perf(opengl): remove long delay when destroying shader programs (#9037)

src/drivers/opengles/opengl_shader/lv_opengl_shader_manager.c

@@ -213,6 +213,7 @@ lv_result_t lv_opengl_shader_manager_select_shader(lv_opengl_shader_manager_t *
         GL_CALL(glGetShaderInfoLog(shader_map_key.id, sizeof(info_log), NULL, info_log));
         LV_LOG_WARN("Failed to compile shader for glsl version '%s': %s", lv_opengles_glsl_version_to_string(glsl_version),
                     info_log);
+        GL_CALL(glDeleteShader(shader_map_key.id));
         return LV_RESULT_INVALID;
     }
 
@@ -269,6 +270,7 @@ lv_opengl_shader_manager_get_program(lv_opengl_shader_manager_t * manager,
         GL_CALL(glGetProgramInfoLog(program_id, sizeof(info_log), NULL,
                                     info_log));
         LV_LOG_WARN("Failed to link program: %s", info_log);
+        GL_CALL(glDeleteProgram(program_id));
         return NULL;
     }
     LV_LOG_TRACE("Linking program with shaders V: %d F:%d P: %d", vertex_shader_id, fragment_shader_id, program_id);

src/drivers/opengles/opengl_shader/lv_opengl_shader_program.c

@@ -76,7 +76,20 @@ void lv_opengl_shader_program_destroy(lv_opengl_shader_program_t * program)
     }
 #endif
 
-    GL_CALL(glDeleteProgram(program->id));
+    /* We should be able to call the function below without issue at this point
+     * but because of subtle issues regarding lazy updates of shader resources
+     * this induces significant pause on some platforms.  Since the shaders
+     * have already been detached, we can safely skip this function and leave
+     * the empty programs in OpenGL's cache until the app shuts down, it's a
+     * very small amount of memory.
+     *
+     * To-do: Consider setting a flag at this point and if that flag is true
+     * when the app finally shuts down, then perform the glDeleteProgram calls
+     * if necessary.  That is not really necessary, OpenGL will do that anyways
+     * when it shuts down. */
+
+    /* GL_CALL(glDeleteProgram(program->id)); */
+
 }
 
 GLuint lv_opengl_shader_program_get_id(lv_opengl_shader_program_t * program)