  = 1 << 6,	/* box has height (perhaps due to children) */
 	MAKE_HEIGHT = 1 << 7,	/* box causes its own height */
-	NEED_MIN    = 1 << 8	/* minimum width is required for layout */
+	NEED_MIN    = 1 << 8,	/* minimum width is required for layout */
+	REPLACE_DIM = 1 << 9	/* replaced element has given dimensions */
 } box_flags;
 
 /* Sides of a box */
diff --git a/render/box_construct.c b/render/box_construct.c
index b47405c12..f780d0714 100644
--- a/render/box_construct.c
+++ b/render/box_construct.c
@@ -1159,6 +1159,11 @@ bool box_image(BOX_SPECIAL_PARAMS)
 	bool ok;
 	char *s, *url;
 	xmlChar *alt, *src;
+	enum css_width_e wtype;
+	enum css_height_e htype;
+	css_fixed value = 0;
+	css_unit wunit = CSS_UNIT_PX;
+	css_unit hunit = CSS_UNIT_PX;
 
 	if (box->style && css_computed_display(box->style, 
 			n->parent == NULL) == CSS_DISPLAY_NONE)
@@ -1196,6 +1201,17 @@ bool box_image(BOX_SPECIAL_PARAMS)
 	ok = html_fetch_object(content, url, box, image_types,
 			content->available_width, 1000, false);
 	free(url);
+
+	wtype = css_computed_width(box->style, &value, &wunit);
+	htype = css_computed_height(box->style, &value, &hunit);
+
+	if (wtype == CSS_WIDTH_SET && wunit != CSS_UNIT_PCT &&
+			htype == CSS_HEIGHT_SET && hunit != CSS_UNIT_PCT) {
+		/* We know the dimensions the image will be shown at before it's
+		 * fetched. */
+		box->flags |= REPLACE_DIM;
+	}
+
 	return ok;
 }
 
diff --git a/render/html.c b/render/html.c
index cde8d79ef..cf9fdea81 100644
--- a/render/html.c
+++ b/render/html.c
@@ -1415,8 +1415,29 @@ nserror html_object_callback(hlcache_handle *object,
 		break;
 
 	case CONTENT_MSG_DONE:
-		html_object_done(box, object, o->background);
-		c->active--;
+
+		if (box->flags & REPLACE_DIM) {
+			union content_msg_data data;
+
+			c->active--;
+			html_object_done(box, object, o->background);
+
+			if (!box_visible(box))
+				break;
+
+			box_coords(box, &x, &y);
+
+			data.redraw.x = x + box->padding[LEFT];
+			data.redraw.y = y + box->padding[TOP];
+			data.redraw.width = box->width;
+			data.redraw.height = box->height;
+			data.redraw.full_redraw = true;
+
+			content_broadcast(c, CONTENT_MSG_REDRAW, data);
+		} else {
+			c->active--;
+			html_object_done(box, object, o->background);
+		}
 		break;
 
 	case CONTENT_MSG_ERROR:
@@ -1500,12 +1521,14 @@ nserror html_object_callback(hlcache_handle *object,
 	/* If  1) the configuration option to reflow pages while objects are
 	 *        fetched is set
 	 *     2) an object is newly fetched & converted,
-	 *     3) the object's parent HTML is ready for reformat,
-	 *     4) the time since the previous reformat is more than the
+	 *     3) the box's dimensions need to change due to being replaced
+	 *     4) the object's parent HTML is ready for reformat,
+	 *     5) the time since the previous reformat is more than the
 	 *        configured minimum time between reformats
 	 * then reformat the page to display newly fetched objects */
 	else if (option_incremental_reflow &&
 			event->type == CONTENT_MSG_DONE &&
+			!(box->flags & REPLACE_DIM) &&
 			(c->status == CONTENT_STATUS_READY ||
 			 c->status == CONTENT_STATUS_DONE) &&
 			(wallclock() > c->reformat_time)) {
@@ -1532,14 +1555,16 @@ void html_object_done(struct box *box, hlcache_handle *object,
 
 	box->object = object;
 
-	/* invalidate parent min, max widths */
-	for (b = box; b; b = b->parent)
-		b->max_width = UNKNOWN_MAX_WIDTH;
+	if (!(box->flags & REPLACE_DIM)) {
+		/* invalidate parent min, max widths */
+		for (b = box; b; b = b->parent)
+			b->max_width = UNKNOWN_MAX_WIDTH;
 
-	/* delete any clones of this box */
-	while (box->next && (box->next->flags & CLONE)) {
-		/* box_free_box(box->next); */
-		box->next = box->next->next;
+		/* delete any clones of this box */
+		while (box->next && (box->next->flags & CLONE)) {
+			/* box_free_box(box->next); */
+			box->next = box->next->next;
+		}
 	}
 }
 
diff --git a/render/html_redraw.c b/render/html_redraw.c
index 9ae43bce1..c5d20b26f 100644
--- a/render/html_redraw.c
+++ b/render/html_redraw.c
@@ -427,7 +427,8 @@ bool html_redraw_box(struct box *box, int x_parent, int y_parent,
 	if (bg_box && bg_box->type != BOX_BR &&
 			bg_box->type != BOX_TEXT &&
 			bg_box->type != BOX_INLINE_END &&
-			(bg_box->type != BOX_INLINE || bg_box->object)) {
+			(bg_box->type != BOX_INLINE || bg_box->object ||
+			box->flags & REPLACE_DIM)) {
 		/* find intersection of clip box and border edge */
 		struct rect p;
 		p.x0 = x - border_left < r.x0 ? r.x0 : x - border_left;
@@ -471,7 +472,8 @@ bool html_redraw_box(struct box *box, int x_parent, int y_parent,
 	/* borders for block level content and replaced inlines */
 	if (box->style && box->type != BOX_TEXT &&
 			box->type != BOX_INLINE_END &&
-			(box->type != BOX_INLINE || box->object) &&
+			(box->type != BOX_INLINE || box->object ||
+			box->flags & REPLACE_DIM) &&
 			(border_top || border_right ||
 			 border_bottom || border_left)) {
 		if (!html_redraw_borders(box, x_parent, y_parent,
diff --git a/render/layout.c b/render/layout.c
index 2c97ead0a..ca3f84853 100644
--- a/render/layout.c
+++ b/render/layout.c
@@ -270,6 +270,8 @@ bool layout_block_context(struct box *block, int viewport_height,
 		layout_get_object_dimensions(block, &block->width,
 				&block->height, false, true);
 		return true;
+	} else if (block->flags & REPLACE_DIM) {
+		return true;
 	}
 
 	/* special case if the block contains an radio button or checkbox */
@@ -359,8 +361,9 @@ bool layout_block_context(struct box *block, int viewport_height,
 		 * left and right margins to avoid any floats. */
 		lm = rm = 0;
 
-                if (box->type == BOX_BLOCK || box->object) {
-                	if (!box->object && box->style &&
+		if (box->type == BOX_BLOCK || box->object) {
+			if (!box->object && !(box->flags & REPLACE_DIM) &&
+					box->style &&
 					css_computed_overflow(box->style) !=
 					CSS_OVERFLOW_VISIBLE) {
 				/* box establishes new block formatting context
@@ -1115,7 +1118,8 @@ void layout_block_find_dimensions(int available_width, int viewport_height,
 			&width, &height, &max_width, &min_width,
 			margin, padding, border);
 
-	if (box->object && content_get_type(box->object) != CONTENT_HTML) {
+	if (box->object && !(box->flags & REPLACE_DIM) &&
+			content_get_type(box->object) != CONTENT_HTML) {
 		/* block-level replaced element, see 10.3.4 and 10.6.2 */
 		layout_get_object_dimensions(box, &width, &height,
 				true, true);
@@ -1432,7 +1436,8 @@ void layout_float_find_dimensions(int available_width,
 	padding[RIGHT] += scrollbar_width;
 	padding[BOTTOM] += scrollbar_width;
 
-	if (box->object && content_get_type(box->object) != CONTENT_HTML) {
+	if (box->object && !(box->flags & REPLACE_DIM) &&
+			content_get_type(box->object) != CONTENT_HTML) {
 		/* Floating replaced element, with intrinsic width or height.
 		 * See 10.3.6 and 10.6.2 */
 		layout_get_object_dimensions(box, &width, &height,
@@ -2011,7 +2016,8 @@ bool layout_inline_container(struct box *inline_container, int width,
 				whitespace == CSS_WHITE_SPACE_PRE_WRAP);
 		}
 
-		if ((!c->object && c->text && (c->length || is_pre)) ||
+		if ((!c->object && !(c->flags & REPLACE_DIM) && c->text &&
+				(c->length || is_pre)) ||
 				c->type == BOX_BR)
 			has_text_children = true;
 	}
@@ -2363,7 +2369,8 @@ bool layout_line(struct box *first, int *width, int *y,
 			continue;
 		}
 
-		if (!b->object && !b->gadget) {
+		if (!b->object && !b->gadget &&
+				!(b->flags & REPLACE_DIM)) {
 			/* inline non-replaced, 10.3.1 and 10.6.1 */
 			b->height = line_height(b->style ? b->style :
 					b->parent->parent->style);
@@ -2458,7 +2465,7 @@ bool layout_line(struct box *first, int *width, int *y,
 			b->height = AUTO;
 		}
 
-		if (b->object) {
+		if (b->object && !(b->flags & REPLACE_DIM)) {
 			layout_get_object_dimensions(b, &b->width, &b->height,
 					true, true);
 		} else {
@@ -2551,7 +2558,7 @@ bool layout_line(struct box *first, int *width, int *y,
 			}
 
 			space_before = space_after;
-			if (b->object)
+			if (b->object || b->flags & REPLACE_DIM)
 				space_after = 0;
 			else if (b->text || b->type == BOX_INLINE_END) {
 				if (b->space == UNKNOWN_WIDTH) {
@@ -2705,6 +2712,7 @@ bool layout_line(struct box *first, int *width, int *y,
 		if ((split_box->type == BOX_INLINE ||
 				split_box->type == BOX_TEXT) &&
 				!split_box->object &&
+				!(split_box->flags & REPLACE_DIM) &&
 				!split_box->gadget && split_box->text) {
 			/* skip leading spaces, otherwise code gets fooled into
 			 * thinking it's all one long word */
@@ -2858,7 +2866,8 @@ bool layout_line(struct box *first, int *width, int *y,
 			d->y = *y;
 			continue;
 		} else if ((d->type == BOX_INLINE &&
-				((d->object || d->gadget) == false)) ||
+				((d->object || d->gadget) == false) &&
+				!(d->flags & REPLACE_DIM)) ||
 				d->type == BOX_BR ||
 				d->type == BOX_TEXT ||
 				d->type == BOX_INLINE_END) {
@@ -3012,7 +3021,8 @@ struct box *layout_minmax_line(struct box *first,
 		assert(b->style);
 		font_plot_style_from_css(b->style, &fstyle);
 
-		if (b->type == BOX_INLINE && !b->object) {
+		if (b->type == BOX_INLINE && !b->object &&
+				!(b->flags & REPLACE_DIM)) {
 			fixed = frac = 0;
 			calculate_mbp_width(b->style, LEFT, true, true, true,
 					&fixed, &frac);
@@ -3040,7 +3050,8 @@ struct box *layout_minmax_line(struct box *first,
 			continue;
 		}
 
-		if (!b->object && !b->gadget) {
+		if (!b->object && !b->gadget &&
+				!(b->flags & REPLACE_DIM)) {
 			/* inline non-replaced, 10.3.1 and 10.6.1 */
 			if (!b->text)
 				continue;
@@ -3140,9 +3151,11 @@ struct box *layout_minmax_line(struct box *first,
 			height = AUTO;
 		}
 
-		if (b->object) {
-			layout_get_object_dimensions(b, &width, &height,
-					true, false);
+		if (b->object || (b->flags & REPLACE_DIM)) {
+			if (b->object) {
+				layout_get_object_dimensions(b, &width, &height,
+						true, false);
+			}
 
 			fixed = frac = 0;
 			calculate_mbp_width(b->style, LEFT, true, true, true,