Add concept of browser scroll offset saving in local history

desktop/browser.c

@@ -887,7 +887,7 @@ nserror browser_window_create(enum browser_window_create_flags flags,
 	}
 
 	if (url != NULL) {
-		enum browser_window_nav_flags nav_flags = BW_NAVIGATE_NONE;
+		enum browser_window_nav_flags nav_flags = BW_NAVIGATE_NO_TERMINAL_HISTORY_UPDATE;
 		if (flags & BW_CREATE_UNVERIFIABLE)
 			nav_flags |= BW_NAVIGATE_UNVERIFIABLE;
 		if (flags & BW_CREATE_HISTORY)
@@ -1355,6 +1355,7 @@ browser_window_callback(hlcache_handle *c,
 {
 	struct browser_window *bw = pw;
 	nserror res = NSERROR_OK;
+	float sx, sy;
 
 	switch (event->type) {
 	case CONTENT_MSG_DOWNLOAD:
@@ -1485,6 +1486,19 @@ browser_window_callback(hlcache_handle *c,
 		browser_window_stop_throbber(bw);
 		browser_window_update_favicon(c, bw, NULL);
 
+		if (browser_window_history_get_scroll(bw, &sx, &sy) == NSERROR_OK) {
+			int scrollx = (int)((float)content_get_width(bw->current_content) * sx);
+			int scrolly = (int)((float)content_get_height(bw->current_content) * sy);
+			struct rect rect;
+			rect.x0 = rect.x1 = scrollx;
+			rect.y0 = rect.y1 = scrolly;
+			if (browser_window_set_scroll(bw, &rect) != NSERROR_OK) {
+				NSLOG(netsurf, WARNING,
+				      "Unable to set browser scroll offsets to %d by %d",
+				      scrollx, scrolly);
+			}
+		}
+
 		browser_window_history_update(bw, c);
 		hotlist_update_url(hlcache_handle_get_url(c));
 
@@ -2014,6 +2028,20 @@ browser_window_navigate(struct browser_window *bw,
 
 	NSLOG(netsurf, INFO, "bw %p, url %s", bw, nsurl_access(url));
 
+	/* If we're navigating and we have a history entry and a content
+	 * then update the history entry before we navigate to save our
+	 * current state.  However since history navigation pre-moves
+	 * the history state, we ensure that we only do this if we've not
+	 * been suppressed.  In the suppressed case, the history code
+	 * updates the history itself before navigating.
+	 */
+	if (bw->current_content != NULL &&
+	    bw->history != NULL &&
+	    bw->history->current != NULL &&
+	    !(flags & BW_NAVIGATE_NO_TERMINAL_HISTORY_UPDATE)) {
+		browser_window_history_update(bw, bw->current_content);
+	}
+
 	/* don't allow massively nested framesets */
 	for (cur = bw; cur->parent; cur = cur->parent) {
 		depth++;

desktop/browser_history.c

@@ -32,6 +32,7 @@
 #include "utils/utils.h"
 #include "netsurf/layout.h"
 #include "netsurf/content.h"
+#include "netsurf/window.h"
 #include "content/hlcache.h"
 #include "content/urldb.h"
 #include "netsurf/bitmap.h"
@@ -377,6 +378,8 @@ browser_window_history_add(struct browser_window *bw,
 	entry->page.url = nsurl_ref(hlcache_handle_get_url(content));
 	entry->page.frag_id = frag_id ? lwc_string_ref(frag_id) : NULL;
 	entry->page.title = title;
+	entry->page.scroll_x = 0.0f;
+	entry->page.scroll_y = 0.0f;
 
 	/* create thumbnail for localhistory view */
 	NSLOG(netsurf, DEBUG,
@@ -424,6 +427,7 @@ nserror browser_window_history_update(struct browser_window *bw,
 {
 	struct history *history;
 	char *title;
+	int sx, sy;
 
 	assert(bw != NULL);
 
@@ -442,7 +446,7 @@ nserror browser_window_history_update(struct browser_window *bw,
 	if (title == NULL) {
 		return NSERROR_NOMEM;
 	}
-
+	NSLOG(netsurf, INFO, "Updating history entry for %s", title);
 	free(history->current->page.title);
 	history->current->page.title = title;
 
@@ -450,10 +454,41 @@ nserror browser_window_history_update(struct browser_window *bw,
 		guit->bitmap->render(history->current->page.bitmap, content);
 	}
 
+	if (guit->window->get_scroll(bw->window, &sx, &sy)) {
+		/* Successfully got scroll offsets, update the entry */
+		history->current->page.scroll_x = \
+			(float)sx / (float)content_get_width(content);
+		history->current->page.scroll_y = \
+			(float)sy / (float)content_get_height(content);
+		NSLOG(netsurf, INFO, "Updated scroll offsets to %g by %g",
+		      history->current->page.scroll_x,
+		      history->current->page.scroll_y);
+	}
 	return NSERROR_OK;
 }
 
+/* exported interface documented in desktop/browser_private.h */
+nserror
+browser_window_history_get_scroll(struct browser_window *bw,
+				  float *sx, float *sy)
+{
+	struct history *history;
 
+	assert(bw != NULL);
+
+	history = bw->history;
+
+	if (!history ||
+	    !history->current ||
+	    !history->current->page.bitmap) {
+		return NSERROR_INVALID;
+	}
+
+	*sx = history->current->page.scroll_x;
+	*sy = history->current->page.scroll_y;
+
+	return NSERROR_OK;
+}
 
 /* exported interface documented in desktop/browser_history.h */
 void browser_window_history_destroy(struct browser_window *bw)
@@ -565,9 +600,11 @@ nserror browser_window_history_go(struct browser_window *bw,
 				url, NULL, bw, NULL);
 		history->current = current;
 	} else {
+		browser_window_history_update(bw, bw->current_content);
 		history->current = entry;
 		error = browser_window_navigate(bw, url, NULL,
-				BW_NAVIGATE_NONE, NULL, NULL, NULL);
+				BW_NAVIGATE_NO_TERMINAL_HISTORY_UPDATE,
+				NULL, NULL, NULL);
 	}
 
 	nsurl_unref(url);

desktop/browser_private.h

@@ -46,6 +46,8 @@ struct history_page {
 	lwc_string *frag_id; /** Fragment identifier, or NULL. */
 	char *title;  /**< Page title, never NULL. */
 	struct bitmap *bitmap;  /**< Thumbnail bitmap, or NULL. */
+	float scroll_x; /**< Scroll X offset when visited */
+	float scroll_y; /**< Scroll Y offset when visited */
 };
 
 /**
@@ -325,7 +327,7 @@ nserror browser_window_history_add(struct browser_window *bw,
 		struct hlcache_handle *content, lwc_string *frag_id);
 
 /**
- * Update the thumbnail for the current entry.
+ * Update the thumbnail and scroll offsets for the current entry.
  *
  * \param bw The browser window to update the history within.
  * \param content content for current entry
@@ -334,6 +336,17 @@ nserror browser_window_history_add(struct browser_window *bw,
 nserror browser_window_history_update(struct browser_window *bw,
 		struct hlcache_handle *content);
 
+/**
+ * Retrieve the stored scroll offsets for the current history entry
+ *
+ * \param bw The browser window to retrieve scroll offsets for.
+ * \param sx Pointer to a float for the X scroll offset
+ * \param sy Pointer to a float for the Y scroll offset
+ * \return NSERROR_OK or error code on failure.
+ */
+nserror browser_window_history_get_scroll(struct browser_window *bw,
+					  float *sx, float *sy);
+
 /**
  * Free a history structure.
  *

include/netsurf/browser_window.h

@@ -116,7 +116,10 @@ enum browser_window_nav_flags {
 	 *    A transaction is unverifiable if the user does not
 	 *    have that option.
 	 */
-	BW_NAVIGATE_UNVERIFIABLE	= (1 << 2)
+	BW_NAVIGATE_UNVERIFIABLE	= (1 << 2),
+
+	/** suppress initial history updates (used by back/fwd/etc) */
+	BW_NAVIGATE_NO_TERMINAL_HISTORY_UPDATE = (1 << 3)
 };
 
 /**