Writing and re-writing text?

[david-bethesda]

I'm trying to create a text area on the screen where I can write some text (like a sensor value) and then periodically replace this with new text somehow. I can't find anything about how to do common operations like this. How do I erase the prior value and replace it with the new value? thanks

[ajb2k3]

You can hold use a label to display a sensor value and place it inside a loop so that it will constantly check the sensors reading and update the value.

[david-bethesda]

Thanks @ajb2k3 but I'm writing this particular code in C++ / Arduino so I'm using M5.Lcd

[AgreeDK]

@david-bethesda you select where to write the text, x & y, then make a function to first erase the area with fill rect and then write the new text at x,y

[david-bethesda]

@agreedk thanks! I guess that means I have to figure out how tall a font is in pixels, and how wide the phrase is, ugh. Feels very imprecise and clunky.

[macsbug]

Hello @david-bethesda

Use "backgroundcolor"

setTextColor(uint16_t color, uint16_t backgroundcolor);
m5-docs/docs/en/api/lcd.md
https://github.com/m5stack/m5-docs/blob/master/docs/en/api/lcd.md

#include <M5Stack.h>
void setup() {
M5.begin();
M5.Lcd.setTextSize(2);

// Numerical Value
M5.Lcd.setCursor(5, 10);
M5.Lcd.setTextColor(TFT_WHITE, TFT_BLACK);
M5.Lcd.println(123456.78);
M5.Lcd.setCursor(5, 10);
M5.Lcd.println(" "); // "........."
M5.Lcd.setCursor(5, 10);
M5.Lcd.println(1.41);

// Stirng
M5.Lcd.setCursor(5, 50);
M5.Lcd.println("987654.32");
M5.Lcd.setCursor(5, 50);
M5.Lcd.println(" "); // "........."
M5.Lcd.setCursor(5, 50);
M5.Lcd.setTextColor(TFT_WHITE, TFT_BLACK);
M5.Lcd.println("3.14");

}

void loop() {

}

If there is no background color

If there is a background color

[david-bethesda]

@macsbug Thank you!