在android4.4.3上面，联系人的头像默认显示首字母，但是不支持中文字符，如下图：
如果联系人名字的第一位是英文字符(a-z || A-Z)，则默认头像将显示该首字母。
如果支持中文时显示第一个汉字，那就happy了。
那就看看如何通过修改源代码来实现这一小功能吧～
我们还是先了解下联系人头像加载的流程吧～
联系人头像加载这个问题还是很有意思的，在Contacts中使用ContactPhotoManager类(严格来讲是这个类的子类)来实现头像的异步加载。
这个类还使用了LruCache来缓存图片，相当的强大，对图像的异步加载和缓存有兴趣的同志们可以看看。
以主页面的联系人列表加载头像为例。大致的调用流程为(只针对没有设置头像的联系人，即photoUri是null):
DefaultContactListAdapter->bindView()
ContactEntryListAdapter->buildQuickContact()
ContactEntryListAdapter->getDefaultImageRequestFromCursor()
ContactPhotoManagerImpl->loadPhoto()->provider:LetterTileDefaultImageProvider// 注意，使用的是DEFAULT_AVATAR对象
LetterTileDefaultImageProvider->applyDefaultImage()
LetterTileDefaultImageProvider->getDefaultImageForContact()
LetterTileDrawable->drawLetterTile()->firsr char:高
在drawLetterTile函数执行drawText之前会调用isEnglishLetter来判断字符串的首字符是否为英文字符，如果是，则将首字母画上去；
否则，使用默认头像
private static boolean isEnglishLetter(final char c) {return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');}
通过上面的流程解析，我们可以确定，是isEnglishLetter函数导致在中文字符不被描画。
嗯，那我们就改造一下这个函数吧。不废话，直接上代码～
private static boolean isEnglishLetter(final char c) {return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || isChineseLetter(c);}
private static boolean isChineseLetter(final char c) {return isChinese(String.valueOf(c));}
至于isChinese函数的实现，代码就不贴了，有兴趣的可以参考我的一篇判断字符为中文、日文、韩文的文章(/Lefter/p/3804051.html)
经过这个改造后，我们就可以让默认头像显示中文名字的第一个汉字了！
具体修改如下。严重OK
private static boolean isEnglishLetter(final char c) {
return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
}
private static boolean isChineseLetter(final char c) {
return isChinese(c);
}
private static boolean isChinese(char c) {
Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
|| ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
|| ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A
|| ub == Character.UnicodeBlock.GENERAL_PUNCTUATION
|| ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
|| ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS) {
return true;
}
return false;
}
//具体路径 com.mon.lettertiles;LetterTileDrawable.java
private void drawLetterTile(final Canvas canvas) {
// Draw background color.
sPaint.setColor(pickColor(mIdentifier));
sPaint.setAlpha(mPaint.getAlpha());
canvas.drawRect(getBounds(), sPaint);
// Draw letter/digit only if the first character is an english letter
if (mDisplayName != null && (isEnglishLetter(mDisplayName.charAt(0)) || isChineseLetter(mDisplayName.charAt(0)))) {
// Draw letter or digit.
sFirstChar[0] = Character.toUpperCase(mDisplayName.charAt(0));
// Scale text by canvas bounds and user selected scaling factor
final int minDimension = Math.min(getBounds().width(), getBounds().height());
sPaint.setTextSize(mScale * sLetterToTileRatio * minDimension);
//sPaint.setTextSize(sTileLetterFontSize);
sPaint.getTextBounds(sFirstChar, 0, 1, sRect);
sPaint.setColor(sTileFontColor);
final Rect bounds = getBounds();
// Draw the letter in the canvas, vertically shifted up or down by the user-defined
// offset
canvas.drawText(sFirstChar, 0, 1, bounds.centerX(),
bounds.centerY() + mOffset * bounds.height() + sRect.height() / 2,
sPaint);
}else {
// Draw the default image if there is no letter/digit to be drawn
final Bitmap bitmap = getBitmapForContactType(mContactType);
drawBitmap(bitmap, bitmap.getWidth(), bitmap.getHeight(),
canvas);
}
}
//为什么头像的背景会有8种颜色
<!-- Make sure to also update LetterTileProvider#NUM_OF_TILE_COLORS when adding or removing
colors -->
<array name="letter_tile_colors">
<item>#33b679</item>
<item>#536173</item>
<item>#855e86</item>
<item>#df5948</item>
<item>#aeb857</item>
<item>#547bca</item>
<item>#ae6b23</item>
<item>#e5ae4f</item>
</array>
/** This should match the total number of colors defined in colors.xml for letter_tile_color */
private static final int NUM_OF_TILE_COLORS = 8; //八种颜色随机生成
//获取颜色
private int pickColor(final String identifier) {
if (TextUtils.isEmpty(identifier) || mContactType == TYPE_VOICEMAIL) {
return sDefaultColor;
}
// String.hashCode() implementation is not supposed to change across java versions, so
// this should guarantee the same email address always maps to the same color.
// The email should already have been normalized by the ContactRequest.
//随机取得颜色值
final int color = Math.abs(identifier.hashCode()) % NUM_OF_TILE_COLORS;
return sColors.getColor(color, sDefaultColor);
}
