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1 files changed, 117 insertions, 0 deletions

diff --git a/setupwizardlib/src/main/java/com/android/setupwizardlib/view/StickyHeaderScrollView.java b/setupwizardlib/src/main/java/com/android/setupwizardlib/view/StickyHeaderScrollView.java
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+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.setupwizardlib.view;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.os.Build;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.WindowInsets;
+
+/**
+ * This class provides sticky header functionality in a scroll view, to use with
+ * SetupWizardIllustration. To use this, add a subview tagged with "sticky", or a subview tagged
+ * with "stickyContainer" and one of its child tagged as "sticky". The sticky container will be
+ * drawn when the sticky element hits the top of the view.
+ *
+ * <p>There are a few things to note:
+ * <ol>
+ *   <li>The two supported scenarios are StickyHeaderScrollView -> subview (stickyContainer) ->
+ *   sticky, and StickyHeaderScrollView -> container -> subview (sticky).
+ *   The arrow (->) represents parent/child relationship and must be immediate child.
+ *   <li>If fitsSystemWindows is true, then this will offset the sticking position by the height of
+ *   the system decorations at the top of the screen.
+ *   <li>For versions before Honeycomb, this will behave like a regular ScrollView.
+ * </ol>
+ *
+ * @see StickyHeaderListView
+ */
+public class StickyHeaderScrollView extends BottomScrollView {
+
+    private View mSticky;
+    private View mStickyContainer;
+    private int mStatusBarInset = 0;
+
+    public StickyHeaderScrollView(Context context) {
+        super(context);
+    }
+
+    public StickyHeaderScrollView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public StickyHeaderScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+
+    @Override
+    protected void onLayout(boolean changed, int l, int t, int r, int b) {
+        super.onLayout(changed, l, t, r, b);
+        if (mSticky == null) {
+            updateStickyView();
+        }
+        updateStickyHeaderPosition();
+    }
+
+    public void updateStickyView() {
+        mSticky = findViewWithTag("sticky");
+        mStickyContainer = findViewWithTag("stickyContainer");
+    }
+
+    private void updateStickyHeaderPosition() {
+        // Note: for pre-Honeycomb the header will not be moved, so this ScrollView essentially
+        // behaves like a normal BottomScrollView.
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
+            if (mSticky != null) {
+                // The view to draw when sticking to the top
+                final View drawTarget = mStickyContainer != null ? mStickyContainer : mSticky;
+                // The offset to draw the view at when sticky
+                final int drawOffset = mStickyContainer != null ? mSticky.getTop() : 0;
+                // Position of the draw target, relative to the outside of the scrollView
+                final int drawTop = drawTarget.getTop() - getScrollY();
+                if (drawTop + drawOffset < mStatusBarInset || !drawTarget.isShown()) {
+                    // ScrollView translates the whole canvas so we have to compensate for that
+                    drawTarget.setTranslationY(getScrollY() - drawOffset);
+                } else {
+                    drawTarget.setTranslationY(0);
+                }
+            }
+        }
+    }
+
+    @Override
+    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
+        super.onScrollChanged(l, t, oldl, oldt);
+        updateStickyHeaderPosition();
+    }
+
+    @Override
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+    public WindowInsets onApplyWindowInsets(WindowInsets insets) {
+        if (getFitsSystemWindows()) {
+            mStatusBarInset = insets.getSystemWindowInsetTop();
+            insets = insets.replaceSystemWindowInsets(
+                    insets.getSystemWindowInsetLeft(),
+                    0, /* top */
+                    insets.getSystemWindowInsetRight(),
+                    insets.getSystemWindowInsetBottom()
+            );
+        }
+        return insets;
+    }
+}