How to get N text that can be fit on Screen/TextView with a specific size?

Question

I have a large story in String format. I want to show the text in gallery. What I want to do is to slice all the text in such a way that all my view in gallery show the text which fit on the screen.

So that I can make my string in part, where each part will be shown on screen and each part will cover the whole screen.

One thing to be note is that user can change text size Large , Small so the text on screen will also be change as size change.

I am wondering if there is a way to do this.

Solution

Thank you so much to userSeven7s for helping me. Based on your example I am able to make an example. Here it is:

package com.gsoft.measure.text;

import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainScreen extends Activity {

    private final String TAG = "MainScreen";
    private String textToBeShown = "These are the text";
    private String sampleText = "Here are more text";
    private TextView mTextView = null;

    Handler handler = new Handler() {

        public void handleMessage(Message msg) {
            if (msg.what == 1) {
                updateUI();
            }
        };
    };

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

        mTextView = (TextView) findViewById(R.id.ui_main_textView);
        mTextView.setTextSize(20f);
        for (int i = 0; i < 100; i++) {
            textToBeShown = textToBeShown + " =" + i + "= " + sampleText;
        }

        // I am using timer as the in UI is not created and
        // we can't get the width.
        TimerTask task = new TimerTask() {

            @Override
            public void run() {
                // So that UI thread can handle UI work
                handler.sendEmptyMessage(1);
            }
        };
        Timer timer = new Timer();
        timer.schedule(task, 1000 * 1);
    }

    @Override
    protected void onResume() {
        super.onResume();

    }

    private void updateUI() {

        // Set text
        mTextView.setText(textToBeShown);
        // Check the width
        Log.e(TAG, "Width = " + mTextView.getWidth());

        // Check height of one line
        Log.e(TAG, "Line height= " + mTextView.getLineHeight());

        // Check total height for TextView
        Log.e(TAG, "Text height= " + mTextView.getHeight());

        // No of line we can show in textview
        int totalLine = mTextView.getHeight() / mTextView.getLineHeight();
        Log.e(TAG, "Total Lines are height= " + totalLine);


        for (int i = 0; i < totalLine; i++) {
            // Get No of characters fit in that textView
            int number = mTextView.getPaint().breakText(textToBeShown, 0, textToBeShown.length(), true,
                    mTextView.getWidth(), null);
            Log.e(TAG, "Number of chracters = " + number);

            // Show the text that fit into line
            Log.e(TAG, textToBeShown.substring(0, number));
            // Update the text to show next
            textToBeShown = textToBeShown.substring(number, textToBeShown.length());
        }
    }
}

Here is my XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout_id_for_value"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/black"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/ui_main_textView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="@color/twitter"
        android:textColor="@color/white" />

</LinearLayout>

Answer 1

You check the TextView source code and see how they decide where to ellipsize the string.

The code for TextView is here.

Alternatively, you can use TextUtils class's public static CharSequence ellipsize(CharSequence text, TextPaint p, float avail, TruncateAt where) method.

TextPaint p should be the TextView's paint object.

Update:

Another alternative is to use Paint.getTextWidths(char[] text, int index, int count, float[] widths).

textpaint.getTextWidths(char[] text, int index, int count, float[] widths);

int i = 0;
int prev_i = 0;
while (i < count) {
    textWidth = 0;
    for (int i = prev_i; (i < count) || (textWidth < availableWidth); i++) {
        textWidth += widths[i];
    }
    String textThatFits = mOriginalText.subString(prev_i, i);
    mTextview.setText(textThatFits);
    prev_i = i;
}

i is the number of characters that fit in the TextView.
availableWidth is the width of the TextView in pixels.

This code is approximate and contains syntax errors. You will have to do some minor changes to get it working.

Update 2:

Another alternative would be to use

int breakText (CharSequence text,      
                int start, int end,   
                boolean measureForwards,   
                float maxWidth, float[] measuredWidth). 

I think this is the best solution for you. Check its documentation here.

Update:

Sample code using paint.breakText method.

paint.setSubpixelText(true);
int prevPos = 0;
while (nextPos  < chars.length) {
    int nextPos = paint.breakText(chars, prevPos, chars.length, maxWidth, null);
    tvStr = str.substring(prevPos, nextPos);
    prevPos = nextPos+1;
}