Android example source code file (BitmapPixels.java)

This example Android source code file (BitmapPixels.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, bitmappixels, drawing, graphicsactivity, intbuffer, io, n, nio, override, sampleview, shortbuffer, ui, view

The BitmapPixels.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.graphics.drawable.*;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.*;

import java.nio.IntBuffer;
import java.nio.ShortBuffer;

public class BitmapPixels extends GraphicsActivity {
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SampleView(this));
    }
    
    private static class SampleView extends View {
        private Bitmap mBitmap1;
        private Bitmap mBitmap2;
        private Bitmap mBitmap3;
        private Bitmap mBitmap4;

        // access the red component from a premultiplied color
        private static int getR32(int c) { return (c >>  0) & 0xFF; }
        // access the red component from a premultiplied color
        private static int getG32(int c) { return (c >>  8) & 0xFF; }
        // access the red component from a premultiplied color
        private static int getB32(int c) { return (c >> 16) & 0xFF; }
        // access the red component from a premultiplied color
        private static int getA32(int c) { return (c >> 24) & 0xFF; }

        /**
         * This takes components that are already in premultiplied form, and
         * packs them into an int in the correct device order.
         */
        private static int pack8888(int r, int g, int b, int a) {
            return (r << 0) | ( g << 8) | (b << 16) | (a << 24);
        }

        private static short pack565(int r, int g, int b) {
            return (short)((r << 11) | ( g << 5) | (b << 0));
        }

        private static short pack4444(int r, int g, int b, int a) {
            return (short)((a << 0) | ( b << 4) | (g << 8) | (r << 12));
        }
        
        private static int mul255(int c, int a) {
            int prod = c * a + 128;
            return (prod + (prod >> 8)) >> 8;
        }

        /**
         * Turn a color int into a premultiplied device color
         */
        private static int premultiplyColor(int c) {
            int r = Color.red(c);
            int g = Color.green(c);
            int b = Color.blue(c);
            int a = Color.alpha(c);
            // now apply the alpha to r, g, b
            r = mul255(r, a);
            g = mul255(g, a);
            b = mul255(b, a);
            // now pack it in the correct order
            return pack8888(r, g, b, a);
        }
        
        private static void makeRamp(int from, int to, int n,
                                     int[] ramp8888, short[] ramp565,
                                     short[] ramp4444) {
            int r = getR32(from) << 23;
            int g = getG32(from) << 23;
            int b = getB32(from) << 23;
            int a = getA32(from) << 23;
            // now compute our step amounts per componenet (biased by 23 bits)
            int dr = ((getR32(to) << 23) - r) / (n - 1);
            int dg = ((getG32(to) << 23) - g) / (n - 1);
            int db = ((getB32(to) << 23) - b) / (n - 1);
            int da = ((getA32(to) << 23) - a) / (n - 1);

            for (int i = 0; i < n; i++) {
                ramp8888[i] = pack8888(r >> 23, g >> 23, b >> 23, a >> 23);
                ramp565[i] = pack565(r >> (23+3), g >> (23+2), b >> (23+3));
                ramp4444[i] = pack4444(r >> (23+4), g >> (23+4), b >> (23+4),
                                       a >> (23+4));
                r += dr;
                g += dg;
                b += db;
                a += da;
            }
        }
        
        private static IntBuffer makeBuffer(int[] src, int n) {
            IntBuffer dst = IntBuffer.allocate(n*n);
            for (int i = 0; i < n; i++) {
                dst.put(src);
            }
            dst.rewind();
            return dst;
        }
        
        private static ShortBuffer makeBuffer(short[] src, int n) {
            ShortBuffer dst = ShortBuffer.allocate(n*n);
            for (int i = 0; i < n; i++) {
                dst.put(src);
            }
            dst.rewind();
            return dst;
        }
        
        public SampleView(Context context) {
            super(context);
            setFocusable(true);
            
            final int N = 100;
            int[] data8888 = new int[N];
            short[] data565 = new short[N];
            short[] data4444 = new short[N];
            
            makeRamp(premultiplyColor(Color.RED), premultiplyColor(Color.GREEN),
                     N, data8888, data565, data4444);
            
            mBitmap1 = Bitmap.createBitmap(N, N, Bitmap.Config.ARGB_8888);
            mBitmap2 = Bitmap.createBitmap(N, N, Bitmap.Config.RGB_565);
            mBitmap3 = Bitmap.createBitmap(N, N, Bitmap.Config.ARGB_4444);
            
            mBitmap1.copyPixelsFromBuffer(makeBuffer(data8888, N));
            mBitmap2.copyPixelsFromBuffer(makeBuffer(data565, N));
            mBitmap3.copyPixelsFromBuffer(makeBuffer(data4444, N));
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(0xFFCCCCCC);            
            
            int y = 10;
            canvas.drawBitmap(mBitmap1, 10, y, null);
            y += mBitmap1.getHeight() + 10;
            canvas.drawBitmap(mBitmap2, 10, y, null);
            y += mBitmap2.getHeight() + 10;
            canvas.drawBitmap(mBitmap3, 10, y, null);
        }
    }
}