src/Tools/jEdit/src/font_info.scala

tuned signature: more operations;

/*  Title:      Tools/jEdit/src/font_info.scala
    Author:     Makarius

Font information, derived from main jEdit view font.
*/

package isabelle.jedit


import isabelle._


import java.awt.Font

import org.gjt.sp.jedit.jEdit


object Font_Info {
  /* size range */

  val min_size = 5
  val max_size = 250

  def restrict_size(size: Float): Float = size max min_size.toFloat min max_size.toFloat


  /* main jEdit font */

  def main_family(): String = jEdit.getProperty("view.font")

  def main_size(scale: Double = 1.0): Float =
    restrict_size(jEdit.getIntegerProperty("view.fontsize", 16).toFloat * scale.toFloat)

  def main(scale: Double = 1.0, zoom: Zoom = null): Font_Info =
    Font_Info(main_family(), main_size(if (zoom == null) scale else scale * zoom.scale))

  class Zoom extends GUI.Zoom { tooltip = "Zoom factor for output font size" }


  /* incremental size change */

  object main_change {
    private def change_size(change: Float => Float): Unit = {
      GUI_Thread.require {}

      val size0 = main_size()
      val size = restrict_size(change(size0)).round
      if (size != size0) {
        jEdit.setIntegerProperty("view.fontsize", size)
        jEdit.propertiesChanged()
        jEdit.saveSettings()
        jEdit.getActiveView().getStatus.setMessageAndClear("Text font size: " + size)
      }
    }

    // owned by GUI thread
    private var steps = 0
    private val delay = Delay.last(PIDE.session.input_delay, gui = true) {
      change_size { size =>
        var i = size.round
        while (steps != 0 && i > 0) {
          if (steps > 0) { i += (i / 10) max 1; steps -= 1 }
          else { i -= (i / 10) max 1; steps += 1 }
        }
        steps = 0
        i.toFloat
      }
    }

    def step(i: Int): Unit = {
      steps += i
      delay.invoke()
    }

    def reset(size: Float): Unit = {
      delay.revoke()
      steps = 0
      change_size(_ => size)
    }
  }
}

sealed case class Font_Info(family: String, size: Float) {
  def font: Font = new Font(family, Font.PLAIN, size.round)
}