android html 图片缩放比例,Android 详解实现TextView加载带图片标签的Html并按比例缩放...

最近在做商城类项目，有这样一个需求：商品详情里边有一个商品描述，这个字段最初设计的是用来显示一段描述文字，做完以后设计说需要支持图文的详情，没办法改吧～谁让咱是程序猿呢，很自然的就想到TextView加载Html标签，加载不带图片的Html片段很简单只要setText(Html.fromHtml(...))就可以了,仔细看了下源码

/**

* Returns displayable styled text from the provided HTML string.

* Any

tags in the HTML will display as a generic

* replacement image which your program can then go through and

* replace with real images.

*

*

This uses TagSoup to handle real HTML, including all of the brokenness found in the wild.

*/

public static Spanned fromHtml(String source) {

return fromHtml(source, null, null);

}大概意思就是说此方法根据提供的Html返回一个带样式的字符串，然而所有的

标签将被显示成一个通用的图形，你可以在你的程序中替换为真正的图片，这不是扯呢吗？那是难倒服务器还单独把图片传过来？这显然不行啊，而且这个方法的实现是在

fromHtml(source, null, null);中，进去接着看

/**

* Returns displayable styled text from the provided HTML string.

* Any

tags in the HTML will use the specified ImageGetter

* to request a representation of the image (use null if you don't

* want this) and the specified TagHandler to handle unknown tags

* (specify null if you don't want this).

*

*

This uses TagSoup to handle real HTML, including all of the brokenness found in the wild.

*/

public static Spanned fromHtml(String source, ImageGetter imageGetter,

TagHandler tagHandler) {

Parser parser = new Parser();

try {

parser.setProperty(Parser.schemaProperty, HtmlParser.schema);

} catch (org.xml.sax.SAXNotRecognizedException e) {

// Should not happen.

throw new RuntimeException(e);

} catch (org.xml.sax.SAXNotSupportedException e) {

// Should not happen.

throw new RuntimeException(e);

}

HtmlToSpannedConverter converter =

new HtmlToSpannedConverter(source, imageGetter, tagHandler,

parser);

return converter.convert();

}

跟上边一个参数的方法差不多，重点是这一句Returns displayable styled text from the provided HTML string. Any

tags in the HTML will use the specified ImageGetter to request a representation of the image (use null if you don't want this) and the specified TagHandler to handle unknown tags (specify null if you don't want this).大概意思是说任何

标签将使用指定的ImageGetter请求图像的表示，看完这个就感觉有点意思了，接着看

/**

* Retrieves images for HTML

tags.

*/

public static interface ImageGetter {

/**

* This methos is called when the HTML parser encounters an

*

tag. The source argument is the

* string from the "src" attribute; the return value should be

* a Drawable representation of the image or null

* for a generic replacement image. Make sure you call

* setBounds() on your Drawable if it doesn't already have

* its bounds set.

*/

public Drawable getDrawable(String source);

}这是一个接口，需要我们自己实现，接口里边的方法是当HTML解释遇到

标签时候会调用，参数source就是

中的src，也就是图片的路径了，好了到这里已经有点眉目了，前边不是说让用真实图片替换那个通用的图形嘛，这下有路径了，再看返回参数Drawable,好说啊，从一个网络地址获取Drawable没有直接方法，不过从一个流有啊，

/**

* Create a drawable from an inputstream

*/

public static Drawable createFromStream(InputStream is, String srcName) {

Trace.traceBegin(Trace.TRACE_TAG_RESOURCES, srcName != null ? srcName : "Unknown drawable");

try {

return createFromResourceStream(null, null, is, srcName);

} finally {

Trace.traceEnd(Trace.TRACE_TAG_RESOURCES);

}

}封装个方法以便以后使用(封装真的很重要)

Drawable getImageFromNetwork(String imageUrl) {

URL myFileUrl = null;

Drawable drawable = null;

try {

myFileUrl = new URL(imageUrl);

} catch (MalformedURLException e) {

e.printStackTrace();

}

try {

HttpURLConnection conn = (HttpURLConnection) myFileUrl

.openConnection();

conn.setDoInput(true);

conn.connect();

InputStream is = conn.getInputStream();

drawable = Drawable.createFromStream(is, null);

is.close();

} catch (IOException e) {

e.printStackTrace();

}

return drawable;

}好了，既然是读取网络上的图片就要考虑异步加载了，

Android API > 9 (Honeycomb及之后)版本里，对UI线程/主线程里是不允许联网操作的，如果有网络操作，会抛出NetworkOnMainThreadException的异常，解决办法很简单，另起一个线程就可以了

new Thread(new Runnable() {

Message msg = Message.obtain();

@Override

public void run() {

Html.ImageGetter imageGetter=new Html.ImageGetter() {

@Override

public Drawable getDrawable(String source) {

Drawable drawable =getImageFromNetwork(source);

drawable.setBounds(0,0,drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight());

return drawable;

}

};

CharSequence charSequence = Html.fromHtml(html, imageGetter, null);

msg.what = 0x101;

msg.obj = charSequence;

mHandler.sendMessage(msg);

}

}).start();在线程里边加载html并通过imageGetter把解析出来的src转成Drawable，并把CharSequence传出去，写到这基本上功能就实现了，运行一下，图片也出来了

然而这是个虾米啊。。图片怎么辣么一丢丢，这特么怎么看，一万只草泥马在奔腾，接着改吧，既然小那就放大放大放大～～

刚才实现的ImageGetter里边不是有setBounds嘛，改一下宽高就行了，

int screenWidth = getWindowManager().getDefaultDisplay().getWidth(); // 屏幕宽(像素，如：480px)

int screenHeight = getWindowManager().getDefaultDisplay().getHeight(); // 屏幕高(像素，

Log.e("getDefaultDisplay", "screenWidth=" + screenWidth + "; screenHeight=" + screenHeight);

int w=screenWidth/2;

int h=w/(drawable.getIntrinsicWidth()/drawable.getIntrinsicHeight());

drawable.setBounds(0,0,w,h);

宽取屏幕一半，高按原图比例缩放，到次才算大功告成，有什么不对的地方还请路过大神指导～

源码下载