Android 在呈现后获取 webview 内容的高度 [英] Android get height of webview content once rendered

问题描述

我试图在渲染后获取 web 视图的高度.它总是返回 null，我试过 getHeight、getMeasuredHeight、getContentHeight 并且它总是返回 null.

I'm trying to get the height of a webview once it has been rendered. It always returns null, I've tried getHeight, getMeasuredHeight, getContentHeight and it always returns null.

布局:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/instructions"
    android:background="@color/transparent_black" >

        <WebView
            android:id="@+id/top_content"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </RelativeLayout>

活动

public class TestActivity extends MenuActivity {

private final static String TAG = "HearingTest";
private String urlTopContent;
private WebView topContent;
private boolean mMoreInfoTop = true;
private int mYdelta = 0;
private int mBottomOffset = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.right_hearing_test);

        String topHtml = this.getString(R.string.top_content);
        //String bottomHtml = this.getString(R.string.bottom_content);

        urlTopContent = "file:///android_asset/html/" + topHtml;
        WebViewSettings();
        LoadWebPage(urlTopContent);
    }

    public void WebViewSettings(){

        topContent = (WebView) findViewById(R.id.top_content);
        topContent.getSettings().setJavaScriptEnabled(true);
        topContent.getSettings().setBuiltInZoomControls(true);
        topContent.getSettings().setSupportZoom(true);
        topContent.getSettings().setLoadWithOverviewMode(true);
        topContent.setBackgroundColor(0);
        topContent.canGoBack();

        int topHeight = topContent.getContentHeight();
        Log.d("Top Height", "Height: " + topHeight);            

        topContent.setWebViewClient(new WebViewClient(){

            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                if (Uri.parse(url).getHost().equals(urlTopContent)) {
                    // This is my web site, so do not override; let my WebView load the page
                    return false;
                }
                // Otherwise, the link is not for a page on my site, so launch another Activity that handles URLs
                Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                startActivity(intent);
                return true;
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                View webViewHeight = (View) findViewById(R.id.top_content);
                int height = webViewHeight.getHeight();
                Log.d("Top Content","Top Content Height:" + height);
            }
        });
    }

    public void LoadWebPage(String url){

        try {
            topContent.loadUrl(url);
            Log.d("Loading Web Page", "URL" + url + "connected");
        } 
        catch (Exception e) {
                Log.d("Loading Web Page", "URL: " + url + " couldn't connect.");
        }
    }

}

我什至不知道是否有可能在渲染后获得 web 视图的高度，但我不明白为什么你不能.如果有人得到和解决方案，将不胜感激.

I don't even know if it's possible to get the height of the web view after it has rendered but I don't see why you couldn't. if anyones got and solutions it would be greatly appreciated.

推荐答案

您可以在该 WebView 上使用 ViewTreeObserver 来获取渲染其内容后的实际高度.

You can use ViewTreeObserver on that WebView to get actual height after rendering its content.

这是示例代码.

ViewTreeObserver viewTreeObserver  = mWebView.getViewTreeObserver();

viewTreeObserver.addOnPreDrawListener(new OnPreDrawListener() {
                   @Override
                   public boolean onPreDraw() {                                
                           int height = mWebView.getMeasuredHeight();
                           if( height != 0 ){
                                   Toast.makeText(getActivity(), "height:"+height,Toast.LENGTH_SHORT).show();
                                   mWebView.getViewTreeObserver().removeOnPreDrawListener(this);
                           }
                           return false;
                   }
           });

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