lcd/skin_engine: Add the ability to draw onto the backdrop layer

The framebuffer the lcd driver uses can now be changed on the fly
which means that regular lcd_* drawing functions can draw onto the
"backdrop" buffer. The skin engine can use this to create layered
effects.

Add the tag %VB to a viewport to draw that viewport onto the
backdrop layer. If you want to draw an image onto the backdrop
framebuffer use %x(backdrop filename) instead of %X() inside
a viewport with %VB.

Change-Id: I741498e2af6d4f2d78932cabe8942317893e7cfc

7 files changed, 72 insertions, 9 deletions

diff --git a/apps/gui/skin_engine/skin_backdrops.c b/apps/gui/skin_engine/skin_backdrops.c
index 12b21ccb50..15b68589a9 100644
--- a/apps/gui/skin_engine/skin_backdrops.c
+++ b/apps/gui/skin_engine/skin_backdrops.c
@@ -95,6 +95,10 @@ int skin_backdrop_assign(char* backdrop, char *bmpdir,
         filename[2] = '\0'; /* we check this later to see if we actually have an
                                image to load. != '\0' means display the image */
     }
+    else if (!strcmp(backdrop, BACKDROP_BUFFERNAME))
+    {
+        strcpy(filename, backdrop);
+    }
     else
     {
         get_image_filename(backdrop, bmpdir, filename, sizeof(filename));
@@ -156,15 +160,20 @@ bool skin_backdrops_preload(void)
                 {
                     backdrops[i].buffer = core_get_data(backdrops[i].buflib_handle);
                     handle_being_loaded = backdrops[i].buflib_handle;
-                    backdrops[i].loaded =
-                             screens[screen].backdrop_load(filename, backdrops[i].buffer);
-                    handle_being_loaded = -1;
-                    if (!backdrops[i].loaded)
+                    if (strcmp(filename, BACKDROP_BUFFERNAME))
                     {
-                        core_free(backdrops[i].buflib_handle);
-                        backdrops[i].buflib_handle = -1;
-                        retval = false;
+                        backdrops[i].loaded =
+                                screens[screen].backdrop_load(filename, backdrops[i].buffer);
+                        handle_being_loaded = -1;
+                        if (!backdrops[i].loaded)
+                        {
+                            core_free(backdrops[i].buflib_handle);
+                            backdrops[i].buflib_handle = -1;
+                            retval = false;
+                        }
                     }
+                    else
+                        backdrops[i].loaded = true;
                 }
                 else
                     retval = false;
@@ -176,10 +185,21 @@ bool skin_backdrops_preload(void)
     return retval;
 }
 
+void* skin_backdrop_get_buffer(int backdrop_id)
+{
+    if (backdrop_id < 0)
+        return NULL;
+    return backdrops[backdrop_id].buffer;
+}
+
 void skin_backdrop_show(int backdrop_id)
 {
     if (backdrop_id < 0)
+    {
+        screens[0].backdrop_show(NULL);
+        current_lcd_backdrop[0] = -1;
         return;
+    }
     enum screen_type screen = backdrops[backdrop_id].screen;
     if ((backdrops[backdrop_id].loaded == false) ||
         (backdrops[backdrop_id].name[0] == '-' &&
diff --git a/apps/gui/skin_engine/skin_engine.h b/apps/gui/skin_engine/skin_engine.h
index ac839fff2e..625467ea3b 100644
--- a/apps/gui/skin_engine/skin_engine.h
+++ b/apps/gui/skin_engine/skin_engine.h
@@ -70,6 +70,8 @@ bool skin_backdrops_preload(void);
 void skin_backdrop_show(int backdrop_id);
 void skin_backdrop_load_setting(void);
 void skin_backdrop_unload(int backdrop_id);
+#define BACKDROP_BUFFERNAME "#backdrop_buffer#"
+void* skin_backdrop_get_buffer(int backdrop_id);
 
 /* do the button loop as often as required for the peak meters to update
  * with a good refresh rate. 
diff --git a/apps/gui/skin_engine/skin_parser.c b/apps/gui/skin_engine/skin_parser.c
index 340cbbdb01..0fe8789bcb 100644
--- a/apps/gui/skin_engine/skin_parser.c
+++ b/apps/gui/skin_engine/skin_parser.c
@@ -1832,6 +1832,7 @@ static int convert_viewport(struct wps_data *data, struct skin_element* element)
     viewport_set_defaults(&skin_vp->vp, curr_screen);
     
 #if (LCD_DEPTH > 1) || (defined(HAVE_REMOTE_LCD) && (LCD_REMOTE_DEPTH > 1))
+    skin_vp->output_to_backdrop_buffer = false;
     skin_vp->start_fgcolour = skin_vp->vp.fg_pattern;
     skin_vp->start_bgcolour = skin_vp->vp.bg_pattern;
 #endif
@@ -2023,6 +2024,11 @@ static int skin_element_callback(struct skin_element* element, void* data)
                 case SKIN_TOKEN_VIEWPORT_TEXTSTYLE:
                     function = parse_viewporttextstyle;
                     break;
+                case SKIN_TOKEN_VIEWPORT_DRAWONBG:
+                    curr_vp->output_to_backdrop_buffer = true;
+                    backdrop_filename = BACKDROP_BUFFERNAME;
+                    wps_data->use_extra_framebuffer = true;
+                    break;
 #endif
 #ifdef HAVE_LCD_COLOR
                 case SKIN_TOKEN_VIEWPORT_GRADIENT_SETUP:
diff --git a/apps/gui/skin_engine/skin_render.c b/apps/gui/skin_engine/skin_render.c
index 951d34a724..d4ddf99c34 100644
--- a/apps/gui/skin_engine/skin_render.c
+++ b/apps/gui/skin_engine/skin_render.c
@@ -385,11 +385,22 @@ static void do_tags_in_hidden_conditional(struct skin_element* branch,
                             skin_viewport->hidden_flags |= VP_DRAW_WASHIDDEN;
                         else
                         {
+                            if (skin_viewport->output_to_backdrop_buffer)
+                            {
+                                void *backdrop = skin_backdrop_get_buffer(data->backdrop_id);
+                                gwps->display->set_framebuffer(backdrop);
+                                skin_backdrop_show(-1);
+                            }
                             gwps->display->set_viewport(&skin_viewport->vp);
                             gwps->display->clear_viewport();
                             gwps->display->scroll_stop(&skin_viewport->vp);
                             gwps->display->set_viewport(&info->skin_vp->vp);
                             skin_viewport->hidden_flags |= VP_DRAW_HIDDEN;
+                            if (skin_viewport->output_to_backdrop_buffer)
+                            {
+                                gwps->display->set_framebuffer(NULL);
+                                skin_backdrop_show(data->backdrop_id);
+                            }
                         }
                     }
                 }
@@ -767,6 +778,7 @@ void skin_render(struct gui_wps *gwps, unsigned refresh_mode)
             data->wps_progress_pat[i] = display->get_locked_pattern();
     }
 #endif
+
     viewport = SKINOFFSETTOPTR(skin_buffer, data->tree);
     skin_viewport = SKINOFFSETTOPTR(skin_buffer, viewport->data);
     label = SKINOFFSETTOPTR(skin_buffer, skin_viewport->label);
@@ -786,6 +798,16 @@ void skin_render(struct gui_wps *gwps, unsigned refresh_mode)
 #if (LCD_DEPTH > 1) || (defined(HAVE_REMOTE_LCD) && LCD_REMOTE_DEPTH > 1)
         skin_viewport->vp.fg_pattern = skin_viewport->start_fgcolour;
         skin_viewport->vp.bg_pattern = skin_viewport->start_bgcolour;
+        if (skin_viewport->output_to_backdrop_buffer)
+        {
+            display->set_framebuffer(skin_backdrop_get_buffer(data->backdrop_id));
+            skin_backdrop_show(-1);
+        }
+        else
+        {
+            display->set_framebuffer(NULL);
+            skin_backdrop_show(data->backdrop_id);
+        }
 #endif
 #ifdef HAVE_LCD_COLOR
         skin_viewport->vp.lss_pattern = skin_viewport->start_gradient.start;
@@ -822,7 +844,10 @@ void skin_render(struct gui_wps *gwps, unsigned refresh_mode)
                                  skin_viewport, vp_refresh_mode);
         refresh_mode = old_refresh_mode;
     }
-    
+#ifdef HAVE_LCD_BITMAP
+    display->set_framebuffer(NULL);
+    skin_backdrop_show(data->backdrop_id);
+#endif
     /* Restore the default viewport */
     display->set_viewport(NULL);
     display->update();
diff --git a/apps/gui/skin_engine/wps_internals.h b/apps/gui/skin_engine/wps_internals.h
index c55c8d2515..1ea5dbf467 100644
--- a/apps/gui/skin_engine/wps_internals.h
+++ b/apps/gui/skin_engine/wps_internals.h
@@ -44,7 +44,6 @@
 #include "statusbar.h"
 #include "metadata.h"
 
-
 #define TOKEN_VALUE_ONLY 0x0DEADC0D
 
 /* wps_data*/
@@ -166,6 +165,7 @@ struct skin_viewport {
     OFFSETTYPE(char*) label;
     int   parsed_fontid;
 #if LCD_DEPTH > 1
+    bool output_to_backdrop_buffer;
     unsigned start_fgcolour;
     unsigned start_bgcolour;
 #ifdef HAVE_LCD_COLOR
@@ -328,6 +328,7 @@ struct wps_data
 #endif
 #ifdef HAVE_BACKDROP_IMAGE
     int backdrop_id;
+    bool use_extra_framebuffer;
 #endif
 
 #ifdef HAVE_TOUCHSCREEN
diff --git a/apps/screen_access.c b/apps/screen_access.c
index 5ab08b7fc5..43000e1360 100644
--- a/apps/screen_access.c
+++ b/apps/screen_access.c
@@ -262,6 +262,9 @@ struct screen screens[NB_SCREENS] =
 #ifdef HAVE_BUTTONBAR
         .has_buttonbar=false,
 #endif
+#if defined(HAVE_LCD_BITMAP)
+        .set_framebuffer = (void*)lcd_set_framebuffer,
+#endif
     },
 #if NB_SCREENS == 2
     {
@@ -357,6 +360,9 @@ struct screen screens[NB_SCREENS] =
 #ifdef HAVE_BUTTONBAR
         .has_buttonbar=false,
 #endif
+#if defined(HAVE_LCD_BITMAP)
+        .set_framebuffer = (void*)lcd_remote_set_framebuffer,
+#endif
     }
 #endif /* NB_SCREENS == 2 */
 };
diff --git a/apps/screen_access.h b/apps/screen_access.h
index a9d1408898..343829b915 100644
--- a/apps/screen_access.h
+++ b/apps/screen_access.h
@@ -160,6 +160,9 @@ struct screen
     bool (*backdrop_load)(const char *filename, char* backdrop_buffer);
     void (*backdrop_show)(char* backdrop_buffer);
 #endif
+#if defined(HAVE_LCD_BITMAP)
+    void (*set_framebuffer)(void *framebuffer);
+#endif
 };
 
 #if defined(HAVE_LCD_BITMAP) || defined(HAVE_REMOTE_LCD)