Question

我正在创建一个printdocumentadapter类来生成要打印的pdf。我需要根据我的数据变量（只是一个包含文本的字符串）自动计算需要多少页。因此，在实际使用onwrite方法实例化画布对象之前，我需要先以像素或dp找出画布的宽度和高度。这是课程文件：

public class CustomPrintDocumentAdapter extends PrintDocumentAdapter {

private Activity cur;

private int pageCount = 1;

private PrintedPdfDocument pdf;

private String data;

private int textSize = 16;

public CustomPrintDocumentAdapter(Activity current, String data){
    this.cur = current;
    this.data = data;
}

@Override
public void onLayout(PrintAttributes oldAttributes, PrintAttributes newAttributes, CancellationSignal cancellationSignal, LayoutResultCallback callback, Bundle extras) {
    pdf = new PrintedPdfDocument(cur,newAttributes);
    if(cancellationSignal.isCanceled()){
        callback.onLayoutCancelled();
    }

    PrintDocumentInfo info = new PrintDocumentInfo.Builder("print_output.pdf").setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT).setPageCount(pageCount).build();

    callback.onLayoutFinished(info,true);
}

@Override
public void onWrite(PageRange[] pages, ParcelFileDescriptor destination, CancellationSignal cancellationSignal, WriteResultCallback callback) {
    PdfDocument.Page page = pdf.startPage(1);
    drawPage(page);
    pdf.finishPage(page);

    try{
        pdf.writeTo(new FileOutputStream(destination.getFileDescriptor()));
    }catch(IOException ie){
        callback.onWriteFailed(ie.toString());
    }finally{
        pdf.close();
    }

    callback.onWriteFinished(pages);
}

public void drawPage(PdfDocument.Page page){

    Canvas canvas = page.getCanvas();
    TextPaint paint = new TextPaint();
    paint.setColor(Color.BLACK);
    paint.setTextSize(16);
    StaticLayout.Builder.obtain(data,0,data.length(),paint,canvas.getWidth()).build().draw(canvas);

    Log.d("CustomPrintDocumentAdapter","Canvas width in pixels: "+canvas.getWidth());
    //prints D/CustomPrintDocumentAdapter: Canvas width in pixels: 590
    //Canvas width in pixel is 590px????
    //my screen is only 480 pixels wide yet the canvas displayed is smaller than my screen??
}

}

所以我的问题是如何在onLayout方法中以像素为单位找到画布对象的宽度和高度？

我正计划使画布填充纸上的所有区域（任何尺寸）。

如何在实例化canvas对象之前找到android canvas的宽度？

0 个答案: