Java tutorial
//package com.java2s; /* * Copyright 2012 Google Inc. * * 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. */ import android.content.Context; import android.graphics.Rect; import android.text.TextUtils; import android.view.Gravity; import android.view.View; import android.widget.Toast; public class Main { /** * 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; /** * Internal helper method to show the cheat sheet toast. */ private static boolean show(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 // NOTE: We can't use Gravity.BOTTOM because when the keyboard is up // its height isn't factored in. cheatSheet.setGravity(Gravity.TOP | Gravity.CENTER_HORIZONTAL, viewCenterX - screenWidth / 2, screenPos[1] - displayFrame.top - estimatedToastHeight); } cheatSheet.show(); return true; } }