Upstream Layout.java and associated files

chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/contextualsearch/ContextualSearchPanelBase.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.compositor.bottombar.contextualsearch;
+
+import android.content.Context;
+
+import org.chromium.base.VisibleForTesting;
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.compositor.bottombar.contextualsearch.ContextualSearchPanel.PanelState;
+import org.chromium.chrome.browser.compositor.bottombar.contextualsearch.ContextualSearchPanel.StateChangeReason;
+import org.chromium.chrome.browser.util.MathUtils;
+
+/**
+ * Base abstract class for the Contextual Search Panel.
+ */
+abstract class ContextualSearchPanelBase extends ContextualSearchPanelStateHandler {
+
+    /**
+     * The height of the expanded Contextual Search Panel relative to the height
+     * of the screen.
+     */
+    private static final float EXPANDED_PANEL_HEIGHT_PERCENTAGE = .7f;
+
+    /**
+     * The height of the Toolbar in dps.
+     */
+    private static final float TOOLBAR_HEIGHT_DP = 56.f;
+
+    /**
+     * The height of the Contextual Search Panel's Shadow in dps.
+     */
+    private static final float PANEL_SHADOW_HEIGHT_DP = 16.f;
+
+    /**
+     * The brightness of the base page when the Panel is peeking.
+     */
+    private static final float BASE_PAGE_BRIGHTNESS_STATE_PEEKED = 1.f;
+
+    /**
+     * The brightness of the base page when the Panel is expanded.
+     */
+    private static final float BASE_PAGE_BRIGHTNESS_STATE_EXPANDED = .7f;
+
+    /**
+     * The brightness of the base page when the Panel is maximized.
+     */
+    private static final float BASE_PAGE_BRIGHTNESS_STATE_MAXIMIZED = .3f;
+
+    /**
+     * The opacity of the search provider icon when the Panel is peeking.
+     */
+    private static final float SEARCH_PROVIDER_ICON_OPACITY_STATE_PEEKED = 1.f;
+
+    /**
+     * The opacity of the search provider icon when the Panel is expanded.
+     */
+    private static final float SEARCH_PROVIDER_ICON_OPACITY_STATE_EXPANDED = 1.f;
+
+    /**
+     * The opacity of the search provider icon when the Panel is maximized.
+     */
+    private static final float SEARCH_PROVIDER_ICON_OPACITY_STATE_MAXIMIZED = 0.f;
+
+    /**
+     * The opacity of the search icon when the Panel is peeking.
+     */
+    private static final float SEARCH_ICON_OPACITY_PEEKED = 0.f;
+
+    /**
+     * The opacity of the search icon when the Panel is expanded.
+     */
+    private static final float SEARCH_ICON_OPACITY_EXPANDED = 0.f;
+
+    /**
+     * The opacity of the search icon when the Panel is maximized.
+     */
+    private static final float SEARCH_ICON_OPACITY_MAXIMIZED = 1.f;
+
+    /**
+     * The margin top of the Contextual Search Bar in dps.
+     */
+    private static final float SEARCH_BAR_MARGIN_TOP_DP = 16.f;
+
+    /**
+     * The padding left of the Search Icon in dps.
+     */
+    private static final float SEARCH_ICON_PADDING_LEFT_DP = 16.f;
+
+    /**
+     * The height of the promo state Contextual Search Panel search bar, in dps.
+     */
+    private static final float SEARCH_BAR_HEIGHT_STATE_PROMO = 24.f;
+
+    /**
+     * How much the Promo Panel should displace in order to make some elements
+     * invisible (like the Search Provider Icon and the Search Bar Text).
+     */
+    private static final float DISAPPEARING_ELEMENT_THRESHOLD_DP = 10.f;
+
+    /**
+     * The height of the Search Bar's border in dps.
+     */
+    private static final float SEARCH_BAR_BORDER_HEIGHT_DP = 1.f;
+
+    /**
+     * The height of the Progress Bar in dps.
+     */
+    private static final float PROGRESS_BAR_HEIGHT_DP = 2.f;
+
+    /**
+     * The distance from the Progress Bar must be away from the bottom of the
+     * screen in order to be completely visible. The closer the Progress Bar
+     * gets to the bottom of the screen, the lower its opacity will be. When the
+     * Progress Bar is at the very bottom of the screen (when the Search Panel
+     * is peeking) it will be completely invisible.
+     */
+    private static final float PROGRESS_BAR_VISIBILITY_THRESHOLD_DP = 10.f;
+
+    /**
+     * The height of the Search Bar when the Panel is peeking, in dps.
+     */
+    private final float mSearchBarHeightPeeking;
+
+    /**
+     * The height of the Search Bar when the Panel is displaying the Promo, in dps.
+     */
+    private final float mSearchBarHeightPromo;
+
+    /**
+     * The height of the Search Bar when the Panel is expanded, in dps.
+     */
+    private final float mSearchBarHeightExpanded;
+
+    /**
+     * The height of the Search Bar when the Panel is maximized, in dps.
+     */
+    private final float mSearchBarHeightMaximized;
+
+    /**
+     * Ratio of dps per pixel.
+     */
+    private final float mPxToDp;
+
+    /**
+     * The approximate Y coordinate of the selection in pixels.
+     */
+    private float mBasePageSelectionYPx = -1.f;
+
+    /**
+     * The Y coordinate to apply to the Base Page in order to keep the selection
+     * in view when the Search Panel is in its EXPANDED state.
+     */
+    private float mBasePageTargetY = 0.f;
+
+    /**
+     * The Y coordinate to apply to the Base Page in order to keep the selection
+     * in view when the Search Panel is in its PROMO state.
+     */
+    private float mPromoBasePageTargetY = 0.f;
+
+    /**
+     * Whether the Panel is showing.
+     */
+    private boolean mIsShowing;
+
+    // ============================================================================================
+    // Constructor
+    // ============================================================================================
+
+    /**
+     * @param context The current Android {@link Context}.
+     */
+    public ContextualSearchPanelBase(Context context) {
+        mPxToDp = 1.f / context.getResources().getDisplayMetrics().density;
+
+        mSearchBarHeightPeeking = context.getResources().getDimension(
+                R.dimen.contextual_search_bar_height) * mPxToDp;
+        mSearchBarHeightMaximized = TOOLBAR_HEIGHT_DP + PANEL_SHADOW_HEIGHT_DP;
+        mSearchBarHeightExpanded =
+                Math.round((mSearchBarHeightPeeking + mSearchBarHeightMaximized) / 2.f);
+        mSearchBarHeightPromo = SEARCH_BAR_HEIGHT_STATE_PROMO + PANEL_SHADOW_HEIGHT_DP;
+
+        initializeUiState();
+    }
+
+    // ============================================================================================
+    // Layout Integration
+    // ============================================================================================
+
+    private float mLayoutWidth;
+    private float mLayoutHeight;
+    private boolean mIsToolbarShowing;
+
+    /**
+     * Called when the size of the view has changed.
+     *
+     * @param width  The new width in dp.
+     * @param height The new width in dp.
+     * @param isToolbarShowing Whether the Toolbar is showing.
+     */
+    public final void onSizeChanged(float width, float height, boolean isToolbarShowing) {
+        mLayoutWidth = width;
+        mLayoutHeight = height;
+        mIsToolbarShowing = isToolbarShowing;
+    }
+
+    /**
+     * Returns the Y position of the Contextual Search Panel.
+     * Layouts supporting Contextual Search should override this method.
+     *
+     * @return The current Y-position of the Contextual Search Panel.
+     */
+    public float getContextualSearchPanelY() {
+        return getFullscreenHeight() - mHeight;
+    }
+
+    /**
+     * @param y The y coordinate.
+     * @return The Y coordinate relative the fullscreen height.
+     */
+    public float getFullscreenY(float y) {
+        if (mIsToolbarShowing) {
+            y += TOOLBAR_HEIGHT_DP / mPxToDp;
+        }
+        return y;
+    }
+
+    /**
+     * @return Whether the Panel is showing.
+     */
+    public boolean isShowing() {
+        return mIsShowing;
+    }
+
+    /**
+     * Starts showing the Panel.
+     */
+    protected void startShowing() {
+        mIsShowing = true;
+    }
+
+    /**
+     * @return The fullscreen width.
+     */
+    private float getFullscreenWidth() {
+        return mLayoutWidth;
+    }
+
+    /**
+     * @return The fullscreen height.
+     */
+    private float getFullscreenHeight() {
+        float height = mLayoutHeight;
+        // NOTE(pedrosimonetti): getHeight() only returns the content height
+        // when the Toolbar is not showing. If we don't add the Toolbar height
+        // here, there will be a "jump" when swiping the Search Panel around.
+        // TODO(pedrosimonetti): Find better way to get the fullscreen height.
+        if (mIsToolbarShowing) {
+            height += TOOLBAR_HEIGHT_DP;
+        }
+        return height;
+    }
+
+    // ============================================================================================
+    // UI States
+    // ============================================================================================
+
+    // --------------------------------------------------------------------------------------------
+    // Test Infrastructure
+    // --------------------------------------------------------------------------------------------
+
+    /**
+     * @param offsetY The vertical offset of the Contextual Search Panel to be
+     *            set.
+     */
+    @VisibleForTesting
+    public void setOffsetYForTesting(float offsetY) {
+        mOffsetY = offsetY;
+    }
+
+    /**
+     * @param isMaximized The setting for whether the Search Panel is fully
+     *            maximized.
+     */
+    @VisibleForTesting
+    public void setMaximizedForTesting(boolean isMaximized) {
+        mIsMaximized = isMaximized;
+    }
+
+    /**
+     * @param searchBarHeight The height of the Contextual Search Bar to be set.
+     */
+    @VisibleForTesting
+    public void setSearchBarHeightForTesting(float searchBarHeight) {
+        mSearchBarHeight = searchBarHeight;
+    }
+
+    /**
+     * @param searchBarBorderHeight The height of the Search Bar border to be
+     *            set.
+     */
+    @VisibleForTesting
+    public void setSearchBarBorderHeight(float searchBarBorderHeight) {
+        mSearchBarBorderHeight = searchBarBorderHeight;
+    }
+
+    // --------------------------------------------------------------------------------------------
+    // Contextual Search Panel states
+    // --------------------------------------------------------------------------------------------
+
+    private float mOffsetY;
+    private float mHeight;
+    private float mWidth;
+    private boolean mIsMaximized;
+
+    /**
+     * @return The vertical offset of the Contextual Search Panel.
+     */
+    public float getOffsetY() {
+        return mOffsetY;
+    }
+
+    /**
+     * @return The height of the Contextual Search Panel.
+     */
+    public float getHeight() {
+        return mHeight;
+    }
+
+    /**
+     * @return The width of the Contextual Search Panel.
+     */
+    public float getWidth() {
+        return mWidth;
+    }
+
+    /**
+     * @return Whether the Search Panel is fully maximized.
+     */
+    public boolean isMaximized() {
+        return mIsMaximized;
+    }
+
+    // --------------------------------------------------------------------------------------------
+    // Contextual Search Bar states
+    // --------------------------------------------------------------------------------------------
+
+    private float mSearchBarMarginTop;
+    private float mSearchBarHeight;
+    private float mSearchBarTextOpacity;
+    private boolean mIsSearchBarBorderVisible;
+    private float mSearchBarBorderY;
+    private float mSearchBarBorderHeight;
+    private float mSearchProviderIconOpacity;
+    private float mSearchIconPaddingLeft;
+    private float mSearchIconOpacity;
+
+    /**
+     * @return The top margin of the Contextual Search Bar.
+     */
+    public float getSearchBarMarginTop() {
+        return mSearchBarMarginTop;
+    }
+
+    /**
+     * @return The height of the Contextual Search Bar.
+     */
+    public float getSearchBarHeight() {
+        return mSearchBarHeight;
+    }
+
+    /**
+     * @return The opacity of the Contextual Search Bar text.
+     */
+    public float getSearchBarTextOpacity() {
+        return mSearchBarTextOpacity;
+    }
+
+    /**
+     * @return Whether the Search Bar border is visible.
+     */
+    public boolean isSearchBarBorderVisible() {
+        return mIsSearchBarBorderVisible;
+    }
+
+    /**
+     * @return The Y coordinate of the Search Bar border.
+     */
+    public float getSearchBarBorderY() {
+        return mSearchBarBorderY;
+    }
+
+    /**
+     * @return The height of the Search Bar border.
+     */
+    public float getSearchBarBorderHeight() {
+        return mSearchBarBorderHeight;
+    }
+
+    /**
+     * @return The opacity of the search provider's icon.
+     */
+    public float getSearchProviderIconOpacity() {
+        return mSearchProviderIconOpacity;
+    }
+
+    /**
+     * @return The left padding of the search icon.
+     */
+    public float getSearchIconPaddingLeft() {
+        return mSearchIconPaddingLeft;
+    }
+
+    /**
+     * @return The opacity of the search icon.
+     */
+    public float getSearchIconOpacity() {
+        return mSearchIconOpacity;
+    }
+
+    // --------------------------------------------------------------------------------------------
+    // Base Page states
+    // --------------------------------------------------------------------------------------------
+
+    private float mBasePageY;
+    private float mBasePageBrightness;
+
+    /**
+     * @return The vertical offset of the base page.
+     */
+    public float getBasePageY() {
+        return mBasePageY;
+    }
+
+    /**
+     * @return The brightness of the base page.
+     */
+    public float getBasePageBrightness() {
+        return mBasePageBrightness;
+    }
+
+    // --------------------------------------------------------------------------------------------
+    // Progress Bar states
+    // --------------------------------------------------------------------------------------------
+
+    private float mProgressBarOpacity;
+    private boolean mIsProgressBarVisible;
+    private float mProgressBarY;
+    private float mProgressBarHeight;
+    private int mProgressBarCompletion;
+
+    /**
+     * @return Whether the Progress Bar is visible.
+     */
+    public boolean isProgressBarVisible() {
+        return mIsProgressBarVisible;
+    }
+
+    /**
+     * @param isVisible Whether the Progress Bar should be visible.
+     */
+    protected void setProgressBarVisible(boolean isVisible) {
+        mIsProgressBarVisible = isVisible;
+    }
+
+    /**
+     * @return The Y coordinate of the Progress Bar.
+     */
+    public float getProgressBarY() {
+        return mProgressBarY;
+    }
+
+    /**
+     * @return The Progress Bar height.
+     */
+    public float getProgressBarHeight() {
+        return mProgressBarHeight;
+    }
+
+    /**
+     * @return The Progress Bar opacity.
+     */
+    public float getProgressBarOpacity() {
+        return mProgressBarOpacity;
+    }
+
+    /**
+     * @return The completion percentage of the Progress Bar.
+     */
+    public int getProgressBarCompletion() {
+        return mProgressBarCompletion;
+    }
+
+    /**
+     * @param completion The completion percentage to be set.
+     */
+    protected void setProgressBarCompletion(int completion) {
+        mProgressBarCompletion = completion;
+    }
+
+    // --------------------------------------------------------------------------------------------
+    // Promo states
+    // --------------------------------------------------------------------------------------------
+
+    private float mPromoContentHeight;
+    private boolean mShouldHidePromoHeader;
+    private static final float DEFAULT_PROMO_HEIGHT_DP = 250.f;
+
+     /**
+     * Sets the height of the promo content.
+     */
+    protected void setPromoContentHeight(float height) {
+        mPromoContentHeight = height;
+        updateBasePageTargetY();
+    }
+
+    /**
+     * Gets the height of the promo content.
+     */
+    public float getPromoContentHeight() {
+        return mPromoContentHeight > 0.0f
+                ? mPromoContentHeight : DEFAULT_PROMO_HEIGHT_DP;
+    }
+
+    /**
+     * @param shouldHidePromoHeader Sets whether the promo's header should be hidden.
+     */
+    protected void setShouldHidePromoHeader(boolean shouldHidePromoHeader) {
+        mShouldHidePromoHeader = shouldHidePromoHeader;
+    }
+
+    /**
+     * @return Gets whether the promo's header should be hidden.
+     */
+    public boolean shouldHidePromoHeader() {
+        return mShouldHidePromoHeader;
+    }
+
+    // ============================================================================================
+    // Helpers
+    // ============================================================================================
+
+    /**
+     * Initializes the UI state.
+     */
+    private void initializeUiState() {
+        mIsShowing = false;
+
+        // Static values.
+        mSearchBarMarginTop = SEARCH_BAR_MARGIN_TOP_DP;
+        mSearchIconPaddingLeft = SEARCH_ICON_PADDING_LEFT_DP;
+        mProgressBarHeight = PROGRESS_BAR_HEIGHT_DP;
+        mSearchBarBorderHeight = SEARCH_BAR_BORDER_HEIGHT_DP;
+
+        // Dynamic values.
+        mSearchBarHeight = mSearchBarHeightPeeking;
+    }
+
+    /**
+     * Gets the height of the Contextual Search Panel in dps for a given
+     * |state|.
+     *
+     * @param state The state whose height will be calculated.
+     * @return The height of the Contextual Search Panel in dps for a given
+     *         |state|.
+     */
+    protected float getPanelHeightFromState(PanelState state) {
+        float fullscreenHeight = getFullscreenHeight();
+        float panelHeight = 0;
+
+        if (state == PanelState.UNDEFINED) {
+            panelHeight = 0;
+        } else if (state == PanelState.CLOSED) {
+            panelHeight = 0;
+        } else if (state == PanelState.PEEKED) {
+            panelHeight = mSearchBarHeightPeeking;
+        } else if (state == PanelState.PROMO) {
+            panelHeight = getPromoContentHeight()
+                    + mSearchBarHeightPromo;
+        } else if (state == PanelState.EXPANDED) {
+            panelHeight = fullscreenHeight * EXPANDED_PANEL_HEIGHT_PERCENTAGE
+                    + PANEL_SHADOW_HEIGHT_DP;
+        } else if (state == PanelState.MAXIMIZED) {
+            panelHeight = fullscreenHeight + PANEL_SHADOW_HEIGHT_DP;
+        }
+
+        return panelHeight;
+    }
+
+    /**
+     * Finds the state which has the nearest height compared to a given
+     * |desiredPanelHeight|.
+     *
+     * @param desiredPanelHeight The height to compare to.
+     * @return The nearest panel state.
+     */
+    protected PanelState findNearestPanelStateFromHeight(float desiredPanelHeight) {
+        PanelState closestPanelState = PanelState.CLOSED;
+        float smallestHeightDiff = Float.POSITIVE_INFINITY;
+
+        // Iterate over all states and find the one which has the nearest
+        // height.
+        for (PanelState state : PanelState.values()) {
+            if (!isValidState(state)) {
+                continue;
+            }
+
+            float height = getPanelHeightFromState(state);
+            float heightDiff = Math.abs(desiredPanelHeight - height);
+            if (heightDiff < smallestHeightDiff) {
+                closestPanelState = state;
+                smallestHeightDiff = heightDiff;
+            }
+        }
+
+        return closestPanelState;
+    }
+
+    /**
+     * Sets the last panel height within the limits allowable by our UI.
+     *
+     * @param height The height of the panel in dps.
+     */
+    protected void setClampedPanelHeight(float height) {
+        final float clampedHeight = MathUtils.clamp(height,
+                getPanelHeightFromState(getMaximumState()),
+                getPanelHeightFromState(PanelState.PEEKED));
+        setPanelHeight(clampedHeight);
+    }
+
+    @Override
+    protected void setPanelState(PanelState state, StateChangeReason reason) {
+        super.setPanelState(state, reason);
+
+        if (state == PanelState.CLOSED) {
+            mIsShowing = false;
+        }
+    }
+
+    /**
+     * Sets the panel height.
+     *
+     * @param height The height of the panel in dps.
+     */
+    protected void setPanelHeight(float height) {
+        updatePanelForHeight(height);
+    }
+
+    /**
+     * @param state The Panel state.
+     * @return Whether the Panel height matches the one from the given state.
+     */
+    protected boolean doesPanelHeightMatchState(PanelState state) {
+        return state == getPanelState() && getHeight() == getPanelHeightFromState(state);
+    }
+
+    // ============================================================================================
+    // UI Update Handling
+    // ============================================================================================
+
+    /**
+     * Updates the UI state for a given |height|.
+     *
+     * @param height The Contextual Search Panel height.
+     */
+    private void updatePanelForHeight(float height) {
+        PanelState endState = findLargestPanelStateFromHeight(height);
+        PanelState startState = getPreviousPanelState(endState);
+        float percentage = getStateCompletion(height, startState, endState);
+
+        updatePanelSize(height, endState, percentage);
+
+        if (endState == PanelState.CLOSED || endState == PanelState.PEEKED) {
+            updatePanelForCloseOrPeek(percentage);
+        } else if (endState == PanelState.EXPANDED) {
+            updatePanelForExpansion(percentage);
+        } else if (endState == PanelState.MAXIMIZED) {
+            updatePanelForMaximization(percentage);
+        } else if (endState == PanelState.PROMO) {
+            updatePanelForOpeningPromo(percentage);
+        }
+    }
+
+    /**
+     * Updates the Panel size information.
+     *
+     * @param height The Contextual Search Panel height.
+     * @param endState The final state of transition being executed.
+     * @param percentage The completion percentage of the transition.
+     */
+    private void updatePanelSize(float height, PanelState endState, float percentage) {
+        mWidth = getFullscreenWidth();
+        mHeight = height;
+        mOffsetY = getContextualSearchPanelY();
+        mIsMaximized = height == getPanelHeightFromState(PanelState.MAXIMIZED);
+    }
+
+    /**
+     * Finds the largest Panel state which is being transitioned to/from.
+     * Whenever the Panel is in between states, let's say, when resizing the
+     * Panel from its peeked to expanded state, we need to know those two states
+     * in order to calculate how closely we are from one of them. This method
+     * will always return the nearest state with the largest height, and
+     * together with the state preceding it, it's possible to calculate how far
+     * the Panel is from them.
+     *
+     * @param panelHeight The height to compare to.
+     * @return The panel state which is being transitioned to/from.
+     */
+    private PanelState findLargestPanelStateFromHeight(float panelHeight) {
+        PanelState stateFound = PanelState.CLOSED;
+
+        // Iterate over all states and find the largest one which is being
+        // transitioned to/from.
+        for (PanelState state : PanelState.values()) {
+            if (!isValidState(state)) {
+                continue;
+            }
+            if (panelHeight <= getPanelHeightFromState(state)) {
+                stateFound = state;
+                break;
+            }
+        }
+
+        return stateFound;
+    }
+
+    /**
+     * Gets the state completion percentage, taking into consideration the
+     * |height| of the Contextual Search Panel, and the initial and final
+     * states. A completion of 0 means the Panel is in the initial state and a
+     * completion of 1 means the Panel is in the final state.
+     *
+     * @param height The height of the Contextual Search Panel.
+     * @param startState The initial state of the Panel.
+     * @param endState The final state of the Panel.
+     * @return The completion percentage.
+     */
+    private float getStateCompletion(float height, PanelState startState, PanelState endState) {
+        float startSize = getPanelHeightFromState(startState);
+        float endSize = getPanelHeightFromState(endState);
+        float percentage = (height - startSize) / (endSize - startSize);
+        return percentage;
+    }
+
+    /**
+     * Updates the UI state for the closed to peeked transition (and vice
+     * versa), according to a completion |percentage|.
+     *
+     * @param percentage The completion percentage.
+     */
+    private void updatePanelForCloseOrPeek(float percentage) {
+        // Base page offset.
+        mBasePageY = 0.f;
+
+        // Base page brightness.
+        mBasePageBrightness = BASE_PAGE_BRIGHTNESS_STATE_PEEKED;
+
+        // Search Bar height.
+        mSearchBarHeight = mSearchBarHeightPeeking;
+
+        // Search Bar border.
+        mIsSearchBarBorderVisible = false;
+
+        // Search Bar text opacity.
+        mSearchBarTextOpacity = 1.f;
+
+        // Search provider icon opacity.
+        mSearchProviderIconOpacity = SEARCH_PROVIDER_ICON_OPACITY_STATE_PEEKED;
+
+        // Search icon opacity.
+        mSearchIconOpacity = SEARCH_ICON_OPACITY_PEEKED;
+
+        // Progress Bar.
+        mProgressBarOpacity = 0.f;
+    }
+
+    /**
+     * Updates the UI state for the peeked to expanded transition (and vice
+     * versa), according to a completion |percentage|.
+     *
+     * @param percentage The completion percentage.
+     */
+    private void updatePanelForExpansion(float percentage) {
+        // Base page offset.
+        float baseBaseY = MathUtils.interpolate(
+                0.f,
+                getBasePageTargetY(),
+                percentage);
+        mBasePageY = baseBaseY;
+
+        // Base page brightness.
+        float brightness = MathUtils.interpolate(
+                BASE_PAGE_BRIGHTNESS_STATE_PEEKED,
+                BASE_PAGE_BRIGHTNESS_STATE_EXPANDED,
+                percentage);
+        mBasePageBrightness = brightness;
+
+        // Search Bar height.
+        float searchBarHeight = Math.round(MathUtils.interpolate(
+                mSearchBarHeightPeeking,
+                mSearchBarHeightExpanded,
+                percentage));
+        mSearchBarHeight = searchBarHeight;
+
+        // Search Bar text opacity.
+        mSearchBarTextOpacity = 1.f;
+
+        // Search Bar border.
+        mIsSearchBarBorderVisible = true;
+        mSearchBarBorderY = searchBarHeight - SEARCH_BAR_BORDER_HEIGHT_DP + 1;
+
+        // Search provider icon opacity.
+        mSearchProviderIconOpacity = SEARCH_PROVIDER_ICON_OPACITY_STATE_PEEKED;
+
+        // Search icon opacity.
+        mSearchIconOpacity = SEARCH_ICON_OPACITY_PEEKED;
+
+        // Progress Bar.
+        float peekedHeight = getPanelHeightFromState(PanelState.PEEKED);
+        float threshold = PROGRESS_BAR_VISIBILITY_THRESHOLD_DP / mPxToDp;
+        float diff = Math.min(mHeight - peekedHeight, threshold);
+        // Fades the Progress Bar the closer it gets to the bottom of the
+        // screen.
+        float progressBarOpacity = MathUtils.interpolate(0.f, 1.f, diff / threshold);
+        mProgressBarOpacity = progressBarOpacity;
+        mProgressBarY = searchBarHeight - PROGRESS_BAR_HEIGHT_DP + 1;
+    }
+
+    /**
+     * Updates the UI state for the expanded to maximized transition (and vice
+     * versa), according to a completion |percentage|.
+     *
+     * @param percentage The completion percentage.
+     */
+    private void updatePanelForMaximization(float percentage) {
+        // Base page offset.
+        mBasePageY = getBasePageTargetY();
+
+        // Base page brightness.
+        float brightness = MathUtils.interpolate(
+                BASE_PAGE_BRIGHTNESS_STATE_EXPANDED,
+                BASE_PAGE_BRIGHTNESS_STATE_MAXIMIZED,
+                percentage);
+        mBasePageBrightness = brightness;
+
+        // Search Bar height.
+        float searchBarHeight = Math.round(MathUtils.interpolate(
+                mSearchBarHeightExpanded,
+                mSearchBarHeightMaximized,
+                percentage));
+        mSearchBarHeight = searchBarHeight;
+
+        // Search Bar border.
+        mIsSearchBarBorderVisible = true;
+        mSearchBarBorderY = searchBarHeight - SEARCH_BAR_BORDER_HEIGHT_DP + 1;
+
+        // Search Bar text opacity.
+        mSearchBarTextOpacity = 1.f;
+
+        // Search provider icon opacity.
+        float searchProviderIconOpacity = MathUtils.interpolate(
+                SEARCH_PROVIDER_ICON_OPACITY_STATE_EXPANDED,
+                SEARCH_PROVIDER_ICON_OPACITY_STATE_MAXIMIZED,
+                percentage);
+        mSearchProviderIconOpacity = searchProviderIconOpacity;
+
+        // Search icon opacity.
+        float searchIconOpacity = MathUtils.interpolate(
+                SEARCH_ICON_OPACITY_EXPANDED,
+                SEARCH_ICON_OPACITY_MAXIMIZED,
+                percentage);
+        mSearchIconOpacity = searchIconOpacity;
+
+        // Progress Bar.
+        mProgressBarOpacity = 1.f;
+        mProgressBarY = searchBarHeight - PROGRESS_BAR_HEIGHT_DP + 1;
+    }
+
+    /**
+     * Updates the UI state for the peeked to promo transition (and vice versa),
+     * according to a completion |percentage|.
+     *
+     * @param percentage The completion percentage.
+     */
+    private void updatePanelForOpeningPromo(float percentage) {
+        // Base page offset.
+        float baseBaseY = MathUtils.interpolate(
+                0,
+                getPromoBasePageOffsetY(),
+                percentage);
+        mBasePageY = baseBaseY;
+
+        // Base page brightness.
+        float brightness = MathUtils.interpolate(
+                BASE_PAGE_BRIGHTNESS_STATE_PEEKED,
+                BASE_PAGE_BRIGHTNESS_STATE_EXPANDED,
+                percentage);
+        mBasePageBrightness = brightness;
+
+        // Search Bar height.
+        float searchBarHeight = Math.round(MathUtils.interpolate(
+                mSearchBarHeightPeeking,
+                mSearchBarHeightPromo,
+                percentage));
+        mSearchBarHeight = searchBarHeight;
+
+        // Search Bar border.
+        mIsSearchBarBorderVisible = false;
+
+        // Search Bar text opacity.
+        float peekedHeight = getPanelHeightFromState(PanelState.PEEKED);
+        float threshold = DISAPPEARING_ELEMENT_THRESHOLD_DP / mPxToDp;
+        float diff = Math.min(mHeight - peekedHeight, threshold);
+        float disappearingElementOpacity = MathUtils.interpolate(1.f, 0.f, diff / threshold);
+        mSearchBarTextOpacity = disappearingElementOpacity;
+
+        // Search provider icon opacity.
+        boolean shouldDisplaySearchProviderIcon = shouldHidePromoHeader();
+        mSearchProviderIconOpacity =
+                shouldDisplaySearchProviderIcon ? 1.f : disappearingElementOpacity;
+
+        // Search icon opacity.
+        mSearchIconOpacity = SEARCH_ICON_OPACITY_PEEKED;
+
+        // Progress Bar.
+        mProgressBarOpacity = 0.f;
+        mProgressBarY = searchBarHeight - PROGRESS_BAR_HEIGHT_DP + 1;
+    }
+
+    // ============================================================================================
+    // Base Page Offset
+    // ============================================================================================
+
+    /**
+     * Updates the coordinate of the existing selection.
+     * @param y The y coordinate of the selection in pixels.
+     */
+    protected void updateBasePageSelectionYPx(float y) {
+        mBasePageSelectionYPx = y;
+        updateBasePageTargetY();
+    }
+
+    /**
+     * Updates the target offset of the Base Page in order to keep the selection in view
+     * after expanding the Panel.
+     */
+    private void updateBasePageTargetY() {
+        mBasePageTargetY = calculateBasePageTargetY(PanelState.EXPANDED);
+        mPromoBasePageTargetY = calculateBasePageTargetY(PanelState.PROMO);
+    }
+
+    /**
+     * Calculates the target offset of the Base Page in order to keep the selection in view
+     * after expanding the Panel to the given |expandedState|.
+     *
+     * @param expandedState
+     * @return The target offset Y.
+     */
+    private float calculateBasePageTargetY(PanelState expandedState) {
+        // Convert from px to dp.
+        final float selectionY = mBasePageSelectionYPx * mPxToDp;
+
+        // Calculate the exact height of the expanded Panel without taking into
+        // consideration the height of the shadow (what is returned by the
+        // getPanelFromHeight method). We need the measurement of the portion
+        // of the Panel that occludes the page.
+        final float expandedHeight = getPanelHeightFromState(expandedState)
+                - PANEL_SHADOW_HEIGHT_DP;
+
+        // Calculate the offset to center the selection on the available area.
+        final float fullscreenHeight = getFullscreenHeight();
+        final float availableHeight = fullscreenHeight - expandedHeight;
+        float offset = -selectionY + availableHeight / 2;
+
+        // Make sure offset is negative to prevent Base Page from moving down,
+        // because there's nothing to render above the Page.
+        offset = Math.min(offset, 0.f);
+        // If visible, the Toolbar will be hidden. Therefore, we need to adjust
+        // the offset to account for this difference.
+        if (mIsToolbarShowing)
+            offset -= TOOLBAR_HEIGHT_DP;
+        // Make sure the offset is not greater than the expanded height, because
+        // there's nothing to render below the Page.
+        offset = Math.max(offset, -expandedHeight);
+
+        return offset;
+    }
+
+    /**
+     * @return The Y coordinate to apply to the Base Page in order to keep the selection
+     *         in view when the Search Panel is in EXPANDED state.
+     */
+    public float getBasePageTargetY() {
+        return mBasePageTargetY;
+    }
+
+    /**
+     * @return The Y coordinate to apply to the Base Page in order to keep the
+     *         selection in view when the Search Panel is in PROMO state.
+     */
+    private float getPromoBasePageOffsetY() {
+        return mPromoBasePageTargetY;
+    }
+
+    // ============================================================================================
+    // Promo
+    // ============================================================================================
+
+    /**
+     * Updates the UI state for a given |height| when performing the opt-in animation.
+     *
+     * @param height The Contextual Search Panel height.
+     */
+    protected void setPanelHeightForPromoOptInAnimation(float height) {
+        PanelState endState = PanelState.EXPANDED;
+        PanelState startState = PanelState.PROMO;
+        float percentage = getStateCompletion(height, startState, endState);
+
+        updatePanelSize(height, endState, percentage);
+
+        updatePanelForPromoOptInAnimation(percentage);
+    }
+
+    /**
+     * Updates the UI state for the PROMO to EXPANDED transition (and vice versa),
+     * according to a completion |percentage|.
+     *
+     * @param percentage The completion percentage.
+     */
+    private void updatePanelForPromoOptInAnimation(float percentage) {
+        // Base page offset.
+        float baseBaseY = MathUtils.interpolate(
+                getPromoBasePageOffsetY(),
+                getBasePageTargetY(),
+                percentage);
+        mBasePageY = baseBaseY;
+
+        // Base page brightness.
+        mBasePageBrightness = BASE_PAGE_BRIGHTNESS_STATE_EXPANDED;
+
+        // Search Bar height.
+        float searchBarHeight = Math.round(MathUtils.interpolate(
+                mSearchBarHeightPromo,
+                mSearchBarHeightExpanded,
+                percentage));
+        mSearchBarHeight = searchBarHeight;
+
+        // Search Bar border.
+        mIsSearchBarBorderVisible = false;
+
+        // Search Bar text opacity.
+        final float threshold = 0.5f;
+        float searchBarTextOpacity = MathUtils.interpolate(0.f, 1.f,
+                Math.max(percentage - threshold, 0) / threshold);
+        mSearchBarTextOpacity = searchBarTextOpacity;
+
+        // Search provider icon opacity.
+        boolean shouldDisplaySearchProviderIcon = shouldHidePromoHeader();
+        mSearchProviderIconOpacity = shouldDisplaySearchProviderIcon
+                ? 1.f : MathUtils.interpolate(0.f, 1.f, percentage);
+
+        // Search icon opacity.
+        mSearchIconOpacity = SEARCH_ICON_OPACITY_PEEKED;
+
+        // Progress Bar.
+        mProgressBarOpacity = percentage == 1.f ? 1.f : 0.f;
+        mProgressBarY = searchBarHeight - PROGRESS_BAR_HEIGHT_DP + 1;
+    }
+}