doodle.interact.algebra.MouseMove.scala Maven / Gradle / Ivy

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/*
 * Copyright 2015 Creative Scala
 *
 * 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 doodle
package interact
package algebra

import cats.effect.IO
import doodle.core.Point
import fs2.Stream

/** Algebra for generating a stream of events giving the current mouse location.
  * Whenever the mouse moves a new event is generated. The algebra applies to a
  * Renderer's Canvas data type instead of the F data type, and hence gives the
  * mouse location in the canvas rather than relative to any Picture rendered on
  * the canvas.
  */
trait MouseMove[Canvas] {

  /** Return a stream that has an event every time the mouse moves across the
    * canvas. The coordinate system used is the global coordinate system used by
    * the Canvas, which usually means the origin is centered on the canvas.
    */
  def mouseMove(canvas: Canvas): Stream[IO, Point]
}