Signal-Android/image-editor/lib/src/main/java/org/signal/imageeditor/core/model/ThumbRenderer.java

package org.signal.imageeditor.core.model;

import org.signal.imageeditor.core.Bounds;
import org.signal.imageeditor.core.Renderer;

import java.util.UUID;

/**
 * A special {@link Renderer} that controls another {@link EditorElement}.
 * <p>
 * It has a reference to the {@link EditorElement#getId()} and a {@link ControlPoint} which it is in control of.
 * <p>
 * The presence of this interface on the selected element is used to launch a ThumbDragEditSession.
 */
public interface ThumbRenderer extends Renderer {

  enum ControlPoint {

    CENTER_LEFT   (Bounds.LEFT,     Bounds.CENTRE_Y),
    CENTER_RIGHT  (Bounds.RIGHT,    Bounds.CENTRE_Y),

    TOP_CENTER    (Bounds.CENTRE_X, Bounds.TOP),
    BOTTOM_CENTER (Bounds.CENTRE_X, Bounds.BOTTOM),

    TOP_LEFT      (Bounds.LEFT,     Bounds.TOP),
    TOP_RIGHT     (Bounds.RIGHT,    Bounds.TOP),
    BOTTOM_LEFT   (Bounds.LEFT,     Bounds.BOTTOM),
    BOTTOM_RIGHT  (Bounds.RIGHT,    Bounds.BOTTOM);

    private final float x;
    private final float y;

    ControlPoint(float x, float y) {
      this.x = x;
      this.y = y;
    }

    public float getX() {
      return x;
    }

    public float getY() {
      return y;
    }

    public ControlPoint opposite() {
      switch (this) {
        case CENTER_LEFT:   return CENTER_RIGHT;
        case CENTER_RIGHT:  return CENTER_LEFT;
        case TOP_CENTER:    return BOTTOM_CENTER;
        case BOTTOM_CENTER: return TOP_CENTER;
        case TOP_LEFT:      return BOTTOM_RIGHT;
        case TOP_RIGHT:     return BOTTOM_LEFT;
        case BOTTOM_LEFT:   return TOP_RIGHT;
        case BOTTOM_RIGHT:  return TOP_LEFT;
        default:
          throw new RuntimeException();
      }
    }

    public boolean isHorizontalCenter() {
      return this == ControlPoint.CENTER_LEFT || this == ControlPoint.CENTER_RIGHT;
    }

    public boolean isVerticalCenter() {
      return this == ControlPoint.TOP_CENTER || this == ControlPoint.BOTTOM_CENTER;
    }

    public boolean isCenter() {
      return isHorizontalCenter() || isVerticalCenter();
    }
  }

  ControlPoint getControlPoint();

  UUID getElementToControl();
}