render: egl: Add utility functions for saving/restoring context

include/wlr/render/egl.h

@@ -30,6 +30,13 @@
 #include <wlr/render/dmabuf.h>
 #include <wlr/render/drm_format_set.h>
 
+struct wlr_egl_context {
+	EGLDisplay display;
+	EGLContext context;
+	EGLSurface draw_surface;
+	EGLSurface read_surface;
+};
+
 struct wlr_egl {
 	EGLenum platform;
 	EGLDisplay display;
@@ -137,6 +144,18 @@ bool wlr_egl_unset_current(struct wlr_egl *egl);
 
 bool wlr_egl_is_current(struct wlr_egl *egl);
 
+/**
+ * Save the current EGL context to the structure provided in the argument.
+ *
+ * This includes display, context, draw surface and read surface.
+ */
+void wlr_egl_save_context(struct wlr_egl_context *context);
+
+/**
+ * Restore EGL context that was previously saved using wlr_egl_save_current().
+ */
+bool wlr_egl_restore_context(struct wlr_egl_context *context);
+
 bool wlr_egl_swap_buffers(struct wlr_egl *egl, EGLSurface surface,
 	pixman_region32_t *damage);
 

render/egl.c

@@ -411,6 +411,18 @@ bool wlr_egl_is_current(struct wlr_egl *egl) {
 	return eglGetCurrentContext() == egl->context;
 }
 
+void wlr_egl_save_context(struct wlr_egl_context *context) {
+	context->display = eglGetCurrentDisplay();
+	context->context = eglGetCurrentContext();
+	context->draw_surface = eglGetCurrentSurface(EGL_DRAW);
+	context->read_surface = eglGetCurrentSurface(EGL_READ);
+}
+
+bool wlr_egl_restore_context(struct wlr_egl_context *context) {
+	return eglMakeCurrent(context->display, context->draw_surface,
+			context->read_surface, context->context);
+}
+
 bool wlr_egl_swap_buffers(struct wlr_egl *egl, EGLSurface surface,
 		pixman_region32_t *damage) {
 	// Never block when swapping buffers on Wayland