new backend: add interface for query blur size

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/backend/backend.h

@@ -213,6 +213,7 @@ struct backend_operations {
 	/// Create a blur context that can be used to call `blur`
 	void *(*create_blur_context)(backend_t *base, enum blur_method, void *args);
 	void (*destroy_blur_context)(backend_t *base, void *ctx);
+	void (*get_blur_size)(void *blur_context, int *width, int *height);
 
 	// ===========         Hooks        ============
 	/// Let the backend hook into the event handling queue

src/backend/gl/gl_common.c

@@ -907,6 +907,12 @@ out:
 	return ctx;
 }
 
+void gl_get_blur_size(void *blur_context, int *width, int *height) {
+	struct gl_blur_context *ctx = blur_context;
+	*width = ctx->resize_width;
+	*height = ctx->resize_height;
+}
+
 // clang-format off
 const char *win_shader_glsl = GLSL(330,
 	uniform float opacity;

src/backend/gl/gl_common.h

@@ -105,6 +105,7 @@ bool gl_blur(backend_t *base, double opacity, void *, const region_t *reg_blur,
              const region_t *reg_visible);
 void *gl_create_blur_context(backend_t *base, enum blur_method, void *args);
 void gl_destroy_blur_context(backend_t *base, void *ctx);
+void gl_get_blur_size(void *blur_context, int *width, int *height);
 
 bool gl_is_image_transparent(backend_t *base, void *image_data);
 void gl_fill(backend_t *base, struct color, const region_t *clip);

src/backend/gl/glx.c

@@ -472,6 +472,7 @@ struct backend_operations glx_ops = {
     .fill = gl_fill,
     .create_blur_context = gl_create_blur_context,
     .destroy_blur_context = gl_destroy_blur_context,
+    .get_blur_size = gl_get_blur_size,
     .max_buffer_age = 5,        // Why?
 };
 

src/backend/xrender/xrender.c

@@ -530,6 +530,12 @@ void destroy_blur_context(backend_t *base, void *ctx_) {
 	free(ctx);
 }
 
+void get_blur_size(void *blur_context, int *width, int *height) {
+	struct _xrender_blur_context *ctx = blur_context;
+	*width = ctx->resize_width;
+	*height = ctx->resize_height;
+}
+
 backend_t *backend_xrender_init(session_t *ps) {
 	auto xd = ccalloc(1, struct _xrender_data);
 	init_backend_base(&xd->base, ps);
@@ -632,6 +638,7 @@ struct backend_operations xrender_ops = {
     .copy = copy,
     .create_blur_context = create_blur_context,
     .destroy_blur_context = destroy_blur_context,
+    .get_blur_size = get_blur_size,
 };
 
 // vim: set noet sw=8 ts=8: