API: created helper functions to inherit image formats

src/imgio.c

@@ -189,20 +189,43 @@ jpeg_save(const unsigned int* src_buf, const JPEG* attr, const char* name)
 }
 
 void
-ppm_to_jpeg(PPM* in, JPEG* out)
+transcode_to_jpeg(PPM* in, JPEG* out)
 {
-	unsigned int* src_buf = ppm_load(in->name, in);
+	unsigned int* dst = ppm_load(in->name, in);
 	out->width = in->width;
 	out->height = in->height;
-	jpeg_save(src_buf, out, out->name);
+	jpeg_save(dst, out, out->name);
+        free(dst);
 }
 
 void
-jpeg_to_ppm(JPEG* input, PPM* out)
+transcode_to_ppm(JPEG* input, PPM* out)
 {
-	unsigned int* src_buf = jpeg_load(input);
+	unsigned int* dst = jpeg_load(input);
 	out->width = input->width;
 	out->height = input->height;
 	out->len = out->width * out->height;
-	ppm_save(src_buf, *out);
+	ppm_save(dst, *out);
+        free(dst);
+}
+
+PPM
+inherit_from_jpeg(const JPEG* in, const char fmt) {
+        PPM image = {
+                .width = in->width,
+                .height = in->height,
+                .len = in->width * in->height,
+                .fmt = fmt
+        };
+        return image;
+}
+
+JPEG
+inherit_from_ppm(const PPM* in) {
+        JPEG image = {
+                .width = in->width,
+                .height = in->height,
+                .len = in->width * in->height,
+        };
+        return image;
 }