Add support for centrally places tooltips (screen center)

coachmark/src/commonMain/kotlin/com/pseudoankit/coachmark/demo/UnifyCoachmarkDemo.kt

@@ -24,7 +24,7 @@ import com.pseudoankit.coachmark.shape.Arrow
 import com.pseudoankit.coachmark.shape.Balloon
 import com.pseudoankit.coachmark.util.CoachMarkKey
 
-public enum class Keys { Text1, Text2, TextStart, TextBottom, TextTop }
+public enum class Keys { Text1, Text2, TextCenter, TextStart, TextBottom, TextTop }
 
 
 @Composable
@@ -85,6 +85,18 @@ private fun ColumnScope.PlotTextsAndUseLocalCoachMarkScope() {
         placement = ToolTipPlacement.End
     )
 
+    CoachMarkTargetText(
+        text = "Will show tooltip centrally",
+        alignment = Alignment.CenterHorizontally,
+        key = Keys.TextCenter,
+        placement = ToolTipPlacement.ScreenCenter,
+        tooltip = {
+            Balloon(arrow = Arrow.Top()) {
+                Text(text = "tooltip on screen center at enableCoachmark method", color = Color.White)
+            }
+        }
+    )
+
     CoachMarkTargetText(
         text = "Will show tooltip to left",
         alignment = Alignment.End,
@@ -156,6 +168,12 @@ private fun Tooltip(key: CoachMarkKey) {
             }
         }
 
+        Keys.TextCenter -> {
+            Balloon(arrow = Arrow.Top()) {
+                Text(text = "A tooltip on screen center root level", color = Color.White)
+            }
+        }
+
         Keys.TextStart -> {
             Balloon(arrow = Arrow.End()) {
                 Text(text = "A tooltip to the left  root level", color = Color.White)

coachmark/src/commonMain/kotlin/com/pseudoankit/coachmark/model/ToolTipPlacement.kt

@@ -26,5 +26,11 @@ public enum class ToolTipPlacement {
     /**
      * denotes that tooltip will be placed at bottom of actual view
      */
-    Bottom
+    Bottom,
+
+    /**
+     * denotes that tooltip will be placed at the center of the screen, regardless of the actual view.
+     */
+    ScreenCenter
+
 }

coachmark/src/commonMain/kotlin/com/pseudoankit/coachmark/overlay/OverlayLayout.kt

@@ -62,8 +62,8 @@ public fun OverlayLayout(
 
         // place children
         layout(constraints.maxWidth, constraints.maxHeight) {
-            place(placeableCurrent, configCurrent)
-            place(placeablePrevious, configPrevious)
+            place(placeableCurrent, configCurrent, constraints.maxWidth, constraints.maxHeight)
+            place(placeablePrevious, configPrevious, constraints.maxWidth, constraints.maxHeight)
         }
     }
 }
@@ -125,8 +125,15 @@ private fun measure(
  * Centralizes null checks and switching on toolTipPlacement value.
  * @param placeable no-op if null
  * @param config no-op if null
+ * @param containerWidth the width of the container overlay
+ * @param containerHeight the height of the container overlay
  */
-private fun Placeable.PlacementScope.place(placeable: Placeable?, config: TooltipConfig?) {
+private fun Placeable.PlacementScope.place(
+    placeable: Placeable?,
+    config: TooltipConfig?,
+    containerWidth: Int,
+    containerHeight: Int
+) {
     if (placeable != null && config != null) {
         val layout = config.layout
         var x = 0
@@ -142,6 +149,10 @@ private fun Placeable.PlacementScope.place(placeable: Placeable?, config: Toolti
         fun centerHorizontally() =
             (layout.startX + calculateCenteringOffset(layout.width, placeable.width)).toInt()
 
+        fun centerVerticallyToScreen() = (containerHeight - placeable.height) / 2
+
+        fun centerHorizontallyToScreen() = (containerWidth - placeable.width) / 2
+
         when (config.toolTipPlacement) {
             ToolTipPlacement.Start -> {
                 x = layout.startX.toInt() - placeable.width
@@ -162,6 +173,11 @@ private fun Placeable.PlacementScope.place(placeable: Placeable?, config: Toolti
                 x = centerHorizontally()
                 y = layout.endY.toInt()
             }
+
+            ToolTipPlacement.ScreenCenter -> {
+                x = centerHorizontallyToScreen()
+                y = centerVerticallyToScreen()
+            }
         }
 
         placeable.placeRelative(x, y)