1 files changed, 98 insertions, 0 deletions
diff --git a/src/frontend.c b/src/frontend.c
new file mode 100644
index 0000000..171a7f3
--- /dev/null
+++ b/src/frontend.c
@@ -0,0 +1,98 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <malloc.h>
+#include <string.h>
+
+#include "frontend.h"
+#include "plotters.h"
+
+#define MAX_FRONTENDS 16
+
+struct nsfb_frontend_s {
+    enum nsfb_frontend_e type;
+    const nsfb_frontend_rtns_t *rtns;
+    const char *name;
+};
+
+static struct nsfb_frontend_s frontends[MAX_FRONTENDS];
+static int frontend_count = 0;
+
+/* internal routine which lets frontends register their presence at runtime */
+void _nsfb_register_frontend(const enum nsfb_frontend_e type, 
+                             const nsfb_frontend_rtns_t *rtns, 
+                             const char *name)
+{
+    if (frontend_count >= MAX_FRONTENDS)
+        return; /* no space for additional frontends */
+
+    frontends[frontend_count].type = type;
+    frontends[frontend_count].rtns = rtns;
+    frontends[frontend_count].name = name;
+    frontend_count++;
+}
+
+/* default frontend implementations */
+static int frontend_defaults(nsfb_t *nsfb)
+{
+    nsfb->width = 800;
+    nsfb->height = 600;
+    nsfb->bpp = 32;
+
+    /* select plotters for bpp */
+    select_plotters(nsfb);
+
+    return 0;
+}
+
+static int frontend_claim(nsfb_t *nsfb, nsfb_bbox_t *box)
+{
+    nsfb=nsfb;
+    box=box;
+    return 0;
+}
+
+static int frontend_release(nsfb_t *nsfb, nsfb_bbox_t *box)
+{
+    nsfb=nsfb;
+    box=box;
+    return 0;
+}
+
+nsfb_frontend_rtns_t *nsfb_frontend_get_rtns(enum nsfb_frontend_e type)
+{
+    int fend_loop;
+    nsfb_frontend_rtns_t *rtns = NULL;
+
+    for (fend_loop = 0; fend_loop < frontend_count; fend_loop++) {
+        if (frontends[fend_loop].type == type) {
+            rtns = malloc(sizeof(nsfb_frontend_rtns_t));
+            memcpy(rtns, 
+                   frontends[fend_loop].rtns, 
+                   sizeof(nsfb_frontend_rtns_t));
+
+            /* frontend must have an initialisor, finaliser and input method */
+            if ((rtns->initialise == NULL) || 
+                (rtns->finalise == NULL) || 
+                (rtns->input == NULL) ) {
+                free(rtns);
+                rtns = NULL;
+            }
+
+            /* The rest may be empty but to avoid the null check every time
+             * provide default implementations. 
+             */
+            if (rtns->defaults == NULL) 
+                rtns->defaults = frontend_defaults;
+
+            if (rtns->claim == NULL) 
+                rtns->claim = frontend_claim;
+
+            if (rtns->release == NULL) 
+                rtns->release = frontend_release;
+
+            break;
+        }
+    }
+    return rtns;
+}