Suggested changes from code review

Set font for Transparent_Sprite_Demo_Colormap to correct value (4)
renamed setColorMap to createPalette
renamed cmpPixel to readPixelValue
added setPaletteColor / getPaletteColor
added error check to createPalette

Extensions/Sprite.cpp

@@ -171,17 +171,22 @@ void* TFT_eSprite::callocSprite(int16_t w, int16_t h, uint8_t frames)
 }
 
 /***************************************************************************************
-** Function name:           setColorMap
+** Function name:           createPalette
-** Description:             Set a colour map for a 4-bit per pixel sprite
+** Description:             Set a palette for a 4-bit per pixel sprite
 *************************************************************************************x*/
 
-void TFT_eSprite::setColorMap(uint16_t colorMap[], int colors)
+void TFT_eSprite::createPalette(uint16_t colorMap[], int colors)
 {
   if (_colorMap != nullptr)
   {
     free(_colorMap);
   }
 
+  if (colorMap == nullptr)
+  {
+    return; // do nothing other than clear the existing map
+  }
+
   // allocate color map
   _colorMap = (uint16_t *)calloc(16, sizeof(uint16_t));
   if (colors > 16)
@@ -263,6 +268,28 @@ void TFT_eSprite::setBitmapColor(uint16_t c, uint16_t b)
   _tft->bitmap_bg = b;
 }
 
+/***************************************************************************************
+** Function name:           setPaletteColor
+** Description:             Set the palette color at the given index
+***************************************************************************************/
+void TFT_eSprite::setPaletteColor(uint8_t index, uint16_t color)
+{
+  if (_colorMap == nullptr || index > 15)
+    return; // out of bounds
+  _colorMap[index] = color;
+}
+
+/***************************************************************************************
+** Function name:           getPaletteColor
+** Description:             Return the palette color at index, or 0 (black) on error.
+***************************************************************************************/
+uint16_t TFT_eSprite::getPaletteColor(uint8_t index)
+{
+  if (_colorMap == nullptr || index > 15)
+    return 0;
+
+  return _colorMap[index];
+}
 
 /***************************************************************************************
 ** Function name:           deleteSprite
@@ -754,10 +781,10 @@ void TFT_eSprite::pushSprite(int32_t x, int32_t y, uint16_t transp)
 
 
 /***************************************************************************************
-** Function name:           cmapPixel
+** Function name:           readPixelValue
 ** Description:             Read the color map index of a pixel at defined coordinates
 *************************************************************************************x*/
-uint8_t TFT_eSprite::cmapPixel(int32_t x, int32_t y)
+uint8_t TFT_eSprite::readPixelValue(int32_t x, int32_t y)
 {
   if ((x < 0) || (x >= _iwidth) || (y < 0) || (y >= _iheight) || !_created) return 0xFFFF;
 
@@ -892,7 +919,9 @@ void  TFT_eSprite::pushImage(int32_t x, int32_t y, int32_t w, int32_t h, uint16_
   {
     // not supported.  The image is unlikely to have the correct colors for the color map.
     // we could implement a way to push a 4-bit image using the color map?
+    #ifdef TFT_eSPI_DEBUG
     Serial.println("pushImage(int32_t x, int32_t y, int32_t w, int32_t h, uint16_t *data) not implemented");
+    #endif
     return;
   }
 
@@ -995,7 +1024,9 @@ void  TFT_eSprite::pushImage(int32_t x, int32_t y, int32_t w, int32_t h, const u
 
   else if (_bpp == 4)
   {
+    #ifdef TFT_eSPI_DEBUG
     Serial.println("TFT_eSprite::pushImage(int32_t x, int32_t y, int32_t w, int32_t h, const uint16_t *data) not implemented");
+    #endif
     return;
   }
 
@@ -1286,8 +1317,8 @@ void TFT_eSprite::scroll(int16_t dx, int16_t dy)
     { // move pixels one by one
       for (uint16_t xp = 0; xp < w; xp++)
       {
-        if (dx <= 0) drawPixel(tx + xp, ty, cmapPixel(fx + xp, fy));
+        if (dx <= 0) drawPixel(tx + xp, ty, readPixelValue(fx + xp, fy));
-        if (dx >  0) drawPixel(tx - xp, ty, cmapPixel(fx - xp, fy));
+        if (dx >  0) drawPixel(tx - xp, ty, readPixelValue(fx - xp, fy));
       }
       if (dy <= 0)  { ty++; fy++; }
       else  { ty--; fy--; }

Extensions/Sprite.h

@@ -37,8 +37,14 @@ class TFT_eSprite : public TFT_eSPI {
   void*    setColorDepth(int8_t b);
   int8_t   getColorDepth(void);
 
-           // Set the colour map for a 4 bit depth sprite.  Only the first 16 colours in the map are used.
+           // Set the palette for a 4 bit depth sprite.  Only the first 16 colours in the map are used.
-  void     setColorMap(uint16_t *colorMap, int colors);
+  void     createPalette(uint16_t *palette, int colors = 16);
+
+            // Set a single palette index to the given color
+  void     setPaletteColor(uint8_t index, uint16_t color);
+
+            // Get the color at the given palette index
+  uint16_t getPaletteColor(uint8_t index);
 
            // Set foreground and background colours for 1 bit per pixel Sprite
   void     setBitmapColor(uint16_t fg, uint16_t bg);
@@ -104,7 +110,7 @@ class TFT_eSprite : public TFT_eSPI {
   uint16_t readPixel(int32_t x0, int32_t y0);
 
            // return the color map index of the pixel at x,y (used when scrolling)
-  uint8_t  cmapPixel(int32_t x, int32_t y);
+  uint8_t  readPixelValue(int32_t x, int32_t y);
 
            // Write an image (colour bitmap) to the sprite.  Not implemented for _bpp == 4.
   void     pushImage(int32_t x0, int32_t y0, int32_t w, int32_t h, uint16_t *data);

examples/Sprite/Sprite_colorMap/Sprite_colorMap.ino

@@ -84,7 +84,7 @@ void loop(void)
   cmap[14] = TFT_YELLOW;
   cmap[15] = TFT_WHITE;
 
-  spr.setColorMap(cmap, 16);
+  spr.createPalette(cmap, 16);
  
   spr.pushSprite(-40, -40);
   spr.pushSprite(tft.width() / 2 - WIDTH / 2, tft.height() / 2 - HEIGHT / 2, 10);
@@ -147,7 +147,7 @@ void loop(void)
     cmap[i] = random(0x10000);
   }
 
-  spr.setColorMap(cmap, 16);
+  spr.createPalette(cmap, 16);
   // Now push the sprite to the TFT at position 0,0 on screen
 
   spr.pushSprite(-40, -40);
@@ -162,7 +162,7 @@ void loop(void)
   // Draw a blue rectangle in sprite so when we move it 1 pixel it does not leave a trail
   // on the blue screen background
   cmap[14] = TFT_BLUE;
-  spr.setColorMap(cmap, 16);
+  spr.createPalette(cmap, 16);
 
   spr.drawRect(0, 0, WIDTH, HEIGHT, 14);
 

examples/Sprite/Sprite_scroll_cmap/Sprite_scroll_cmap.ino

@@ -63,7 +63,7 @@ void setup() {
   // Create a sprite for the graph
   graph1.setColorDepth(4);
   graph1.createSprite(128, 61);
-  graph1.setColorMap(cmap, 16);
+  graph1.createPalette(cmap, 16);
   graph1.fillSprite(9); // Note: Sprite is filled with black when created
 
   // The scroll area is set to the full sprite size upon creation of the sprite
@@ -74,7 +74,7 @@ void setup() {
   // Create a sprite for the scrolling numbers
   stext1.setColorDepth(4);
   stext1.createSprite(32, 64);
-  stext1.setColorMap(cmap, 16);
+  stext1.createPalette(cmap, 16);
   stext1.fillSprite(9); // Fill sprite with blue
   stext1.setScrollRect(0, 0, 32, 64, 9);     // here we set scroll gap fill color to blue
   stext1.setTextColor(15); // White text, no background
@@ -83,7 +83,7 @@ void setup() {
   // Create a sprite for Hello World
   stext2.setColorDepth(4);
   stext2.createSprite(80, 16);
-  stext2.setColorMap(cmap, 16);
+  stext2.createPalette(cmap, 16);
   stext2.fillSprite(7);
   stext2.setScrollRect(0, 0, 40, 16, 7); // Scroll the "Hello" in the first 40 pixels
   stext2.setTextColor(15); // White text, no background

examples/Sprite/Transparent_Sprite_Demo_Colormap/Transparent_Sprite_Demo_Colormap.ino

@@ -102,7 +102,7 @@ void drawStar(int x, int y, int star_color)
   cmap[14] = TFT_YELLOW;
   cmap[15] = TFT_WHITE; // this one will be transparent.
 
-  img.setColorMap(cmap, 16);
+  img.createPalette(cmap, 16);
 
   // Fill Sprite with a "transparent" colour
   // TFT_TRANSPARENT is already defined for convenience
@@ -156,7 +156,7 @@ void numberBox(int x, int y, float num )
   img.setTextDatum(MR_DATUM);
 
   // Draw the number to 3 decimal places at 70,20 in font 4
-  img.drawFloat(num, 3, 70, 20, 1);
+  img.drawFloat(num, 3, 70, 20, 4);
 
   // Push sprite to TFT screen CGRAM at coordinate x,y (top left corner)
   // All black pixels will not be drawn hence will show as "transparent"