当我试图得到整个页面截图它返回一个白屏

Question

我试图在webview中以编程方式获得整个屏幕截图。当我测试我的代码时，它返回一个白屏

我试过不同的代码，但我不能完成它。有时返回白屏，有时返回黑屏。我还添加了清单互联网权限，并编写了外部存储权限。我的xml文件只存在于webview中。

我也试过"睡"五秒钟，但它不起作用。

public static Bitmap loadBitmapFromView(WebView v, int width, int height) 
{
    Bitmap b = Bitmap.createBitmap(width , height, Bitmap.Config.ARGB_8888);                
    Canvas c = new Canvas(b);
    v.layout(0, 0, v.getLayoutParams().width, v.getLayoutParams().height);
    v.draw(c);  
    FileOutputStream fos = null;
    try 
    {
        fos = new FileOutputStream("/sdcard/image.jpg" );
    } 
    catch (FileNotFoundException e1) 
    {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
    b.compress(Bitmap.CompressFormat.JPEG, 90, fos);
    try 
    {
        fos.close();
    } 
    catch (IOException e) 
    {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return b;
}

我在onpageFinished()中调用这个方法。通过loadBitmapFromView(webView, webView.getWidth(), webView.getHeight());，我确保加载整个页面。在我看来，当webview在调用之前没有加载时，它会尝试获取屏幕截图。但我在onpageFinished()方法中调用它。当webview加载完成时，它会运行。

Other parts of my code
public class Wv extends Activity 
{  
    private static WebView webView;
    CustomWebViewClient webViewClient;
    ProgressDialog mProgressDialog;
      public void onCreate(Bundle savedInstanceState) 
      {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView = (WebView) findViewById(R.id.webView1);
        mProgressDialog = new ProgressDialog(this);
        mProgressDialog.setMessage("Loading...");
        webView.loadUrl("file:///sdcard/ZipDemo/HTML_Friday.html");
        webViewClient = new CustomWebViewClient();         
        webView.setWebViewClient(webViewClient);     
    }

      private class CustomWebViewClient extends WebViewClient 
        {
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                   super.onPageStarted(view, url, favicon);
                if(!mProgressDialog.isShowing())
                {
                    mProgressDialog.show();
                }
            }  
            @Override 
            public void onPageFinished(WebView view, String url) {

                   super.onPageFinished(view, url); 
                if(mProgressDialog.isShowing()){
                    mProgressDialog.dismiss();
                }
loadBitmapFromView(webView,webView.getWidth(),webView.getHeight());
         }
       }

Answer 1

是否启用了视图的DrawingCache?

public static Bitmap getBitmapFromView(View view) {
    try {
      view.setDrawingCacheEnabled(true);
      view.buildDrawingCache(true);
      Bitmap bitmap = Bitmap.createBitmap(view.getDrawingCache());
      view.setDrawingCacheEnabled(false); // clear drawing cache
      return bitmap;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }

你应该在View的post-method中使用它:(http://developer.android.com/reference/android/view/View.html#post(java.lang.Runnable))

view.post(new Runnable() {
    @Override
    public void run() {
    }
  });

Answer 2

通过删除CustomWebViewClient类并创建新的button.onPageFinished()方法来解决问题。当我创建按钮时，问题就解决了。这是代码

public class Wv extends Activity 
{  
    private WebView webView;
    private Button screenShot;
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView = (WebView) findViewById(R.id.webView1);
        screenShot=(Button) findViewById(R.id.button_screenshot);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setLoadWithOverviewMode(true);
        webView.getSettings().setUseWideViewPort(true);
        webView.loadUrl("file:///android_asset/HTML_Friday.html");
      screenShot.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub          
            Picture picture = webView.capturePicture();
            Bitmap b = Bitmap.createBitmap(picture.getWidth(),picture.getHeight(), Bitmap.Config.ARGB_8888);
            Canvas c = new Canvas(b);
            File screen = new File(Environment.getExternalStorageDirectory()
                    .toString(), "tt12.jpg");
            if (screen.exists())
                screen.delete();
            picture.draw(c);
            FileOutputStream fos = null;
            try {
                fos = new FileOutputStream(screen);
                if (fos != null) {
                    b.compress(Bitmap.CompressFormat.JPEG, 90, fos);
                    fos.close();
                }
            } catch (Exception e) {
                e.getMessage();
            }
        }
    });
   }    
 }