Android example source code file (TextAlign.java)

This example Android source code file (TextAlign.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, app, center, content, dy, dy*2, graphicsactivity, left, os, override, paint, path, positioned, sampleview, string, text_r, textalign, textonpath, ui, view

The TextAlign.java Android example source code

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.apis.graphics;

import com.example.android.apis.R;

import android.app.Activity;
import android.content.Context;
import android.graphics.*;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.*;

public class TextAlign extends GraphicsActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SampleView(this));
    }
    
    private static class SampleView extends View {
        private Paint   mPaint;
        private float   mX;
        private float[] mPos;
        
        private Path    mPath;
        private Paint   mPathPaint;
        
        private static final int DY = 30;
        private static final String TEXT_L = "Left";
        private static final String TEXT_C = "Center";
        private static final String TEXT_R = "Right";
        private static final String POSTEXT = "Positioned";
        private static final String TEXTONPATH = "Along a path";
        
        private static void makePath(Path p) {
            p.moveTo(10, 0);
            p.cubicTo(100, -50, 200, 50, 300, 0);
        }
        
        private float[] buildTextPositions(String text, float y, Paint paint) {
            float[] widths = new float[text.length()];
            // initially get the widths for each char
            int n = paint.getTextWidths(text, widths);
            // now popuplate the array, interleaving spaces for the Y values
            float[] pos = new float[n * 2];
            float accumulatedX = 0;
            for (int i = 0; i < n; i++) {
                pos[i*2 + 0] = accumulatedX;
                pos[i*2 + 1] = y;
                accumulatedX += widths[i];
            }
            return pos;
        }
        
        public SampleView(Context context) {
            super(context);
            setFocusable(true);
            
            mPaint = new Paint();
            mPaint.setAntiAlias(true);
            mPaint.setTextSize(30);
            mPaint.setTypeface(Typeface.SERIF);
            
            mPos = buildTextPositions(POSTEXT, 0, mPaint);
            
            mPath = new Path();
            makePath(mPath);

            mPathPaint = new Paint();
            mPathPaint.setAntiAlias(true);
            mPathPaint.setColor(0x800000FF);
            mPathPaint.setStyle(Paint.Style.STROKE);
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.WHITE);

            Paint p = mPaint;
            float x = mX;
            float y = 0;
            float[] pos = mPos;
            
            // draw the normal strings

            p.setColor(0x80FF0000);
            canvas.drawLine(x, y, x, y+DY*3, p);
            p.setColor(Color.BLACK);
            
            canvas.translate(0, DY);
            p.setTextAlign(Paint.Align.LEFT);
            canvas.drawText(TEXT_L, x, y, p);

            canvas.translate(0, DY);
            p.setTextAlign(Paint.Align.CENTER);
            canvas.drawText(TEXT_C, x, y, p);

            canvas.translate(0, DY);
            p.setTextAlign(Paint.Align.RIGHT);
            canvas.drawText(TEXT_R, x, y, p);
            
            canvas.translate(100, DY*2);

            // now draw the positioned strings
    
            p.setColor(0xBB00FF00);
            for (int i = 0; i < pos.length/2; i++) {
                canvas.drawLine(pos[i*2+0], pos[i*2+1]-DY,
                                pos[i*2+0], pos[i*2+1]+DY*2, p);
            }
            p.setColor(Color.BLACK);

            p.setTextAlign(Paint.Align.LEFT);
            canvas.drawPosText(POSTEXT, pos, p);
            
            canvas.translate(0, DY);
            p.setTextAlign(Paint.Align.CENTER);
            canvas.drawPosText(POSTEXT, pos, p);
            
            canvas.translate(0, DY);
            p.setTextAlign(Paint.Align.RIGHT);
            canvas.drawPosText(POSTEXT, pos, p);
            
            // now draw the text on path
            
            canvas.translate(-100, DY*2);

            canvas.drawPath(mPath, mPathPaint);
            p.setTextAlign(Paint.Align.LEFT);
            canvas.drawTextOnPath(TEXTONPATH, mPath, 0, 0, p);

            canvas.translate(0, DY*1.5f);
            canvas.drawPath(mPath, mPathPaint);
            p.setTextAlign(Paint.Align.CENTER);
            canvas.drawTextOnPath(TEXTONPATH, mPath, 0, 0, p);
            
            canvas.translate(0, DY*1.5f);
            canvas.drawPath(mPath, mPathPaint);
            p.setTextAlign(Paint.Align.RIGHT);
            canvas.drawTextOnPath(TEXTONPATH, mPath, 0, 0, p);
        }

        @Override
        protected void onSizeChanged(int w, int h, int ow, int oh) {
            super.onSizeChanged(w, h, ow, oh);
            mX = w * 0.5f;  // remember the center of the screen
        }
    }
}