refactor: return bool from image and upscale APIs (#1728)

src/upscaler.cpp

@@ -199,23 +199,41 @@ upscaler_ctx_t* new_upscaler_ctx(const char* esrgan_path_c_str,
     return upscaler_ctx;
 }
 
-sd_image_t* upscale(upscaler_ctx_t* upscaler_ctx, sd_image_t input_image, uint32_t upscale_factor) {
+bool upscale(upscaler_ctx_t* upscaler_ctx,
+             sd_image_t input_image,
+             uint32_t upscale_factor,
+             sd_image_t** images_out,
+             int* num_images_out) {
+    if (images_out != nullptr) {
+        *images_out = nullptr;
+    }
+    if (num_images_out != nullptr) {
+        *num_images_out = 0;
+    }
     if (upscaler_ctx == nullptr || upscaler_ctx->upscaler == nullptr) {
-        return nullptr;
+        return false;
     }
 
     sd_image_t* result_images = (sd_image_t*)calloc(1, sizeof(sd_image_t));
     if (result_images == nullptr) {
-        return nullptr;
+        return false;
     }
 
     result_images[0] = upscaler_ctx->upscaler->upscale(input_image, upscale_factor);
     if (result_images[0].data == nullptr) {
         free(result_images);
-        return nullptr;
+        return false;
     }
 
-    return result_images;
+    if (num_images_out != nullptr) {
+        *num_images_out = 1;
+    }
+    if (images_out != nullptr) {
+        *images_out = result_images;
+    } else {
+        free_sd_images(result_images, 1);
+    }
+    return true;
 }
 
 int get_upscale_factor(upscaler_ctx_t* upscaler_ctx) {