[M3][Color] Internal color library update

PiperOrigin-RevId: 547561948

lib/java/com/google/android/material/color/utilities/ContrastCurve.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.material.color.utilities;
+
+import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP;
+
+import androidx.annotation.RestrictTo;
+
+/**
+ * A class containing the contrast curve for a dynamic color on its background.
+ *
+ * <p>The four values correspond to contrast requirements for contrast levels -1.0, 0.0, 0.5, and
+ * 1.0, respectively.
+ *
+ * @hide
+ */
+@RestrictTo(LIBRARY_GROUP)
+public final class ContrastCurve {
+  /** Contrast requirement for contrast level -1.0 */
+  private final double low;
+
+  /** Contrast requirement for contrast level 0.0 */
+  private final double normal;
+
+  /** Contrast requirement for contrast level 0.5 */
+  private final double medium;
+
+  /** Contrast requirement for contrast level 1.0 */
+  private final double high;
+
+  /**
+   * Creates a `ContrastCurve` object.
+   *
+   * @param low Contrast requirement for contrast level -1.0
+   * @param normal Contrast requirement for contrast level 0.0
+   * @param medium Contrast requirement for contrast level 0.5
+   * @param high Contrast requirement for contrast level 1.0
+   */
+  public ContrastCurve(double low, double normal, double medium, double high) {
+    this.low = low;
+    this.normal = normal;
+    this.medium = medium;
+    this.high = high;
+  }
+
+  /**
+   * Returns the contrast ratio at a given contrast level.
+   *
+   * @param contrastLevel The contrast level. 0.0 is the default (normal); -1.0 is the lowest; 1.0
+   *     is the highest.
+   * @return The contrast ratio, a number between 1.0 and 21.0.
+   */
+  public double getContrast(double contrastLevel) {
+    if (contrastLevel <= -1.0) {
+      return this.low;
+    } else if (contrastLevel < 0.0) {
+      return MathUtils.lerp(this.low, this.normal, (contrastLevel - -1) / 1);
+    } else if (contrastLevel < 0.5) {
+      return MathUtils.lerp(this.normal, this.medium, (contrastLevel - 0) / 0.5);
+    } else if (contrastLevel < 1.0) {
+      return MathUtils.lerp(this.medium, this.high, (contrastLevel - 0.5) / 0.5);
+    } else {
+      return this.high;
+    }
+  }
+}