Update progress bar to scale with conditional tasks.

ground/src/main/java/com/google/android/ground/ui/datacollection/DataCollectionFragment.kt

@@ -100,17 +100,20 @@ class DataCollectionFragment : AbstractFragment(), BackPressListener {
     }
 
     // Reset progress bar
-    progressBar.progress = 0
-    progressBar.max = (tasks.size - 1) * PROGRESS_SCALE
+    val (start, taskSize) = viewModel.getRelativePosition()
+    progressBar.progress = start
+    progressBar.max = (taskSize - 1) * PROGRESS_SCALE
   }
 
   private fun onTaskChanged() {
-    val index = viewModel.getAbsolutePosition()
-    viewPager.currentItem = index
+    viewPager.currentItem = viewModel.getAbsolutePosition()
 
+    // Reset progress bar
+    val (currIndex, taskSize) = viewModel.getRelativePosition()
+    progressBar.max = (taskSize - 1) * PROGRESS_SCALE
     progressBar.clearAnimation()
 
-    val progressAnimator = ValueAnimator.ofInt(progressBar.progress, index * PROGRESS_SCALE)
+    val progressAnimator = ValueAnimator.ofInt(progressBar.progress, currIndex * PROGRESS_SCALE)
     progressAnimator.duration = 400L
     progressAnimator.interpolator = FastOutSlowInInterpolator()
 

ground/src/main/java/com/google/android/ground/ui/datacollection/DataCollectionViewModel.kt

@@ -148,7 +148,7 @@ internal constructor(
    * the previous Data Collection screen if the user input was valid.
    */
   fun onPreviousClicked(taskViewModel: AbstractTaskViewModel) {
-    check(getAbsolutePosition() != 0)
+    check(getRelativePosition().first != 0)
 
     val validationError = taskViewModel.validate()
     if (validationError != null) {
@@ -198,6 +198,19 @@ internal constructor(
     return tasks.indexOf(tasks.first { it.id == currentTaskId.value })
   }
 
+  /** Get the index of the current task within the (possibly conditional) task sequence. */
+  fun getRelativePosition(): Pair<Int, Int> {
+    var currentIndex = 0
+    var size = 0
+    getTaskSequence().forEachIndexed { index, task ->
+      if (task.id == currentTaskId.value) {
+        currentIndex = index
+      }
+      size++
+    }
+    return currentIndex to size
+  }
+
   /**
    * Retrieves the current task sequence given the inputs and conditions set on the tasks. Setting a
    * start ID will always generate a sequence with the start ID as the first element, and if