Fix scrolling with 'loop=True'

Author: markshannon

inc/microbit/microbitimage.h

@@ -69,7 +69,7 @@ void microbit_image_set_from_char(greyscale_t *img, char c);
 microbit_image_obj_t *microbit_image_for_char(char c);
 mp_obj_t microbit_image_slice(microbit_image_obj_t *img, mp_int_t start, mp_int_t width, mp_int_t stride);
 /* ref exists so that we can pull a string out of an object and not have it GC'ed while oterating over it */
-mp_obj_t scrolling_string_image_iterable(const char* str, mp_uint_t len, mp_obj_t ref, bool monospace);
+mp_obj_t scrolling_string_image_iterable(const char* str, mp_uint_t len, mp_obj_t ref, bool monospace, bool repeat);
 
 #define SMALL_IMAGE(p0, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10, p11, p12, p13, p14, p15, p16, p17, p18, p19, p20, p21, p22, p23, p44) \
 { \

source/microbit/microbitdisplay.cpp

@@ -396,7 +396,7 @@ void microbit_display_animate(microbit_display_obj_t *self, mp_obj_t iterable, m
 #define DEFAULT_SCROLL_SPEED       150
 
 void microbit_display_scroll(microbit_display_obj_t *self, const char* str) {
-    mp_obj_t iterable = scrolling_string_image_iterable(str, strlen(str), NULL, false);
+    mp_obj_t iterable = scrolling_string_image_iterable(str, strlen(str), NULL, false, false);
     microbit_display_animate(self, iterable, DEFAULT_SCROLL_SPEED, false, true);
 }
 
@@ -415,10 +415,7 @@ mp_obj_t microbit_display_scroll_func(mp_uint_t n_args, const mp_obj_t *pos_args
     mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(scroll_allowed_args), scroll_allowed_args, args);
     mp_uint_t len;
     const char* str = mp_obj_str_get_data(args[0].u_obj, &len);
-    mp_obj_t iterable = scrolling_string_image_iterable(str, len, args[0].u_obj, args[3].u_bool /*monospace?*/);
-    if (args[4].u_bool) { /*loop*/
-        iterable = microbit_repeat_iterator(iterable);
-    }
+    mp_obj_t iterable = scrolling_string_image_iterable(str, len, args[0].u_obj, args[3].u_bool /*monospace?*/, args[4].u_bool /*loop*/);
     microbit_display_animate(self, iterable, args[1].u_int /*delay*/, false/*clear*/, args[2].u_bool/*wait?*/);
     return mp_const_none;
 }

source/microbit/microbitimage.cpp

@@ -662,30 +662,34 @@ typedef struct _scrolling_string_t {
     mp_uint_t len;
     mp_obj_t ref;
     bool monospace;
+    bool repeat;
 } scrolling_string_t;
 
 typedef struct _scrolling_string_iterator_t {
     mp_obj_base_t base; 
     mp_obj_t ref;
     greyscale_t *img;
     char const *next_char;
+    char const *start;
     char const *end;
     uint8_t offset;
     uint8_t offset_limit;
     bool monospace;
+    bool repeat;
     char right;
 } scrolling_string_iterator_t;
 
 extern const mp_obj_type_t microbit_scrolling_string_type;
 extern const mp_obj_type_t microbit_scrolling_string_iterator_type;
 
-mp_obj_t scrolling_string_image_iterable(const char* str, mp_uint_t len, mp_obj_t ref, bool monospace) {
+mp_obj_t scrolling_string_image_iterable(const char* str, mp_uint_t len, mp_obj_t ref, bool monospace, bool repeat) {
     scrolling_string_t *result = m_new_obj(scrolling_string_t);
     result->base.type = &microbit_scrolling_string_type;
     result->str = str;
     result->len = len;
     result->ref = ref;
     result->monospace = monospace;
+    result->repeat = repeat;
     return result;
 }
 
@@ -709,34 +713,45 @@ STATIC unsigned int rightmost_non_blank_column(const unsigned char *font_data) {
     return 2;
 }
 
+static void restart(scrolling_string_iterator_t *iter) {
+    iter->next_char = iter->start;
+    iter->offset = 0;
+    if (iter->start < iter->end) {
+        iter->right = *iter->next_char;
+        if (iter->monospace) {
+            iter->offset_limit = 5;
+        } else {
+            iter->offset_limit = rightmost_non_blank_column(get_font_data_from_char(iter->right)) + 1;
+        }
+    } else {
+        iter->right = ' ';
+        iter->offset_limit = 5;
+    }
+}
+
 STATIC mp_obj_t get_microbit_scrolling_string_iter(mp_obj_t o_in) {
     scrolling_string_t *str = (scrolling_string_t *)o_in;
     scrolling_string_iterator_t *result = m_new_obj(scrolling_string_iterator_t);
     result->base.type = &microbit_scrolling_string_iterator_type;
     result->img = greyscale_new(5,5);
-    result->offset = 0;
-    result->next_char = str->str;
+    result->start = str->str;
     result->ref = str->ref;
     result->monospace = str->monospace;
-    result->end = result->next_char + str->len;
-    if (str->len) {
-        result->right = *result->next_char;
-        if (result->monospace) {
-            result->offset_limit = 5;
-        } else {
-            result->offset_limit = rightmost_non_blank_column(get_font_data_from_char(result->right)) + 1;
-        }
-    } else {
-        result->right = ' ';
-        result->offset_limit = 5;
-    }
+    result->end = result->start + str->len;
+    result->repeat = str->repeat;
+    restart(result);
     return result;
 }
 
 STATIC mp_obj_t microbit_scrolling_string_iter_next(mp_obj_t o_in) {
     scrolling_string_iterator_t *iter = (scrolling_string_iterator_t *)o_in;
     if (iter->next_char == iter->end && iter->offset == 5) {
-        return MP_OBJ_STOP_ITERATION;
+        if (iter->repeat) {
+            restart(iter);
+            iter->img->clear();
+        } else {
+            return MP_OBJ_STOP_ITERATION;
+        }
     }
     iter->img->shiftLeftInplace(1);
     const unsigned char *font_data;