html: Partially compute styles when generating boxes.

Resolve final width and em-scaled numbers at layout time.

4 files changed, 168 insertions, 121 deletions

diff --git a/include/mupdf/html.h b/include/mupdf/html.h
index 868014d0..613ab65c 100644
--- a/include/mupdf/html.h
+++ b/include/mupdf/html.h
@@ -4,19 +4,21 @@
 #include "mupdf/fitz.h"
 
 typedef struct html_document_s html_document;
-typedef struct html_page_s html_page;
+typedef struct box html_page;
 
 struct html_document_s
 {
 	fz_document super;
 	fz_context *ctx;
-	fz_xml *root;
+	fz_xml *xml;
+	struct box *box;
 };
 
 html_document *html_open_document(fz_context *ctx, const char *filename);
 html_document *html_open_document_with_stream(fz_context *ctx, fz_stream *file);
 
 void html_layout_document(html_document *doc, float w, float h);
+void html_run_box(fz_context *ctx, struct box *page, fz_device *dev, const fz_matrix *ctm);
 
 enum
 {
@@ -97,6 +99,14 @@ enum { TA_LEFT, TA_RIGHT, TA_CENTER, TA_JUSTIFY };
 
 enum { TOP, RIGHT, BOTTOM, LEFT };
 
+enum { N_NUMBER='p', N_SCALE='m', N_PERCENT='%' };
+
+struct number
+{
+	float value;
+	int unit;
+};
+
 struct color
 {
 	unsigned char r, g, b;
@@ -105,24 +115,25 @@ struct color
 struct computed_style
 {
 	int position;
-	float top, right, bottom, left;
-	float margin[4];
-	float padding[4];
-	float border_width[4];
+	struct number top, right, bottom, left;
+	struct number margin[4];
+	struct number padding[4];
+	struct number border_width[4];
 	int border_style;
 	struct color border_color;
 	struct color color;
 	struct color background_color;
 	const char *font_family;
 	int bold, italic, smallcaps;
-	float font_size;
-	float line_height;
+	struct number font_size;
+	struct number line_height;
 	int vertical_align;
 	int text_align;
-	float text_indent;
+	struct number text_indent;
 };
 
 void apply_styles(fz_context *ctx, struct style *style, struct rule *rule, fz_xml *node);
-void compute_style(struct computed_style *cstyle, struct style *style, float width);
+void compute_style(struct computed_style *cstyle, struct style *style);
+float from_number(struct number, float em, float width);
 
 #endif
diff --git a/source/html/css-apply.c b/source/html/css-apply.c
index a99eed2b..8526f7b9 100644
--- a/source/html/css-apply.c
+++ b/source/html/css-apply.c
@@ -717,60 +717,84 @@ get_style_property_display(struct style *node)
 	return DIS_INLINE;
 }
 
-static float
-compute_number(struct value *value, float em, float hundred, float scale, float initial)
+static struct number
+make_number(float v, int u)
+{
+	struct number n;
+	n.value = v;
+	n.unit = u;
+	return n;
+}
+
+static struct number
+number_from_value(struct value *value, float initial, int initial_unit)
 {
 	char *p;
 
 	if (!value)
-		return initial;
+		return make_number(initial, initial_unit);
 
 	if (value->type == CSS_PERCENT)
-		return strtof(value->data, &p) * hundred / 100;
+		return make_number(strtof(value->data, NULL), N_PERCENT);
 
 	if (value->type == CSS_NUMBER)
-		return strtof(value->data, &p) * scale;
+		return make_number(strtof(value->data, NULL), N_NUMBER);
 
 	if (value->type == CSS_LENGTH)
 	{
 		float x = strtof(value->data, &p);
 
 		if (p[0] == 'e' && p[1] == 'm')
-			return x * em;
+			return make_number(x, N_SCALE);
 		if (p[0] == 'e' && p[1] == 'x')
-			return x * em / 2;
+			return make_number(x / 2, N_SCALE);
 
 		if (p[0] == 'i' && p[1] == 'n')
-			return x * 72;
+			return make_number(x * 72, N_NUMBER);
 		if (p[0] == 'c' && p[1] == 'm')
-			return x * 7200 / 254;
+			return make_number(x * 7200 / 254, N_NUMBER);
 		if (p[0] == 'm' && p[1] == 'm')
-			return x * 720 / 254;
+			return make_number(x * 720 / 254, N_NUMBER);
 		if (p[0] == 'p' && p[1] == 'c')
-			return x * 12;
+			return make_number(x * 12, N_NUMBER);
 
 		if (p[0] == 'p' && p[1] == 't')
-			return x;
+			return make_number(x, N_NUMBER);
 		if (p[0] == 'p' && p[1] == 'x')
-			return x;
+			return make_number(x, N_NUMBER);
 
-		return x;
+		return make_number(x, N_NUMBER);
 	}
 
-	return initial;
+	return make_number(initial, initial_unit);
+}
+
+static struct number number_from_property(struct style *node, const char *property, float initial, int initial_unit)
+{
+	return number_from_value(get_style_property(node, property), initial, initial_unit);
+}
+
+float
+from_number(struct number number, float em, float width)
+{
+	switch (number.unit) {
+	default:
+	case N_NUMBER: return number.value;
+	case N_SCALE: return number.value * em;
+	case N_PERCENT: return number.value * width;
+	}
 }
 
 void
-compute_style(struct computed_style *style, struct style *node, float width)
+compute_style(struct computed_style *style, struct style *node)
 {
 	struct value *value;
-	float em = 12;
 
 	memset(style, 0, sizeof *style);
 
 	style->position = POS_STATIC;
 	style->text_align = TA_LEFT;
-	style->font_size = 12;
+	style->font_size = make_number(1, N_SCALE);
 
 	value = get_style_property(node, "position");
 	if (value)
@@ -808,45 +832,37 @@ compute_style(struct computed_style *style, struct style *node, float width)
 	}
 
 	value = get_style_property(node, "font-size");
-	if (value) {
-		if (!strcmp(value->data, "xx-large")) style->font_size = 20;
-		else if (!strcmp(value->data, "x-large")) style->font_size = 16;
-		else if (!strcmp(value->data, "large")) style->font_size = 14;
-		else if (!strcmp(value->data, "medium")) style->font_size = 12;
-		else if (!strcmp(value->data, "small")) style->font_size = 10;
-		else if (!strcmp(value->data, "x-small")) style->font_size = 8;
-		else if (!strcmp(value->data, "xx-small")) style->font_size = 6;
-		else if (!strcmp(value->data, "larger")) style->font_size = em + 2;
-		else if (!strcmp(value->data, "smaller")) style->font_size = em - 2;
-		else style->font_size = compute_number(value, em, em, 1, 12);
-	} else {
-		style->font_size = 12;
-	}
-	em = style->font_size;
-
-	value = get_style_property(node, "line-height");
-	style->line_height = compute_number(value, em, em, em, 1.2 * em);
-
-	value = get_style_property(node, "text-indent");
-	style->text_indent = compute_number(value, em, width, 1, 0);
-
-	value = get_style_property(node, "margin-top");
-	style->margin[0] = compute_number(value, em, width, 1, 0);
-	value = get_style_property(node, "margin-right");
-	style->margin[1] = compute_number(value, em, width, 1, 0);
-	value = get_style_property(node, "margin-bottom");
-	style->margin[2] = compute_number(value, em, width, 1, 0);
-	value = get_style_property(node, "margin-left");
-	style->margin[3] = compute_number(value, em, width, 1, 0);
-
-	value = get_style_property(node, "padding-top");
-	style->padding[0] = compute_number(value, em, width, 1, 0);
-	value = get_style_property(node, "padding-right");
-	style->padding[1] = compute_number(value, em, width, 1, 0);
-	value = get_style_property(node, "padding-bottom");
-	style->padding[2] = compute_number(value, em, width, 1, 0);
-	value = get_style_property(node, "padding-left");
-	style->padding[3] = compute_number(value, em, width, 1, 0);
+	if (value)
+	{
+		if (!strcmp(value->data, "xx-large")) style->font_size = make_number(20, N_NUMBER);
+		else if (!strcmp(value->data, "x-large")) style->font_size = make_number(16, N_NUMBER);
+		else if (!strcmp(value->data, "large")) style->font_size = make_number(14, N_NUMBER);
+		else if (!strcmp(value->data, "medium")) style->font_size = make_number(12, N_NUMBER);
+		else if (!strcmp(value->data, "small")) style->font_size = make_number(10, N_NUMBER);
+		else if (!strcmp(value->data, "x-small")) style->font_size = make_number(8, N_NUMBER);
+		else if (!strcmp(value->data, "xx-small")) style->font_size = make_number(6, N_NUMBER);
+		else if (!strcmp(value->data, "larger")) style->font_size = make_number(1.25f, N_SCALE);
+		else if (!strcmp(value->data, "smaller")) style->font_size = make_number(0.8f, N_SCALE);
+		else style->font_size = number_from_value(value, 12, N_NUMBER);
+	}
+	else
+	{
+		style->font_size = make_number(1, N_SCALE);
+	}
+
+	style->line_height = number_from_property(node, "line-height", 1.2, N_SCALE);
+
+	style->text_indent = number_from_property(node, "text-indent", 0, N_NUMBER);
+
+	style->margin[0] = number_from_property(node, "margin-top", 0, N_NUMBER);
+	style->margin[1] = number_from_property(node, "margin-right", 0, N_NUMBER);
+	style->margin[2] = number_from_property(node, "margin-bottom", 0, N_NUMBER);
+	style->margin[3] = number_from_property(node, "margin-left", 0, N_NUMBER);
+
+	style->padding[0] = number_from_property(node, "padding-top", 0, N_NUMBER);
+	style->padding[1] = number_from_property(node, "padding-right", 0, N_NUMBER);
+	style->padding[2] = number_from_property(node, "padding-bottom", 0, N_NUMBER);
+	style->padding[3] = number_from_property(node, "padding-left", 0, N_NUMBER);
 
 	{
 		const char *font_family = get_style_property_string(node, "font-family", "serif");
@@ -880,13 +896,20 @@ print_style(struct computed_style *style)
 	printf("\tfont-weight = %s;\n", style->bold ? "bold" : "normal");
 	printf("\tfont-style = %s;\n", style->italic ? "italic" : "normal");
 	printf("\tfont-variant = %s;\n", style->smallcaps ? "small-caps" : "normal");
-	printf("\tfont-size = %g;\n", style->font_size);
-	printf("\tline-height = %g;\n", style->line_height);
-	printf("\ttext-indent = %g;\n", style->text_indent);
+
+	printf("\tfont-size = %g%c;\n", style->font_size.value, style->font_size.unit);
+	printf("\tline-height = %g%c;\n", style->line_height.value, style->line_height.unit);
+	printf("\ttext-indent = %g%c;\n", style->text_indent.value, style->text_indent.unit);
 	printf("\tvertical-align = %d;\n", style->vertical_align);
-	printf("\tmargin = %g %g %g %g;\n",
-		style->margin[0], style->margin[1], style->margin[2], style->margin[3]);
-	printf("\tpadding = %g %g %g %g;\n",
-		style->padding[0], style->padding[1], style->padding[2], style->padding[3]);
+	printf("\tmargin = %g%c %g%c %g%c %g%c;\n",
+		style->margin[0].value, style->margin[0].unit,
+		style->margin[1].value, style->margin[1].unit,
+		style->margin[2].value, style->margin[2].unit,
+		style->margin[3].value, style->margin[3].unit);
+	printf("\tpadding = %g%c %g%c %g%c %g%c;\n",
+		style->padding[0].value, style->padding[0].unit,
+		style->padding[1].value, style->padding[1].unit,
+		style->padding[2].value, style->padding[2].unit,
+		style->padding[3].value, style->padding[3].unit);
 	printf("}\n");
 }
diff --git a/source/html/handler.c b/source/html/handler.c
index f5002437..859721c8 100644
--- a/source/html/handler.c
+++ b/source/html/handler.c
@@ -1,9 +1,5 @@
 #include "mupdf/html.h"
 
-struct html_page_s
-{
-};
-
 void
 html_close_document(html_document *doc)
 {
@@ -21,7 +17,7 @@ html_page *
 html_load_page(html_document *doc, int number)
 {
 	printf("html: load page %d\n", number);
-	return (html_page*)"nothing";
+	return doc->box;
 }
 
 void
@@ -43,6 +39,7 @@ void
 html_run_page(html_document *doc, html_page *page, fz_device *dev, const fz_matrix *ctm, fz_cookie *cookie)
 {
 	printf("html: run page\n");
+	html_run_box(doc->ctx, page, dev, ctm);
 }
 
 html_document *
@@ -50,15 +47,14 @@ html_open_document_with_stream(fz_context *ctx, fz_stream *file)
 {
 	html_document *doc;
 	fz_buffer *buf;
-	fz_xml *root;
+	fz_xml *xml;
 
 	buf = fz_read_all(file, 0);
-	root = fz_parse_xml(ctx, buf->data, buf->len, 1);
+	xml = fz_parse_xml(ctx, buf->data, buf->len, 1);
 	fz_drop_buffer(ctx, buf);
 
 	doc = fz_malloc_struct(ctx, html_document);
 	doc->ctx = ctx;
-	doc->root = root;
 
 	doc->super.close = (void*)html_close_document;
 	doc->super.count_pages = (void*)html_count_pages;
@@ -67,6 +63,9 @@ html_open_document_with_stream(fz_context *ctx, fz_stream *file)
 	doc->super.run_page_contents = (void*)html_run_page;
 	doc->super.free_page = (void*)html_free_page;
 
+	doc->xml = xml;
+	doc->box = NULL;
+
 	html_layout_document(doc, 400, 600);
 
 	return doc;
diff --git a/source/html/layout.c b/source/html/layout.c
index 8079213d..898e0eb7 100644
--- a/source/html/layout.c
+++ b/source/html/layout.c
@@ -43,10 +43,10 @@ struct box
 	float x, y, w, h;
 	struct box *up, *down, *last, *next;
 	fz_xml *node;
-	struct style style;
+	struct computed_style style;
 };
 
-struct box *new_box(fz_context *ctx, fz_xml *node, struct style *up_style)
+struct box *new_box(fz_context *ctx, fz_xml *node)
 {
 	struct box *box;
 
@@ -63,9 +63,6 @@ struct box *new_box(fz_context *ctx, fz_xml *node, struct style *up_style)
 
 	box->node = node;
 
-	box->style.up = up_style;
-	box->style.count = 0;
-
 	return box;
 }
 
@@ -120,7 +117,7 @@ static void insert_inline_box(fz_context *ctx, struct box *box, struct box *top)
 		}
 		else
 		{
-			struct box *flow = new_box(ctx, NULL, &top->style);
+			struct box *flow = new_box(ctx, NULL);
 			insert_box(ctx, flow, BOX_FLOW, top);
 			insert_box(ctx, box, BOX_INLINE, flow);
 		}
@@ -135,24 +132,24 @@ static void insert_inline_box(fz_context *ctx, struct box *box, struct box *top)
 	}
 }
 
-static void generate_boxes(fz_context *ctx, fz_xml *node, struct box *top, struct rule *rule)
+static void generate_boxes(fz_context *ctx, fz_xml *node, struct box *top, struct rule *rule, struct style *up_style)
 {
-	struct style *up_style;
+	struct style style;
 	struct box *box;
 	int display;
 
-	/* link styles separately because splitting inline blocks breaks the style/box tree symmetry */
-	up_style = &top->style;
-
 	while (node)
 	{
-		box = new_box(ctx, node, up_style);
+		style.up = up_style;
+		style.count = 0;
+
+		box = new_box(ctx, node);
 
 		if (fz_xml_tag(node))
 		{
-			apply_styles(ctx, &box->style, rule, node);
+			apply_styles(ctx, &style, rule, node);
 
-			display = get_style_property_display(&box->style);
+			display = get_style_property_display(&style);
 
 			// TOOD: <br>
 			// TODO: <img>
@@ -174,7 +171,7 @@ static void generate_boxes(fz_context *ctx, fz_xml *node, struct box *top, struc
 				}
 
 				if (fz_xml_down(node))
-					generate_boxes(ctx, fz_xml_down(node), box, rule);
+					generate_boxes(ctx, fz_xml_down(node), box, rule, &style);
 			}
 		}
 		else
@@ -182,44 +179,44 @@ static void generate_boxes(fz_context *ctx, fz_xml *node, struct box *top, struc
 			insert_inline_box(ctx, box, top);
 		}
 
+		compute_style(&box->style, &style);
+
 		node = fz_xml_next(node);
 	}
 }
 
-static void layout_inline(fz_context *ctx, struct box *box, struct box *top)
+static void layout_inline(fz_context *ctx, struct box *box, struct box *top, float em)
 {
-	struct computed_style style;
 	struct box *child;
 	const char *s;
 
-	compute_style(&style, &box->style, top->w);
+	em = from_number(box->style.font_size, em, em);
 
 	box->x = top->x + top->w;
 	box->y = top->y;
-	box->h = style.font_size;
+	box->h = em;
 	box->w = 0;
 
 	s = fz_xml_text(box->node);
 	if (s)
 	{
-		box->w += strlen(s) * 0.5 * style.font_size;
+		box->w += strlen(s) * 0.5 * em;
 	}
 
 	for (child = box->down; child; child = child->next)
 	{
-		layout_inline(ctx, child, top);
+		layout_inline(ctx, child, top, em);
 		if (child->h > box->h)
 			box->h = child->h;
 		top->w += child->w;
 	}
 }
 
-static void layout_flow(fz_context *ctx, struct box *box, struct box *top)
+static void layout_flow(fz_context *ctx, struct box *box, struct box *top, float em)
 {
-	struct computed_style style;
 	struct box *child;
 
-	compute_style(&style, &box->style, top->w);
+	em = from_number(box->style.font_size, em, em);
 
 	box->x = top->x;
 	box->y = top->y + top->h;
@@ -228,35 +225,40 @@ static void layout_flow(fz_context *ctx, struct box *box, struct box *top)
 
 	for (child = box->down; child; child = child->next)
 	{
-		layout_inline(ctx, child, box);
+		layout_inline(ctx, child, box, em);
 		if (child->h > box->h)
 			box->h = child->h;
 		box->w += child->w;
 	}
 }
 
-static void layout_block(fz_context *ctx, struct box *box, struct box *top)
+static void layout_block(fz_context *ctx, struct box *box, struct box *top, float em)
 {
-	struct computed_style style;
 	struct box *child;
+	float margin[4];
 
-	compute_style(&style, &box->style, top->w);
+	em = from_number(box->style.font_size, em, em);
 
-	box->x = top->x + style.margin[LEFT];
-	box->y = top->y + top->h + style.margin[TOP];
-	box->w = top->w - (style.margin[LEFT] + style.margin[RIGHT]);
+	margin[0] = from_number(box->style.margin[0], em, top->w);
+	margin[1] = from_number(box->style.margin[1], em, top->w);
+	margin[2] = from_number(box->style.margin[2], em, top->w);
+	margin[3] = from_number(box->style.margin[3], em, top->w);
+
+	box->x = top->x + margin[LEFT];
+	box->y = top->y + top->h + margin[TOP];
+	box->w = top->w - (margin[LEFT] + margin[RIGHT]);
 	box->h = 0;
 
 	for (child = box->down; child; child = child->next)
 	{
 		if (child->type == BOX_BLOCK)
-			layout_block(ctx, child, box);
+			layout_block(ctx, child, box, em);
 		else if (child->type == BOX_FLOW)
-			layout_flow(ctx, child, box);
+			layout_flow(ctx, child, box, em);
 		box->h += child->h;
 	}
 
-	box->h += style.margin[BOTTOM];
+	box->h += margin[BOTTOM];
 }
 
 static void indent(int level)
@@ -290,6 +292,12 @@ static void print_box(fz_context *ctx, struct box *box, int level)
 	}
 }
 
+void
+html_run_box(fz_context *ctx, struct box *box, fz_device *dev, const fz_matrix *ctm)
+{
+
+}
+
 static char *concat_text(fz_context *ctx, fz_xml *root)
 {
 	fz_xml  *node;
@@ -356,6 +364,7 @@ html_layout_document(html_document *doc, float w, float h)
 	struct rule *css = NULL;
 	struct box *root_box;
 	struct box *win_box;
+	struct style style;
 
 #if 0
 	strcpy(dirname, argv[i]);
@@ -366,18 +375,23 @@ html_layout_document(html_document *doc, float w, float h)
 #endif
 
 	css = fz_parse_css(doc->ctx, NULL, default_css);
-	css = load_css(doc->ctx, css, doc->root);
+	css = load_css(doc->ctx, css, doc->xml);
 
 	print_rules(css);
 
-	root_box = new_box(doc->ctx, NULL, NULL);
-	generate_boxes(doc->ctx, doc->root, root_box, css);
+	style.up = NULL;
+	style.count = 0;
+	root_box = new_box(doc->ctx, NULL);
 
-	win_box = new_box(doc->ctx, NULL, NULL);
+	generate_boxes(doc->ctx, doc->xml, root_box, css, &style);
+
+	win_box = new_box(doc->ctx, NULL);
 	win_box->w = w;
 	win_box->h = 0;
 
-	layout_block(doc->ctx, root_box, win_box);
+	layout_block(doc->ctx, root_box, win_box, 12);
 
 	print_box(doc->ctx, root_box, 0);
+
+	doc->box = root_box;
 }