Move fast scrolling logic to BaseRecyclerView

- This change has no effect on actual functionality but to make it easier
for widget tray to inherit the goodness of the 1) fast scroller
functionality 2) unify the scroll look and feel with the all apps view

b/21375339

Change-Id: Ib859b1c3352c0b69f16549ded8f20eb82cf58ba8

1 files changed, 55 insertions, 297 deletions

diff --git a/src/com/android/launcher3/allapps/AllAppsRecyclerView.java b/src/com/android/launcher3/allapps/AllAppsRecyclerView.java
index e95fa325a..cc5add3b2 100644
--- a/src/com/android/launcher3/allapps/AllAppsRecyclerView.java
+++ b/src/com/android/launcher3/allapps/AllAppsRecyclerView.java
@@ -15,75 +15,34 @@
  */
 package com.android.launcher3.allapps;
 
-import android.animation.ObjectAnimator;
 import android.content.Context;
-import android.content.res.Resources;
-import android.graphics.Canvas;
-import android.graphics.Color;
-import android.graphics.Paint;
 import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.util.AttributeSet;
-import android.view.MotionEvent;
 import android.view.View;
-import android.view.ViewConfiguration;
+
 import com.android.launcher3.BaseRecyclerView;
 import com.android.launcher3.DeviceProfile;
 import com.android.launcher3.Launcher;
-import com.android.launcher3.R;
 import com.android.launcher3.Utilities;
 
 import java.util.List;
 
 /**
- * A RecyclerView with custom fastscroll support.  This is the main container for the all apps
- * icons.
+ * A RecyclerView with custom fast scroll support for the all apps view.
  */
 public class AllAppsRecyclerView extends BaseRecyclerView {
 
-    /**
-     * The current scroll state of the recycler view.  We use this in updateVerticalScrollbarBounds()
-     * and scrollToPositionAtProgress() to determine the scroll position of the recycler view so
-     * that we can calculate what the scroll bar looks like, and where to jump to from the fast
-     * scroller.
-     */
-    private static class ScrollPositionState {
-        // The index of the first visible row
-        int rowIndex;
-        // The offset of the first visible row
-        int rowTopOffset;
-        // The height of a given row (they are currently all the same height)
-        int rowHeight;
-    }
-
-    private static final float FAST_SCROLL_OVERLAY_Y_OFFSET_FACTOR = 1.5f;
-
     private AlphabeticalAppsList mApps;
     private int mNumAppsPerRow;
     private int mNumPredictedAppsPerRow;
 
-    private Drawable mScrollbar;
-    private Drawable mFastScrollerBg;
-    private Rect mTmpFastScrollerInvalidateRect = new Rect();
-    private Rect mFastScrollerBounds = new Rect();
-    private Rect mVerticalScrollbarBounds = new Rect();
-    private boolean mDraggingFastScroller;
-    private String mFastScrollSectionName;
-    private Paint mFastScrollTextPaint;
-    private Rect mFastScrollTextBounds = new Rect();
-    private float mFastScrollAlpha;
     private int mPredictionBarHeight;
-    private int mDownX;
-    private int mDownY;
-    private int mLastX;
-    private int mLastY;
-    private int mScrollbarWidth;
     private int mScrollbarMinHeight;
-    private int mScrollbarInset;
+
     private Rect mBackgroundPadding = new Rect();
-    private ScrollPositionState mScrollPosState = new ScrollPositionState();
 
     private Launcher mLauncher;
 
@@ -102,25 +61,7 @@ public class AllAppsRecyclerView extends BaseRecyclerView {
     public AllAppsRecyclerView(Context context, AttributeSet attrs, int defStyleAttr,
             int defStyleRes) {
         super(context, attrs, defStyleAttr);
-
         mLauncher = (Launcher) context;
-        Resources res = context.getResources();
-        int fastScrollerSize = res.getDimensionPixelSize(R.dimen.all_apps_fast_scroll_popup_size);
-        mScrollbar = res.getDrawable(R.drawable.all_apps_scrollbar_thumb);
-        mFastScrollerBg = res.getDrawable(R.drawable.all_apps_fastscroll_bg);
-        mFastScrollerBg.setBounds(0, 0, fastScrollerSize, fastScrollerSize);
-        mFastScrollTextPaint = new Paint();
-        mFastScrollTextPaint.setColor(Color.WHITE);
-        mFastScrollTextPaint.setAntiAlias(true);
-        mFastScrollTextPaint.setTextSize(res.getDimensionPixelSize(
-                R.dimen.all_apps_fast_scroll_text_size));
-        mScrollbarWidth = res.getDimensionPixelSize(R.dimen.all_apps_fast_scroll_bar_width);
-        mScrollbarMinHeight =
-                res.getDimensionPixelSize(R.dimen.all_apps_fast_scroll_bar_min_height);
-        mScrollbarInset =
-                res.getDimensionPixelSize(R.dimen.all_apps_fast_scroll_scrubber_touch_inset);
-        setFastScrollerAlpha(getFastScrollerAlpha());
-        setOverScrollMode(View.OVER_SCROLL_NEVER);
     }
 
     /**
@@ -158,28 +99,6 @@ public class AllAppsRecyclerView extends BaseRecyclerView {
     }
 
     /**
-     * Sets the fast scroller alpha.
-     */
-    public void setFastScrollerAlpha(float alpha) {
-        mFastScrollAlpha = alpha;
-        invalidateFastScroller(mFastScrollerBounds);
-    }
-
-    /**
-     * Gets the fast scroller alpha.
-     */
-    public float getFastScrollerAlpha() {
-        return mFastScrollAlpha;
-    }
-
-    /**
-     * Returns the scroll bar width.
-     */
-    public int getScrollbarWidth() {
-        return mScrollbarWidth;
-    }
-
-    /**
      * Scrolls this recycler view to the top.
      */
     public void scrollToTop() {
@@ -191,11 +110,11 @@ public class AllAppsRecyclerView extends BaseRecyclerView {
      */
     public int getScrollPosition() {
         List<AlphabeticalAppsList.AdapterItem> items = mApps.getAdapterItems();
-        getCurScrollState(mScrollPosState, items);
-        if (mScrollPosState.rowIndex != -1) {
+        getCurScrollState(scrollPosState, items);
+        if (scrollPosState.rowIndex != -1) {
             int predictionBarHeight = mApps.getPredictedApps().isEmpty() ? 0 : mPredictionBarHeight;
-            return getPaddingTop() + (mScrollPosState.rowIndex * mScrollPosState.rowHeight) +
-                    predictionBarHeight - mScrollPosState.rowTopOffset;
+            return getPaddingTop() + (scrollPosState.rowIndex * scrollPosState.rowHeight) +
+                    predictionBarHeight - scrollPosState.rowTopOffset;
         }
         return 0;
     }
@@ -206,150 +125,11 @@ public class AllAppsRecyclerView extends BaseRecyclerView {
         addOnItemTouchListener(this);
     }
 
-    @Override
-    protected void dispatchDraw(Canvas canvas) {
-        super.dispatchDraw(canvas);
-        drawVerticalScrubber(canvas);
-        drawFastScrollerPopup(canvas);
-    }
-
-    /**
-     * We intercept the touch handling only to support fast scrolling when initiated from the
-     * scroll bar.  Otherwise, we fall back to the default RecyclerView touch handling.
-     */
-    @Override
-    public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent ev) {
-        return handleTouchEvent(ev);
-    }
-
-    @Override
-    public void onTouchEvent(RecyclerView rv, MotionEvent ev) {
-        handleTouchEvent(ev);
-    }
-
-    /**
-     * Handles the touch event and determines whether to show the fast scroller (or updates it if
-     * it is already showing).
-     */
-    private boolean handleTouchEvent(MotionEvent ev) {
-        ViewConfiguration config = ViewConfiguration.get(getContext());
-
-        int action = ev.getAction();
-        int x = (int) ev.getX();
-        int y = (int) ev.getY();
-        switch (action) {
-            case MotionEvent.ACTION_DOWN:
-                // Keep track of the down positions
-                mDownX = mLastX = x;
-                mDownY = mLastY = y;
-                if (shouldStopScroll(ev)) {
-                    stopScroll();
-                }
-                break;
-            case MotionEvent.ACTION_MOVE:
-                // Check if we are scrolling
-                if (!mDraggingFastScroller && isPointNearScrollbar(mDownX, mDownY) &&
-                        Math.abs(y - mDownY) > config.getScaledTouchSlop()) {
-                    getParent().requestDisallowInterceptTouchEvent(true);
-                    mDraggingFastScroller = true;
-                    animateFastScrollerVisibility(true);
-                }
-                if (mDraggingFastScroller) {
-                    mLastX = x;
-                    mLastY = y;
-
-                    // Scroll to the right position, and update the section name
-                    int top = getPaddingTop() + (mFastScrollerBg.getBounds().height() / 2);
-                    int bottom = getHeight() - getPaddingBottom() -
-                            (mFastScrollerBg.getBounds().height() / 2);
-                    float boundedY = (float) Math.max(top, Math.min(bottom, y));
-                    mFastScrollSectionName = scrollToPositionAtProgress((boundedY - top) /
-                            (bottom - top));
-
-                    // Combine the old and new fast scroller bounds to create the full invalidate
-                    // rect
-                    mTmpFastScrollerInvalidateRect.set(mFastScrollerBounds);
-                    updateFastScrollerBounds();
-                    mTmpFastScrollerInvalidateRect.union(mFastScrollerBounds);
-                    invalidateFastScroller(mTmpFastScrollerInvalidateRect);
-                }
-                break;
-            case MotionEvent.ACTION_UP:
-            case MotionEvent.ACTION_CANCEL:
-                mDraggingFastScroller = false;
-                animateFastScrollerVisibility(false);
-                break;
-        }
-        return mDraggingFastScroller;
-    }
-
-    /**
-     * Animates the visibility of the fast scroller popup.
-     */
-    private void animateFastScrollerVisibility(boolean visible) {
-        ObjectAnimator anim = ObjectAnimator.ofFloat(this, "fastScrollerAlpha", visible ? 1f : 0f);
-        anim.setDuration(visible ? 200 : 150);
-        anim.start();
-    }
-
-    /**
-     * Returns whether a given point is near the scrollbar.
-     */
-    private boolean isPointNearScrollbar(int x, int y) {
-        // Check if we are scrolling
-        updateVerticalScrollbarBounds();
-        mVerticalScrollbarBounds.inset(mScrollbarInset, mScrollbarInset);
-        return mVerticalScrollbarBounds.contains(x, y);
-    }
-
-    /**
-     * Draws the fast scroller popup.
-     */
-    private void drawFastScrollerPopup(Canvas canvas) {
-        if (mFastScrollAlpha > 0f && !mFastScrollSectionName.isEmpty()) {
-            // Draw the fast scroller popup
-            int restoreCount = canvas.save(Canvas.MATRIX_SAVE_FLAG);
-            canvas.translate(mFastScrollerBounds.left, mFastScrollerBounds.top);
-            mFastScrollerBg.setAlpha((int) (mFastScrollAlpha * 255));
-            mFastScrollerBg.draw(canvas);
-            mFastScrollTextPaint.setAlpha((int) (mFastScrollAlpha * 255));
-            mFastScrollTextPaint.getTextBounds(mFastScrollSectionName, 0,
-                    mFastScrollSectionName.length(), mFastScrollTextBounds);
-            float textWidth = mFastScrollTextPaint.measureText(mFastScrollSectionName);
-            canvas.drawText(mFastScrollSectionName,
-                    (mFastScrollerBounds.width() - textWidth) / 2,
-                    mFastScrollerBounds.height() -
-                            (mFastScrollerBounds.height() - mFastScrollTextBounds.height()) / 2,
-                    mFastScrollTextPaint);
-            canvas.restoreToCount(restoreCount);
-        }
-    }
-
-    /**
-     * Draws the vertical scrollbar.
-     */
-    private void drawVerticalScrubber(Canvas canvas) {
-        updateVerticalScrollbarBounds();
-
-        // Draw the scroll bar
-        int restoreCount = canvas.save(Canvas.MATRIX_SAVE_FLAG);
-        canvas.translate(mVerticalScrollbarBounds.left, mVerticalScrollbarBounds.top);
-        mScrollbar.setBounds(0, 0, mScrollbarWidth, mVerticalScrollbarBounds.height());
-        mScrollbar.draw(canvas);
-        canvas.restoreToCount(restoreCount);
-    }
-
-    /**
-     * Invalidates the fast scroller popup.
-     */
-    private void invalidateFastScroller(Rect bounds) {
-        invalidate(bounds.left, bounds.top, bounds.right, bounds.bottom);
-    }
-
     /**
      * Maps the touch (from 0..1) to the adapter position that should be visible.
      */
-    private String scrollToPositionAtProgress(float touchFraction) {
+    @Override
+    public String scrollToPositionAtProgress(float touchFraction) {
         // Ensure that we have any sections
         List<AlphabeticalAppsList.FastScrollSectionInfo> fastScrollSections =
                 mApps.getFastScrollerSections();
@@ -393,27 +173,60 @@ public class AllAppsRecyclerView extends BaseRecyclerView {
         return lastScrollSection.sectionName;
     }
 
+
+    /**
+     * Returns the row index for a app index in the list.
+     */
+    private int findRowForAppIndex(int index) {
+        List<AlphabeticalAppsList.SectionInfo> sections = mApps.getSections();
+        int appIndex = 0;
+        int rowCount = 0;
+        for (AlphabeticalAppsList.SectionInfo info : sections) {
+            int numRowsInSection = (int) Math.ceil((float) info.numApps / mNumAppsPerRow);
+            if (appIndex + info.numApps > index) {
+                return rowCount + ((index - appIndex) / mNumAppsPerRow);
+            }
+            appIndex += info.numApps;
+            rowCount += numRowsInSection;
+        }
+        return appIndex;
+    }
+
+    /**
+     * Returns the total number of rows in the list.
+     */
+    private int getNumRows() {
+        List<AlphabeticalAppsList.SectionInfo> sections = mApps.getSections();
+        int rowCount = 0;
+        for (AlphabeticalAppsList.SectionInfo info : sections) {
+            int numRowsInSection = (int) Math.ceil((float) info.numApps / mNumAppsPerRow);
+            rowCount += numRowsInSection;
+        }
+        return rowCount;
+    }
+
+
     /**
      * Updates the bounds for the scrollbar.
      */
-    private void updateVerticalScrollbarBounds() {
+    @Override
+    public void updateVerticalScrollbarBounds() {
         List<AlphabeticalAppsList.AdapterItem> items = mApps.getAdapterItems();
 
-        // Skip early if there are no items
+        // Skip early if there are no items.
         if (items.isEmpty()) {
-            mVerticalScrollbarBounds.setEmpty();
+            verticalScrollbarBounds.setEmpty();
             return;
         }
 
         // Find the index and height of the first visible row (all rows have the same height)
-        int x;
-        int y;
+        int x, y;
         int predictionBarHeight = mApps.getPredictedApps().isEmpty() ? 0 : mPredictionBarHeight;
         int rowCount = getNumRows();
-        getCurScrollState(mScrollPosState, items);
-        if (mScrollPosState.rowIndex != -1) {
+        getCurScrollState(scrollPosState, items);
+        if (scrollPosState.rowIndex != -1) {
             int height = getHeight() - getPaddingTop() - getPaddingBottom();
-            int totalScrollHeight = rowCount * mScrollPosState.rowHeight + predictionBarHeight;
+            int totalScrollHeight = rowCount * scrollPosState.rowHeight + predictionBarHeight;
             if (totalScrollHeight > height) {
                 int scrollbarHeight = Math.max(mScrollbarMinHeight,
                         (int) (height / ((float) totalScrollHeight / height)));
@@ -422,78 +235,23 @@ public class AllAppsRecyclerView extends BaseRecyclerView {
                 if (Utilities.isRtl(getResources())) {
                     x = mBackgroundPadding.left;
                 } else {
-                    x = getWidth() - mBackgroundPadding.right - mScrollbarWidth;
+                    x = getWidth() - mBackgroundPadding.right - getScrollbarWidth();
                 }
 
                 // To calculate the offset, we compute the percentage of the total scrollable height
                 // that the user has already scrolled and then map that to the scroll bar bounds
                 int availableY = totalScrollHeight - height;
                 int availableScrollY = height - scrollbarHeight;
-                y = (mScrollPosState.rowIndex * mScrollPosState.rowHeight) + predictionBarHeight
-                        - mScrollPosState.rowTopOffset;
+                y = (scrollPosState.rowIndex * scrollPosState.rowHeight) + predictionBarHeight
+                        - scrollPosState.rowTopOffset;
                 y = getPaddingTop() +
                         (int) (((float) (getPaddingTop() + y) / availableY) * availableScrollY);
 
-                mVerticalScrollbarBounds.set(x, y, x + mScrollbarWidth, y + scrollbarHeight);
+                verticalScrollbarBounds.set(x, y, x + getScrollbarWidth(), y + scrollbarHeight);
                 return;
             }
         }
-        mVerticalScrollbarBounds.setEmpty();
-    }
-
-    /**
-     * Updates the bounds for the fast scroller.
-     */
-    private void updateFastScrollerBounds() {
-        if (mFastScrollAlpha > 0f && !mFastScrollSectionName.isEmpty()) {
-            int x;
-            int y;
-
-            // Calculate the position for the fast scroller popup
-            Rect bgBounds = mFastScrollerBg.getBounds();
-            if (Utilities.isRtl(getResources())) {
-                x = mBackgroundPadding.left + getScrollBarSize();
-            } else {
-                x = getWidth() - getPaddingRight() - getScrollBarSize() - bgBounds.width();
-            }
-            y = mLastY - (int) (FAST_SCROLL_OVERLAY_Y_OFFSET_FACTOR * bgBounds.height());
-            y = Math.max(getPaddingTop(), Math.min(y, getHeight() - getPaddingBottom() -
-                    bgBounds.height()));
-            mFastScrollerBounds.set(x, y, x + bgBounds.width(), y + bgBounds.height());
-        } else {
-            mFastScrollerBounds.setEmpty();
-        }
-    }
-
-    /**
-     * Returns the row index for a app index in the list.
-     */
-    private int findRowForAppIndex(int index) {
-        List<AlphabeticalAppsList.SectionInfo> sections = mApps.getSections();
-        int appIndex = 0;
-        int rowCount = 0;
-        for (AlphabeticalAppsList.SectionInfo info : sections) {
-            int numRowsInSection = (int) Math.ceil((float) info.numApps / mNumAppsPerRow);
-            if (appIndex + info.numApps > index) {
-                return rowCount + ((index - appIndex) / mNumAppsPerRow);
-            }
-            appIndex += info.numApps;
-            rowCount += numRowsInSection;
-        }
-        return appIndex;
-    }
-
-    /**
-     * Returns the total number of rows in the list.
-     */
-    private int getNumRows() {
-        List<AlphabeticalAppsList.SectionInfo> sections = mApps.getSections();
-        int rowCount = 0;
-        for (AlphabeticalAppsList.SectionInfo info : sections) {
-            int numRowsInSection = (int) Math.ceil((float) info.numApps / mNumAppsPerRow);
-            rowCount += numRowsInSection;
-        }
-        return rowCount;
+        verticalScrollbarBounds.setEmpty();
     }
 
     /**