Java tutorial
/* * Copyright (C) 2012 Google Inc. * Licensed to 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.mail.ui; import android.content.Context; import android.content.res.Resources; import android.graphics.Canvas; import android.graphics.LinearGradient; import android.graphics.Paint; import android.graphics.RectF; import android.graphics.Shader; import android.support.v4.text.BidiFormatter; import com.android.mail.R; import com.android.mail.providers.Conversation; import com.android.mail.providers.Folder; import com.android.mail.providers.UIProvider.FolderType; import com.android.mail.utils.FolderUri; import com.android.mail.utils.LogTag; import com.android.mail.utils.Utils; import com.google.common.collect.Sets; import java.util.NavigableSet; import java.util.Set; /** * Used to generate folder display information given a raw folders string. * (The raw folders string can be obtained from {@link Conversation#getRawFolders()}.) */ public abstract class FolderDisplayer { public static final String LOG_TAG = LogTag.getLogTag(); protected Context mContext; protected final NavigableSet<Folder> mFoldersSortedSet = Sets.newTreeSet(); protected final FolderDrawableResources mFolderDrawableResources = new FolderDrawableResources(); public static class FolderDrawableResources { public int defaultFgColor; public int defaultBgColor; public int folderRoundedCornerRadius; public int overflowGradientPadding; public int folderHorizontalPadding; public int folderInBetweenPadding; public int folderFontSize; public int folderVerticalOffset; } public FolderDisplayer(Context context) { mContext = context; initializeDrawableResources(); } protected void initializeDrawableResources() { // Set default values used across all folder chips final Resources res = mContext.getResources(); mFolderDrawableResources.defaultFgColor = res.getColor(R.color.default_folder_foreground_color); mFolderDrawableResources.defaultBgColor = res.getColor(R.color.default_folder_background_color); mFolderDrawableResources.folderRoundedCornerRadius = res .getDimensionPixelOffset(R.dimen.folder_rounded_corner_radius); mFolderDrawableResources.folderInBetweenPadding = res.getDimensionPixelOffset(R.dimen.folder_start_padding); } /** * Configure the FolderDisplayer object by filtering and copying from the list of raw folders. * * @param conv {@link Conversation} containing the folders to display. * @param ignoreFolderUri (optional) folder to omit from the displayed set * @param ignoreFolderType -1, or the {@link FolderType} to omit from the displayed set */ public void loadConversationFolders(Conversation conv, final FolderUri ignoreFolderUri, final int ignoreFolderType) { mFoldersSortedSet.clear(); for (Folder folder : conv.getRawFolders()) { // Skip the ignoreFolderType if (ignoreFolderType >= 0 && folder.isType(ignoreFolderType)) { continue; } // skip the ignoreFolder if (ignoreFolderUri != null && ignoreFolderUri.equals(folder.folderUri)) { continue; } mFoldersSortedSet.add(folder); } } /** * Reset this FolderDisplayer so that it can be reused. */ public void reset() { mFoldersSortedSet.clear(); } /** * Helper function to calculate exactly how much space the displayed folders should take. * @param folders the set of folders to display. * @param maxCellWidth this signifies the absolute max for each folder cell, no exceptions. * @param maxLayoutWidth the view's layout width, aka how much space we have. * @param foldersInBetweenPadding the padding between folder chips. * @param foldersHorizontalPadding the padding between the edge of the chip and the text. * @param maxFolderCount the maximum number of folder chips to display. * @param paint work paint. * @return an array of integers that signifies the length of each folder chip. */ public static int[] measureFolderDimen(Set<Folder> folders, int maxCellWidth, int maxLayoutWidth, int foldersInBetweenPadding, int foldersHorizontalPadding, int maxFolderCount, Paint paint) { final int numDisplayedFolders = Math.min(maxFolderCount, folders.size()); if (numDisplayedFolders == 0) { return new int[0]; } // This variable is calculated based on the number of folders we are displaying final int maxAllowedCellSize = Math.min(maxCellWidth, (maxLayoutWidth - (numDisplayedFolders - 1) * foldersInBetweenPadding) / numDisplayedFolders); final int[] measurements = new int[numDisplayedFolders]; int count = 0; int missingWidth = 0; int extraWidth = 0; for (Folder f : folders) { if (count > numDisplayedFolders - 1) { break; } final String folderString = f.name; final int neededWidth = (int) paint.measureText(folderString) + 2 * foldersHorizontalPadding; if (neededWidth > maxAllowedCellSize) { // What we can take from others is the minimum of the width we need to borrow // and the width we are allowed to borrow. final int borrowedWidth = Math.min(neededWidth - maxAllowedCellSize, maxCellWidth - maxAllowedCellSize); final int extraWidthLeftover = extraWidth - borrowedWidth; if (extraWidthLeftover >= 0) { measurements[count] = Math.min(neededWidth, maxCellWidth); extraWidth = extraWidthLeftover; } else { measurements[count] = maxAllowedCellSize + extraWidth; extraWidth = 0; } missingWidth = -extraWidthLeftover; } else { extraWidth = maxAllowedCellSize - neededWidth; measurements[count] = neededWidth; if (missingWidth > 0) { if (extraWidth >= missingWidth) { measurements[count - 1] += missingWidth; extraWidth -= missingWidth; } else { measurements[count - 1] += extraWidth; extraWidth = 0; } } missingWidth = 0; } count++; } return measurements; } public static void drawFolder(Canvas canvas, float x, float y, int width, int height, Folder f, FolderDisplayer.FolderDrawableResources res, BidiFormatter formatter, Paint paint) { drawFolder(canvas, x, y, width, height, f.name, f.getForegroundColor(res.defaultFgColor), f.getBackgroundColor(res.defaultBgColor), res, formatter, paint); } public static void drawFolder(Canvas canvas, float x, float y, int width, int height, String name, int fgColor, int bgColor, FolderDisplayer.FolderDrawableResources res, BidiFormatter formatter, Paint paint) { canvas.save(); canvas.translate(x, y + res.folderVerticalOffset); // Draw the box. paint.setColor(bgColor); paint.setStyle(Paint.Style.FILL); final RectF rect = new RectF(0, 0, width, height); canvas.drawRoundRect(rect, res.folderRoundedCornerRadius, res.folderRoundedCornerRadius, paint); // Draw the text based on the language locale and layout direction. paint.setColor(fgColor); paint.setStyle(Paint.Style.FILL); // Compute the text/gradient indices final int textLength = (int) paint.measureText(name); final int gradientX0; final int gradientX1; final int textX; /*************************************************************************************************** * width - the actual folder chip rectangle. * * textLength - the length of the folder's full name (can be longer than * * the actual chip, which is what overflow gradient is for). * * innerPadding - the padding between the text and the chip edge. * * overflowPadding - the padding between start of overflow and the chip edge. * * * * * * text is in a RTL language * * * * index-0 * * |<---------------------------- width ---------------------------->| * * |<-------------------------textLength------------------>| | * * | |<----- overflowPadding ----->| | * * | |<- innerPadding ->|<-------->|<--------->|<- horizontalPadding ->| * * textX gX1 gX0 * * * * * * text is in a LTR language. * * * * index-0 * * |<------------------------------ width ------------------------------->| * * | |<-------------------------textLength-------------------->| * * | |<-------- overflowPadding ------->| * * |<- horizontalPadding ->|<--------->|<-------->|<- horizontalPadding ->| * * textX gX0 gX1 * * * **************************************************************************************************/ if (formatter.isRtl(name)) { gradientX0 = res.overflowGradientPadding; gradientX1 = res.folderHorizontalPadding; textX = width - res.folderHorizontalPadding - textLength; } else { gradientX0 = width - res.overflowGradientPadding; gradientX1 = width - res.folderHorizontalPadding; textX = res.folderHorizontalPadding; } // Draw the text and the possible overflow gradient // Overflow happens when the text is longer than the chip width minus side paddings. if (textLength > width - 2 * res.folderHorizontalPadding) { final Shader shader = new LinearGradient(gradientX0, 0, gradientX1, 0, fgColor, Utils.getTransparentColor(fgColor), Shader.TileMode.CLAMP); paint.setShader(shader); } final int textY = height / 2 - (int) (paint.descent() + paint.ascent()) / 2; canvas.drawText(name, textX, textY, paint); paint.setShader(null); canvas.restore(); } }