android 短信字符转表情显示过程

android 的短信实现方式普通用户适应的话需要长时间的使用才能习惯，将andorid的短信模式设置成我们常用的（一般人用户）的习惯。在查看字符转图片的过程中可以猜测出腾讯的QQ表情的原理应该是一样的

只是在传送非常用的表情时是将byte数据转换为image.

转载请注明：QQ:273733055 ppwuyi@sohu.com

/***
*
* 此方法描述的是：注意此方法在做表情转换的准备了
* @author:wujun@cqghong.com,ppwuyi@sohu.com
* @version: 2010-5-13 下午03:31:13
*/
private void bindCommonMessage(final MessageItem msgItem) {
if (mDownloadButton != null) {
mDownloadButton.setVisibility(View.GONE);
mDownloadingLabel.setVisibility(View.GONE);
}
// Since the message text should be concatenated with the sender's
// address(or name), I have to display it here instead of
// displaying it by the Presenter.
mBodyTextView.setTransformationMethod(HideReturnsTransformationMethod.getInstance());

// Get and/or lazily set the formatted message from/on the
// MessageItem. Because the MessageItem instances come from a
// cache (currently of size ~50), the hit rate on avoiding the
// expensive formatMessage() call is very high.
CharSequence formattedMessage = msgItem.getCachedFormattedMessage();
if (formattedMessage == null) { //肯定为null应为msgItem.formattedMessage从诞生来就没被注意过一次
formattedMessage = formatMessage(msgItem.mContact, msgItem.mBody, //重点到了
msgItem.mSubject, msgItem.mTimestamp,
msgItem.mHighlight);
msgItem.setCachedFormattedMessage(formattedMessage);
}
mBodyTextView.setText(formattedMessage);

if (msgItem.isSms()) {
hideMmsViewIfNeeded();
} else {
Presenter presenter = PresenterFactory.getPresenter(
"MmsThumbnailPresenter", mContext,
this, msgItem.mSlideshow);
presenter.present();

if (msgItem.mAttachmentType != WorkingMessage.TEXT) {
inflateMmsView();
mMmsView.setVisibility(View.VISIBLE);
setOnClickListener(msgItem);
drawPlaybackButton(msgItem);
} else {
hideMmsViewIfNeeded();
}
}

drawLeftStatusIndicator(msgItem.mBoxId);
drawRightStatusIndicator(msgItem);
}
//------------------------------------------------------------------------------

/***
*
* 此方法描述的是：开始转换了哦
* @author:wujun@cqghong.com,ppwuyi@sohu.com
* @version: 2010-5-13 下午03:32:52
*/
private CharSequence formatMessage(String contact, String body, String subject,
String timestamp, String highlight) {
CharSequence template = mContext.getResources().getText(R.string.name_colon); //遇到鬼了 <主题：<xliff:g id="SUBJECT">%s</xliff:g>>"
SpannableStringBuilder buf = //把他当作StringBuffer只是它可以放的不是 String 而已他能放跟多类型的东西
new SpannableStringBuilder(TextUtils.replace(template,
new String[] { "%s" },
new CharSequence[] { contact })); //替换成联系人

boolean hasSubject = !TextUtils.isEmpty(subject); //主题
if (hasSubject) {
buf.append(mContext.getResources().getString(R.string.inline_subject, subject)); //buff先在是联系人主题 XXXX eg wuyi <主题:dsadasdsa> 我爱我家
}

if (!TextUtils.isEmpty(body)) {
if (hasSubject) {
buf.append(" - "); //如果内容有主题有就+ " - " eg wuyi <主题:sdsadsadsa> -
}
SmileyParser parser = SmileyParser.getInstance(); //获得表情类了哦
buf.append(parser.addSmileySpans(body)); //追查急切关注中
}
if (!TextUtils.isEmpty(timestamp)) {
buf.append("\n");
int startOffset = buf.length();

// put a one pixel high spacer line between the message and the time stamp as requested
// by the spec.
//把之间的信息和时间戳的要求间隔一个像素的高线
//由规范
buf.append("\n");
buf.setSpan(new AbsoluteSizeSpan(3), startOffset, buf.length(),
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

startOffset = buf.length();
buf.append(timestamp);
buf.setSpan(new AbsoluteSizeSpan(12), startOffset, buf.length(),
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
// Make the timestamp text not as dark 改变某区域颜色时间的地方为特殊颜色
int color = mContext.getResources().getColor(R.color.timestamp_color);
buf.setSpan(new ForegroundColorSpan(color), startOffset, buf.length(),
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
if (highlight != null) {
int highlightLen = highlight.length();

String s = buf.toString().toLowerCase();
int prev = 0;
while (true) {
int index = s.indexOf(highlight, prev);
if (index == -1) {
break;
}
buf.setSpan(new StyleSpan(Typeface.BOLD), index, index + highlightLen, 0);
prev = index + highlightLen;
}
}
return buf;
}

//------------------------------------------------------------

/**
* Adds ImageSpans to a CharSequence that replace textual emoticons such
* as :-) with a graphical version.
*
* @param text A CharSequence possibly containing emoticons
* @return A CharSequence annotated with ImageSpans covering any
* recognized emoticons.
* 添加ImageSpans一个CharSequence的表情符号代替文字等 *如用图形版本:-)。
* 核心是把表情字符替换成ImageSpans的对象
*/
public CharSequence addSmileySpans(CharSequence text) {
SpannableStringBuilder builder = new SpannableStringBuilder(text);

Matcher matcher = mPattern.matcher(text);
while (matcher.find()) {
int resId = mSmileyToRes.get(matcher.group());
//注意下面的一块有点不好理解哦但是是核心
builder.setSpan(new ImageSpan(mContext, resId), matcher.start(), matcher.end(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}

return builder;
}

总结：

android 在将字符转化为表情图像其核心代码为

builder.setSpan(new ImageSpan(mContext, resId), matcher.start(), matcher.end(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
原理过程是先匹配到表情字符然后通过new ImageSpan(上下文,表情地址)绘制出一个ImageView然后替换掉表情字符。

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