在Android中从HTML生成位图

Question

如何从Android中的HTML生成位图？

可以WebView用于此或是否有更好的方法(如可能WebView直接使用渲染引擎)？怎么样？

我想实现以下方法......

public Bitmap toBitmap(Context context, String html, Rect rect);

... html要呈现的html 在哪里,是rect所需位图的框架.

Answer 1

一种使用WebView从HTML字符串生成位图的同步方法,可以在AsyncTask中使用:

public Bitmap getBitmap(final WebView w, int containerWidth, int containerHeight, final String baseURL, final String content) {
    final CountDownLatch signal = new CountDownLatch(1);
    final Bitmap b = Bitmap.createBitmap(containerWidth, containerHeight, Bitmap.Config.ARGB_8888);
    final AtomicBoolean ready = new AtomicBoolean(false); 
    w.post(new Runnable() {

        @Override
        public void run() {
            w.setWebViewClient(new WebViewClient() {
                @Override
                public void onPageFinished(WebView view, String url) {
                    ready.set(true);
                }
            });
            w.setPictureListener(new PictureListener() {
                @Override
                public void onNewPicture(WebView view, Picture picture) {
                    if (ready.get()) {
                        final Canvas c = new Canvas(b);
                        view.draw(c);
                        w.setPictureListener(null);
                        signal.countDown();
                    }
                }
            });
            w.layout(0, 0, rect.width(), rect.height());
            w.loadDataWithBaseURL(baseURL, content, "text/html", "UTF-8", null);
        }});
    try {
        signal.await();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    return b;
}

它有一些局限性,但它是一个开始.

Answer 2

您可以使用draw方法让它在您选择的位图中绘制.我做了一个例子,不要忘记清单的互联网和外部存储权限:

public class MainActivity extends Activity {
    private WebView mWebView;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mWebView = new WebView(this);
        setContentView(mWebView);
        mWebView.loadUrl("http://tea.ch");
    }
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
      if (keyCode != KeyEvent.KEYCODE_BACK) return super.onKeyDown(keyCode, event);
      Bitmap bm = Bitmap.createBitmap(200, 300, Bitmap.Config.ARGB_8888);
      Canvas c = new Canvas(bm);
      mWebView.draw(c);
      OutputStream stream = null;
      try {
        stream = new FileOutputStream(Environment.getExternalStorageDirectory() +"/teach.png");
        bm.compress(CompressFormat.PNG, 80, stream);
        if (stream != null) stream.close();
      } catch (IOException e) {
      } finally {
        bm.recycle();
      }

      return super.onKeyDown(keyCode, event);
    }
}