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PiledroMurcia
Asked: 2020-05-06 00:06:52 +0800 CST 2020-05-06 00:06:52 +0800 CST

Paint with random colors

  • 772

I have the following onDraw:

public void onDraw(Canvas canvas) {
    paint = new Paint();
    paint.setColor(Color.RED);
    canvas.drawRect(rectangulo,paint);
}

I would like to know how to implement so that it was not just Color.REDrandom colors.

Something like an array with various colors and the set color calls it?

This is my code:

private static final int[] colores = {Color.GREEN,Color.BLUE,Color.RED};

In the constructor:

r = new Random();
num = r.nextInt(3);

and the Ondraw:

public void onDraw(Canvas canvas) {
  paint = new Paint();
  paint.setColor(colores[num]);
  canvas.drawRect(rectangulo,paint);
}
java

3 Answers

  1. The simplest for random colors is:

    new Color((int)(Math.random() * 0x1000000))

    Leaving your method:

    public void onDraw(Canvas canvas) {
    paint = new Paint();
    paint.setColor(new Color((int)(Math.random() * 0x1000000)));
    canvas.drawRect(rectangulo,paint);
}

    show

    Another way is to create each value of RGBindividually.

    public void onDraw(Canvas canvas) {
    Random r = new Random();
    Color randomColor = new Color( r.nextInt(256), r.nextInt(256), r.nextInt(256) );
    paint = new Paint();
    paint.setColor(randomColor);
    canvas.drawRect(rectangulo,paint);
}

    show

    Note: You have to importjava.util.Random

    • 2

  2. You can create random colors without using Paint

    private String getRandomColor() {
String color = "#";
String[] a = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"};
int r = (int) (Math.random()*  (16 -1) +1);
int g = (int) (Math.random()*  (16 -1) +1);
while (g == r) {
g = (int) (Math.random()*  (16 -1) +1);
}
int b = (int) (Math.random()*  (16 -1) +1);
while (b == r || b == g) {
b = (int) (Math.random()*  (16 -1) +1);
}
color += a[r] + a[g] + a[b];
return color;
}
    • 2
  3. Best Answer

    For that you can use this method:

    public int getRandomColor(){
    Random rnd = new Random();
    return Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
}

    Which is used in this example: Buttons in Android . To call the method, you simply do it like this:

    public void onDraw(Canvas canvas) {
    paint = new Paint();
    paint.setColor(getRandomColor()); //Asigna un color aleatorio.
    canvas.drawRect(rectangulo,paint);
}

    so that each time the method onDraw()is called, it paints a random color.

    enter image description here

    • 1