// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.ui.util;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import android.graphics.Color;
import androidx.annotation.ColorInt;
import androidx.annotation.FloatRange;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.chromium.base.test.BaseRobolectricTestRunner;
/** Unit tests for {@link ColorUtils}. */
@RunWith(BaseRobolectricTestRunner.class)
public class ColorUtilsTest {
// Use fixed fractions to avoid any float addition that might not exactly hit 0f and 1f.
private static final float[] FRACTIONS = {0f, .1f, .2f, .3f, .4f, .5f, .6f, .7f, .8f, .9f, 1f};
// These cannot have any alpha.
private static final int[] BACKGROUNDS = {
Color.parseColor("#FFFFFF"),
Color.parseColor("#000000"),
Color.parseColor("#115599"),
Color.parseColor("#888888")
};
private static final int[] COLORS = {
Color.parseColor("#00000000"),
Color.parseColor("#00123456"),
Color.parseColor("#00FFFFFF"),
Color.parseColor("#FF000000"),
Color.parseColor("#FF123456"),
Color.parseColor("#FFFFFFFF"),
Color.parseColor("#22446688"),
Color.parseColor("#88888888"),
Color.parseColor("#12345678"),
};
@Test
public void testBlendColorsMultiply() {
for (@ColorInt int background : BACKGROUNDS) {
for (@ColorInt int from : COLORS) {
for (@ColorInt int to : COLORS) {
testBlendColorsMultiplyHelper(background, from, to);
}
}
}
}
@Test
public void testGetOpaqueColor() {
for (@ColorInt int input : COLORS) {
@ColorInt int opaqueColor = ColorUtils.getOpaqueColor(input);
assertRbgExactlyEqual("", opaqueColor, input);
assertEquals(255, Color.alpha(opaqueColor));
}
}
@Test
public void testOverlayTransparentColor() {
// Hard coded solved expected color to avoid just duplicating impl in the test.
@ColorInt int expected = Color.parseColor("#FF143658");
@ColorInt int base = Color.parseColor("#FF123456");
@ColorInt int overlay = Color.parseColor("#12345678");
@ColorInt int actual = ColorUtils.overlayColor(base, overlay);
assertColorsExactlyEqual("", expected, actual);
}
@Test
public void testOverlayTransparentColorWithFraction() {
// Hard coded solved expected color to avoid just duplicating impl in the test.
@ColorInt int expected = Color.parseColor("#FF143658");
@ColorInt int base = Color.parseColor("#FF123456");
@ColorInt int overlay = Color.parseColor("#12345678");
@ColorInt int actual = ColorUtils.overlayColor(base, overlay, .63f);
assertColorsExactlyEqual("", expected, actual);
}
@Test
public void testCalculateLuminance() {
assertEquals(
"Color.BLACK should have a luminance of 0.",
0.0f,
ColorUtils.calculateLuminance(Color.BLACK),
0.01f);
assertEquals(
"Color.WHITE should have a luminance of 1.",
1.0f,
ColorUtils.calculateLuminance(Color.WHITE),
0.01f);
assertEquals(
"Color.GRAY should have a luminance of 0.53125.",
0.53125f,
ColorUtils.calculateLuminance(Color.GRAY),
0.01f);
assertEquals(
"Color.GREEN should have a luminance of about 0.71875.",
0.71875f,
ColorUtils.calculateLuminance(Color.GREEN),
0.01f);
assertEquals(
"Color.CYAN should have a luminance of 0.78125.",
0.78125f,
ColorUtils.calculateLuminance(Color.CYAN),
0.01f);
assertEquals(
"Color.YELLOW should have a luminance of 0.9375.",
0.9375f,
ColorUtils.calculateLuminance(Color.YELLOW),
0.01f);
}
private void testBlendColorsMultiplyHelper(
@ColorInt int background, @ColorInt int from, @ColorInt int to) {
String sharedMessage = formatColors("background:%s from:%s to:%s", background, from, to);
// Calculates an expected color by pre-flattening everything onto the background and an
// actual value by using the pre multiply blend mechanism that combines two colors with
// alpha values. These two approaches should return the same color.
@ColorInt int fromFlat = ColorUtils.overlayColor(background, from);
@ColorInt int toFlat = ColorUtils.overlayColor(background, to);
for (@FloatRange(from = 0f, to = 1f) float fraction : FRACTIONS) {
@ColorInt int flatBlend = ColorUtils.getColorWithOverlay(fromFlat, toFlat, fraction);
@ColorInt int blend = ColorUtils.blendColorsMultiply(from, to, fraction);
@ColorInt int blendOnBackground = ColorUtils.overlayColor(background, blend);
String fractionMessage = String.format("%s fraction:%s", sharedMessage, fraction);
// Use a delta to allow rounding errors where things are off by 1.
assertColorsNearlyEqual(fractionMessage, flatBlend, blendOnBackground, /* delta= */ 1);
}
}
private void assertRbgExactlyEqual(
String testMessage, @ColorInt int expected, @ColorInt int actual) {
String compareMessage =
String.format(
"%s expected:%s actual:%s",
testMessage, printColor(expected), printColor(actual));
assertEquals(compareMessage, Color.red(expected), Color.red(actual));
assertEquals(compareMessage, Color.green(expected), Color.green(actual));
assertEquals(compareMessage, Color.blue(expected), Color.blue(actual));
}
private void assertColorsExactlyEqual(
String testMessage, @ColorInt int expected, @ColorInt int actual) {
assertColorsNearlyEqual(testMessage, expected, actual, /* delta= */ 0);
}
private void assertColorsNearlyEqual(
String testMessage, @ColorInt int expected, @ColorInt int actual, int delta) {
String compareMessage =
String.format(
"%s expected:%s actual:%s",
testMessage, printColor(expected), printColor(actual));
assertTrue(compareMessage, Math.abs(Color.red(expected) - Color.red(actual)) <= delta);
assertTrue(compareMessage, Math.abs(Color.green(expected) - Color.green(actual)) <= delta);
assertTrue(compareMessage, Math.abs(Color.blue(expected) - Color.blue(actual)) <= delta);
assertTrue(compareMessage, Math.abs(Color.alpha(expected) - Color.alpha(actual)) <= delta);
}
private String printColor(@ColorInt int color) {
return String.format(
"{r:%s,g:%s,b:%s,a:%s",
Color.red(color), Color.green(color), Color.blue(color), Color.alpha(color));
}
private String formatColors(String formatString, int... colors) {
int length = colors.length;
Object[] colorStrings = new String[length];
for (int i = 0; i < length; ++i) {
colorStrings[i] = printColor(colors[i]);
}
return String.format(formatString, colorStrings);
}
}
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