Elements: GLFilter: initial implementation

GLFilter is an base class for GLShader based filter

Signed-off-by: Vasiliy Doylov <nekocwd@mainlining.org>

src/elements/gl_filter.vala

@@ -0,0 +1,45 @@
+/* gl_filter.vala
+ *
+ * Copyright 2025 Vasiliy Doylov <nekocwd@mainlining.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+public class EyeNeko.Elements.GLFilter : BinBase {
+    public Gst.Element glshader = Gst.ElementFactory.make("glshader");
+
+    construct {
+        add_many(glshader);
+        add_pads(glshader, glshader);
+        notify.connect(update_uniforms);
+        update_uniforms();
+    }
+
+    protected virtual void update_uniforms() {}
+
+    protected void set_shader(string name) {
+        glshader.set_property("fragment", get_shader_source(name));
+    }
+
+    public static string get_shader_source(string name) {
+        try {
+            return (string) resources_lookup_data("/io/gitlab/nekocwd/eyeneko/shaders/" + name + ".glsl", GLib.ResourceLookupFlags.NONE).get_data();
+        } catch (Error err) {
+            warning("Error during shader lookup. %s", err.message);
+            return "";
+        }
+    }
+}

src/meson.build

@@ -12,6 +12,7 @@ eyeneko_sources = [
   'elements/bin_base.vala',
   'elements/downscale.vala',
   'elements/focus_analyze.vala',
+  'elements/gl_filter.vala',
 ]
 
 vapi_dir = meson.current_source_dir() / 'vapi'