Add tool to generate color space conversion 3D LUTs

The tool needs to be run on an Android device and must be compiled
manually (i.e. it's not compiled as part of a regular Android build).

The tool outputs 3D LUTs in a format that can be included directly
in a C/C++ file/header.

Bug: 32984164
Test: ran lutgen and checked output
Change-Id: I96f7d0d088965c3b63c0fb4079ddeaeee7246418
diff --git a/libs/ui/tools/lutgen.cpp b/libs/ui/tools/lutgen.cpp
new file mode 100644
index 0000000..97b0822
--- /dev/null
+++ b/libs/ui/tools/lutgen.cpp
@@ -0,0 +1,196 @@
+/*
+ * Copyright 2017 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.
+ */
+
+#include <algorithm>
+#include <fstream>
+#include <iomanip>
+#include <iostream>
+#include <string>
+
+#include <getopt.h>
+
+#include <ui/ColorSpace.h>
+
+using namespace android;
+using namespace std;
+
+uint32_t gSize = 32;
+ColorSpace gColorSpaceSrc = ColorSpace::DisplayP3();
+ColorSpace gColorSpaceDst = ColorSpace::extendedSRGB();
+string gNameSrc = "DisplayP3";
+string gNameDst = "extendedSRGB";
+
+static void printHelp() {
+    cout << "lutgen -d SIZE -s SOURCE -t TARGET <lut file>" << endl;
+    cout << endl;
+    cout << "Generate a 3D LUT to convert between two color spaces." << endl;
+    cout << endl;
+    cout << "If <lut file> ends in .inc, data is generated without the array declaration." << endl;
+    cout << endl;
+    cout << "Options:" << endl;
+    cout << "  --help, -h" << endl;
+    cout << "    print this message" << endl;
+    cout << "  --dimension=, -d" << endl;
+    cout << "    the dimension of the 3D LUT. Example: 17 for a 17x17x17 LUT. 32 by default" << endl;
+    cout << "  --source=COLORSPACE, -s" << endl;
+    cout << "    the source color space, see below for available names. DisplayP3 by default" << endl;
+    cout << "  --target=COLORSPACE, -t" << endl;
+    cout << "    the target color space, see below for available names. extendedSRGB by default" << endl;
+    cout << endl;
+    cout << "Colorspace names:" << endl;
+    cout << "    sRGB" << endl;
+    cout << "    linearSRGB" << endl;
+    cout << "    extendedSRGB" << endl;
+    cout << "    linearExtendedSRGB" << endl;
+    cout << "    NTSC" << endl;
+    cout << "    BT709" << endl;
+    cout << "    BT2020" << endl;
+    cout << "    AdobeRGB" << endl;
+    cout << "    ProPhotoRGB" << endl;
+    cout << "    DisplayP3" << endl;
+    cout << "    DCIP3" << endl;
+    cout << "    ACES" << endl;
+    cout << "    ACEScg" << endl;
+}
+
+static const ColorSpace findColorSpace(const string& name) {
+    if (name == "linearSRGB") return ColorSpace::linearSRGB();
+    if (name == "extendedSRGB") return ColorSpace::extendedSRGB();
+    if (name == "linearExtendedSRGB") return ColorSpace::linearExtendedSRGB();
+    if (name == "NTSC") return ColorSpace::NTSC();
+    if (name == "BT709") return ColorSpace::BT709();
+    if (name == "BT2020") return ColorSpace::BT2020();
+    if (name == "AdobeRGB") return ColorSpace::AdobeRGB();
+    if (name == "ProPhotoRGB") return ColorSpace::ProPhotoRGB();
+    if (name == "DisplayP3") return ColorSpace::DisplayP3();
+    if (name == "DCIP3") return ColorSpace::DCIP3();
+    if (name == "ACES") return ColorSpace::ACES();
+    if (name == "ACEScg") return ColorSpace::ACEScg();
+    return ColorSpace::sRGB();
+}
+
+static int handleCommandLineArgments(int argc, char* argv[]) {
+    static constexpr const char* OPTSTR = "h:d:s:t:";
+    static const struct option OPTIONS[] = {
+            { "help",       no_argument,       0, 'h' },
+            { "dimension",  required_argument, 0, 'd' },
+            { "source",     required_argument, 0, 's' },
+            { "target",     required_argument, 0, 't' },
+            { 0, 0, 0, 0 }  // termination of the option list
+    };
+
+    int opt;
+    int index = 0;
+
+    while ((opt = getopt_long(argc, argv, OPTSTR, OPTIONS, &index)) >= 0) {
+        string arg(optarg ? optarg : "");
+        switch (opt) {
+            default:
+            case 'h':
+                printHelp();
+                exit(0);
+                break;
+            case 'd':
+                gSize = max(2, min(stoi(arg), 256));
+                break;
+            case 's':
+                gNameSrc = arg;
+                gColorSpaceSrc = findColorSpace(arg);
+                break;
+            case 't':
+                gNameDst = arg;
+                gColorSpaceDst = findColorSpace(arg);
+                break;
+        }
+    }
+
+    return optind;
+}
+
+int main(int argc, char* argv[]) {
+    int optionIndex = handleCommandLineArgments(argc, argv);
+    int numArgs = argc - optionIndex;
+
+    if (numArgs < 1) {
+        printHelp();
+        return 1;
+    }
+    
+    bool isInclude = false;
+
+    string filename(argv[optionIndex]);
+    size_t index = filename.find_last_of('.');
+
+    if (index != string::npos) {
+        string extension(filename.substr(index + 1));
+        isInclude = extension == "inc";
+    }
+
+    ofstream outputStream(filename, ios::trunc);
+    if (outputStream.good()) {
+        auto lut = ColorSpace::createLUT(gSize, gColorSpaceSrc, gColorSpaceDst);
+        auto data = lut.get();
+
+        outputStream << "// generated with lutgen " << filename.c_str() << endl;
+        outputStream << "// 3D LUT stored as an RGB16F texture, in GL order" << endl;
+        outputStream << "// Size is " << gSize << "x" << gSize << "x" << gSize << endl;
+
+        string src(gNameSrc);
+        string dst(gNameDst);
+
+        if (!isInclude) {
+            transform(src.begin(), src.end(), src.begin(), ::toupper);
+            transform(dst.begin(), dst.end(), dst.begin(), ::toupper);
+
+            outputStream << "const size_t LUT_" << src << "_TO_" << dst << "_SIZE = " << gSize << endl;
+            outputStream << "const uint16_t LUT_" << src << "_TO_" << dst << "[] = {";
+        } else {
+            outputStream << "// From " << src << " to " << dst << endl;
+        }
+
+        for (size_t z = 0; z < gSize; z++) {
+            for (size_t y = 0; y < gSize; y++) {
+                for (size_t x = 0; x < gSize; x++) {
+                    if (x % 4 == 0) outputStream << endl << "    ";
+
+                    half3 rgb = half3(*data++);
+
+                    const uint16_t r = rgb.r.getBits();
+                    const uint16_t g = rgb.g.getBits();
+                    const uint16_t b = rgb.b.getBits();
+
+                    outputStream << "0x" << setfill('0') << setw(4) << hex << r << ", ";
+                    outputStream << "0x" << setfill('0') << setw(4) << hex << g << ", ";
+                    outputStream << "0x" << setfill('0') << setw(4) << hex << b << ", ";
+                }
+            }
+        }
+
+        if (!isInclude) {
+            outputStream << endl << "}; // end LUT" << endl;
+        }
+
+        outputStream << endl;
+        outputStream.flush();
+        outputStream.close();
+    } else {
+        cerr << "Could not write to file: " << filename << endl;
+        return 1;
+
+    }
+
+    return 0;
+}