unsigned long testLines(uint16_t color) {
unsigned long start, t;
int x1, y1, x2, y2,
w = tft.width(),
h = tft.height();
tft.fillScreen(ILI9341_BLACK);
x1 = y1 = 0;
y2 = h - 1;
start = micros();
for (x2 = 0; x2 < w; x2 += 6) tft.drawLine(x1, y1, x2, y2, color);
x2 = w - 1;
for (y2 = 0; y2 < h; y2 += 6) tft.drawLine(x1, y1, x2, y2, color);
t = micros() - start; // fillScreen doesn't count against timing
tft.fillScreen(ILI9341_BLACK);
x1 = w - 1;
y1 = 0;
y2 = h - 1;
start = micros();
for (x2 = 0; x2 < w; x2 += 6) tft.drawLine(x1, y1, x2, y2, color);
x2 = 0;
for (y2 = 0; y2 < h; y2 += 6) tft.drawLine(x1, y1, x2, y2, color);
t += micros() - start;
tft.fillScreen(ILI9341_BLACK);
x1 = 0;
y1 = h - 1;
y2 = 0;
start = micros();
for (x2 = 0; x2 < w; x2 += 6) tft.drawLine(x1, y1, x2, y2, color);
x2 = w - 1;
for (y2 = 0; y2 < h; y2 += 6) tft.drawLine(x1, y1, x2, y2, color);
t += micros() - start;
tft.fillScreen(ILI9341_BLACK);
x1 = w - 1;
y1 = h - 1;
y2 = 0;
start = micros();
for (x2 = 0; x2 < w; x2 += 6) tft.drawLine(x1, y1, x2, y2, color);
x2 = 0;
for (y2 = 0; y2 < h; y2 += 6) tft.drawLine(x1, y1, x2, y2, color);
return micros() - start;
}
static void drawLine( int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t color)
{
tft.drawLine(x0 + 120, y0 + 160, x1 + 120, y1 + 160, color);
}