Merge pull request #255 from jquatier/bitmap-scaling-7789

fixing scaling of bitmaps for 7789 display

src/helpers/ui/ST7789Display.cpp

@@ -111,7 +111,39 @@ void ST7789Display::drawRect(int x, int y, int w, int h) {
 }
 
 void ST7789Display::drawXbm(int x, int y, const uint8_t* bits, int w, int h) {
-  display.drawBitmap(x*SCALE_X + X_OFFSET, y*SCALE_Y + Y_OFFSET, w, h, bits);
+  // Calculate the base position in display coordinates
+  uint16_t startX = x * SCALE_X + X_OFFSET;
+  uint16_t startY = y * SCALE_Y + Y_OFFSET;
+  
+  // Width in bytes for bitmap processing
+  uint16_t widthInBytes = (w + 7) / 8;
+  
+  // Process the bitmap row by row
+  for (uint16_t by = 0; by < h; by++) {
+    // Calculate the target y-coordinates for this logical row
+    int y1 = startY + (int)(by * SCALE_Y);
+    int y2 = startY + (int)((by + 1) * SCALE_Y);
+    int block_h = y2 - y1;
+    
+    // Scan across the row bit by bit
+    for (uint16_t bx = 0; bx < w; bx++) {
+      // Calculate the target x-coordinates for this logical column
+      int x1 = startX + (int)(bx * SCALE_X);
+      int x2 = startX + (int)((bx + 1) * SCALE_X);
+      int block_w = x2 - x1;
+      
+      // Get the current bit
+      uint16_t byteOffset = (by * widthInBytes) + (bx / 8);
+      uint8_t bitMask = 0x80 >> (bx & 7);
+      bool bitSet = pgm_read_byte(bits + byteOffset) & bitMask;
+      
+      // If the bit is set, draw a block of pixels
+      if (bitSet) {
+        // Draw the block as a filled rectangle
+        display.fillRect(x1, y1, block_w, block_h);
+      }
+    }
+  }
 }
 
 uint16_t ST7789Display::getTextWidth(const char* str) {