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app/src/main/kotlin/space/subread/overlay/OverlayView.kt (10781 bytes)

 package space.subread.overlay
 
 import android.annotation.SuppressLint
 import android.content.ClipData
 import android.content.ClipboardManager
 import android.content.Context
 import android.graphics.Color
 import android.graphics.Typeface
 import android.text.SpannableString
 import android.text.Spanned
 import android.text.style.BackgroundColorSpan
 import android.text.style.ForegroundColorSpan
 import android.text.style.RelativeSizeSpan
 import android.util.TypedValue
 import android.view.Gravity
 import android.view.MotionEvent
 import android.view.View
 import android.widget.Button
 import android.widget.LinearLayout
 import android.widget.TextView
 import androidx.core.view.isVisible
 
 /**
  * The panel over the media player: the subtitle line, and a few buttons.
  *
  * A tap on the line selects the word under the finger. A drag makes the selection longer, word
  * by word. The selection goes to a dictionary with "Look up". The system text selection is not
  * used: it needs a window with the input focus, and then the player below gets no keys.
  *
  * Black on white and nothing that moves, so that the panel is usable on an e-ink screen.
  */
 @SuppressLint("ViewConstructor", "SetTextI18n")
 class OverlayView(context: Context, private val events: Events) : LinearLayout(context) {
 
     interface Events {
         fun onDrag(dx: Float, dy: Float)
         fun onDragEnd()
         fun onClose()
         fun onLookUp(word: String)
         /** "Share": the selection goes to an app that the user picks in the share sheet. */
         fun onShare(word: String)
         /** The play button: pause the player when it plays, else start it. */
         fun onTogglePlay()
         fun onShiftLines(steps: Int)
         fun onNudge(ms: Long)
         /** The selection went away: a tap beside a word, or a new line. */
         fun onSelectionCleared() {}
     }
 
     /**
      * The text on the panel, without the selection marks. With the lines around, the line
      * before and the line after are in it too, each on its own row.
      */
     var line: String = ""
         private set
 
     /** The parts of [line] that are the lines around: they are drawn small and grey. */
     private var around: List<IntRange> = emptyList()
 
     /** The part of [line] that is selected. */
     var selection: IntRange? = null
         private set
 
     val text = TextView(context)
     private val lookUpRow = LinearLayout(context)
     private val syncRow = LinearLayout(context)
     private val offsetLabel = TextView(context)
     private val playButton = button("▶", "Start the player") { events.onTogglePlay() }
     private var anchor: IntRange? = null
 
     init {
         orientation = VERTICAL
         setBackgroundResource(R.drawable.panel)
         val pad = dp(6)
         setPadding(pad, pad, pad, pad)
 
         val top = LinearLayout(context).apply { gravity = Gravity.CENTER_VERTICAL }
         top.addView(button("≡", "Move the subtitles") {}.also(::dragWith), wrap())
         text.setTextColor(Color.BLACK)
         text.typeface = Typeface.DEFAULT
         text.setPadding(dp(8), dp(4), dp(8), dp(4))
         text.setLineSpacing(0f, 1.15f)
         selectWith(text)
         top.addView(text, LayoutParams(0, LayoutParams.WRAP_CONTENT, 1f))
         top.addView(playButton, wrap())
         top.addView(button("⋯", "Timing") { toggle(syncRow) }, wrap())
         top.addView(button("✕", "Close the subtitles") { events.onClose() }, wrap())
         addView(top, LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT))
 
         lookUpRow.gravity = Gravity.END
         lookUpRow.addView(button("Copy", null) { copy() }, wrap())
         lookUpRow.addView(button("Share", null) { share() }, wrap())
         lookUpRow.addView(button("Look up", null) { lookUp() }, wrap())
         lookUpRow.visibility = View.GONE
         addView(lookUpRow, LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT))
 
         syncRow.gravity = Gravity.CENTER
         syncRow.addView(button("◀ line", "The line before is the line now") { events.onShiftLines(-1) }, wrap())
         syncRow.addView(button("−0.5 s", "Subtitles later") { events.onNudge(-500) }, wrap())
         offsetLabel.setTextColor(Color.BLACK)
         offsetLabel.setPadding(dp(8), 0, dp(8), 0)
         syncRow.addView(offsetLabel, wrap())
         syncRow.addView(button("+0.5 s", "Subtitles sooner") { events.onNudge(500) }, wrap())
         syncRow.addView(button("line ▶", "The next line is the line now") { events.onShiftLines(1) }, wrap())
         syncRow.visibility = View.GONE
         addView(syncRow, LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT))
     }
 
     fun setTextSize(sp: Float) = text.setTextSize(TypedValue.COMPLEX_UNIT_SP, sp)
 
     /** Lets [percent] of the player show through the panel. The text and the buttons stay as they are. */
     fun setTransparency(percent: Int) {
         background.mutate().alpha = 255 * (100 - percent.coerceIn(0, 100)) / 100
     }
 
     fun showPlaying(playing: Boolean) {
         playButton.text = if (playing) "⏸" else "▶"
         playButton.contentDescription = if (playing) "Pause the player" else "Start the player"
     }
 
     fun showOffset(ms: Long) {
         offsetLabel.text = "%+.1f s".format(ms / 1000.0)
     }
 
     /**
      * Shows a subtitle line, with the line [before] it and the line [after] it when they are
      * given. The selection goes away when the text changes.
      */
     fun showLine(value: String, before: String? = null, after: String? = null) {
         val whole = listOfNotNull(before, value, after).joinToString("\n")
         if (whole == line) return
         line = whole
         around = buildList {
             if (before != null) add(0 until before.length)
             if (after != null) add(whole.length - after.length until whole.length)
         }
         text.setTypeface(Typeface.DEFAULT, Typeface.NORMAL)
         select(null)
     }
 
     /** Shows a word of the app to the user, where the line would be: no player, no file. */
     fun showStatus(value: String) {
         line = ""
         around = emptyList()
         selection = null
         lookUpRow.visibility = View.GONE
         text.setTypeface(Typeface.DEFAULT, Typeface.ITALIC)
         text.text = value
     }
 
     /** Selects the word at the point [x], [y] of the text view. For a tap, and for tests. */
     fun selectAt(x: Float, y: Float, extend: Boolean = false) {
         val offset = offsetAt(x, y) ?: return select(if (extend) selection else null)
         val from = anchor
         if (extend && from != null) {
             select(Words.between(line, from, offset))
         } else {
             anchor = Words.at(line, offset)
             select(anchor)
         }
     }
 
     private fun select(range: IntRange?) {
         selection = range
         if (range == null) anchor = null
         val marked = SpannableString(line)
         for (part in around) {
             marked.setSpan(ForegroundColorSpan(Color.DKGRAY), part.first, part.last + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
             marked.setSpan(RelativeSizeSpan(0.85f), part.first, part.last + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
         }
         if (range != null) {
             marked.setSpan(BackgroundColorSpan(Color.BLACK), range.first, range.last + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
             marked.setSpan(ForegroundColorSpan(Color.WHITE), range.first, range.last + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
         }
         text.text = marked
         lookUpRow.visibility = if (range == null) View.GONE else View.VISIBLE
         if (range == null) events.onSelectionCleared()
     }
 
     /** The index of the character under the point; null when the point is not on a character. */
     private fun offsetAt(x: Float, y: Float): Int? {
         val layout = text.layout ?: return null
         if (line.isEmpty()) return null
         val inX = x - text.totalPaddingLeft
         val inY = y - text.totalPaddingTop
         if (inY < 0 || inY > layout.height) return null
         val row = layout.getLineForVertical(inY.toInt())
         if (inX < layout.getLineLeft(row) || inX > layout.getLineRight(row)) return null
         // The offset of a point is a place between two characters. The character under the
         // finger is the one before that place when the finger is on its right half.
         val between = layout.getOffsetForHorizontal(row, inX)
         val under = if (between > layout.getLineStart(row) && layout.getPrimaryHorizontal(between) > inX) between - 1 else between
         return under.coerceIn(0, line.length - 1)
     }
 
     private fun selected(): String? = selection?.let { line.substring(it.first, it.last + 1) }
 
     private fun lookUp() {
         events.onLookUp(selected() ?: return)
     }
 
     private fun share() {
         events.onShare(selected() ?: return)
     }
 
     private fun copy() {
         val word = selected() ?: return
         context.getSystemService(ClipboardManager::class.java).setPrimaryClip(ClipData.newPlainText("subtitle", word))
     }
 
     @SuppressLint("ClickableViewAccessibility") // The buttons of the panel do the same for a screen reader.
     private fun selectWith(view: TextView) {
         view.setOnTouchListener { _, event ->
             when (event.actionMasked) {
                 MotionEvent.ACTION_DOWN -> selectAt(event.x, event.y)
                 MotionEvent.ACTION_MOVE -> selectAt(event.x, event.y, extend = true)
             }
             true
         }
     }
 
     @SuppressLint("ClickableViewAccessibility") // A drag has no equal for a screen reader; the panel works where it is.
     private fun dragWith(handle: View) {
         var lastX = 0f
         var lastY = 0f
         handle.setOnTouchListener { _, event ->
             when (event.actionMasked) {
                 MotionEvent.ACTION_DOWN -> {
                     lastX = event.rawX
                     lastY = event.rawY
                 }
                 MotionEvent.ACTION_MOVE -> {
                     events.onDrag(event.rawX - lastX, event.rawY - lastY)
                     lastX = event.rawX
                     lastY = event.rawY
                 }
                 MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> events.onDragEnd()
             }
             true
         }
     }
 
     private fun toggle(row: View) {
         row.isVisible = !row.isVisible
     }
 
     private fun button(label: String, description: String?, onClick: () -> Unit) = Button(context).apply {
         text = label
         isAllCaps = false
         contentDescription = description ?: label
         minWidth = dp(44)
         minimumWidth = dp(44)
         setOnClickListener { onClick() }
     }
 
     private fun wrap() = LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)
 
     private fun dp(value: Int) = (value * resources.displayMetrics.density).toInt()
 }