TextAlign.java

← Back

The file containing the source code shown below is located in the corresponding directory in <sdk>/samples/android-<version>/...

/*
 * Copyright (C) 2007 The Android开源工程
 *
 * 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 android.content.Context;
import android.graphics.*;
import android.os.Bundle;
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
        }
    }
}