MLECO-2082: Adding visual wake word use case
MLECO-2083: Refactoring img_class and visual wake word

*Added source files for visual wake word
*Added tests
*Added docs
*Added new images for visual wake word demo
*Refactored common functions in img_class, visual wake word and other usecases

Change-Id: Ibd25854e19a5517f940a8d3086a5d4835fab89e9
Signed-off-by: Éanna Ó Catháin <eanna.ocathain@arm.com>
diff --git a/source/use_case/vww/src/UseCaseHandler.cc b/source/use_case/vww/src/UseCaseHandler.cc
new file mode 100644
index 0000000..fb2e837
--- /dev/null
+++ b/source/use_case/vww/src/UseCaseHandler.cc
@@ -0,0 +1,182 @@
+/*
+ * Copyright (c) 2021 Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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 "UseCaseHandler.hpp"
+#include "VisualWakeWordModel.hpp"
+#include "Classifier.hpp"
+#include "InputFiles.hpp"
+#include "UseCaseCommonUtils.hpp"
+#include "hal.h"
+
+namespace arm {
+namespace app {
+
+    /**
+    * @brief            Helper function to load the current image into the input
+    *                   tensor.
+    * @param[in]        imIdx         Image index (from the pool of images available
+    *                                 to the application).
+    * @param[out]       inputTensor   Pointer to the input tensor to be populated.
+    * @return           true if tensor is loaded, false otherwise.
+    **/
+    static bool LoadImageIntoTensor(uint32_t imIdx,
+                                     TfLiteTensor *inputTensor);
+
+    /* Image inference classification handler. */
+    bool ClassifyImageHandler(ApplicationContext &ctx, uint32_t imgIndex, bool runAll)
+    {
+        auto& platform = ctx.Get<hal_platform &>("platform");
+        auto& profiler = ctx.Get<Profiler&>("profiler");
+
+        constexpr uint32_t dataPsnImgDownscaleFactor = 1;
+        constexpr uint32_t dataPsnImgStartX = 10;
+        constexpr uint32_t dataPsnImgStartY = 35;
+
+        constexpr uint32_t dataPsnTxtInfStartX = 150;
+        constexpr uint32_t dataPsnTxtInfStartY = 70;
+
+
+        platform.data_psn->clear(COLOR_BLACK);
+        time_t infTimeMs = 0;
+
+        auto& model = ctx.Get<Model&>("model");
+
+        /* If the request has a valid size, set the image index. */
+        if (imgIndex < NUMBER_OF_FILES) {
+            if (!SetAppCtxIfmIdx(ctx, imgIndex,"imgIndex")) {
+                return false;
+            }
+        }
+        if (!model.IsInited()) {
+            printf_err("Model is not initialised! Terminating processing.\n");
+            return false;
+        }
+
+        auto curImIdx = ctx.Get<uint32_t>("imgIndex");
+
+        TfLiteTensor *outputTensor = model.GetOutputTensor(0);
+        TfLiteTensor *inputTensor = model.GetInputTensor(0);
+
+        if (!inputTensor->dims) {
+            printf_err("Invalid input tensor dims\n");
+            return false;
+        } else if (inputTensor->dims->size < 3) {
+            printf_err("Input tensor dimension should be >= 3\n");
+            return false;
+        }
+        TfLiteIntArray* inputShape = model.GetInputShape(0);
+        const uint32_t nCols = inputShape->data[2];
+        const uint32_t nRows = inputShape->data[1];
+        const uint32_t nChannels = (inputShape->size == 4) ? inputShape->data[3] : 1;
+
+        std::vector<ClassificationResult> results;
+
+        do {
+
+            /* Strings for presentation/logging. */
+            std::string str_inf{"Running inference... "};
+
+            /* Copy over the data. */
+            LoadImageIntoTensor(ctx.Get<uint32_t>("imgIndex"), inputTensor);
+
+            /* Display this image on the LCD. */
+            platform.data_psn->present_data_image(
+                (uint8_t *) inputTensor->data.data,
+                nCols, nRows, nChannels,
+                dataPsnImgStartX, dataPsnImgStartY, dataPsnImgDownscaleFactor);
+
+            /* If the data is signed. */
+            if (model.IsDataSigned()) {
+                image::ConvertImgToInt8(inputTensor->data.data, inputTensor->bytes);
+            }
+
+            /* Display message on the LCD - inference running. */
+            platform.data_psn->present_data_text(
+                                str_inf.c_str(), str_inf.size(),
+                                dataPsnTxtInfStartX, dataPsnTxtInfStartY, 0);
+
+            /* Run inference over this image. */
+            info("Running inference on image %" PRIu32 " => %s\n", ctx.Get<uint32_t>("imgIndex"),
+                get_filename(ctx.Get<uint32_t>("imgIndex")));
+
+            if (!RunInference(model, profiler)) {
+                return false;
+            }
+
+            /* Erase. */
+            str_inf = std::string(str_inf.size(), ' ');
+            platform.data_psn->present_data_text(
+                                str_inf.c_str(), str_inf.size(),
+                                dataPsnTxtInfStartX, dataPsnTxtInfStartY, 0);
+
+            auto& classifier = ctx.Get<Classifier&>("classifier");
+            classifier.GetClassificationResults(outputTensor, results,
+                                                ctx.Get<std::vector <std::string>&>("labels"), 1);
+
+            /* Add results to context for access outside handler. */
+            ctx.Set<std::vector<ClassificationResult>>("results", results);
+
+#if VERIFY_TEST_OUTPUT
+            arm::app::DumpTensor(outputTensor);
+#endif /* VERIFY_TEST_OUTPUT */
+
+            if (!image::PresentInferenceResult(platform, results, infTimeMs)) {
+                return false;
+            }
+
+            profiler.PrintProfilingResult();
+            IncrementAppCtxIfmIdx(ctx,"imgIndex");
+
+        } while (runAll && ctx.Get<uint32_t>("imgIndex") != curImIdx);
+
+        return true;
+    }
+
+    static bool LoadImageIntoTensor(const uint32_t imIdx,
+                                     TfLiteTensor *inputTensor)
+    {
+        const size_t copySz = inputTensor->bytes < IMAGE_DATA_SIZE ?
+                                inputTensor->bytes : IMAGE_DATA_SIZE;
+        if (imIdx >= NUMBER_OF_FILES) {
+            printf_err("invalid image index %" PRIu32 " (max: %u)\n", imIdx,
+                       NUMBER_OF_FILES - 1);
+            return false;
+        }
+
+        const uint32_t nChannels = (inputTensor->dims->size == 4) ? inputTensor->dims->data[3] : 1;
+
+        const uint8_t* srcPtr = get_img_array(imIdx);
+        auto* dstPtr = (uint8_t*)inputTensor->data.data;
+        if (1 == nChannels) {
+            /**
+             * Visual Wake Word model accepts only one channel =>
+             * Convert image to grayscale here
+             **/
+            for (size_t i = 0; i < copySz; ++i, srcPtr += 3) {
+                *dstPtr++ = 0.2989*(*srcPtr) +
+                            0.587*(*(srcPtr+1)) +
+                            0.114*(*(srcPtr+2));
+            }
+        } else {
+            memcpy(inputTensor->data.data, srcPtr, copySz);
+        }
+
+        debug("Image %" PRIu32 " loaded\n", imIdx);
+        return true;
+    }
+
+} /* namespace app */
+} /* namespace arm */   
\ No newline at end of file