Movable FAB in ViewPostDetailActivity.

app/src/main/java/ml/docilealligator/infinityforreddit/customviews/MovableFloatingActionButton.java

@@ -0,0 +1,121 @@
+package ml.docilealligator.infinityforreddit.customviews;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewGroup;
+
+import com.google.android.material.floatingactionbutton.FloatingActionButton;
+
+public class MovableFloatingActionButton extends FloatingActionButton implements View.OnTouchListener {
+    private final static float CLICK_DRAG_TOLERANCE = 50;
+    private long downTime = 0;
+    private boolean moved = false;
+    private boolean longClicked = false;
+
+    private float downRawX, downRawY;
+    private float dX, dY;
+
+    public MovableFloatingActionButton(Context context) {
+        super(context);
+        init();
+    }
+
+    public MovableFloatingActionButton(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        init();
+    }
+
+    public MovableFloatingActionButton(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        init();
+    }
+
+    private void init() {
+        setOnTouchListener(this);
+    }
+
+    @Override
+    public boolean onTouch(View view, MotionEvent motionEvent) {
+        ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams)view.getLayoutParams();
+
+        int action = motionEvent.getAction();
+        if (action == MotionEvent.ACTION_DOWN) {
+            downTime = System.currentTimeMillis();
+            moved = false;
+
+            downRawX = motionEvent.getRawX();
+            downRawY = motionEvent.getRawY();
+            dX = view.getX() - downRawX;
+            dY = view.getY() - downRawY;
+
+            return true;
+
+        } else if (action == MotionEvent.ACTION_MOVE) {
+            if (!moved) {
+                if (System.currentTimeMillis() - downTime >= 300) {
+                    if (!longClicked) {
+                        longClicked = true;
+                        return performLongClick();
+                    } else {
+                        moved = true;
+                    }
+                }
+                float upRawX = motionEvent.getRawX();
+                float upRawY = motionEvent.getRawY();
+
+                float upDX = upRawX - downRawX;
+                float upDY = upRawY - downRawY;
+
+                if (Math.abs(upDX) < CLICK_DRAG_TOLERANCE && Math.abs(upDY) < CLICK_DRAG_TOLERANCE) {
+                    return true;
+                } else {
+                    moved = true;
+                }
+            }
+
+            int viewWidth = view.getWidth();
+            int viewHeight = view.getHeight();
+
+            View viewParent = (View)view.getParent();
+            int parentWidth = viewParent.getWidth();
+            int parentHeight = viewParent.getHeight();
+
+            float newX = motionEvent.getRawX() + dX;
+            newX = Math.max(layoutParams.leftMargin, newX); // Don't allow the FAB past the left hand side of the parent
+            newX = Math.min(parentWidth - viewWidth - layoutParams.rightMargin, newX); // Don't allow the FAB past the right hand side of the parent
+
+            float newY = motionEvent.getRawY() + dY;
+            newY = Math.max(layoutParams.topMargin, newY); // Don't allow the FAB past the top of the parent
+            newY = Math.min(parentHeight - viewHeight - layoutParams.bottomMargin, newY); // Don't allow the FAB past the bottom of the parent
+
+            view.animate()
+                    .x(newX)
+                    .y(newY)
+                    .setDuration(0)
+                    .start();
+
+            return true;
+        } else if (action == MotionEvent.ACTION_UP) {
+            if (longClicked) {
+                longClicked = false;
+                return true;
+            }
+
+            float upRawX = motionEvent.getRawX();
+            float upRawY = motionEvent.getRawY();
+
+            float upDX = upRawX - downRawX;
+            float upDY = upRawY - downRawY;
+
+            if (Math.abs(upDX) < CLICK_DRAG_TOLERANCE && Math.abs(upDY) < CLICK_DRAG_TOLERANCE) {
+                return System.currentTimeMillis() - downTime >= 300 ? performLongClick() : performClick();
+            } else {
+                return true;
+            }
+        } else {
+            return super.onTouchEvent(motionEvent);
+        }
+    }
+}

app/src/main/res/layout/activity_view_post_detail.xml

@@ -39,7 +39,7 @@
         android:layout_height="match_parent"
         app:layout_behavior="@string/appbar_scrolling_view_behavior" />
 
-    <com.google.android.material.floatingactionbutton.FloatingActionButton
+    <ml.docilealligator.infinityforreddit.customviews.MovableFloatingActionButton
         android:id="@+id/fab_view_post_detail_activity"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"