[FL-878] Gui: screen streaming (#337)

* GUI: canvas streaming
* Fix right status bar icon alignment

applications/gui/canvas.c

@@ -39,6 +39,16 @@ void canvas_commit(Canvas* canvas) {
     u8g2_SendBuffer(&canvas->fb);
 }
 
+uint8_t* canvas_get_buffer(Canvas* canvas) {
+    furi_assert(canvas);
+    return u8g2_GetBufferPtr(&canvas->fb);
+}
+
+size_t canvas_get_buffer_size(Canvas* canvas) {
+    furi_assert(canvas);
+    return u8g2_GetBufferTileWidth(&canvas->fb) * u8g2_GetBufferTileHeight(&canvas->fb) * 8;
+}
+
 void canvas_frame_set(
     Canvas* canvas,
     uint8_t offset_x,
@@ -219,4 +229,4 @@ void canvas_draw_glyph(Canvas* canvas, uint8_t x, uint8_t y, uint16_t ch) {
     x += canvas->offset_x;
     y += canvas->offset_y;
     u8g2_DrawGlyph(&canvas->fb, x, y, ch);
-}
+}