CODEWITHSUNDEEP
javaandroidandroid-color
JayVDiyk
JayVDiyk

Reputation: 4487

Get Darker Color by Factor Given Color Int

Here is how I get a Lighter color given an int. But I am wondering how can I convert this to give me a darker color?

How should I modify the method below to give a darker color? 

public static int getLighterColorByValue(int color, float factor) {
    int red = (int) ((Color.red(color) * (1 - factor) / 255 + factor) * 255);
    int green = (int) ((Color.green(color) * (1 - factor) / 255 + factor) * 255);
    int blue = (int) ((Color.blue(color) * (1 - factor) / 255 + factor) * 255);
    return Color.argb(Color.alpha(color), red, green, blue);
}

Upvotes: 1

Views: 188

Answers (1)

Andy Turner
Andy Turner

Reputation: 140318

Considering only the red channel (since the logic for the others is identical):

int red = (int) ((Color.red(color) * (1 - factor) / 255 + factor) * 255);

You are calculating a weighted sum between the current red channel and 255 (full intensity). In simplified terms:

int newRed = (1 - factor) * oldRed + factor * 255;

So, instead of blending with full intensity, blend with zero intensity:

int newRed = (1 - factor) * oldRed + factor * 0;

or, more simply:

int newRed = (1 - factor) * oldRed;

So, using the format of your original code, just drop the + factor:

int red = (int) ((Color.red(color) * (1 - factor) / 255) * 255);

But since 1 - factor is a float, dividing by 255 and multiplying by 255 gets you back to the same number again. So, more simply:

int red = (int) ((Color.red(color) * (1 - factor));
int green = (int) ((Color.green(color) * (1 - factor));
int blue = (int) ((Color.blue(color) * (1 - factor));

Sanity check:

  • If factor == 0, the new color is the same as the original color
  • It factor == 1, (1 - factor) == 0, so red == green == blue == 0, i.e. the new color is black.

Upvotes: 2

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