Android example source code file (UnicodeChart.java)

This example Android source code file (UnicodeChart.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, content, graphicsactivity, keyevent, os, override, paint, sampleview, ui, unicodechart, view, xmul, ybase, ymul

The UnicodeChart.java Android example source code

/*
 * Copyright (C) 2008 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 android.app.Activity;
import android.content.Context;
import android.graphics.*;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.Window;

public class UnicodeChart extends GraphicsActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        
        setContentView(new SampleView(this));
    }
    
    private static class SampleView extends View {
        private Paint mBigCharPaint;
        private Paint mLabelPaint;
        private final char[] mChars = new char[256];
        private final float[] mPos = new float[512];
        
        private int mBase;
        
        private static final int XMUL = 20;
        private static final int YMUL = 28;
        private static final int YBASE = 18;

        public SampleView(Context context) {
            super(context);
            setFocusable(true);
            setFocusableInTouchMode(true);
            
            mBigCharPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mBigCharPaint.setTextSize(15);
            mBigCharPaint.setTextAlign(Paint.Align.CENTER);
            
            mLabelPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mLabelPaint.setTextSize(8);
            mLabelPaint.setTextAlign(Paint.Align.CENTER);
            
            // the position array is the same for all charts
            float[] pos = mPos;
            int index = 0;
            for (int col = 0; col < 16; col++) {
                final float x = col * 20 + 10;
                for (int row = 0; row < 16; row++) {
                    pos[index++] = x;
                    pos[index++] = row * YMUL + YBASE;
                }
            }
        }
        
        private float computeX(int index) {
            return (index >> 4) * 20 + 10;
        }

        private float computeY(int index) {
            return (index & 0xF) * YMUL + YMUL;
        }
        
        private void drawChart(Canvas canvas, int base) {
            char[] chars = mChars;
            for (int i = 0; i < 256; i++) {
                int unichar = base + i;
                chars[i] = (char)unichar;
                
                canvas.drawText(Integer.toHexString(unichar),
                                computeX(i), computeY(i), mLabelPaint);
            }
            canvas.drawPosText(chars, 0, 256, mPos, mBigCharPaint);
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.WHITE);            

            canvas.translate(0, 1);
            drawChart(canvas, mBase * 256);
        }

        @Override public boolean onKeyDown(int keyCode, KeyEvent event) {
            switch (keyCode) {
                case KeyEvent.KEYCODE_DPAD_LEFT:
                    if (mBase > 0) {
                        mBase -= 1;
                        invalidate();
                    }
                    return true;
                case KeyEvent.KEYCODE_DPAD_RIGHT:
                    mBase += 1;
                    invalidate();
                    return true;
                default:
                    break;
            }
            return super.onKeyDown(keyCode, event);
        }
    }
}