Disable refresh if not at the top, resolves #1450

2 files changed, 81 insertions, 0 deletions

diff --git a/app/src/main/kotlin/com/pitchedapps/frost/activities/LoginActivity.kt b/app/src/main/kotlin/com/pitchedapps/frost/activities/LoginActivity.kt
index ed207896..42a0f6bb 100644
--- a/app/src/main/kotlin/com/pitchedapps/frost/activities/LoginActivity.kt
+++ b/app/src/main/kotlin/com/pitchedapps/frost/activities/LoginActivity.kt
@@ -87,6 +87,9 @@ class LoginActivity : BaseActivity() {
             toolbar(toolbar)
         }
         profileLoader = GlideApp.with(profile)
+        swipeRefresh.setOnChildScrollUpCallback { parent, child ->
+            web.canScrollVertically(-1)
+        }
         launch {
             for (refreshing in refreshChannel.uniqueOnly(this)) {
                 if (refreshing) swipeRefresh.isEnabled = true
diff --git a/app/src/main/kotlin/com/pitchedapps/frost/views/SwipeRefreshLayout.kt b/app/src/main/kotlin/com/pitchedapps/frost/views/SwipeRefreshLayout.kt
new file mode 100644
index 00000000..0ab11fc6
--- /dev/null
+++ b/app/src/main/kotlin/com/pitchedapps/frost/views/SwipeRefreshLayout.kt
@@ -0,0 +1,78 @@
+package com.pitchedapps.frost.views
+
+import android.content.Context
+import android.util.AttributeSet
+import android.view.MotionEvent
+import android.view.View
+import android.view.ViewConfiguration
+import android.webkit.WebView
+import android.widget.ListView
+import androidx.core.widget.ListViewCompat
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout.OnChildScrollUpCallback
+import com.pitchedapps.frost.utils.L
+
+/**
+ * Variant that forbids refreshing if child layout is not at the top
+ * Inspired by https://github.com/slapperwan/gh4a/blob/master/app/src/main/java/com/gh4a/widget/SwipeRefreshLayout.java
+ *
+ */
+class SwipeRefreshLayout @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null) :
+    SwipeRefreshLayout(context, attrs) {
+
+    private var preventRefresh: Boolean = false
+    private var downY: Float = -1f
+    private val touchSlop = ViewConfiguration.get(context).scaledTouchSlop
+
+    /**
+     * Copy of [canChildScrollUp], with additional support if necessary
+     */
+    private val canChildScrollUp = OnChildScrollUpCallback { parent, child ->
+        when (child) {
+            is WebView -> child.canScrollVertically(-1).apply {
+                L.d { "Webview can scroll up $this" }
+            }
+            is ListView -> ListViewCompat.canScrollList(child, -1)
+            // Supports webviews as well
+            else -> child?.canScrollVertically(-1) ?: false
+        }
+    }
+
+    init {
+        setOnChildScrollUpCallback(canChildScrollUp)
+    }
+
+    override fun onInterceptTouchEvent(ev: MotionEvent): Boolean {
+        if (ev.action != MotionEvent.ACTION_DOWN && preventRefresh) {
+            return false
+        }
+        when (ev.action) {
+            MotionEvent.ACTION_DOWN -> {
+                downY = ev.y
+                preventRefresh = canChildScrollUp()
+            }
+            MotionEvent.ACTION_MOVE -> {
+                if (downY - ev.y > touchSlop) {
+                    preventRefresh = true
+                    return false
+                }
+            }
+        }
+        return super.onInterceptTouchEvent(ev)
+    }
+
+    override fun onNestedScroll(target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int) {
+        if (preventRefresh) {
+            /*
+             * Ignoring offsetInWindow since
+             * 1. It doesn't seem to matter in the typical use case
+             * 2. It isn't being transferred to the underlying array used by the super class
+             */
+            dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, null)
+        } else {
+            super.onNestedScroll(target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed)
+        }
+    }
+
+    interface OnRefreshListener : SwipeRefreshLayout.OnRefreshListener
+}
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