1/* 2 * Copyright (C) 2012 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 17// Stats (mean and stdev) scoring in the native. 18 19#include "stats_scorer.h" 20 21#include <jni.h> 22#include <math.h> 23 24void Java_androidx_media_filterpacks_numeric_StatsFilter_score( 25 JNIEnv* env, jobject thiz, jobject imageBuffer, jfloatArray statsArray) 26{ 27 unsigned char* pImg = static_cast<unsigned char*>(env->GetDirectBufferAddress(imageBuffer)); 28 int numPixels = env->GetDirectBufferCapacity(imageBuffer); // 1 byte per pixel 29 float sum = 0.0; 30 float sumSquares = 0.0; 31 32 for (int i = 0; i < numPixels; ++i) { 33 float val = static_cast<float>(pImg[i]); 34 sum += val; 35 sumSquares += val * val; 36 } 37 jfloat result[2]; 38 result[0] = sum / numPixels; // mean 39 result[1] = sqrt((sumSquares - numPixels * result[0] * result[0]) / (numPixels - 1)); // stdev. 40 env->SetFloatArrayRegion(statsArray, 0, 2, result); 41} 42 43void Java_androidx_media_filterpacks_numeric_StatsFilter_regionscore( 44 JNIEnv* env, jobject thiz, jobject imageBuffer, jint width, jint height, 45 jfloat left, jfloat top, jfloat right, jfloat bottom, jfloatArray statsArray) 46{ 47 unsigned char* pImg = static_cast<unsigned char*>(env->GetDirectBufferAddress(imageBuffer)); 48 int xStart = static_cast<int>(width * left); 49 int xEnd = static_cast<int>(width * right); 50 int yStart = static_cast<int>(height * top); 51 int yEnd = static_cast<int>(height * bottom); 52 int numPixels = (xEnd - xStart) * (yEnd - yStart); 53 float sum = 0.0; 54 float sumSquares = 0.0; 55 56 for (int y = yStart; y < yEnd; y++) { 57 int disp = width * y; 58 for (int x = xStart; x < xEnd; ++x) { 59 float val = static_cast<float>(*(pImg + disp + x)); 60 sum += val; 61 sumSquares += val * val; 62 } 63 } 64 jfloat result[2]; 65 result[0] = sum / numPixels; // mean 66 result[1] = (numPixels == 1) ? 67 0 : sqrt((sumSquares - numPixels * result[0] * result[0]) / (numPixels - 1)); // stdev. 68 env->SetFloatArrayRegion(statsArray, 0, 2, result); 69} 70 71