initial prototype

imageInput.c

@@ -6,17 +6,156 @@
 #define BUFFER_SIZE 100
 #define FILE_HEADER_STRING "__info2_image_file_format__"
 
-// TODO Implementieren Sie geeignete Hilfsfunktionen für das Lesen der Bildserie aus einer Datei
+typedef enum
+{
+    IMG_SUCCESS = 0,
+    IMG_ERR_INVALID_HEADER, // Header did not match
+    IMG_ERR_READ,           // Failed to read from file, maybe it's too short
+    IMG_ERR,                // General Error
+} ImageError;
+
+static ImageError checkHeader(FILE *file);
+static ImageError readPictureParams(unsigned short *number, unsigned short *width, unsigned short *height, FILE *file);
+static ImageError readImage(size_t numPixels, GrayScalePixelType *pixelBuffer, unsigned char *label, FILE *file);
+static ImageError parseImageFile(FILE *file, GrayScaleImageSeries *series);
 
-// TODO Vervollständigen Sie die Funktion readImages unter Benutzung Ihrer Hilfsfunktionen
 GrayScaleImageSeries *readImages(const char *path)
 {
-    GrayScaleImageSeries *series = NULL;
+    GrayScaleImageSeries *series = calloc(1, sizeof(GrayScaleImageSeries));
+    if (series == NULL)
+    {
+        return NULL;
+    }
 
+    FILE *file = fopen(path, "rb");
+    if (file == NULL)
+    {
+        clearSeries(series);
+        series = NULL;
+        return NULL; // fopen failed
+    }
+
+    if (parseImageFile(file, series))
+    {
+        clearSeries(series);
+        series = NULL;
+    }
+
+    fclose(file);
     return series;
 }
 
-// TODO Vervollständigen Sie die Funktion clearSeries, welche eine Bildserie vollständig aus dem Speicher freigibt
+static ImageError parseImageFile(FILE *file, GrayScaleImageSeries *series)
+{
+    if (checkHeader(file))
+    {
+        return IMG_ERR; // header check failed
+    }
+
+    unsigned short number, width, height;
+    if (readPictureParams(&number, &width, &height, file))
+    {
+        return IMG_ERR; // read failed
+    }
+    size_t pixels = width * height;
+
+    // now setup the image series
+    series->images = calloc(number, sizeof(GrayScaleImage));
+    if (series->images == NULL)
+    {
+        return IMG_ERR;
+    }
+
+    series->labels = malloc(number * sizeof(unsigned char));
+    if (series->labels == NULL)
+    {
+        return IMG_ERR;
+    }
+
+    series->count = number;
+    for (size_t imageIdx = 0; imageIdx < number; imageIdx++)
+    {
+        GrayScaleImage *curImage = &series->images[imageIdx];
+
+        curImage->buffer = malloc(sizeof(GrayScalePixelType) * pixels);
+        if (curImage->buffer == NULL)
+        {
+            return IMG_ERR;
+        }
+
+        curImage->width = width;
+        curImage->height = height;
+
+        if (readImage(pixels, curImage->buffer, &series->labels[imageIdx], file))
+        {
+            return IMG_ERR;
+        }
+    }
+    return IMG_SUCCESS;
+}
+
+static ImageError checkHeader(FILE *file)
+{
+    size_t len = strlen(FILE_HEADER_STRING);
+    char headerBuf[len + 1];
+    size_t charsRead = fread(headerBuf, 1, len, file);
+    if (charsRead < len)
+    {
+        return IMG_ERR_READ;
+    }
+    headerBuf[len] = '\0';
+    return strcmp(headerBuf, FILE_HEADER_STRING) == 0 ? IMG_SUCCESS : IMG_ERR_INVALID_HEADER;
+}
+
+static ImageError readPictureParams(unsigned short *number, unsigned short *width, unsigned short *height, FILE *file)
+{
+    if (1 != fread(number, sizeof(unsigned short), 1, file))
+    {
+        return IMG_ERR_READ;
+    }
+
+    if (1 != fread(width, sizeof(unsigned short), 1, file))
+    {
+        return IMG_ERR_READ;
+    }
+
+    if (1 != fread(height, sizeof(unsigned short), 1, file))
+    {
+        return IMG_ERR_READ;
+    }
+
+    return IMG_SUCCESS;
+}
+
+static ImageError readImage(size_t numPixels, GrayScalePixelType *pixelBuffer, unsigned char *label, FILE *file)
+{
+    if (numPixels > fread(pixelBuffer, sizeof(GrayScalePixelType), numPixels, file))
+    {
+        return IMG_ERR_READ;
+    }
+
+    if (1 != fread(label, sizeof(unsigned char), 1, file))
+    {
+        return IMG_ERR_READ;
+    }
+
+    return IMG_SUCCESS;
+}
+
+// frees memory for each image buffer, image, label and finally series
 void clearSeries(GrayScaleImageSeries *series)
 {
+    if (series)
+    {
+
+        int seriesLen = series->count;
+        for (size_t imageIdx = 0; imageIdx < seriesLen; imageIdx++)
+        {
+            free(series->images[imageIdx].buffer);
+        }
+
+        free(series->images);
+        free(series->labels);
+        free(series);
+    }
 }