Add a new renderer API

Goals:

- Extensibility: we need to be able to add new params to the calls
  to render a texture/rect. For instance we'll need to add fences to
  the render texture operation for explicit sync purposes.
- No implicit state: no more bind_buffer, begin, end.
- No matrices: these hurt Pixman and we don't need them.
- Clip regions for optimized damage repainting.

Closes: https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3188

render/meson.build

@@ -8,6 +8,7 @@ endif
 wlr_files += files(
 	'dmabuf.c',
 	'drm_format_set.c',
+	'pass.c',
 	'pixel_format.c',
 	'swapchain.c',
 	'wlr_renderer.c',

render/pass.c

@@ -0,0 +1,25 @@
+#include <assert.h>
+#include <string.h>
+#include <wlr/render/interface.h>
+#include <wlr/render/wlr_renderer.h>
+
+void wlr_render_pass_init(struct wlr_render_pass *render_pass,
+		const struct wlr_render_pass_impl *impl) {
+	assert(impl->submit && impl->add_texture && impl->add_rect);
+	memset(render_pass, 0, sizeof(*render_pass));
+	render_pass->impl = impl;
+}
+
+bool wlr_render_pass_submit(struct wlr_render_pass *render_pass) {
+	return render_pass->impl->submit(render_pass);
+}
+
+void wlr_render_pass_add_texture(struct wlr_render_pass *render_pass,
+		const struct wlr_render_texture_options *options) {
+	render_pass->impl->add_texture(render_pass, options);
+}
+
+void wlr_render_pass_add_rect(struct wlr_render_pass *render_pass,
+		const struct wlr_render_rect_options *options) {
+	render_pass->impl->add_rect(render_pass, options);
+}

render/wlr_renderer.c

@@ -33,11 +33,13 @@
 
 void wlr_renderer_init(struct wlr_renderer *renderer,
 		const struct wlr_renderer_impl *impl) {
-	assert(impl->begin);
-	assert(impl->clear);
-	assert(impl->scissor);
-	assert(impl->render_subtexture_with_matrix);
-	assert(impl->render_quad_with_matrix);
+	if (!impl->begin_buffer_pass) {
+		assert(impl->begin);
+		assert(impl->clear);
+		assert(impl->scissor);
+		assert(impl->render_subtexture_with_matrix);
+		assert(impl->render_quad_with_matrix);
+	}
 	assert(impl->get_shm_texture_formats);
 	assert(impl->get_render_buffer_caps);
 
@@ -409,3 +411,11 @@ int wlr_renderer_get_drm_fd(struct wlr_renderer *r) {
 	}
 	return r->impl->get_drm_fd(r);
 }
+
+struct wlr_render_pass *wlr_renderer_begin_buffer_pass(
+		struct wlr_renderer *renderer, struct wlr_buffer *buffer) {
+	if (!renderer->impl->begin_buffer_pass) {
+		return NULL;
+	}
+	return renderer->impl->begin_buffer_pass(renderer, buffer);
+}