ST7789/PicoGraphics: Fix palette bugs, add reserve.

libraries/pico_graphics/pico_graphics.cpp

@@ -37,16 +37,16 @@ namespace pimoroni {
 
   int PicoGraphics::search_palette(RGB565 c) {
     for(auto i = 0u; i < 256; i++) {
-      if(palette_status[i] && palette[i] == c) return i;
+      if((palette_status[i] & PaletteStatusUsed) && palette[i] == c) return i;
     }
     return -1;
   }
 
   int PicoGraphics::put_palette(RGB565 c) {
     for(auto i = 0u; i < 256; i++) {
-      if(!palette_status[i]) {
+      if(!(palette_status[i] & (PaletteStatusUsed | PaletteStatusReserved))) {
         palette[i] = c;
-        palette_status[i] = true;
+        palette_status[i] = PaletteStatusUsed;
         return i;
       }
     }
@@ -55,21 +55,33 @@ namespace pimoroni {
 
   void PicoGraphics::set_palette(uint8_t i, uint16_t c) {
     palette[i] = c;
-    palette_status[i] = true;
+    palette_status[i] |= PaletteStatusUsed;
   }
 
-  void PicoGraphics::empty_palette() { 
+  int PicoGraphics::reserve_palette() {
-    for (auto i = 0u; i < 255; i++) {
+    for (auto i = 0u; i < 256; i++) {
+      if (!palette_status[i]) {
+        palette_status[i] = PaletteStatusReserved;
+        return i;
+      }
+    }
+    return -1;
+  }
+
+  void PicoGraphics::empty_palette() {
+    for (auto i = 0u; i < 256; i++) {
       palette[i] = 0;
-      palette_status[i] = false;
+      palette_status[i] = 0;
     }
   }
 
   void PicoGraphics::rgb332_palette() {
-    for (auto i = 0u; i < 255; i++) {
+    for (auto i = 0u; i < 256; i++) {
+      // Convert the implicit RGB332 (i) into RGB565
+      // 0b11100 000 0b00011100 0b00000011
       palette[i] = ((i & 0b11100000) << 8) | ((i & 0b00011100) << 6) | ((i & 0b00000011) << 3);
       palette[i] = __builtin_bswap16(palette[i]);
-      palette_status[i] = true;
+      palette_status[i] = PaletteStatusUsed;
     }
   }
 

libraries/pico_graphics/pico_graphics.hpp

@@ -55,14 +55,19 @@ namespace pimoroni {
 
     const bitmap::font_t *font;
 
-    uint16_t palette[256];
+    RGB565 palette[256];
-    bool palette_status[256];
+    uint8_t palette_status[256];
 
     enum PaletteMode {
       PaletteModeRGB332 = 0,
       PaletteModeUSER = 1
     };
 
+    enum PaletteStatus : uint8_t {
+      PaletteStatusReserved = 1,
+      PaletteStatusUsed = 2
+    };
+
     PaletteMode palette_mode = PaletteModeRGB332;
 
   public:
@@ -96,6 +101,7 @@ namespace pimoroni {
 
     int create_pen(uint8_t r, uint8_t g, uint8_t b);
 
+    int reserve_palette();
     void empty_palette();
     void rgb332_palette();
 

micropython/modules/st7789/st7789.c

@@ -12,6 +12,7 @@ MP_DEFINE_CONST_FUN_OBJ_2(GenericST7789_set_framebuffer_obj, GenericST7789_set_f
 // Palette management
 MP_DEFINE_CONST_FUN_OBJ_2(GenericST7789_set_palette_mode_obj, GenericST7789_set_palette_mode);
 MP_DEFINE_CONST_FUN_OBJ_3(GenericST7789_set_palette_obj, GenericST7789_set_palette);
+MP_DEFINE_CONST_FUN_OBJ_1(GenericST7789_reserve_palette_obj, GenericST7789_reserve_palette);
 
 // Pen
 MP_DEFINE_CONST_FUN_OBJ_2(GenericST7789_set_pen_obj, GenericST7789_set_pen);
@@ -42,6 +43,7 @@ STATIC const mp_rom_map_elem_t GenericST7789_locals_dict_table[] = {
 
     { MP_ROM_QSTR(MP_QSTR_set_palette_mode), MP_ROM_PTR(&GenericST7789_set_palette_mode_obj) },
     { MP_ROM_QSTR(MP_QSTR_set_palette), MP_ROM_PTR(&GenericST7789_set_palette_obj) },
+    { MP_ROM_QSTR(MP_QSTR_reserve_palette), MP_ROM_PTR(&GenericST7789_reserve_palette_obj) },
 
     { MP_ROM_QSTR(MP_QSTR_set_backlight), MP_ROM_PTR(&GenericST7789_set_backlight_obj) },
     { MP_ROM_QSTR(MP_QSTR_create_pen), MP_ROM_PTR(&GenericST7789_create_pen_obj) },

micropython/modules/st7789/st7789.cpp

@@ -313,6 +313,18 @@ mp_obj_t GenericST7789_set_palette(mp_obj_t self_in, mp_obj_t index, mp_obj_t co
     return mp_const_none;
 }
 
+mp_obj_t GenericST7789_reserve_palette(mp_obj_t self_in) {
+    GenericST7789_obj_t *self = MP_OBJ_TO_PTR2(self_in, GenericST7789_obj_t);
+
+    int result = self->st7789->reserve_palette();
+
+    if (result == -1) {
+        mp_raise_ValueError("reserve_palette failed. No space in palette!");
+    }
+
+    return mp_obj_new_int(result);
+}
+
 mp_obj_t GenericST7789_create_pen(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     enum { ARG_self, ARG_r, ARG_g, ARG_b };
     static const mp_arg_t allowed_args[] = {
@@ -334,7 +346,7 @@ mp_obj_t GenericST7789_create_pen(size_t n_args, const mp_obj_t *pos_args, mp_ma
     );
 
     if (result == -1) {
-        mp_raise_ValueError("create_pen failed. No space in palette!");
+        mp_raise_ValueError("create_pen failed. No matching colour or space in palette!");
     }
 
     return mp_obj_new_int(result);

micropython/modules/st7789/st7789.h

@@ -19,6 +19,7 @@ extern mp_obj_t GenericST7789_set_backlight(mp_obj_t self_in, mp_obj_t brightnes
 // Palette management
 extern mp_obj_t GenericST7789_set_palette_mode(mp_obj_t self_in, mp_obj_t mode);
 extern mp_obj_t GenericST7789_set_palette(mp_obj_t self_in, mp_obj_t index, mp_obj_t colour);
+extern mp_obj_t GenericST7789_reserve_palette(mp_obj_t self_in);
 
 // Pen
 extern mp_obj_t GenericST7789_set_pen(mp_obj_t self_in, mp_obj_t pen);