CheatSheet.java

package org.qii.weiciyuan.support.lib;

/**
 * User: qii
 * Date: 13-2-5
 * https://plus.google.com/113735310430199015092/posts/QrMMFNck5MA
 */

import android.app.Activity;
import android.content.Context;
import android.graphics.Rect;
import android.text.TextUtils;
import android.view.Gravity;
import android.view.View;
import android.widget.Toast;
import org.qii.weiciyuan.support.utils.SmileyPickerUtility;

/**
 * Helper class for showing cheat sheets (tooltips) for icon-only UI elements on long-press. This is
 * already default platform behavior for icon-only {@link android.app.ActionBar} items and tabs.
 * This class provides this behavior for any other such UI element.
 * <p/>
 * <p>Based on the original action bar implementation in <a href="https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/core/java/com/android/internal/view/menu/ActionMenuItemView.java">
 * ActionMenuItemView.java</a>.
 */
public class CheatSheet {


    /**
     * The estimated height of a toast, in dips (density-independent pixels). This is used to
     * determine whether or not the toast should appear above or below the UI element.
     */
    private static final int ESTIMATED_TOAST_HEIGHT_DIPS = 48;


    /**
     * Sets up a cheat sheet (tooltip) for the given view by setting its {@link
     * android.view.View.OnLongClickListener}. When the view is long-pressed, a {@link Toast} with
     * the given text will be shown either above (default) or below the view (if there isn't room
     * above it).
     *
     * @param view      The view to add a cheat sheet for.
     * @param textResId The string resource containing the text to show on long-press.
     */
    public static void setup(final Activity activity, View view, final int textResId) {
        view.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                return showCheatSheet(activity, view, view.getContext().getString(textResId));
            }
        });
    }

    public static void setup(final Activity activity, View view, final String text) {
        view.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                return showCheatSheet(activity, view, text);
            }
        });
    }

    /**
     * Removes the cheat sheet for the given view by removing the view's {@link
     * android.view.View.OnLongClickListener}.
     *
     * @param view The view whose cheat sheet should be removed.
     */
    public static void remove(final View view) {
        view.setOnLongClickListener(null);
    }

    /**
     * Internal helper method to show the cheat sheet toast.
     */
    private static boolean showCheatSheet(Activity activity, View view, CharSequence text) {
        if (TextUtils.isEmpty(text)) {
            return false;
        }

        final int[] screenPos = new int[2]; // origin is device display
        final Rect displayFrame = new Rect(); // includes decorations (e.g. status bar)
        view.getLocationOnScreen(screenPos);
        view.getWindowVisibleDisplayFrame(displayFrame);

        final Context context = view.getContext();
        final int viewWidth = view.getWidth();
        final int viewHeight = view.getHeight();
        final int viewCenterX = screenPos[0] + viewWidth / 2;
        final int screenWidth = context.getResources().getDisplayMetrics().widthPixels;
        final int estimatedToastHeight = (int) (ESTIMATED_TOAST_HEIGHT_DIPS
                * context.getResources().getDisplayMetrics().density);

        Toast cheatSheet = Toast.makeText(context, text, Toast.LENGTH_SHORT);
        boolean showBelow = screenPos[1] < estimatedToastHeight;
        if (showBelow) {
            // Show below
            // Offsets are after decorations (e.g. status bar) are factored in
            cheatSheet.setGravity(Gravity.TOP | Gravity.CENTER_HORIZONTAL,
                    viewCenterX - screenWidth / 2,
                    screenPos[1] - displayFrame.top + viewHeight);
        } else {
            // Show above
            // Offsets are after decorations (e.g. status bar) are factored in

            //softkeyboard height
            int height = SmileyPickerUtility.getScreenHeight(activity)
                    - SmileyPickerUtility.getStatusBarHeight(activity)
                    - SmileyPickerUtility.getAppHeight(activity);

            cheatSheet.setGravity(Gravity.BOTTOM | Gravity.CENTER_HORIZONTAL,
                    viewCenterX - screenWidth / 2,
                    displayFrame.bottom - screenPos[1] + height);
        }

        cheatSheet.show();
        return true;
    }
}