Implement scroll_text()

micropython/modules/pico_scroll/README.md

@@ -114,6 +114,14 @@ for j in range(256*6):
 
 N.B. the first 32 characters are white space... 
 
+### scroll_text
+
+Scroll a string across the picoscroll, starting off the right hand side, to the left, with a given delay in ms.
+
+```python
+picoscroll.scroll_text("Hello, world!", 8, 100)
+```
+
 ### show_bitmap_1d
 
 Show a view of a bitmap stored as the 7 least significant bits of

micropython/modules/pico_scroll/pico_scroll.c

@@ -22,6 +22,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_0(picoscroll_update_obj, picoscroll_update);
 STATIC MP_DEFINE_CONST_FUN_OBJ_3(picoscroll_set_pixel_obj, picoscroll_set_pixel);
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(picoscroll_set_pixels_obj, picoscroll_set_pixels);
 STATIC MP_DEFINE_CONST_FUN_OBJ_3(picoscroll_show_text_obj, picoscroll_show_text);
+STATIC MP_DEFINE_CONST_FUN_OBJ_3(picoscroll_scroll_text_obj, picoscroll_scroll_text);
 STATIC MP_DEFINE_CONST_FUN_OBJ_3(picoscroll_show_bitmap_1d_obj, picoscroll_show_bitmap_1d);
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(picoscroll_clear_obj, picoscroll_clear);
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(picoscroll_is_pressed_obj, picoscroll_is_pressed);
@@ -36,6 +37,7 @@ STATIC const mp_map_elem_t picoscroll_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_set_pixel), MP_ROM_PTR(&picoscroll_set_pixel_obj) },
     { MP_ROM_QSTR(MP_QSTR_set_pixels), MP_ROM_PTR(&picoscroll_set_pixels_obj) },
     { MP_ROM_QSTR(MP_QSTR_show_text), MP_ROM_PTR(&picoscroll_show_text_obj) },
+    { MP_ROM_QSTR(MP_QSTR_scroll_text), MP_ROM_PTR(&picoscroll_scroll_text_obj) },
     { MP_ROM_QSTR(MP_QSTR_show_bitmap_1d), MP_ROM_PTR(&picoscroll_show_bitmap_1d_obj) },
     { MP_ROM_QSTR(MP_QSTR_clear), MP_ROM_PTR(&picoscroll_clear_obj) },
     { MP_ROM_QSTR(MP_QSTR_is_pressed), MP_ROM_PTR(&picoscroll_is_pressed_obj) },        

micropython/modules/pico_scroll/pico_scroll.cpp

@@ -1,6 +1,7 @@
 #include "hardware/spi.h"
 #include "hardware/sync.h"
 #include "pico/binary_info.h"
+#include "pico/stdlib.h"
 
 #include "../../../libraries/pico_scroll/pico_scroll.hpp"
 
@@ -60,6 +61,53 @@ mp_obj_t picoscroll_set_pixel(mp_obj_t x_obj, mp_obj_t y_obj, mp_obj_t v_obj) {
     return mp_const_none;
 }
 
+mp_obj_t picoscroll_scroll_text(mp_obj_t text_obj, mp_obj_t brightness_obj,
+                                mp_obj_t delay_ms_obj) {
+    if (scroll != nullptr) {
+        mp_buffer_info_t bufinfo;
+        unsigned char *buffer;
+        int text_len, bfr_len;
+
+        mp_get_buffer_raise(text_obj, &bufinfo, MP_BUFFER_READ);
+        unsigned char *values = (unsigned char *)bufinfo.buf;
+        int brightness = mp_obj_get_int(brightness_obj);
+        int delay_ms = mp_obj_get_int(delay_ms_obj);
+
+        text_len = bufinfo.len;
+        bfr_len = 6 * text_len;
+
+        int width = PicoScroll::WIDTH;
+        int height = PicoScroll::HEIGHT;
+
+        buffer = (unsigned char *)m_malloc(sizeof(unsigned char) * bfr_len);
+        render(values, text_len, buffer, bfr_len);
+
+        for (int offset = -width; offset < bfr_len; offset++) {
+            scroll->clear();
+
+            for (int x = 0; x < width; x++) {
+                int k = offset + x;
+                if ((k >= 0) && (k < bfr_len)) {
+                    unsigned char col = buffer[k];
+                    for (int y = 0; y < height; y++) {
+                        int val = brightness * ((col >> y) & 1);
+                        scroll->set_pixel(x, y, val);
+                    }
+                }
+            }
+	    scroll->update();
+	    sleep_ms(delay_ms);
+	}
+        m_free(buffer);
+    } else {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+    }
+
+    return mp_const_none;
+}
+
+// TODO refactor this to not need a buffer - should be able to render
+// view into static 17 bytes
 mp_obj_t picoscroll_show_text(mp_obj_t text_obj, mp_obj_t brightness_obj,
                               mp_obj_t offset_obj) {
     if (scroll != nullptr) {

micropython/modules/pico_scroll/pico_scroll.h

@@ -9,6 +9,7 @@ extern mp_obj_t picoscroll_update();
 extern mp_obj_t picoscroll_set_pixel(mp_obj_t x_obj, mp_obj_t y_obj, mp_obj_t v_obj);
 extern mp_obj_t picoscroll_set_pixels(mp_obj_t image_obj);
 extern mp_obj_t picoscroll_show_text(mp_obj_t text_obj, mp_obj_t brightness, mp_obj_t offset);
+extern mp_obj_t picoscroll_scroll_text(mp_obj_t text_obj, mp_obj_t brightness, mp_obj_t delay);
 extern mp_obj_t picoscroll_show_bitmap_1d(mp_obj_t bitmap_obj, mp_obj_t brightness, mp_obj_t offset);
 extern mp_obj_t picoscroll_clear();
 extern mp_obj_t picoscroll_is_pressed(mp_obj_t button_obj);