scroll_engine: Major rework to support pixel-based scrolling and scroll callbacks.

Much of the scrolling work is moved from lcd-bitmap-common to lcd-scroll.c,
a small scroll callback routine remains. This callback can potentially be
overridden by more extensive scrollers.

The callback also gets fed with pixel-based scrolling information, which
finally removes the strict line-based nature of the scroll engine. Along with
this is the change from scroll_stop_viewport_line() to scroll_stop_viewport_rect()
which works on a pixel-based rectangle instead of lines.

The ultimate goal is to move most of the scroll work to apps, which can
much better decide which line decorations to apply etc. This work is laying
the ground work.

Change-Id: I3b2885cf7d8696ddd9253d5a9a73318d3d42831a

3 files changed, 10 insertions, 5 deletions

diff --git a/apps/gui/skin_engine/skin_render.c b/apps/gui/skin_engine/skin_render.c
index 67f1f0f448..28483cbc49 100644
--- a/apps/gui/skin_engine/skin_render.c
+++ b/apps/gui/skin_engine/skin_render.c
@@ -779,7 +779,9 @@ void skin_render_viewport(struct skin_element* viewport, struct gui_wps *gwps,
         if (refresh_type && needs_update)
         {
             if (info.force_redraw)
-                display->scroll_stop_viewport_line(&skin_viewport->vp, info.line_number);
+                display->scroll_stop_viewport_rect(&skin_viewport->vp,
+                    0, info.line_number*display->getcharheight(),
+                    skin_viewport->vp.width, display->getcharheight());
             write_line(display, align, info.line_number,
                     info.line_scrolls, info.text_style);
         }
@@ -967,8 +969,11 @@ void skin_render_playlistviewer(struct playlistviewer* viewer,
         /* only update if the line needs to be, and there is something to write */
         if (refresh_type && needs_update)
         {
+            struct viewport *vp = SKINOFFSETTOPTR(skin_buffer, viewer->vp);
             if (!info.force_redraw)
-                display->scroll_stop_viewport_line(&skin_viewport->vp, info.line_number);
+                display->scroll_stop_viewport_rect(vp,
+                    0, info.line_number*display->getcharheight(),
+                    vp->width, display->getcharheight());
             write_line(display, align, info.line_number,
                     info.line_scrolls, info.text_style);
         }
diff --git a/apps/screen_access.c b/apps/screen_access.c
index 161e596aa2..f454e0adef 100644
--- a/apps/screen_access.c
+++ b/apps/screen_access.c
@@ -247,9 +247,9 @@ struct screen screens[NB_SCREENS] =
         .scroll_delay=&lcd_scroll_delay,
         .clear_display=&lcd_clear_display,
         .clear_viewport=&lcd_clear_viewport,
+        .scroll_stop_viewport_rect=&lcd_scroll_stop_viewport_rect,
         .scroll_stop=&lcd_scroll_stop,
         .scroll_stop_viewport=&lcd_scroll_stop_viewport,
-        .scroll_stop_viewport_line=&lcd_scroll_stop_viewport_line,
         .update=&lcd_update,
         .update_viewport=&lcd_update_viewport,
         .backlight_on=&backlight_on,
@@ -348,9 +348,9 @@ struct screen screens[NB_SCREENS] =
         .scroll_delay=&lcd_remote_scroll_delay,
         .clear_display=&lcd_remote_clear_display,
         .clear_viewport=&lcd_remote_clear_viewport,
+        .scroll_stop_viewport_rect=&lcd_remote_scroll_stop_viewport_rect,
         .scroll_stop=&lcd_remote_scroll_stop,
         .scroll_stop_viewport=&lcd_remote_scroll_stop_viewport,
-        .scroll_stop_viewport_line=&lcd_remote_scroll_stop_viewport_line,
         .update=&lcd_remote_update,
         .update_viewport=&lcd_remote_update_viewport,
         .backlight_on=&remote_backlight_on,
diff --git a/apps/screen_access.h b/apps/screen_access.h
index 448437c637..90b63ea338 100644
--- a/apps/screen_access.h
+++ b/apps/screen_access.h
@@ -149,7 +149,7 @@ struct screen
     void (*clear_viewport)(void);
     void (*scroll_stop)(void);
     void (*scroll_stop_viewport)(const struct viewport *vp);
-    void (*scroll_stop_viewport_line)(const struct viewport *vp, int line);
+    void (*scroll_stop_viewport_rect)(const struct viewport* vp, int x, int y, int width, int height);
     void (*update)(void);
     void (*update_viewport)(void);
     void (*backlight_on)(void);