当我尝试获取整个页面的屏幕截图时 returns 出现白屏？

Question

我试图在 webview 中以编程方式获取整个屏幕截图。当我测试我的代码时，returns 出现白屏。

我尝试了不同的代码，但无法完成。有时 returns 是白屏，有时 returns 是黑屏。我还添加了我的清单 Internet 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 "sleep" 五秒钟，但没用。

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()中调用了这个方法。通过 loadBitmapFromView(webView, webView.getWidth(), webView.getHeight()); 我确保加载整个页面。在我看来，当 webview 在调用之前未加载时，它会尝试获取屏幕截图。但是我在 onpageFinished() 方法中调用它。它在 webview 完全加载时运行。

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

您是否启用了 View 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;
    }
  }

您应该在视图的 post-方法中使用它：(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 class 并创建新的 button.onPageFinished() 方法解决了问题，但效果不佳。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();

            }
        }
    });
   }    
 }

当我尝试获取整个页面的屏幕截图时 returns 出现白屏？

When I try to get whole page screenshot it returns a white screen?

android

screenshot

webview