[project @ 2004-11-20 00:02:56 by bursa]

Improvements to overflow and scrolling: scrollbars now have most of the usual RISC OS behaviour. Better rendering of dotted and dashed borders.

svn path=/import/netsurf/; revision=1363

11 files changed, 471 insertions, 122 deletions

diff --git a/!NetSurf/Resources/de/Messages b/!NetSurf/Resources/de/Messages
index 502eccdc9..3f26a2c47 100644
--- a/!NetSurf/Resources/de/Messages
+++ b/!NetSurf/Resources/de/Messages
@@ -242,6 +242,17 @@ SaveText:Webpage
 SaveObject:Object
 SaveLink:Link
 
+ScrollUp:Click the arrow to scroll up
+ScrollPUp:Click to scroll up one page
+ScrollV:Drag the bar to scroll vertically
+ScrollPDown:Click to scroll down one page
+ScrollDown:Click the arrow to scroll down
+ScrollLeft:Click the arrow to scroll left
+ScrollPLeft:Click to scroll left one page
+ScrollH:Drag the bar to scroll horizontally
+ScrollPRight:Click to scroll right one page
+ScrollRight:Click the arrow to scroll right
+
 # Interactive help
 HelpToolbar0:Schaltet zurück auf die zuvor dargestellte Seite.|MDer Inhalt wird dabei nicht aktualisiert.
 HelpToolbar1:Schaltet vorwärts auf die nächste Seite.|MDer Inhalt wird dabei nicht aktualisiert.
diff --git a/!NetSurf/Resources/en/Messages b/!NetSurf/Resources/en/Messages
index 1b9dde9b1..dd3bb0b80 100644
--- a/!NetSurf/Resources/en/Messages
+++ b/!NetSurf/Resources/en/Messages
@@ -242,6 +242,17 @@ SaveText:Webpage
 SaveObject:Object
 SaveLink:Link
 
+ScrollUp:Click the arrow to scroll up
+ScrollPUp:Click to scroll up one page
+ScrollV:Drag the bar to scroll vertically
+ScrollPDown:Click to scroll down one page
+ScrollDown:Click the arrow to scroll down
+ScrollLeft:Click the arrow to scroll left
+ScrollPLeft:Click to scroll left one page
+ScrollH:Drag the bar to scroll horizontally
+ScrollPRight:Click to scroll right one page
+ScrollRight:Click the arrow to scroll right
+
 # Interactive help
 HelpToolbar0:\Tback button.|M\Straverse back one page in the history tree.|MDoes not resubmit form information.
 HelpToolbar1:\Tforward button.|M\Straverse forward one page in the history tree.|MDoes not resubmit form information.
diff --git a/!NetSurf/Resources/fr/Messages b/!NetSurf/Resources/fr/Messages
index a61cb2194..14c9bb6e4 100644
--- a/!NetSurf/Resources/fr/Messages
+++ b/!NetSurf/Resources/fr/Messages
@@ -242,6 +242,17 @@ SaveText:PageWeb
 SaveObject:Objet
 SaveLink:Lien
 
+ScrollUp:Click the arrow to scroll up
+ScrollPUp:Click to scroll up one page
+ScrollV:Drag the bar to scroll vertically
+ScrollPDown:Click to scroll down one page
+ScrollDown:Click the arrow to scroll down
+ScrollLeft:Click the arrow to scroll left
+ScrollPLeft:Click to scroll left one page
+ScrollH:Drag the bar to scroll horizontally
+ScrollPRight:Click to scroll right one page
+ScrollRight:Click the arrow to scroll right
+
 # Interactive help
 HelpToolbar0:\Tle bouton de retour.|M\Srevenir d'une page en arrière dans l'historique.|MNe renvoie pas l'information de formulaire.
 HelpToolbar1:\Tle bouton d'avance.|M\Savancer d'une page dans l'historique.|MNe renvoie pas l'information de formulaire.
diff --git a/desktop/browser.c b/desktop/browser.c
index 8d589863f..640e2d8ea 100644
--- a/desktop/browser.c
+++ b/desktop/browser.c
@@ -56,6 +56,9 @@ static void browser_window_mouse_click_html(struct browser_window *bw,
 		browser_mouse_click click, int x, int y);
 static void browser_window_mouse_drag_html(struct browser_window *bw,
 		int x, int y);
+static const char *browser_window_scrollbar_click(struct browser_window *bw,
+		browser_mouse_click click, struct box *box,
+		int box_x, int box_y, int x, int y);
 static void browser_radio_set(struct content *content,
 		struct form_control *radio);
 static void browser_redraw_box(struct content *c, struct box *box);
@@ -631,7 +634,9 @@ void browser_window_mouse_click_html(struct browser_window *bw,
 	gui_pointer_shape pointer = GUI_POINTER_DEFAULT;
 	int box_x = 0, box_y = 0;
 	int gadget_box_x = 0, gadget_box_y = 0;
+	int scroll_box_x = 0, scroll_box_y = 0;
 	struct box *gadget_box = 0;
+	struct box *scroll_box = 0;
 	struct content *c = bw->current_content;
 	struct box *box;
 	struct content *content = c;
@@ -681,24 +686,26 @@ void browser_window_mouse_click_html(struct browser_window *bw,
 		if (box->style && box->style->cursor != CSS_CURSOR_UNKNOWN)
 			pointer = get_pointer_shape(box->style->cursor);
 
-		if ((box->type == BOX_BLOCK || box->type == BOX_INLINE_BLOCK ||
-				box->type == BOX_FLOAT_LEFT ||
-				box->type == BOX_FLOAT_RIGHT) &&
-				box->style &&
-				box->style->overflow == CSS_OVERFLOW_SCROLL) {
-			if (box_x + box->padding[LEFT] + box->width < x) {
-				/* vertical scrollbar */
-				bw->drag_type = DRAGGING_VSCROLL;
-				bw->scrolling_box = box;
-				bw->scrolling_last_x = x;
-				bw->scrolling_last_y = y;
-			}
+		if (box->style && box->type != BOX_BR &&
+				box->type != BOX_INLINE &&
+				(box->style->overflow == CSS_OVERFLOW_SCROLL ||
+				 box->style->overflow == CSS_OVERFLOW_AUTO) &&
+				((box_vscrollbar_present(box) &&
+				  box_x + box->scroll_x + box->padding[LEFT] +
+				  box->width < x) ||
+				 (box_hscrollbar_present(box) &&
+				  box_y + box->scroll_y + box->padding[TOP] +
+				  box->height < y))) {
+			scroll_box = box;
+			scroll_box_x = box_x + box->scroll_x;
+			scroll_box_y = box_y + box->scroll_y;
 		}
 	}
 
-	if (bw->drag_type == DRAGGING_VSCROLL ||
-			bw->drag_type == DRAGGING_HSCROLL) {
-		status = messages_get("Scrollbar");
+	if (scroll_box) {
+		status = browser_window_scrollbar_click(bw, click, scroll_box,
+				scroll_box_x, scroll_box_y,
+				x - scroll_box_x, y - scroll_box_y);
 
 	} else if (gadget) {
 		switch (gadget->type) {
@@ -728,7 +735,8 @@ void browser_window_mouse_click_html(struct browser_window *bw,
 			/* drop through */
 		case GADGET_SUBMIT:
 			if (gadget->form) {
-				res = url_join(gadget->form->action, base_url, &url);
+				res = url_join(gadget->form->action, base_url,
+						&url);
 				snprintf(status_buffer, sizeof status_buffer,
 						messages_get("FormSubmit"),
 						(res == URL_FUNC_OK) ? url :
@@ -830,33 +838,166 @@ void browser_window_mouse_click_html(struct browser_window *bw,
 void browser_window_mouse_drag_html(struct browser_window *bw,
 		int x, int y)
 {
-	int scroll_y;
+	int scroll_x, scroll_y;
 	struct box *box;
 
 	if (bw->drag_type == DRAGGING_VSCROLL) {
 		box = bw->scrolling_box;
 		assert(box);
-		if (y == bw->scrolling_last_y)
-			return;
-
-		scroll_y = box->scroll_y + (y - bw->scrolling_last_y);
-		bw->scrolling_last_y = y;
-
+		scroll_y = bw->scrolling_start_scroll_y +
+				(float) (y - bw->scrolling_start_y) /
+				(float) bw->scrolling_well_height *
+				(float) (box->descendant_y1 -
+				box->descendant_y0);
 		if (scroll_y < box->descendant_y0)
 			scroll_y = box->descendant_y0;
 		else if (box->descendant_y1 - box->height < scroll_y)
 			scroll_y = box->descendant_y1 - box->height;
-
 		if (scroll_y == box->scroll_y)
 			return;
 		box->scroll_y = scroll_y;
+		browser_redraw_box(bw->current_content, bw->scrolling_box);
 
+	} else if (bw->drag_type == DRAGGING_HSCROLL) {
+		box = bw->scrolling_box;
+		assert(box);
+		scroll_x = bw->scrolling_start_scroll_x +
+				(float) (x - bw->scrolling_start_x) /
+				(float) bw->scrolling_well_width *
+				(float) (box->descendant_x1 -
+				box->descendant_x0);
+		if (scroll_x < box->descendant_x0)
+			scroll_x = box->descendant_x0;
+		else if (box->descendant_x1 - box->width < scroll_x)
+			scroll_x = box->descendant_x1 - box->width;
+		if (scroll_x == box->scroll_x)
+			return;
+		box->scroll_x = scroll_x;
 		browser_redraw_box(bw->current_content, bw->scrolling_box);
 	}
 }
 
 
 /**
+ * Handle mouse clicks in a box scrollbar.
+ *
+ * \param  bw     browser window
+ * \param  click  type of mouse click
+ * \param  box    scrolling box
+ * \param  box_x  position of box in global document coordinates
+ * \param  box_y  position of box in global document coordinates
+ * \param  x      coordinate of click relative to box position
+ * \param  y      coordinate of click relative to box position
+ * \return status bar message
+ */
+
+const char *browser_window_scrollbar_click(struct browser_window *bw,
+		browser_mouse_click click, struct box *box,
+		int box_x, int box_y, int x, int y)
+{
+	const int w = SCROLLBAR_WIDTH;
+	bool vscroll, hscroll;
+	int well_height, bar_top, bar_height;
+	int well_width, bar_left, bar_width;
+	const char *status = 0;
+	bool vert;
+	int z, scroll, bar_start, bar_size, well_size, page;
+
+	box_scrollbar_dimensions(box,
+			box->padding[LEFT] + box->width + box->padding[RIGHT],
+			box->padding[TOP] + box->height + box->padding[BOTTOM],
+			w,
+			&vscroll, &hscroll,
+			&well_height, &bar_top, &bar_height,
+			&well_width, &bar_left, &bar_width);
+
+	/* store some data for scroll drags */
+	bw->scrolling_box = box;
+	bw->scrolling_start_x = box_x + x;
+	bw->scrolling_start_y = box_y + y;
+	bw->scrolling_start_scroll_x = box->scroll_x;
+	bw->scrolling_start_scroll_y = box->scroll_y;
+	bw->scrolling_well_width = well_width;
+	bw->scrolling_well_height = well_height;
+
+	/* determine which scrollbar was clicked */
+	if (box_vscrollbar_present(box) &&
+			box->padding[LEFT] + box->width < x) {
+		vert = true;
+		z = y;
+		scroll = box->scroll_y;
+		well_size = well_height;
+		bar_start = bar_top;
+		bar_size = bar_height;
+		page = box->height;
+	} else {
+		vert = false;
+		z = x;
+		scroll = box->scroll_x;
+		well_size = well_width;
+		bar_start = bar_left;
+		bar_size = bar_width;
+		page = box->width;
+	}
+
+	/* find icon in scrollbar and calculate scroll */
+	if (z < w) {
+		status = messages_get(vert ? "ScrollUp" : "ScrollLeft");
+		if (click == BROWSER_MOUSE_CLICK_1)
+			scroll -= 16;
+		else if (click == BROWSER_MOUSE_CLICK_2)
+			scroll += 16;
+	} else if (z < w + bar_start + w / 4) {
+		status = messages_get(vert ? "ScrollPUp" : "ScrollPLeft");
+		if (click == BROWSER_MOUSE_CLICK_1)
+			scroll -= page;
+		else if (click == BROWSER_MOUSE_CLICK_2)
+			scroll += page;
+	} else if (z < w + bar_start + bar_size - w / 4) {
+		status = messages_get(vert ? "ScrollV" : "ScrollH");
+		if (click == BROWSER_MOUSE_CLICK_1)
+			bw->drag_type = vert ? DRAGGING_VSCROLL :
+					DRAGGING_HSCROLL;
+	} else if (z < w + well_size) {
+		status = messages_get(vert ? "ScrollPDown" : "ScrollPRight");
+		if (click == BROWSER_MOUSE_CLICK_1)
+			scroll += page;
+		else if (click == BROWSER_MOUSE_CLICK_2)
+			scroll -= page;
+	} else {
+		status = messages_get(vert ? "ScrollDown" : "ScrollRight");
+		if (click == BROWSER_MOUSE_CLICK_1)
+			scroll += 16;
+		else if (click == BROWSER_MOUSE_CLICK_2)
+			scroll -= 16;
+	}
+
+	/* update box and redraw */
+	if (vert) {
+		if (scroll < box->descendant_y0)
+			scroll = box->descendant_y0;
+		else if (box->descendant_y1 - box->height < scroll)
+			scroll = box->descendant_y1 - box->height;
+		if (scroll != box->scroll_y) {
+			box->scroll_y = scroll;
+			browser_redraw_box(bw->current_content, box);
+		}
+	} else {
+		if (scroll < box->descendant_x0)
+			scroll = box->descendant_x0;
+		else if (box->descendant_x1 - box->width < scroll)
+			scroll = box->descendant_x1 - box->width;
+		if (scroll != box->scroll_x) {
+			box->scroll_x = scroll;
+			browser_redraw_box(bw->current_content, box);
+		}
+	}
+
+	return status;
+}
+
+
+/**
  * Set a radio form control and clear the others in the group.
  *
  * \param  content  content containing the form, of type CONTENT_TYPE
@@ -868,8 +1009,9 @@ void browser_radio_set(struct content *content,
 {
 	struct form_control *control;
 
-	/* some sanity checking */
-	if (content == NULL || radio == NULL || radio->form == NULL)
+	assert(content);
+	assert(radio);
+	if (!radio->form)
 		return;
 
 	if (radio->selected)
diff --git a/desktop/browser.h b/desktop/browser.h
index c77a5d13f..750cf329b 100644
--- a/desktop/browser.h
+++ b/desktop/browser.h
@@ -58,9 +58,15 @@ struct browser_window {
 
 	/** Box currently being scrolled, or 0. */
 	struct box *scrolling_box;
-	/** Mouse position last scroll movement. */
-	int scrolling_last_x;
-	int scrolling_last_y;
+	/** Mouse position at start of current scroll drag. */
+	int scrolling_start_x;
+	int scrolling_start_y;
+	/** Scroll offsets at start of current scroll draw. */
+	int scrolling_start_scroll_x;
+	int scrolling_start_scroll_y;
+	/** Well dimensions for current scroll drag. */
+	int scrolling_well_width;
+	int scrolling_well_height;
 
 	/** Referer for current fetch, or 0. */
 	char *referer;
diff --git a/desktop/plotters.h b/desktop/plotters.h
index 0be1213a6..60465f3e8 100644
--- a/desktop/plotters.h
+++ b/desktop/plotters.h
@@ -24,7 +24,7 @@ struct font_data;
 struct plotter_table {

 	bool (*clg)(colour c);

 	bool (*rectangle)(int x0, int y0, int width, int height,

-			colour c, bool dotted);

+			int line_width, colour c, bool dotted, bool dashed);

 	bool (*line)(int x0, int y0, int x1, int y1, int width,

 			colour c, bool dotted, bool dashed);

 	bool (*polygon)(int *p, unsigned int n, colour fill);

diff --git a/render/box.c b/render/box.c
index d9fcb6233..cdca6c66f 100644
--- a/render/box.c
+++ b/render/box.c
@@ -3064,8 +3064,7 @@ siblings:
 
 bool box_contains_point(struct box *box, int x, int y)
 {
-	if (box->style && (box->style->overflow == CSS_OVERFLOW_HIDDEN ||
-			box->style->overflow == CSS_OVERFLOW_SCROLL)) {
+	if (box->style && box->style->overflow != CSS_OVERFLOW_VISIBLE) {
 		if (box->x <= x &&
 				x < box->x + box->padding[LEFT] + box->width +
 				box->padding[RIGHT] &&
diff --git a/render/box.h b/render/box.h
index c50c7ef00..b401799fa 100644
--- a/render/box.h
+++ b/render/box.h
@@ -249,4 +249,14 @@ struct box *box_at_point(struct box *box, int x, int y,
 struct box *box_object_at_point(struct content *c, int x, int y);
 struct box *box_find_by_id(struct box *box, const char *id);
 
+bool box_vscrollbar_present(const struct box *box);
+bool box_hscrollbar_present(const struct box *box);
+void box_scrollbar_dimensions(const struct box *box,
+		int padding_width, int padding_height, int w,
+		bool *vscroll, bool *hscroll,
+		int *well_height,
+		int *bar_top, int *bar_height,
+		int *well_width,
+		int *bar_left, int *bar_width);
+
 #endif
diff --git a/render/html_redraw.c b/render/html_redraw.c
index 28796d1a0..a46edbd47 100644
--- a/render/html_redraw.c
+++ b/render/html_redraw.c
@@ -43,7 +43,8 @@ static bool html_redraw_file(int x, int y, int width, int height,
 static bool html_redraw_background(int x, int y,
 		struct box *box, float scale, colour background_colour);
 static bool html_redraw_scrollbars(struct box *box, float scale,
-		int x, int y, int padding_width, int padding_height);
+		int x, int y, int padding_width, int padding_height,
+		colour background_colour);
 
 bool html_redraw_debug = false;
 
@@ -161,10 +162,10 @@ bool html_redraw_box(struct box *box,
 	/* dotted debug outlines */
 	if (html_redraw_debug) {
 		if (!plot.rectangle(x, y, padding_width, padding_height,
-				0x0000ff, true))
+				1, 0x0000ff, true, false))
 			return false;
 		if (!plot.rectangle(x + padding_left, y + padding_top,
-				width, height, 0xff0000, true))
+				width, height, 1, 0xff0000, true, false))
 			return false;
 		if (!plot.rectangle(x - (box->border[LEFT] +
 				box->margin[LEFT]) * scale,
@@ -176,7 +177,7 @@ bool html_redraw_box(struct box *box,
 				padding_height + (box->border[TOP] +
 				box->margin[TOP] + box->border[BOTTOM] +
 				box->margin[BOTTOM]) * scale,
-				0x00ffff, true))
+				1, 0x00ffff, true, false))
 			return false;
 	}
 
@@ -259,14 +260,6 @@ bool html_redraw_box(struct box *box,
 			if (!plot.clip(x0, y0, x1, y1))
 				return false;
 		}
-
-		/* scrollbars */
-		if (box->style->overflow == CSS_OVERFLOW_SCROLL) {
-			if (!html_redraw_scrollbars(box, scale, x, y,
-					padding_width, padding_height))
-				return false;
-		}
-
 	}
 
 	if (box->object) {
@@ -350,6 +343,15 @@ bool html_redraw_box(struct box *box,
 				return false;
 	}
 
+	/* scrollbars */
+	if (box->style && box->type != BOX_BR && box->type != BOX_INLINE &&
+			(box->style->overflow == CSS_OVERFLOW_SCROLL ||
+			box->style->overflow == CSS_OVERFLOW_AUTO))
+		if (!html_redraw_scrollbars(box, scale, x, y,
+				padding_width, padding_height,
+				current_background_color))
+			return false;
+
 	if (box->type == BOX_BLOCK || box->type == BOX_INLINE_BLOCK ||
 			box->type == BOX_TABLE_CELL || box->object)
 		if (!plot.clip(clip_x0, clip_y0, clip_x1, clip_y1))
@@ -750,27 +752,186 @@ bool html_redraw_background(int x, int y,
  */
 
 bool html_redraw_scrollbars(struct box *box, float scale,
-		int x, int y, int padding_width, int padding_height)
+		int x, int y, int padding_width, int padding_height,
+		colour background_colour)
 {
-	int w = SCROLLBAR_WIDTH * scale;
+	const int w = SCROLLBAR_WIDTH * scale;
+	bool vscroll, hscroll;
+	int well_height, bar_top, bar_height;
+	int well_width, bar_left, bar_width;
+	const colour vcolour = box->style->border[RIGHT].color;
+	const colour hcolour = box->style->border[BOTTOM].color;
+
+	box_scrollbar_dimensions(box, padding_width, padding_height, w,
+			&vscroll, &hscroll,
+			&well_height, &bar_top, &bar_height,
+			&well_width, &bar_left, &bar_width);
+
+#define TRIANGLE(x0, y0, x1, y1, x2, y2, c) \
+	if (!plot.line(x0, y0, x1, y1, scale, c, false, false))	\
+		return false;						\
+	if (!plot.line(x0, y0, x2, y2, scale, c, false, false))	\
+		return false;						\
+	if (!plot.line(x1, y1, x2, y2, scale, c, false, false))	\
+		return false;
 
-	/* vertical scrollbar */
-	if (box->descendant_y0 < box->descendant_y1) {
-		int bar_top = (float) padding_height * (float) box->scroll_y /
-				(float) (box->descendant_y1 -
-				box->descendant_y0);
-		int bar_height = (float) padding_height * (float) box->height /
-				(float) (box->descendant_y1 -
-				box->descendant_y0);
+	/* fill scrollbar well(s) with background colour */
+	if (vscroll)
 		if (!plot.fill(x + padding_width - w, y,
 				x + padding_width, y + padding_height,
-				0x777777))
+				background_colour))
+			return false;
+	if (hscroll)
+		if (!plot.fill(x, y + padding_height - w,
+				x + padding_width, y + padding_height,
+				background_colour))
 			return false;
-		if (!plot.fill(x + padding_width - w + 4, y + bar_top,
-				x + padding_width - 4, y + bar_top + bar_height,
-				0xbbbbbb))
+
+	/* vertical scrollbar */
+	if (vscroll) {
+		/* left line */
+		if (!plot.line(x + padding_width - w, y,
+				x + padding_width - w, y + padding_height,
+				scale, vcolour, false, false))
+			return false;
+		/* up arrow */
+		TRIANGLE(x + padding_width - w / 2, y + w / 4,
+				x + padding_width - w * 3 / 4, y + w * 3 / 4,
+				x + padding_width - w / 4, y + w * 3 / 4,
+				vcolour);
+		/* separator */
+		if (!plot.line(x + padding_width - w, y + w,
+				x + padding_width, y + w,
+				scale, vcolour, false, false))
+			return false;
+		/* bar */
+		if (!plot.rectangle(x + padding_width - w * 3 / 4,
+				y + w + bar_top + w / 4,
+				w / 2, bar_height - w / 2,
+				scale, vcolour, false, false))
+			return false;
+		/* separator */
+		if (!plot.line(x + padding_width - w, y + w + well_height,
+				x + padding_width, y + w + well_height,
+				scale, vcolour, false, false))
+			return false;
+		/* down arrow */
+		TRIANGLE(x + padding_width - w / 2,
+				y + w + well_height + w * 3 / 4,
+				x + padding_width - w * 3 / 4,
+				y + w + well_height + w / 4,
+				x + padding_width - w / 4,
+				y + w + well_height + w / 4,
+				vcolour);
+	}
+
+	/* horizontal scrollbar */
+	if (hscroll) {
+		/* top line */
+		if (!plot.line(x, y + padding_height - w,
+				x + well_width + w + w, y + padding_height - w,
+				scale, hcolour, false, false))
+			return false;
+		/* left arrow */
+		TRIANGLE(x + w / 4, y + padding_height - w / 2,
+				x + w * 3 / 4, y + padding_height - w * 3 / 4,
+				x + w * 3 / 4, y + padding_height - w / 4,
+				hcolour);
+		/* separator */
+		if (!plot.line(x + w, y + padding_height - w,
+				x + w, y + padding_height,
+				scale, hcolour, false, false))
 			return false;
+		/* bar */
+		if (!plot.rectangle(x + w + bar_left + w / 4,
+				y + padding_height - w * 3 / 4,
+				bar_width - w / 2, w / 2,
+				scale, hcolour, false, false))
+			return false;
+		/* separator */
+		if (!plot.line(x + w + well_width, y + padding_height - w,
+				x + w + well_width, y + padding_height,
+				scale, hcolour, false, false))
+			return false;
+		/* right arrow */
+		TRIANGLE(x + w + well_width + w * 3 / 4,
+				y + padding_height - w / 2,
+				x + w + well_width + w / 4,
+				y + padding_height - w * 3 / 4,
+				x + w + well_width + w / 4,
+				y + padding_height - w / 4,
+				hcolour);
 	}
 
 	return true;
 }
+
+
+/**
+ * Determine if a box has a vertical scrollbar.
+ *
+ * \param  box  scrolling box
+ * \return the box has a vertical scrollbar
+ */
+
+bool box_vscrollbar_present(const struct box * const box)
+{
+	return box->descendant_y0 < -box->border[TOP] ||
+			box->padding[TOP] + box->height + box->padding[BOTTOM] +
+			box->border[BOTTOM] < box->descendant_y1;
+}
+
+
+/**
+ * Determine if a box has a horizontal scrollbar.
+ *
+ * \param  box  scrolling box
+ * \return the box has a horizontal scrollbar
+ */
+
+bool box_hscrollbar_present(const struct box * const box)
+{
+	return box->descendant_x0 < -box->border[LEFT] ||
+			box->padding[LEFT] + box->width + box->padding[RIGHT] +
+			box->border[RIGHT] < box->descendant_x1;
+}
+
+
+/**
+ * Calculate scrollbar dimensions and positions for a box.
+ *
+ * \param  box             scrolling box
+ * \param  padding_width   scaled width of padding box
+ * \param  padding_height  scaled height of padding box
+ * \param  w               scaled scrollbar width
+ * \param  vscroll         updated to vertical scrollbar present
+ * \param  hscroll         updated to horizontal scrollbar present
+ * \param  well_height     updated to vertical well height
+ * \param  bar_top         updated to top position of vertical scrollbar
+ * \param  bar_height      updated to height of vertical scrollbar
+ * \param  well_width      updated to horizontal well width
+ * \param  bar_left        updated to left position of horizontal scrollbar
+ * \param  bar_width       updated to width of horizontal scrollbar
+ */
+
+void box_scrollbar_dimensions(const struct box * const box,
+		const int padding_width, const int padding_height, const int w,
+		bool * const vscroll, bool * const hscroll,
+		int * const well_height,
+		int * const bar_top, int * const bar_height,
+		int * const well_width,
+		int * const bar_left, int * const bar_width)
+{
+	*vscroll = box_vscrollbar_present(box);
+	*hscroll = box_hscrollbar_present(box);
+	*well_height = padding_height - w - w;
+	*bar_top = (float) *well_height * (float) box->scroll_y /
+			(float) (box->descendant_y1 - box->descendant_y0);
+	*bar_height = (float) *well_height * (float) box->height /
+			(float) (box->descendant_y1 - box->descendant_y0);
+	*well_width = padding_width - w - w - (*vscroll ? w : 0);
+	*bar_left = (float) *well_width * (float) box->scroll_x /
+			(float) (box->descendant_x1 - box->descendant_x0);
+	*bar_width = (float) *well_width * (float) box->width /
+			(float) (box->descendant_x1 - box->descendant_x0);
+}
diff --git a/render/layout.c b/render/layout.c
index 253ce648a..96255b540 100644
--- a/render/layout.c
+++ b/render/layout.c
@@ -355,10 +355,12 @@ void layout_block_find_dimensions(int available_width, struct box *box)
 	box->width = layout_solve_width(available_width, width, margin,
 			padding, border);
 
-	if (style->overflow == CSS_OVERFLOW_SCROLL) {
-		/* make space for vertical scrollbar */
+	if (style->overflow == CSS_OVERFLOW_SCROLL ||
+			style->overflow == CSS_OVERFLOW_AUTO) {
+		/* make space for scrollbars */
 		box->width -= SCROLLBAR_WIDTH;
 		box->padding[RIGHT] += SCROLLBAR_WIDTH;
+		box->padding[BOTTOM] += SCROLLBAR_WIDTH;
 	}
 
 	if (box->object && box->object->type == CONTENT_HTML &&
@@ -423,7 +425,8 @@ int layout_solve_width(int available_width, int width,
 void layout_float_find_dimensions(int available_width,
 		struct css_style *style, struct box *box)
 {
-	int scrollbar_width = style->overflow == CSS_OVERFLOW_SCROLL ?
+	int scrollbar_width = (style->overflow == CSS_OVERFLOW_SCROLL ||
+			style->overflow == CSS_OVERFLOW_AUTO) ?
 			SCROLLBAR_WIDTH : 0;
 
 	layout_find_dimensions(available_width, style,
@@ -461,6 +464,7 @@ void layout_float_find_dimensions(int available_width,
 	}
 
 	box->padding[RIGHT] += scrollbar_width;
+	box->padding[BOTTOM] += scrollbar_width;
 
 	if (box->object) {
 		/* floating replaced element, see 10.3.6 and 10.6.2 */
diff --git a/riscos/plotters.c b/riscos/plotters.c
index 33a618cac..e25c5ddcc 100644
--- a/riscos/plotters.c
+++ b/riscos/plotters.c
@@ -22,9 +22,11 @@
 

 static bool ro_plot_clg(colour c);

 static bool ro_plot_rectangle(int x0, int y0, int width, int height,

-		colour c, bool dotted);

+		int line_width, colour c, bool dotted, bool dashed);

 static bool ro_plot_line(int x0, int y0, int x1, int y1, int width,

 		colour c, bool dotted, bool dashed);

+static bool ro_plot_path(const draw_path * const path, int width,

+		colour c, bool dotted, bool dashed);

 static bool ro_plot_polygon(int *p, unsigned int n, colour fill);

 static bool ro_plot_fill(int x0, int y0, int x1, int y1, colour c);

 static bool ro_plot_clip(int clip_x0, int clip_y0,

@@ -88,82 +90,74 @@ bool ro_plot_clg(colour c)
 

 

 bool ro_plot_rectangle(int x0, int y0, int width, int height,

-		colour c, bool dotted)

+		int line_width, colour c, bool dotted, bool dashed)

 {

-	os_plot_code plot_code = (dotted ? os_PLOT_DOTTED : os_PLOT_SOLID) |

-			os_PLOT_BY;

-	os_error *error;

+	const int path[] = { draw_MOVE_TO,

+			(ro_plot_origin_x + x0 * 2) * 256,

+			(ro_plot_origin_y - y0 * 2 - 1) * 256,

+			draw_LINE_TO,

+			(ro_plot_origin_x + (x0 + width) * 2) * 256,

+			(ro_plot_origin_y - y0 * 2 - 1) * 256,

+			draw_LINE_TO,

+			(ro_plot_origin_x + (x0 + width) * 2) * 256,

+			(ro_plot_origin_y - (y0 + height) * 2 - 1) * 256,

+			draw_LINE_TO,

+			(ro_plot_origin_x + x0 * 2) * 256,

+			(ro_plot_origin_y - (y0 + height) * 2 - 1) * 256,

+			draw_CLOSE_LINE,

+			(ro_plot_origin_x + x0 * 2) * 256,

+			(ro_plot_origin_y - y0 * 2 - 1) * 256,

+			draw_END_PATH };

+

+	return ro_plot_path((const draw_path *) path, line_width, c,

+			dotted, dashed);

+}

 

-	error = xcolourtrans_set_gcol(c << 8, 0, os_ACTION_OVERWRITE, 0, 0);

-	if (error) {

-		LOG(("xcolourtrans_set_gcol: 0x%x: %s",

-				error->errnum, error->errmess));

-		return false;

-	}

-	error = xos_plot(os_MOVE_TO,

-			ro_plot_origin_x + x0 * 2,

-			ro_plot_origin_y - y0 * 2);

-	if (error) {

-		LOG(("xos_plot: 0x%x: %s", error->errnum, error->errmess));

-		return false;

-	}

-	error = xos_plot(plot_code, width * 2, 0);

-	if (error) {

-		LOG(("xos_plot: 0x%x: %s", error->errnum, error->errmess));

-		return false;

-	}

-	error = xos_plot(plot_code, 0, -height * 2);

-	if (error) {

-		LOG(("xos_plot: 0x%x: %s", error->errnum, error->errmess));

-		return false;

-	}

-	error = xos_plot(plot_code, -width * 2, 0);

-	if (error) {

-		LOG(("xos_plot: 0x%x: %s", error->errnum, error->errmess));

-		return false;

-	}

-	error = xos_plot(plot_code, 0, height * 2);

-	if (error) {

-		LOG(("xos_plot: 0x%x: %s", error->errnum, error->errmess));

-		return false;

-	}

 

-	return true;

+bool ro_plot_line(int x0, int y0, int x1, int y1, int width,

+		colour c, bool dotted, bool dashed)

+{

+	const int path[] = { draw_MOVE_TO,

+			(ro_plot_origin_x + x0 * 2) * 256,

+			(ro_plot_origin_y - y0 * 2 - 1) * 256,

+			draw_LINE_TO,

+			(ro_plot_origin_x + x1 * 2) * 256,

+			(ro_plot_origin_y - y1 * 2 - 1) * 256,

+			draw_END_PATH };

+

+	return ro_plot_path((const draw_path *) path, width, c, dotted, dashed);

 }

 

 

-static int path[] = { draw_MOVE_TO, 0, 0, draw_LINE_TO, 0, 0,

-	draw_END_PATH, 0 };

-static const draw_line_style line_style = { draw_JOIN_MITRED,

-	draw_CAP_BUTT, draw_CAP_BUTT, 0, 0x7fffffff,

-	0, 0, 0, 0 };

-static const int dash_pattern_dotted[] = { 0, 1, 512 };

-static const int dash_pattern_dashed[] = { 0, 1, 2048 };

-

-bool ro_plot_line(int x0, int y0, int x1, int y1, int width,

+bool ro_plot_path(const draw_path * const path, int width,

 		colour c, bool dotted, bool dashed)

 {

-	const draw_dash_pattern *dash_pattern;

+	static const draw_line_style line_style = { draw_JOIN_MITRED,

+			draw_CAP_BUTT, draw_CAP_BUTT, 0, 0x7fffffff,

+			0, 0, 0, 0 };

+	draw_dash_pattern dash = { 0, 1, { 512 } };

+	const draw_dash_pattern *dash_pattern = 0;

 	os_error *error;

 

-	if (dotted)

-		dash_pattern = (const draw_dash_pattern *) &dash_pattern_dotted;

-	else if (dashed)

-		dash_pattern = (const draw_dash_pattern *) &dash_pattern_dashed;

-	else

-		dash_pattern = NULL;

-

-	path[1] = (ro_plot_origin_x + x0 * 2) * 256;

-	path[2] = (ro_plot_origin_y - y0 * 2 - 1) * 256;

-	path[4] = (ro_plot_origin_x + x1 * 2) * 256;

-	path[5] = (ro_plot_origin_y - y1 * 2 - 1) * 256;

+	if (width < 1)

+		width = 1;

+

+	if (dotted) {

+		dash.elements[0] = 512 * width;

+		dash_pattern = &dash;

+	} else if (dashed) {

+		dash.elements[0] = 1536 * width;

+		dash_pattern = &dash;

+	}

+

 	error = xcolourtrans_set_gcol(c << 8, 0, os_ACTION_OVERWRITE, 0, 0);

 	if (error) {

 		LOG(("xcolourtrans_set_gcol: 0x%x: %s",

 				error->errnum, error->errmess));

 		return false;

 	}

-	error = xdraw_stroke((draw_path *) path, 0, 0, 0, width * 2 * 256,

+

+	error = xdraw_stroke(path, 0, 0, 0, width * 2 * 256,

 			&line_style, dash_pattern);

 	if (error) {

 		LOG(("xdraw_stroke: 0x%x: %s",