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

1 files changed, 6 insertions, 0 deletions

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: