Android:PdfDocument 生成空 pdf

Question

        PdfDocument document = new PdfDocument();
        // crate a page description
        PageInfo pageInfo = new PageInfo.Builder(300, 300, 1).create();
        // create a new page from the PageInfo
        Page page = document.startPage(pageInfo);
        // repaint the user's text into the page
        View content = findViewById(R.id.textarea);
        content.draw(page.getCanvas());
        // do final processing of the page
        document.finishPage(page);
        try {
             File f = getPDFPath();
             FileOutputStream fos = new FileOutputStream(f);
             document.writeTo(fos);
             document.close();
             fos.close();

        } catch (IOException e) {
            throw new RuntimeException("Error generating file", e);
        }

其中 findViewById(R.id.textarea); 指的是带有一些文本的 TextView，但上面的代码只生成空的 pdf。可能是什么问题？

是否有任何链接包含使用 Android 原生 API 生成 pdf 的工作示例？

Answer 1

我有，但经过大量测试后，我意识到我的 View 的高度和宽度为 0，因为我使用的是 TextView。 所以我设法等到 View (TextView)加载并开始创建文档后，看看代码，希望你能修复它:

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_main);

     final TextView tv = (TextView) findViewById(R.id.textView1);
        ViewTreeObserver vto = tv.getViewTreeObserver(); 
        vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() { 
            @Override 
            public void onGlobalLayout() { 
                Toast.makeText(MainActivity.this, tv.getWidth() + " x " + tv.getHeight(), Toast.LENGTH_LONG).show();    

                try {
                    File file1 = new File("/mnt/sdcard/test/");
                    if(!file1.exists()){
                        file1.mkdirs();
                    }

                    File file = new File("/mnt/sdcard/test", "filename"+System.currentTimeMillis()+".pdf");
                    PrintAttributes printAttrs = new PrintAttributes.Builder().
                            setColorMode(PrintAttributes.COLOR_MODE_COLOR).
                            setMediaSize(PrintAttributes.MediaSize.ISO_A4).
                            setResolution(new Resolution("zooey", PRINT_SERVICE, 450, 700)).
                            setMinMargins(Margins.NO_MARGINS).
                            build();
                    PdfDocument document = new PrintedPdfDocument(MainActivity.this, printAttrs);
                     PageInfo pageInfo = new PageInfo.Builder(450, 700, 1).create();
                     Page page = document.startPage(pageInfo);

                     if (page != null) {

                           View view = findViewById(R.id.textView1);//getContentView();                          
                           view.layout(0, 0, view.getWidth(),
                                   view.getHeight());
                           Log.i("draw view", " content size: "+view.getWidth()+" / "+view.getHeight());
                           view.draw(page.getCanvas());
                           // Move the canvas for the next view.
                           page.getCanvas().translate(0, view.getHeight());
                       }    

                     document.finishPage(page);
                     os = new FileOutputStream(file);
                            document.writeTo(os);
                            document.close();
                            os.close();
                            Log.i("done", file.getAbsolutePath().toString());

                        } catch (IOException e) {
                            throw new RuntimeException("Error generating file", e);
                        }

                tv.getViewTreeObserver().removeGlobalOnLayoutListener(this);
            } 
        });

}

里面的魔法:

 final TextView tv = (TextView) findViewById(R.id.textView1);
        ViewTreeObserver vto = tv.getViewTreeObserver(); 
        vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() { 
            @Override 
            public void onGlobalLayout() { 
         // create document here
} 
        });