Cosmic Unicorn: Implement RGB888 frame convert.

Author: Gadgetoid

libraries/cosmic_unicorn/cosmic_unicorn.cpp

@@ -567,16 +567,16 @@ namespace pimoroni {
       }
       else if(graphics->pen_type == PicoGraphics::PEN_P8 || graphics->pen_type == PicoGraphics::PEN_P4) {
         int offset = 0;
-        graphics->frame_convert(PicoGraphics::PEN_RGB565, [this, offset](void *data, size_t length) mutable {
-          uint16_t *p = (uint16_t *)data;
-          for(auto i = 0u; i < length / 2; i++) {
+        graphics->frame_convert(PicoGraphics::PEN_RGB888, [this, offset](void *data, size_t length) mutable {
+          uint32_t *p = (uint32_t *)data;
+          for(auto i = 0u; i < length / 4; i++) {
             int x = offset % 32;
             int y = offset / 32;
 
-            uint16_t col = __builtin_bswap16(*p);
-            uint8_t r = (col & 0b1111100000000000) >> 8;
-            uint8_t g = (col & 0b0000011111100000) >> 3;
-            uint8_t b = (col & 0b0000000000011111) << 3;
+            uint32_t col = *p;
+            uint8_t r = (col & 0xff0000) >> 16;
+            uint8_t g = (col & 0x00ff00) >>  8;
+            uint8_t b = (col & 0x0000ff) >>  0;
 
             set_pixel(x, y, r, g, b);
             offset++;

libraries/pico_graphics/pico_graphics.cpp

@@ -420,4 +420,34 @@ namespace pimoroni {
     // Callback with zero length to ensure previous buffer is fully written
     callback(row_buf[buf_idx], 0);
   }
+
+  // Common function for frame buffer conversion to 565 pixel format
+  void PicoGraphics::frame_convert_rgb888(conversion_callback_func callback, next_pixel_func_rgb888 get_next_pixel)
+  {
+    // Allocate two temporary buffers, as the callback may transfer by DMA
+    // while we're preparing the next part of the row
+    const int BUF_LEN = 64;
+    RGB888 row_buf[2][BUF_LEN];
+    int buf_idx = 0;
+    int buf_entry = 0;
+    for(auto i = 0; i < bounds.w * bounds.h; i++) {
+      row_buf[buf_idx][buf_entry] = get_next_pixel();
+      buf_entry++;
+
+      // Transfer a filled buffer and swap to the next one
+      if (buf_entry == BUF_LEN) {
+          callback(row_buf[buf_idx], BUF_LEN * sizeof(RGB888));
+          buf_idx ^= 1;
+          buf_entry = 0;
+      }
+    }
+
+    // Transfer any remaining pixels ( < BUF_LEN )
+    if(buf_entry > 0) {
+        callback(row_buf[buf_idx], buf_entry * sizeof(RGB888));
+    }
+
+    // Callback with zero length to ensure previous buffer is fully written
+    callback(row_buf[buf_idx], 0);
+  }
 }

libraries/pico_graphics/pico_graphics.hpp

@@ -183,6 +183,7 @@ namespace pimoroni {
 
     typedef std::function<void(void *data, size_t length)> conversion_callback_func;
     typedef std::function<RGB565()> next_pixel_func;
+    typedef std::function<RGB888()> next_pixel_func_rgb888;
     //typedef std::function<void(int y)> scanline_interrupt_func;
 
     //scanline_interrupt_func scanline_interrupt = nullptr;
@@ -271,6 +272,7 @@ namespace pimoroni {
 
   protected:
     void frame_convert_rgb565(conversion_callback_func callback, next_pixel_func get_next_pixel);
+    void frame_convert_rgb888(conversion_callback_func callback, next_pixel_func_rgb888 get_next_pixel);
   };
 
   class PicoGraphics_Pen1Bit : public PicoGraphics {

libraries/pico_graphics/pico_graphics_pen_p8.cpp

@@ -112,6 +112,13 @@ namespace pimoroni {
             frame_convert_rgb565(callback, [&]() {
                 return cache[*src++];
             });
+        } else if (type == PEN_RGB888) {
+            // Treat our void* frame_buffer as uint8_t
+            uint8_t *src = (uint8_t *)frame_buffer;
+
+            frame_convert_rgb888(callback, [&]() {
+                return palette[*src++].to_rgb888();
+            });
         }
     }
 }