92 lines
3 KiB
Java
92 lines
3 KiB
Java
/*
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* Copyright (C) 2008-2009 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not
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* use this file except in compliance with the License. You may obtain a copy of
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* the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations under
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* the License.
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*/
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package com.android.inputmethod.deprecated.voice;
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import android.graphics.Bitmap;
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import android.graphics.Canvas;
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import android.graphics.Paint;
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import java.io.ByteArrayOutputStream;
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import java.nio.ByteBuffer;
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import java.nio.ByteOrder;
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import java.nio.ShortBuffer;
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/**
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* Utility class to draw a waveform into a bitmap, given a byte array
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* that represents the waveform as a sequence of 16-bit integers.
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* Adapted from RecognitionActivity.java.
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*/
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public class WaveformImage {
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private static final int SAMPLING_RATE = 8000;
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private WaveformImage() {
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// Intentional empty constructor.
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}
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public static Bitmap drawWaveform(
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ByteArrayOutputStream waveBuffer, int w, int h, int start, int end) {
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final Bitmap b = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
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final Canvas c = new Canvas(b);
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final Paint paint = new Paint();
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paint.setColor(0xFFFFFFFF); // 0xRRGGBBAA
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paint.setAntiAlias(true);
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paint.setStrokeWidth(0);
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final ShortBuffer buf = ByteBuffer
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.wrap(waveBuffer.toByteArray())
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.order(ByteOrder.nativeOrder())
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.asShortBuffer();
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buf.position(0);
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final int numSamples = waveBuffer.size() / 2;
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final int delay = (SAMPLING_RATE * 100 / 1000);
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int endIndex = end / 2 + delay;
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if (end == 0 || endIndex >= numSamples) {
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endIndex = numSamples;
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}
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int index = start / 2 - delay;
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if (index < 0) {
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index = 0;
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}
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final int size = endIndex - index;
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int numSamplePerPixel = 32;
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int delta = size / (numSamplePerPixel * w);
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if (delta == 0) {
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numSamplePerPixel = size / w;
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delta = 1;
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}
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final float scale = 3.5f / 65536.0f;
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// do one less column to make sure we won't read past
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// the buffer.
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try {
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for (int i = 0; i < w - 1 ; i++) {
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final float x = i;
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for (int j = 0; j < numSamplePerPixel; j++) {
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final short s = buf.get(index);
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final float y = (h / 2) - (s * h * scale);
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c.drawPoint(x, y, paint);
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index += delta;
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}
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}
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} catch (IndexOutOfBoundsException e) {
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// this can happen, but we don't care
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}
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return b;
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}
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}
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