scroll engine: Factor out renderer function so it can be called by lcd code.

This is used by lcd_puts_scroll_worker() to render the line immediately
instead of waiting for the next scroll tick when only the text was updated.
Previously lcd_puts_scroll_worker() did not render anything in this case
which could lead to visible blinking.

This fixes blinking scrolling lines with dynamic text in the skin engine.

Change-Id: I475bde8c8eb7c92f505e3c5ecf4d32bb90690536

firmware/drivers/lcd-bitmap-common.c

@@ -398,6 +398,9 @@ static void LCDFN(puts_scroll_worker)(int x, int y, const unsigned char *string,
         s->height = height;
         s->vp = current_vp;
         LCDFN(scroll_info).lines++;
+    } else {
+        /* if only the text was updated render immediately */
+        LCDFN(scroll_now(s));
     }
 }
 

firmware/drivers/lcd-scroll.c

@@ -123,47 +123,18 @@ void LCDFN(jump_scroll_delay)(int ms)
 }
 #endif
 
-static void LCDFN(scroll_worker)(void)
+/* This renders the scrolling line described by s immediatly.
+ * This can be called to update a scrolling line if the text has changed
+ * without waiting for the next scroll tick
+ *
+ * Returns true if the text scrolled to the end */
+bool LCDFN(scroll_now)(struct scrollinfo *s)
 {
-    int index, width;
-    bool makedelay;
+    int width = LCDFN(getstringsize)(s->linebuffer, NULL, NULL);
+    bool ended = false;
+    /* assume s->scroll_func() don't yield; otherwise this buffer might need
+     * to be mutex'd (the worst case would be minor glitches though) */
     static char line_buf[SCROLL_LINE_SIZE];
-    bool is_default;
-    struct scroll_screen_info *si = &LCDFN(scroll_info);
-    struct scrollinfo *s;
-    struct viewport *vp;
-    int step;
-
-    for ( index = 0; index < si->lines; index++ )
-    {
-        s = &si->scroll[index];
-
-        /* check pause */
-        if (TIME_BEFORE(current_tick, s->start_tick))
-            continue;
-
-        s->start_tick = current_tick;
-
-        /* this runs out of the ui thread, thus we need to
-         * save and restore the current viewport since the ui thread
-         * is unaware of the swapped viewports. the vp must
-         * be switched early so that lcd_getstringsize() picks the
-         * correct font */
-        vp = LCDFN(get_viewport)(&is_default);
-        LCDFN(set_viewport)(s->vp);
-
-        width = LCDFN(getstringsize)(s->linebuffer, NULL, NULL);
-        makedelay = false;
-#ifdef HAVE_LCD_BITMAP
-        step = si->step;
-#else
-        step = 1;
-#endif
-
-        if (s->backward)
-            s->offset -= step;
-        else
-            s->offset += step;
 
     if (s->bidir)
     {   /* scroll bidirectional */
@@ -172,13 +143,13 @@ static void LCDFN(scroll_worker)(void)
             /* at beginning of line */
             s->offset = 0;
             s->backward = false;
-                makedelay = true;
+            ended = true;
         }
         else if (s->offset >= width - s->width) {
             /* at end of line */
             s->offset = width - s->width;
             s->backward = true;
-                makedelay = true;
+            ended = true;
         }
     }
     else
@@ -190,7 +161,7 @@ static void LCDFN(scroll_worker)(void)
         /* scroll forward the whole time */
         if (s->offset >= width) {
             s->offset = 0;
-                makedelay = true;
+            ended = true;
         }
     }
 
@@ -216,6 +187,54 @@ static void LCDFN(scroll_worker)(void)
 #endif
     s->vp->drawmode = drawmode;
 #endif
+
+    return ended;
+}
+
+static void LCDFN(scroll_worker)(void)
+{
+    int index;
+    bool makedelay;
+    bool is_default;
+    struct scroll_screen_info *si = &LCDFN(scroll_info);
+    struct scrollinfo *s;
+    struct viewport *vp;
+    int step;
+
+    for ( index = 0; index < si->lines; index++ )
+    {
+        s = &si->scroll[index];
+
+        /* check pause */
+        if (TIME_BEFORE(current_tick, s->start_tick))
+            continue;
+
+        s->start_tick = current_tick;
+
+        /* this runs out of the ui thread, thus we need to
+         * save and restore the current viewport since the ui thread
+         * is unaware of the swapped viewports. the vp must
+         * be switched early so that lcd_getstringsize() picks the
+         * correct font */
+        vp = LCDFN(get_viewport)(&is_default);
+        LCDFN(set_viewport)(s->vp);
+
+        makedelay = false;
+#ifdef HAVE_LCD_BITMAP
+        step = si->step;
+#else
+        step = 1;
+#endif
+
+
+        if (s->backward)
+            s->offset -= step;
+        else
+            s->offset += step;
+
+        /* put the line onto the display now */
+        makedelay = LCDFN(scroll_now(s));
+
         LCDFN(set_viewport)(vp);
 
         if (makedelay)

firmware/export/scroll_engine.h

@@ -30,6 +30,7 @@
 #include "file.h"
 
 struct viewport;
+struct scrollinfo;
 
 extern void scroll_init(void) INIT_ATTR;
 
@@ -40,6 +41,7 @@ extern void lcd_scroll_delay(int ms);
 extern void lcd_scroll_stop(void);
 extern void lcd_scroll_stop_viewport(const struct viewport *vp);
 extern void lcd_scroll_stop_viewport_rect(const struct viewport *vp, int x, int y, int width, int height);
+extern bool lcd_scroll_now(struct scrollinfo *scroll);
 #ifdef HAVE_REMOTE_LCD
 extern void lcd_remote_scroll_speed(int speed);
 extern void lcd_remote_scroll_delay(int ms);
@@ -47,8 +49,11 @@ extern void lcd_remote_scroll_delay(int ms);
 extern void lcd_remote_scroll_stop(void);
 extern void lcd_remote_scroll_stop_viewport(const struct viewport *vp);
 extern void lcd_remote_scroll_stop_viewport_rect(const struct viewport *vp, int x, int y, int width, int height);
+extern bool lcd_remote_scroll_now(struct scrollinfo *scroll);
 #endif
 
+
+
 /* internal usage, but in multiple drivers
  * larger than the normal linebuffer since it holds the line a second
  * time (+3 spaces) for non-bidir scrolling */