legacy: make sca pixels for pin matrix grow from the inside

legacy/firmware/pinmatrix.c

@@ -47,7 +47,8 @@ void pinmatrix_draw(const char *text) {
   }
   for (int i = 0; i < 3; i++) {
     // 36 is the maximum pixels used for a pin matrix pixel row
-    oledSCA(12 + i * (h + pad), 12 + i * (h + pad) + h - 1, 36);
+    // but we use 56 pixels to add some extra
+    oledSCAInside(12 + i * (h + pad), 12 + i * (h + pad) + h - 1, 56, 38, OLED_WIDTH - 38);
   }
   oledRefresh();
 }

legacy/oled.c

@@ -423,6 +423,7 @@ void oledSwipeRight(void) {
 
 /*
  * Mitigate SCA on lines y1-y2 by setting at least width pixels white
+ * Pixels grow from the outside (left/right border of the screen)
  */
 void oledSCA(int y1, int y2, int width) {
   y1 = MAX(y1, 0);
@@ -443,3 +444,27 @@ void oledSCA(int y1, int y2, int width) {
     }
   }
 }
+
+/*
+ * Mitigate SCA on lines y1-y2 by setting at least width pixels white
+ * Pixels grow from the inside (from columns a/b to the right/left)
+ */
+void oledSCAInside(int y1, int y2, int width, int a, int b) {
+  y1 = MAX(y1, 0);
+  y2 = MIN(y2, OLED_HEIGHT - 1);
+  for (int y = y1; y <= y2; y++) {
+    int pix = 0;
+    for (int x = 0; x < OLED_WIDTH; x++) {
+      pix += oledGetPixel(x, y);
+    }
+    if (width > pix) {
+      pix = width - pix;
+      for (int x = a - pix / 2; x < a; x++) {
+        oledDrawPixel(x, y);
+      }
+      for (int x = b; x < b + (pix + 1) / 2; x++) {
+        oledDrawPixel(x, y);
+      }
+    }
+  }
+}

legacy/oled.h

@@ -57,5 +57,6 @@ void oledFrame(int x1, int y1, int x2, int y2);
 void oledSwipeLeft(void);
 void oledSwipeRight(void);
 void oledSCA(int y1, int y2, int val);
+void oledSCAInside(int y1, int y2, int val, int a, int b);
 
 #endif