Move scroll_text, show_text, bitmap_1d and set_pixels into C++ library

Move scroll_text into the C++ library and make it support std::string.

Move show_bitmap_1d to set_bitmap_1d in the C++ library. Use it as the basis for show_text and scroll_text.

Change show_text to set_text since it does not implicitly show the result.

Add a new pico-scroll demo to show off the scrolling text functionality.

examples/pico_scroll/CMakeLists.txt

@@ -1,10 +1,2 @@
-add_executable(
-  scroll
-  demo.cpp
-)
-
-# Pull in pico libraries that we need
-target_link_libraries(scroll pico_stdlib pico_scroll)
-
-# create map/bin/hex file etc.
-pico_add_extra_outputs(scroll)
+include(demo.cmake)
+include(scroll-text.cmake)

examples/pico_scroll/demo.cmake

@@ -0,0 +1,10 @@
+add_executable(
+  scroll
+  demo.cpp
+)
+
+# Pull in pico libraries that we need
+target_link_libraries(scroll pico_stdlib pico_scroll)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(scroll)

examples/pico_scroll/demo.cpp

@@ -12,6 +12,7 @@ PicoScroll pico_scroll;
 int main() {
 
   pico_scroll.init();
+  pico_scroll.scroll_text("Hello World, how are you today?", 255, 100);
 
 
   bool a_pressed = false;

examples/pico_scroll/scroll-text.cmake

@@ -0,0 +1,10 @@
+add_executable(
+  scroll-text
+  scroll-text.cpp
+)
+
+# Pull in pico libraries that we need
+target_link_libraries(scroll-text pico_stdlib pico_scroll)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(scroll-text)

examples/pico_scroll/scroll-text.cpp

@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include "pico/stdlib.h"
+
+#include "pico_scroll.hpp"
+
+using namespace pimoroni;
+
+PicoScroll pico_scroll;
+
+int main() {
+  stdio_init_all();
+  pico_scroll.init();
+
+  while(true) {
+    pico_scroll.scroll_text("Hello World, how are you today?", 64, 100);
+    sleep_ms(500);
+
+    pico_scroll.set_text("Test", 64);
+    pico_scroll.update();
+    sleep_ms(1000);
+
+    // Set pixels to a chessboard pattern
+    char pixels[PicoScroll::WIDTH * PicoScroll::HEIGHT] = {};
+
+    pico_scroll.set_pixels(pixels);
+    for (int y = 0; y < PicoScroll::HEIGHT; y++) {
+        for (int x = 0; x < PicoScroll::WIDTH; x++) {
+            pixels[y * PicoScroll::WIDTH + x] = ((x + y) & 0b1) * 64;
+        }
+    }
+
+    pico_scroll.set_pixels(pixels);
+    pico_scroll.update();
+
+    sleep_ms(1000);
+  }
+
+  return 0;
+}

libraries/pico_scroll/CMakeLists.txt

@@ -1,10 +1 @@
-add_library(pico_scroll INTERFACE)
-
-target_sources(pico_scroll INTERFACE
-  ${CMAKE_CURRENT_LIST_DIR}/pico_scroll.cpp
-)
-
-target_include_directories(pico_scroll INTERFACE ${CMAKE_CURRENT_LIST_DIR})
-
-# Pull in pico libraries that we need
-target_link_libraries(pico_scroll INTERFACE pico_stdlib hardware_i2c)
+include(pico_scroll.cmake)

libraries/pico_scroll/pico_scroll.cmake

@@ -1,7 +1,11 @@
 add_library(pico_scroll INTERFACE)
 
-target_sources(pico_scroll INTERFACE
+set(PICO_SCROLL_SOURCES
   ${CMAKE_CURRENT_LIST_DIR}/pico_scroll.cpp
+  ${CMAKE_CURRENT_LIST_DIR}/pico_scroll_font.cpp)
+
+target_sources(pico_scroll INTERFACE
+  ${PICO_SCROLL_SOURCES}
 )
 
 target_include_directories(pico_scroll INTERFACE ${CMAKE_CURRENT_LIST_DIR})

libraries/pico_scroll/pico_scroll.cpp

@@ -5,6 +5,7 @@
 #include "hardware/i2c.h"
 
 #include "pico_scroll.hpp"
+#include "pico_scroll_font.hpp"
 
 enum pin {
   SDA   =  4,
@@ -84,6 +85,77 @@ namespace pimoroni {
     memset(__fb, 0, BUFFER_SIZE);
   }
 
+  void PicoScroll::set_pixels(const char *pixels) {
+    for (int y = 0; y < HEIGHT; y++) {
+        for (int x = 0; x < WIDTH; x++) {
+            set_pixel(x, y, pixels[y * WIDTH + x]);
+        }
+    }
+  }
+
+  void PicoScroll::set_bitmap_1d(const char *bitmap, size_t bitmap_len, int brightness, int offset) {
+    for (int x = 0; x < WIDTH; x++) {
+      int k = offset + x;
+      if ((k >= 0) && (k < (int)bitmap_len)) {
+        unsigned char col = bitmap[k];
+        for (int y = 0; y < HEIGHT; y++) {
+          int val = brightness * ((col >> y) & 1);
+          set_pixel(x, y, val);
+        }
+      }
+    }
+  }
+
+  void PicoScroll::set_text(const char *text, size_t text_len, int brightness, int offset) {
+        int draw_buffer_len = PicoScroll::WIDTH + 7;
+        unsigned char draw_buffer[draw_buffer_len];
+
+        // clear the scroll, so only need to write visible bytes
+        clear();
+
+        if ((offset < -WIDTH) || (offset > (int)(6 * text_len))) {
+            return;
+        }
+
+        // compute what can actually be seen, render only that...
+        // modify offset and bfr_len accordingly
+        if (offset < 0) {
+            int space = 1 + (WIDTH + offset) / 6;
+            if (space < (int)text_len) {
+                text_len = space;
+            }
+        } else {
+            int start = offset / 6;
+            offset -= start * 6;
+            text_len = text_len - start;
+            if (text_len > 4) {
+                text_len = 4;
+            }
+        }
+
+        if (draw_buffer_len > (int)(6 * text_len)) {
+            draw_buffer_len = 6 * text_len;
+        }
+
+        render_text(text, text_len, draw_buffer, draw_buffer_len);
+        set_bitmap_1d((const char *)draw_buffer, draw_buffer_len, brightness, offset);
+  }
+
+  void PicoScroll::scroll_text(const char *text, size_t text_len, int brightness, int delay_ms) {
+    int draw_buffer_len = 6 * text_len;
+
+    unsigned char *draw_buffer = (unsigned char *)malloc(sizeof(unsigned char) * draw_buffer_len);
+    render_text(text, text_len, draw_buffer, draw_buffer_len);
+
+    for (int offset = -WIDTH; offset < draw_buffer_len; offset++) {
+        clear();
+        set_bitmap_1d((const char *)draw_buffer, draw_buffer_len, brightness, offset);
+        update();
+        sleep_ms(delay_ms);
+    }
+    free(draw_buffer);
+  }
+
   void PicoScroll::update() {
     i2c_write(COLOR_OFFSET, (const char *)__fb, BUFFER_SIZE);
   }

libraries/pico_scroll/pico_scroll.hpp

@@ -1,3 +1,4 @@
+#include <string>
 #pragma once
 
 namespace pimoroni {
@@ -20,6 +21,16 @@ namespace pimoroni {
   public:
     void init();
     void update();
+    void set_pixels(const char *pixels);
+    void set_bitmap_1d(const char *bitmap, size_t bitmap_len, int brightness, int offset);
+    void scroll_text(const char *text, size_t text_len, int brightness, int delay_ms);
+    void scroll_text(std::string text, int brightness, int delay_ms=100) {
+      scroll_text(text.c_str(), text.length(), brightness, delay_ms);
+    };
+    void set_text(const char *text, size_t text_len, int brightness, int offset);
+    void set_text(std::string text, int brightness, int offset=0) {
+      set_text(text.c_str(), text.length(), brightness, offset);
+    }
     void set_pixel(uint8_t x, uint8_t y, uint8_t v);
     void clear();
     bool is_pressed(uint8_t button);

micropython/modules/pico_scroll/pico_scroll_font.c → libraries/pico_scroll/pico_scroll_font.cpp

@@ -1,4 +1,4 @@
-#include "pico_scroll_font.h"
+#include "pico_scroll_font.hpp"
 
 /* static font data */
 static unsigned char __bitmap[256][5] = {
@@ -133,12 +133,12 @@ static unsigned char __bitmap[256][5] = {
 };
 
 /* render a text string to a pre-allocated buffer - strlen(text) * 6 bytes */
-int render(unsigned char *text, int nchr, unsigned char *buffer, int nbfr) {
+int render_text(const char *text, unsigned int nchr, unsigned char *buffer, unsigned int nbfr) {
     // TODO check nbfr >= 6 * nchr
 
-    for (int i = 0; i < nchr; i++) {
-        unsigned char *symbol = __bitmap[text[i]];
-        for (int j = 0; j < 5; j++) {
+    for (unsigned int i = 0; i < nchr; i++) {
+        unsigned char *symbol = __bitmap[(unsigned int)text[i]];
+        for (unsigned int j = 0; j < 5; j++) {
             buffer[i * 6 + j] = symbol[j];
         }
         buffer[i * 6 + 5] = 0x0;

libraries/pico_scroll/pico_scroll_font.hpp

@@ -0,0 +1,4 @@
+#pragma once
+
+// external font API
+int render_text(const char *text, unsigned int nchr, unsigned char *buffer, unsigned int nbfr);

micropython/modules/pico_scroll/micropython.cmake

@@ -1,10 +1,11 @@
+include(${CMAKE_CURRENT_LIST_DIR}/../../../libraries/pico_scroll/pico_scroll.cmake)
+
 add_library(usermod_pico_scroll INTERFACE)
 
 target_sources(usermod_pico_scroll INTERFACE
     ${CMAKE_CURRENT_LIST_DIR}/pico_scroll.c
-    ${CMAKE_CURRENT_LIST_DIR}/pico_scroll_font.c
     ${CMAKE_CURRENT_LIST_DIR}/pico_scroll.cpp
-    ${CMAKE_CURRENT_LIST_DIR}/../../../libraries/pico_scroll/pico_scroll.cpp
+    ${PICO_SCROLL_SOURCES}
 )
 
 target_include_directories(usermod_pico_scroll INTERFACE