ILBM lib enhancements

convert interleaved to plane-by plane data, display in Intuition
is changed to consider the imaga data width

30years/iffview/Makefile

@@ -11,5 +11,7 @@ iffview: iffview.o ilbm.o filereq.o
 	$(CC) $(CFLAGS) $^ -lamiga -lauto -o $@
 
 # Mostly for testing
+# interestingly, when defining std=c99, LITTLE_ENDIAN disappears as a definition
+# in gcc, so we define it explicitly
 ilbm: ilbm.c
-	gcc -o $@ $< -DSTANDALONE -DDEBUG
+	gcc -o $@ $< -DSTANDALONE -DDEBUG -std=c99 -DLITTLE_ENDIAN

30years/iffview/filereq.c

@@ -100,6 +100,12 @@ struct Requester *open_file(struct Window *window)
         requester.ReqText = &labels[0];
 
         /* scan current directory */
+        /*
+          on AmigaOS versions before 36 (essentially all 1.x versions), the
+          function GetCurrentDirName() does not exist, but it's obtainable
+          by calling Cli() and querying the returned CommandLineInterface
+          structure
+         */
         puts("scanning directory...");
         /*
         // on AmigaOS 1.x, this function does not exist !!!

30years/iffview/iffview.c

@@ -172,22 +172,32 @@ void setup_menu()
 
 struct Image image = { 0, 0, 0, 0, 0, NULL, 0, 0, NULL};
 
+/* Defined automatically in VBCC */
+extern struct Library *DOSBase;
+
 int main(int argc, char **argv)
 {
+    /* version: e.g. 34, revision e.g. 3 for Kickstart 1.3 */
+    printf("DOS, version: %d, revision: %d\n",
+           (int) DOSBase->lib_Version, (int) DOSBase->lib_Revision);
     ILBMData *ilbm_data = NULL;
     if (window = OpenWindow(&newwin)) {
-        int wordwidth, finalsize;
         setup_menu();
         ilbm_data = parse_file("examples/Kickstart13.iff");
         image.Width = ilbm_data->bmheader->w;
         image.Height = ilbm_data->bmheader->h;
         image.Depth = ilbm_data->bmheader->nPlanes;
-        wordwidth = (image.Width + 16) / 16;
-        finalsize = wordwidth * image.Height * image.Depth * sizeof(UWORD);
-        image.ImageData = AllocMem(finalsize, MEMF_CHIP);
-        printf("loaded size: %d, final size: %d\n", ilbm_data->data_bytes, finalsize);
-        memcpy(image.ImageData, ilbm_data->imgdata, ilbm_data->data_bytes);
+        int wordwidth = (image.Width + 16) / 16;
+        int finalsize = wordwidth * image.Height * image.Depth * sizeof(UWORD);
+        image.ImageData = AllocMem(finalsize, MEMF_CHIP|MEMF_CLEAR);
+        ilbm_to_image_data((char *) image.ImageData, ilbm_data, wordwidth * 16, image.Height);
         image.PlanePick = (1 << image.Depth) - 1;
+        /*
+           Note that the image width  is now set to the data's image width.
+           Displayed correctly now.
+         */
+        image.Width = wordwidth * 16;
+
         // Note: rastport is the entire window, including title bars
         DrawImage(window->RPort, &image, 5, 10);
         handle_events();

30years/iffview/ilbm.c

@@ -196,8 +196,10 @@ ILBMData *parse_file(const char *path)
   if (!strncmp("FORM", buffer, 4)) {
 
 #ifdef LITTLE_ENDIAN
+    puts("little endian");
     filesize = __bswap_32(*((ULONG *) &buffer[4])) + CHUNK_HEADER_SIZE;
 #else
+    puts("big endian");
     filesize = *((ULONG *) &buffer[4]) + CHUNK_HEADER_SIZE;
 #endif
 
@@ -235,6 +237,46 @@ void print_ilbm_info(ILBMData *data)
            data->num_colors);
 }
 
+/*
+ * ILBM interleaved bit maps -> Intuition Image data
+ * ILBM is interleaved
+ *   - plane 0/row 0 -> plane 1/row 0 -> ... plane 0/row 1 -> plane 1/row 1 ->...
+ *   - rows are multiples of 8
+ *
+ * but Intuition Image expects its data
+ *   - plane-by-plane
+ *   - as a multiple of 16
+ */
+void ilbm_to_image_data(char *dest, ILBMData *data, int dest_width, int dest_height)
+{
+    if (data->bmheader->w % 8 != 0) {
+        puts("ERROR: source width must be multiple of 8");
+        return;
+    }
+    if (dest_width % 16 != 0) {
+        puts("ERROR: destination width must be multiple of 16");
+        return;
+    }
+    if (dest_width < data->bmheader->w || dest_height < data->bmheader->h) {
+        puts("ERROR: destination dimensions are smaller than source");
+        return;
+    }
+    int src_bytes_per_row = data->bmheader->w / 8;
+    int dest_bytes_per_row = dest_width / 8;
+    char *src_ptr = data->imgdata;
+    int src_offset, img_height = data->bmheader->h, num_planes = data->bmheader->nPlanes;
+    int row_data_size = num_planes * src_bytes_per_row;
+
+    for (int plane = 0; plane < num_planes; plane++) {
+        // copy row-by-row
+        for (int row = 0; row < img_height; row++) {
+            src_offset = (row * row_data_size) + (plane * src_bytes_per_row);
+            memcpy(dest, src_ptr + src_offset, src_bytes_per_row);
+            dest += dest_bytes_per_row;
+        }
+    }
+}
+
 #ifdef STANDALONE
 int main(int argc, char **argv)
 {
@@ -243,6 +285,15 @@ int main(int argc, char **argv)
   } else {
       ILBMData *data = parse_file(argv[1]);
       print_ilbm_info(data);
+
+      int wordwidth = (data->bmheader->w + 16) / 16;
+      int destWidth = wordwidth * 16;
+      int destHeight = data->bmheader->h;
+      int finalsize = wordwidth * data->bmheader->h * data->bmheader->nPlanes * 2;
+      printf("loaded size: %d, final size: %d\n", data->data_bytes, finalsize);
+      char *dest = calloc(finalsize, sizeof(char));
+      ilbm_to_image_data(dest, data, destWidth, destHeight);
+      free(dest);
       free_ilbm_data(data);
   }
 }

30years/iffview/ilbm.h

@@ -89,4 +89,5 @@ typedef struct _ILBMData {
 
 extern ILBMData *parse_file(const char *path);
 extern void free_ilbm_data(ILBMData *data);
+extern void ilbm_to_image_data(char *dest, ILBMData *data, int dest_width, int dest_height);
 #endif /* __ILBM_H__ */