encoder: add convenience input sett. alternatives

Add function returning gpujpeg_encoder_input structure for convenience,
mostly to make tools like clang-tidy happy that the struct is initialized
when defined. It is much better than tempting user to use something like
(`= { 0 }`) to suppress the warning. Also this can be used in C++
brace-or-equal or class initializer section.

libgpujpeg/gpujpeg_common.h

@@ -213,6 +213,7 @@ struct gpujpeg_parameters
  *
  * @param param  Parameters for JPEG coder
  * @return void
+ * @sa gpujpeg_default_parameters
  */
 GPUJPEG_API void
 gpujpeg_set_default_parameters(struct gpujpeg_parameters* param);

libgpujpeg/gpujpeg_encoder.h

@@ -72,6 +72,7 @@ struct gpujpeg_encoder_input
  * @param encoder_input  Encoder input structure
  * @param image  Input image data
  * @return void
+ * @sa gpujpeg_encoder_input_image
  */
 GPUJPEG_API void
 gpujpeg_encoder_input_set_image(struct gpujpeg_encoder_input* input, uint8_t* image);
@@ -82,6 +83,7 @@ gpujpeg_encoder_input_set_image(struct gpujpeg_encoder_input* input, uint8_t* im
  * @param encoder_input  Encoder input structure
  * @param image GPU image data
  * @return void
+ * @sa gpujpeg_encoder_input_gpu_image
  */
 GPUJPEG_API void
 gpujpeg_encoder_input_set_gpu_image(struct gpujpeg_encoder_input* input, uint8_t* image);
@@ -92,10 +94,21 @@ gpujpeg_encoder_input_set_gpu_image(struct gpujpeg_encoder_input* input, uint8_t
  * @param encoder_input  Encoder input structure
  * @param texture_id  OpenGL texture id
  * @return void
+ * @sa gpujpeg_encoder_input_set_texture
  */
 GPUJPEG_API void
 gpujpeg_encoder_input_set_texture(struct gpujpeg_encoder_input* input, struct gpujpeg_opengl_texture* texture);
 
+/// alternative to @ref gpujpeg_encoder_input_set_image returning the struct as a return value
+GPUJPEG_API struct gpujpeg_encoder_input
+gpujpeg_encoder_input_image(uint8_t* image);
+/// alternative to @ref gpujpeg_encoder_input_set_gpu_image returning the struct as a return value
+GPUJPEG_API struct gpujpeg_encoder_input
+gpujpeg_encoder_input_gpu_image(uint8_t* image);
+/// alternative to @ref gpujpeg_encoder_input_set_texture returning the struct as a return value
+GPUJPEG_API struct gpujpeg_encoder_input
+gpujpeg_encoder_input_texture(struct gpujpeg_opengl_texture* texture);
+
 /**
  * Create JPEG encoder
  *

src/gpujpeg_encoder.c

@@ -69,6 +69,30 @@ gpujpeg_encoder_input_set_texture(struct gpujpeg_encoder_input* input, struct gp
     input->texture = texture;
 }
 
+struct gpujpeg_encoder_input
+gpujpeg_encoder_input_image(uint8_t* image)
+{
+    struct gpujpeg_encoder_input ret;
+    gpujpeg_encoder_input_set_image(&ret, image);
+    return ret;
+}
+
+struct gpujpeg_encoder_input
+gpujpeg_encoder_input_gpu_image(uint8_t* image)
+{
+    struct gpujpeg_encoder_input ret;
+    gpujpeg_encoder_input_set_gpu_image(&ret, image);
+    return ret;
+}
+
+struct gpujpeg_encoder_input
+gpujpeg_encoder_input_texture(struct gpujpeg_opengl_texture* texture)
+{
+    struct gpujpeg_encoder_input ret;
+    gpujpeg_encoder_input_set_texture(&ret, texture);
+    return ret;
+}
+
 /* Documented at declaration */
 struct gpujpeg_encoder*
 gpujpeg_encoder_create(cudaStream_t stream)