1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.phone;
18
19import android.graphics.Bitmap;
20import android.os.SystemClock;
21import android.os.SystemProperties;
22import android.util.Log;
23
24
25/**
26 * Image effects used by the in-call UI.
27 */
28public class BitmapUtils {
29    private static final String TAG = "BitmapUtils";
30    private static final boolean DBG =
31            (PhoneApp.DBG_LEVEL >= 1) && (SystemProperties.getInt("ro.debuggable", 0) == 1);
32
33    /** This class is never instantiated. */
34    private BitmapUtils() {
35    }
36
37    //
38    // Gaussian blur effect
39    //
40    // gaussianBlur() and related methods are borrowed from
41    // BackgroundUtils.java in the Music2 code (which itself was based on
42    // code from the old Cooliris android Gallery app.)
43    //
44    // TODO: possibly consider caching previously-generated blurred bitmaps;
45    // see getAdaptedBitmap() and mAdaptedBitmapCache in the music app code.
46    //
47
48    private static final int RED_MASK = 0xff0000;
49    private static final int RED_MASK_SHIFT = 16;
50    private static final int GREEN_MASK = 0x00ff00;
51    private static final int GREEN_MASK_SHIFT = 8;
52    private static final int BLUE_MASK = 0x0000ff;
53
54    /**
55     * Creates a blurred version of the given Bitmap.
56     *
57     * @param bitmap the input bitmap, presumably a 96x96 pixel contact
58     *               thumbnail.
59     */
60    public static Bitmap createBlurredBitmap(Bitmap bitmap) {
61        if (DBG) log("createBlurredBitmap()...");
62        long startTime = SystemClock.uptimeMillis();
63        if (bitmap == null) {
64            Log.w(TAG, "createBlurredBitmap: null bitmap");
65            return null;
66        }
67
68        if (DBG) log("- input bitmap: " + bitmap.getWidth() + " x " + bitmap.getHeight());
69
70        // The bitmap we pass to gaussianBlur() needs to have a width
71        // that's a power of 2, so scale up to 128x128.
72        final int scaledSize = 128;
73        bitmap = Bitmap.createScaledBitmap(bitmap,
74                                           scaledSize, scaledSize,
75                                           true /* filter */);
76        if (DBG) log("- after resize: " + bitmap.getWidth() + " x " + bitmap.getHeight());
77
78        bitmap = gaussianBlur(bitmap);
79        if (DBG) log("- after blur: " + bitmap.getWidth() + " x " + bitmap.getHeight());
80
81        long endTime = SystemClock.uptimeMillis();
82        if (DBG) log("createBlurredBitmap() done (elapsed = " + (endTime - startTime) + " msec)");
83        return bitmap;
84    }
85
86    /**
87     * Apply a gaussian blur filter, and return a new (blurred) bitmap
88     * that's the same size as the input bitmap.
89     *
90     * @param source input bitmap, whose width must be a power of 2
91     */
92    public static Bitmap gaussianBlur(Bitmap source) {
93        int width = source.getWidth();
94        int height = source.getHeight();
95        if (DBG) log("gaussianBlur(): input: " + width + " x " + height);
96
97        // Create a source and destination buffer for the image.
98        int numPixels = width * height;
99        int[] in = new int[numPixels];
100        int[] tmp = new int[numPixels];
101
102        // Get the source pixels as 32-bit ARGB.
103        source.getPixels(in, 0, width, 0, 0, width, height);
104
105        // Gaussian is a separable kernel, so it is decomposed into a horizontal
106        // and vertical pass.
107        // The filter function applies the kernel across each row and transposes
108        // the output.
109        // Hence we apply it twice to provide efficient horizontal and vertical
110        // convolution.
111        // The filter discards the alpha channel.
112        gaussianBlurFilter(in, tmp, width, height);
113        gaussianBlurFilter(tmp, in, width, height);
114
115        // Return a bitmap scaled to the desired size.
116        Bitmap filtered = Bitmap.createBitmap(in, width, height, Bitmap.Config.ARGB_8888);
117        source.recycle();
118        return filtered;
119    }
120
121    private static void gaussianBlurFilter(int[] in, int[] out, int width, int height) {
122        // This function is currently hardcoded to blur with RADIUS = 4.
123        // (If you change RADIUS, you'll have to change the weights[] too.)
124        final int RADIUS = 4;
125        final int[] weights = { 13, 23, 32, 39, 42, 39, 32, 23, 13}; // Adds up to 256
126        int inPos = 0;
127        int widthMask = width - 1; // width must be a power of two.
128        for (int y = 0; y < height; ++y) {
129            // Compute the alpha value.
130            int alpha = 0xff;
131            // Compute output values for the row.
132            int outPos = y;
133            for (int x = 0; x < width; ++x) {
134                int red = 0;
135                int green = 0;
136                int blue = 0;
137                for (int i = -RADIUS; i <= RADIUS; ++i) {
138                    int argb = in[inPos + (widthMask & (x + i))];
139                    int weight = weights[i+RADIUS];
140                    red += weight *((argb & RED_MASK) >> RED_MASK_SHIFT);
141                    green += weight *((argb & GREEN_MASK) >> GREEN_MASK_SHIFT);
142                    blue += weight *(argb & BLUE_MASK);
143                }
144                // Output the current pixel.
145                out[outPos] = (alpha << 24) | ((red >> 8) << RED_MASK_SHIFT)
146                    | ((green >> 8) << GREEN_MASK_SHIFT)
147                        | (blue >> 8);
148                outPos += height;
149            }
150            inPos += width;
151        }
152    }
153
154    //
155    // Debugging
156    //
157
158    private static void log(String msg) {
159        Log.d(TAG, msg);
160    }
161}
162