Rework panelState to Kotlin property

Author: hannesa2

app/src/androidTest/kotlin/info/hannes/slidingup/demo/tools/Matcher.kt

@@ -36,7 +36,7 @@ fun setValue(value: PanelState): ViewAction {
 
         override fun perform(uiController: UiController?, view: View) {
             val slidingUpPanelLayout = view as SlidingUpPanelLayout
-            slidingUpPanelLayout.setPanelState(value)
+            slidingUpPanelLayout.panelState = value
         }
     }
 }

app/src/main/kotlin/info/hannes/slidinguppanel/demo/DemoActivity.kt

@@ -80,7 +80,7 @@ class DemoActivity : AppCompatActivity() {
             }
         })
         binding.slidingLayout.setFadeOnClickListener {
-            binding.slidingLayout.setPanelState(PanelState.COLLAPSED)
+            binding.slidingLayout.panelState = PanelState.COLLAPSED
             Log.i(tag, "FadeOnClickListener ${binding.slidingLayout.panelState}")
         }
         binding.nameMain.text = Html.fromHtml(getString(R.string.hello))
@@ -116,10 +116,10 @@ class DemoActivity : AppCompatActivity() {
         when (item.itemId) {
             R.id.action_toggle -> {
                 if (binding.slidingLayout.panelState != PanelState.HIDDEN) {
-                    binding.slidingLayout.setPanelState(PanelState.HIDDEN)
+                    binding.slidingLayout.panelState = PanelState.HIDDEN
                     item.setTitle(R.string.action_show)
                 } else {
-                    binding.slidingLayout.setPanelState(PanelState.COLLAPSED)
+                    binding.slidingLayout.panelState = PanelState.COLLAPSED
                     item.setTitle(R.string.action_hide)
                 }
                 return true
@@ -128,11 +128,11 @@ class DemoActivity : AppCompatActivity() {
             R.id.action_anchor -> {
                 if (binding.slidingLayout.anchorPoint == 1.0f) {
                     binding.slidingLayout.anchorPoint = 0.7f
-                    binding.slidingLayout.setPanelState(PanelState.ANCHORED)
+                    binding.slidingLayout.panelState = PanelState.ANCHORED
                     item.setTitle(R.string.action_anchor_disable)
                 } else {
                     binding.slidingLayout.anchorPoint = 1.0f
-                    binding.slidingLayout.setPanelState(PanelState.COLLAPSED)
+                    binding.slidingLayout.panelState = PanelState.COLLAPSED
                     item.setTitle(R.string.action_anchor_enable)
                 }
                 return true
@@ -144,7 +144,7 @@ class DemoActivity : AppCompatActivity() {
     @Deprecated("Deprecated in Java")
     override fun onBackPressed() {
         if ((binding.slidingLayout.panelState == PanelState.EXPANDED || binding.slidingLayout.panelState == PanelState.ANCHORED)) {
-            binding.slidingLayout.setPanelState(PanelState.COLLAPSED)
+            binding.slidingLayout.panelState = PanelState.COLLAPSED
         } else {
             super.onBackPressed()
         }

library/src/main/kotlin/com/sothree/slidinguppanel/SlidingUpPanelLayout.kt

@@ -186,39 +186,41 @@ open class SlidingUpPanelLayout @JvmOverloads constructor(
 
     private var slideState: PanelState = DEFAULT_SLIDE_STATE
 
-    val panelState: PanelState
+    var panelState: PanelState = slideState
         get() = slideState
-
-    fun setPanelState(state: PanelState) {
-        // Abort any running animation, to allow state change
-        if (dragHelper?.viewDragState == ViewDragHelper.STATE_SETTLING) {
-            dragHelper?.abort()
-        }
-        require(state !== PanelState.DRAGGING) { "Panel state can't be DRAGGING during state set" }
-        if (!isEnabled ||
-            (!firstLayout && (slideableView == null)) ||
-            (state === slideState) || (slideState === PanelState.DRAGGING)
-        ) return
-        if (firstLayout) {
-            setPanelStateInternal(state)
-        } else {
-            if (slideState === PanelState.HIDDEN) {
-                slideableView!!.visibility = VISIBLE
-                requestLayout()
+        set(value) {
+            slideState = value
+            field = value
+            // Abort any running animation, to allow state change
+            if (dragHelper?.viewDragState == ViewDragHelper.STATE_SETTLING) {
+                dragHelper?.abort()
             }
-            when (state) {
-                PanelState.ANCHORED -> smoothSlideTo(anchorPoint, 0)
-                PanelState.COLLAPSED -> smoothSlideTo(0f, 0)
-                PanelState.EXPANDED -> smoothSlideTo(maxSlideOffset, 0)
-                PanelState.HIDDEN -> {
-                    val newTop = computePanelTopPosition(0.0f) + if (isSlidingUp) +panelHeight else -panelHeight
-                    smoothSlideTo(computeSlideOffset(newTop), 0)
+            require(value !== PanelState.DRAGGING) { "Panel state can't be DRAGGING during state set" }
+            if (!isEnabled ||
+                (!firstLayout && (slideableView == null)) ||
+                (value === slideState) || (slideState === PanelState.DRAGGING)
+            )
+                return
+            if (firstLayout) {
+                setPanelStateInternal(value)
+            } else {
+                if (slideState === PanelState.HIDDEN) {
+                    slideableView!!.visibility = VISIBLE
+                    requestLayout()
                 }
+                when (value) {
+                    PanelState.ANCHORED -> smoothSlideTo(anchorPoint, 0)
+                    PanelState.COLLAPSED -> smoothSlideTo(0f, 0)
+                    PanelState.EXPANDED -> smoothSlideTo(maxSlideOffset, 0)
+                    PanelState.HIDDEN -> {
+                        val newTop = computePanelTopPosition(0.0f) + if (isSlidingUp) +panelHeight else -panelHeight
+                        smoothSlideTo(computeSlideOffset(newTop), 0)
+                    }
 
-                PanelState.DRAGGING -> Unit
+                    PanelState.DRAGGING -> Unit
+                }
             }
         }
-    }
 
     /**
      * If the current slide state is DRAGGING, this will store the last non dragging state