CoreINK screen update

[aerolite]

Hello,

I just got my core.ink and put the ntp-clock to it and works fine. I added battery voltage information to the screen with code below. Then sometime the battery voltage is written on top of previous number. And it's even worse if I use clear() function. Could any one explain the proper way to draw on the screen without blink and without overwrite.

thx

'
void drawBattery()
{
Serial.println("\ndrawBat");
char str[50];
//TimePageSprite.clear(CLEAR_DRAWBUFF | CLEAR_LASTBUFF);
TimePageSprite.FillRect(10,180,90,16,0);
//TimePageSprite.pushSprite();
TimePageSprite.FillRect(10,180,90,16,1);
//TimePageSprite.pushSprite();
//delay(1000);

sprintf(str, "Bat: %.2f V",batVol);
TimePageSprite.drawString(10,180,str,&AsciiFont8x16);
//TimePageSprite.pushSprite();
}
'