Add a clear() method to the LED matrix library

[alranel]

This method makes it easy to turn off the matrix.

[aentinger]

Hi @alranel ☕ 👋

How do you expect this API being used? If I see a clear API in this context I expect the RGB LED matrix to be wiped clean the moment I call it. However, that does not work. I.e. in the following example sketch both 1 and 2 are persistently displayed:

#include "ArduinoGraphics.h"
#include "Arduino_LED_Matrix.h"

ArduinoLEDMatrix matrix;

void setup() {
  matrix.begin();
}

void loop() {
  matrix.beginDraw();
  matrix.clear();
  const char text_1[] = "1";
  matrix.textFont(Font_4x6);
  matrix.beginText(0, 1, 0xFFFFFF);
  matrix.println(text_1);
  matrix.endText();
  matrix.endDraw();

  delay(1000);

  matrix.beginDraw();
  matrix.clear();
  const char text_2[] = "2";
  matrix.textFont(Font_4x6);
  matrix.beginText(8, 1, 0xFFFFFF);
  matrix.println(text_2);
  matrix.endText();
  matrix.endDraw();

  delay(1000);
}

[alranel]

Hi @aentinger!
The intention is to provide a method to wipe the matrix instantly. I implemented it as a shortcut to matrix.loadFrame() called with a blank frame, which AFAIK should work. Maybe it should not be called inside beginDraw()? What do you recommend to achieve this goal?

[alranel]

I added an example to the PR to show the intended usage. I also just tested it and it works.

To add some context: this is what I saw quite a few users doing manually all the time when they need to wipe the matrix. :)