Implement TransitionTag

text-minimessage/src/main/java/net/kyori/adventure/text/minimessage/tag/standard/StandardTags.java

@@ -58,7 +58,8 @@ private StandardTags() {
         GradientTag.RESOLVER,
         RainbowTag.RESOLVER,
         ResetTag.RESOLVER,
-        NewlineTag.RESOLVER
+        NewlineTag.RESOLVER,
+        TransitionTag.RESOLVER
       )
       .build();
 
@@ -181,6 +182,16 @@ private StandardTags() {
     return RainbowTag.RESOLVER;
   }
 
+  /**
+   * Get a resolver for the {@value TransitionTag#TRANSITION} tag.
+   *
+   * @return a resolver for the {@value TransitionTag#TRANSITION} tag
+   * @since 4.10.0
+   */
+  public static TagResolver transition() {
+    return TransitionTag.RESOLVER;
+  }
+
   /**
    * Get a resolver for the {@value ResetTag#RESET} tag.
    *

text-minimessage/src/main/java/net/kyori/adventure/text/minimessage/tag/standard/TransitionTag.java

@@ -0,0 +1,163 @@
+/*
+ * This file is part of adventure, licensed under the MIT License.
+ *
+ * Copyright (c) 2017-2022 KyoriPowered
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package net.kyori.adventure.text.minimessage.tag.standard;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.OptionalDouble;
+import java.util.stream.Stream;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.format.NamedTextColor;
+import net.kyori.adventure.text.format.TextColor;
+import net.kyori.adventure.text.minimessage.Context;
+import net.kyori.adventure.text.minimessage.tag.Inserting;
+import net.kyori.adventure.text.minimessage.tag.Tag;
+import net.kyori.adventure.text.minimessage.tag.resolver.ArgumentQueue;
+import net.kyori.adventure.text.minimessage.tag.resolver.TagResolver;
+import net.kyori.examination.Examinable;
+import net.kyori.examination.ExaminableProperty;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Changes the color based on a phase param.
+ *
+ * @since 4.10.0
+ */
+public final class TransitionTag implements Inserting, Examinable {
+  public static final String TRANSITION = "transition";
+
+  private final TextColor[] colors;
+  private final float phase;
+  private final boolean negativePhase;
+
+  static final TagResolver RESOLVER = TagResolver.resolver(TransitionTag.TRANSITION, TransitionTag::create);
+
+  static Tag create(final ArgumentQueue args, final Context ctx) {
+    float phase = 0;
+    final List<TextColor> textColors;
+    if (args.hasNext()) {
+      textColors = new ArrayList<>();
+      while (args.hasNext()) {
+        final Tag.Argument arg = args.pop();
+        // last argument? maybe this is the phase?
+        if (!args.hasNext()) {
+          final OptionalDouble possiblePhase = arg.asDouble();
+          if (possiblePhase.isPresent()) {
+            phase = (float) possiblePhase.getAsDouble();
+            if (phase < -1f || phase > 1f) {
+              throw ctx.newException(String.format("Gradient phase is out of range (%s). Must be in the range [-1.0f, 1.0f] (inclusive).", phase), args);
+            }
+            break;
+          }
+        }
+
+        final String argValue = arg.value();
+        final TextColor parsedColor;
+        if (argValue.charAt(0) == '#') {
+          parsedColor = TextColor.fromHexString(argValue);
+        } else {
+          parsedColor = NamedTextColor.NAMES.value(arg.lowerValue());
+        }
+        if (parsedColor == null) {
+          throw ctx.newException(String.format("Unable to parse a color from '%s'. Please use named colors or hex (#RRGGBB) colors.", argValue), args);
+        }
+        textColors.add(parsedColor);
+      }
+
+      if (textColors.size() < 2) {
+        throw ctx.newException("Invalid transition, not enough colors. Transitions must have at least two colors.", args);
+      }
+    } else {
+      textColors = Collections.emptyList();
+    }
+
+    return new TransitionTag(phase, textColors);
+  }
+
+  private TransitionTag(final float phase, final List<TextColor> colors) {
+    if (phase < 0) {
+      this.negativePhase = true;
+      this.phase = 1 + phase;
+      Collections.reverse(colors);
+    } else {
+      this.negativePhase = false;
+      this.phase = phase;
+    }
+
+    if (colors.isEmpty()) {
+      this.colors = new TextColor[]{TextColor.color(0xffffff), TextColor.color(0x000000)};
+    } else {
+      this.colors = colors.toArray(new TextColor[0]);
+    }
+  }
+
+  @Override
+  public @NotNull Component value() {
+    return Component.text("", this.color());
+  }
+
+  private TextColor color() {
+    final float steps = 1f / (this.colors.length - 1);
+    for (int colorIndex = 1; colorIndex < this.colors.length; colorIndex++) {
+      final float val = colorIndex * steps;
+      if (val >= this.phase) {
+        final float factor = 1 + (this.phase - val) * (this.colors.length - 1);
+
+        if (this.negativePhase) {
+          // flip the gradient segment for to allow for looping phase -1 through 1
+          return TextColor.lerp(1 - factor, this.colors[colorIndex], this.colors[colorIndex - 1]);
+        } else {
+          return TextColor.lerp(factor, this.colors[colorIndex - 1], this.colors[colorIndex]);
+        }
+      }
+    }
+    return this.colors[0];
+  }
+
+  @Override
+  public @NotNull Stream<? extends ExaminableProperty> examinableProperties() {
+    return Stream.of(
+      ExaminableProperty.of("phase", this.phase),
+      ExaminableProperty.of("colors", this.colors)
+    );
+  }
+
+  @Override
+  public boolean equals(final Object other) {
+    if (this == other) return true;
+    if (other == null || this.getClass() != other.getClass()) return false;
+    final TransitionTag that = (TransitionTag) other;
+    return this.phase == that.phase && Arrays.equals(this.colors, that.colors);
+  }
+
+  @Override
+  public int hashCode() {
+    int result = Objects.hash(this.phase);
+    result = 31 * result + Arrays.hashCode(this.colors);
+    return result;
+  }
+}

text-minimessage/src/test/java/net/kyori/adventure/text/minimessage/tag/standard/TransitionTagTest.java

@@ -0,0 +1,48 @@
+/*
+ * This file is part of adventure, licensed under the MIT License.
+ *
+ * Copyright (c) 2017-2022 KyoriPowered
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package net.kyori.adventure.text.minimessage.tag.standard;
+
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.format.TextColor;
+import net.kyori.adventure.text.minimessage.AbstractTest;
+import org.junit.jupiter.api.Test;
+
+import static net.kyori.adventure.text.Component.text;
+import static net.kyori.adventure.text.format.NamedTextColor.BLACK;
+import static net.kyori.adventure.text.format.NamedTextColor.WHITE;
+import static net.kyori.adventure.text.format.TextColor.color;
+
+class TransitionTagTest extends AbstractTest {
+
+  @Test
+  void testTransition() {
+    final TextColor[] colors = new TextColor[] {BLACK, color(0x808080), WHITE, color(0x808080), BLACK};
+    final float[] phases = new float[] {-1, 0.5f, 0, 0.5f, 1};
+    for (int i = 0; i < colors.length; i++) {
+      final String input = "<transition:white:black:" + phases[i] + ">Hello World";
+      final Component expected = text("", colors[i]).append(text("Hello World"));
+      this.assertParsedEquals(expected, input);
+    }
+  }
+}