Android example source code file (CreateBitmap.java)

This example Android source code file (CreateBitmap.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, bitmap, bytearrayoutputstream, content, createbitmap, graphicsactivity, height, io, os, override, paint, sampleview, stride, ui, view, width

The CreateBitmap.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.*;

import java.io.ByteArrayOutputStream;

public class CreateBitmap extends GraphicsActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SampleView(this));
    }
    
    private static final int WIDTH = 50;
    private static final int HEIGHT = 50;
    private static final int STRIDE = 64;   // must be >= WIDTH
    
    private static int[] createColors() {
        int[] colors = new int[STRIDE * HEIGHT];
        for (int y = 0; y < HEIGHT; y++) {
            for (int x = 0; x < WIDTH; x++) {
                int r = x * 255 / (WIDTH - 1);
                int g = y * 255 / (HEIGHT - 1);
                int b = 255 - Math.min(r, g);
                int a = Math.max(r, g);
                colors[y * STRIDE + x] = (a << 24) | (r << 16) | (g << 8) | b;
            }
        }
        return colors;
    }
        
    private static class SampleView extends View {
        private Bitmap[] mBitmaps;
        private Bitmap[] mJPEG;
        private Bitmap[] mPNG;
        private int[]    mColors;
        private Paint    mPaint;
        
        private static Bitmap codec(Bitmap src, Bitmap.CompressFormat format,
                                    int quality) {
            ByteArrayOutputStream os = new ByteArrayOutputStream();
            src.compress(format, quality, os);            

            byte[] array = os.toByteArray();
            return BitmapFactory.decodeByteArray(array, 0, array.length);
        }

        public SampleView(Context context) {
            super(context);
            setFocusable(true);
            
            mColors = createColors();
            int[] colors = mColors;

            mBitmaps = new Bitmap[6];
            // these three are initialized with colors[]
            mBitmaps[0] = Bitmap.createBitmap(colors, 0, STRIDE, WIDTH, HEIGHT,
                                              Bitmap.Config.ARGB_8888);
            mBitmaps[1] = Bitmap.createBitmap(colors, 0, STRIDE, WIDTH, HEIGHT,
                                              Bitmap.Config.RGB_565);
            mBitmaps[2] = Bitmap.createBitmap(colors, 0, STRIDE, WIDTH, HEIGHT,
                                              Bitmap.Config.ARGB_4444);
            
            // these three will have their colors set later
            mBitmaps[3] = Bitmap.createBitmap(WIDTH, HEIGHT,
                                              Bitmap.Config.ARGB_8888);
            mBitmaps[4] = Bitmap.createBitmap(WIDTH, HEIGHT,
                                              Bitmap.Config.RGB_565);
            mBitmaps[5] = Bitmap.createBitmap(WIDTH, HEIGHT,
                                              Bitmap.Config.ARGB_4444);
            for (int i = 3; i <= 5; i++) {
                mBitmaps[i].setPixels(colors, 0, STRIDE, 0, 0, WIDTH, HEIGHT);
            }
            
            mPaint = new Paint();
            mPaint.setDither(true);
            
            // now encode/decode using JPEG and PNG
            mJPEG = new Bitmap[mBitmaps.length];
            mPNG = new Bitmap[mBitmaps.length];
            for (int i = 0; i < mBitmaps.length; i++) {
                mJPEG[i] = codec(mBitmaps[i], Bitmap.CompressFormat.JPEG, 80);
                mPNG[i] = codec(mBitmaps[i], Bitmap.CompressFormat.PNG, 0);
            }
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.WHITE);

            for (int i = 0; i < mBitmaps.length; i++) {
                canvas.drawBitmap(mBitmaps[i], 0, 0, null);
                canvas.drawBitmap(mJPEG[i], 80, 0, null);
                canvas.drawBitmap(mPNG[i], 160, 0, null);
                canvas.translate(0, mBitmaps[i].getHeight());
            }
            
            // draw the color array directly, w/o craeting a bitmap object
            canvas.drawBitmap(mColors, 0, STRIDE, 0, 0, WIDTH, HEIGHT,
                              true, null);
            canvas.translate(0, HEIGHT);
            canvas.drawBitmap(mColors, 0, STRIDE, 0, 0, WIDTH, HEIGHT,
                              false, mPaint);
        }
    }
}