android - 我如何在 android 的多个页面中显示一个长 TextView (字符串)

Question

我正在开发一个看起来像电子书阅读器(.text、pdf 文件等)的应用程序。我有一个巨大的文本，分为不同的章节或页面。

现在的问题是如何将整个内容分成若干页并逐页显示。我怎么知道适合屏幕的字符数(取决于屏幕大小和字体大小)。我对从哪里开始以及如何进行完全感到困惑。请举例说明帮助我。

Answer 1

这是一个简单的示例应用程序，以防其他人需要它 https://github.com/koros/AndroidReader

import android.content.Context;
import android.os.AsyncTask;
import android.text.TextPaint;

public class PagerTask extends AsyncTask<MainActivity.ViewAndPaint,      MainActivity.ProgressTracker, Void> {

private Context mContext;

public PagerTask(Context context){
    this.mContext = context;
}

protected Void doInBackground(MainActivity.ViewAndPaint... vps) {

    MainActivity.ViewAndPaint vp = vps[0];
    MainActivity.ProgressTracker progress = new MainActivity.ProgressTracker();
    TextPaint paint = vp.paint;
    int numChars = 0;
    int lineCount = 0;
    int maxLineCount = vp.maxLineCount;
    int totalCharactersProcessedSoFar = 0;

    // contentString is the whole string of the book
    int totalPages = 0;
    while (vp.contentString != null && vp.contentString.length() != 0 )
    {
        while ((lineCount < maxLineCount) && (numChars < vp.contentString.length())) {
            numChars = numChars + paint.breakText(vp.contentString.substring(numChars), true, vp.screenWidth, null);
            lineCount ++;
        }

        // Retrieve the String to be displayed in the current textview
        String stringToBeDisplayed = vp.contentString.substring(0, numChars);
        int nextIndex = numChars;
        char nextChar = nextIndex < vp.contentString.length() ? vp.contentString.charAt(nextIndex) : ' ';
        if (!Character.isWhitespace(nextChar)) {
            stringToBeDisplayed = stringToBeDisplayed.substring(0, stringToBeDisplayed.lastIndexOf(" "));
        }
        numChars = stringToBeDisplayed.length();
        vp.contentString = vp.contentString.substring(numChars);

        // publish progress
        progress.totalPages = totalPages;
        progress.addPage(totalPages, totalCharactersProcessedSoFar, totalCharactersProcessedSoFar + numChars);
        publishProgress(progress);

        totalCharactersProcessedSoFar += numChars;

        // reset per page items
        numChars = 0;
        lineCount = 0;

        // increment  page counter
        totalPages ++;
    }

    return null;
}

    @Override
    protected void onProgressUpdate(MainActivity.ProgressTracker... values) {
        ((MainActivity)mContext).onPageProcessedUpdate(values[0]);
    }

}