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/*
* Copyright (C) 2008-2009 Google Inc.
*
* 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.android.inputmethod.voice;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.ShortBuffer;
/**
* Utility class to draw a waveform into a bitmap, given a byte array
* that represents the waveform as a sequence of 16-bit integers.
* Adapted from RecognitionActivity.java.
*/
public class WaveformImage {
private static final int SAMPLING_RATE = 8000;
private WaveformImage() {}
public static Bitmap drawWaveform(
ByteArrayOutputStream waveBuffer, int w, int h, int start, int end) {
final Bitmap b = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
final Canvas c = new Canvas(b);
final Paint paint = new Paint();
paint.setColor(0xFFFFFFFF); // 0xRRGGBBAA
paint.setAntiAlias(true);
paint.setStrokeWidth(0);
final ShortBuffer buf = ByteBuffer
.wrap(waveBuffer.toByteArray())
.order(ByteOrder.nativeOrder())
.asShortBuffer();
buf.position(0);
final int numSamples = waveBuffer.size() / 2;
final int delay = (SAMPLING_RATE * 100 / 1000);
int endIndex = end / 2 + delay;
if (end == 0 || endIndex >= numSamples) {
endIndex = numSamples;
}
int index = start / 2 - delay;
if (index < 0) {
index = 0;
}
final int size = endIndex - index;
int numSamplePerPixel = 32;
int delta = size / (numSamplePerPixel * w);
if (delta == 0) {
numSamplePerPixel = size / w;
delta = 1;
}
final float scale = 3.5f / 65536.0f;
// do one less column to make sure we won't read past
// the buffer.
try {
for (int i = 0; i < w - 1 ; i++) {
final float x = i;
for (int j = 0; j < numSamplePerPixel; j++) {
final short s = buf.get(index);
final float y = (h / 2) - (s * h * scale);
c.drawPoint(x, y, paint);
index += delta;
}
}
} catch (IndexOutOfBoundsException e) {
// this can happen, but we don't care
}
return b;
}
}
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