Scrolling text with st7735 with software.

[zekageri]

Hi!

I want to scroll any text ( its a notification text line on the screen ) while the screen is tft.setRotation(3);.

I achived this with the following code:

String scrollableText = "";
int lastPos = 160;

// This is where the notification function puts the message to the scrollableText buffer and resets the coordinates.
static const inline void addNoty(String msg){
  if(!Firmware_Is_Updating){
    scrollableText = Replace_Accent(msg);
    tft.fillRect(1,87,157,45,WHITE);
    lastPos = 160;
  }else{
    tft.setCursor(0,95);
    tft.setTextSize(2);
    tft.fillRect(0,93,160,45,WHITE);
    tft.print( Replace_Accent(msg) );
  }
}

// This is where the update happens.
static const inline void updateText(){
  if(scrollableText != ""){
    tft.setTextWrap(false,false); // setting text wrap to false because i want to scroll the text
    int minPos = scrollableText.length() * 17; // get the text length multiplied some tested numbers to scroll trought the whole screen
    if(lastPos < -minPos){ lastPos = 160;} // if we reached the minPos we have to reset the position to the other side of the screen
    tft.setCursor(lastPos,93); // always start at the last pos.
    tft.setTextSize(3); // size for readability
    tft.fillRect(1,92,157,45,WHITE); // have to clear the last text from the screen
    lastPos = lastPos - 3; // set the next position.
    tft.print( scrollableText ); // actually print the text
    tft.setTextWrap(true,true); // set the wrap back because some other function writes to the screen too on another task.
  }
}

long startScrollMs = 0;
static const inline void scrollNoty(){
// update the screen every 30 millis if we got IP.
  if(millis() - startScrollMs >= 30){
    startScrollMs = millis();
    if(ETH_Got_IP){
      updateText();
    }
  }
}

The problem is that the text flickering because of this tft.fillRect(1,92,157,45,WHITE); line.

How can i update the text without filling this rect with white background?

[Bodmer]

Have you set the background colour for the text to white, so thne the new text over-writes the old text?

[zekageri]

Have you set the background colour for the text to white, so thne the new text over-writes the old text?

Oh. I thought the text background is default white and my screen background is filled with white default too. The text color is green.

[zekageri]

Here is a video from the flickering on my drive

[zekageri]

Okay. The text background color to WHITE did solved my problem. Thank you for your help!

The update function looks like this now:

static const inline void updateText(){
  if(scrollableText != "" && !writing){
    if(millis() - lastUpdateMs <= LAST_NOTY_DISP_TIME_MS){
      tft.setTextColor(DKGREEN,WHITE);
      tft.setTextWrap(false,false);
      int minPos = scrollableText.length() * 18;
      if(lastPos < -minPos){ lastPos = 160; tft.fillRect(1,92,158,45,WHITE);}
      tft.setCursor(lastPos,93);
      tft.setTextSize(3);
      lastPos = lastPos - 3;
      tft.print( scrollableText );
      tft.setTextWrap(true,true);
    }else if(!resetOnce){
      resetOnce = true;
      tft.fillRect(1,92,158,45,WHITE);
    }
  }
}