From c387a266dc6cf57ed6901890df9496dae7672a78 Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Tue, 5 Mar 2019 20:27:03 +0000
Subject: [PATCH] backend interface: prepare is optional

Also remove xrender's prepare since it overwrite part of the screen
outside the damage region, causing rendering problems.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/backend/backend.c |  2 +-
 src/backend/backend.h |  4 ++--
 src/backend/xrender.c | 13 -------------
 3 files changed, 3 insertions(+), 16 deletions(-)

diff --git a/src/backend/backend.c b/src/backend/backend.c
index d3b4ed5a..bfdd02b0 100644
--- a/src/backend/backend.c
+++ b/src/backend/backend.c
@@ -71,7 +71,7 @@ void paint_all_new(session_t *ps, win *const t, bool ignore_damage) {
 	// TODO Bind root pixmap
 
 	if (ps->backend_data->ops->prepare) {
-		ps->backend_data->ops->prepare(ps->backend_data, &reg_visible);
+		ps->backend_data->ops->prepare(ps->backend_data, &reg_damage);
 	}
 
 	if (ps->root_image) {
diff --git a/src/backend/backend.h b/src/backend/backend.h
index 8aef82cc..03edbf5d 100644
--- a/src/backend/backend.h
+++ b/src/backend/backend.h
@@ -67,8 +67,8 @@ struct backend_operations {
 	/// Usually the backend should clear the buffer, or paint a background
 	/// on the buffer (usually the wallpaper).
 	///
-	/// Optional?
-	void (*prepare)(backend_t *backend_data, const region_t *reg_paint);
+	/// Optional
+	void (*prepare)(backend_t *backend_data, const region_t *reg_damage);
 
 	/**
 	 * Paint the content of an image onto the (possibly buffered)
diff --git a/src/backend/xrender.c b/src/backend/xrender.c
index d0b2d068..51382b31 100644
--- a/src/backend/xrender.c
+++ b/src/backend/xrender.c
@@ -260,18 +260,6 @@ static void deinit(backend_t *backend_data) {
 	free(xd);
 }
 
-static void prepare(backend_t *base, const region_t *reg_paint) {
-	struct _xrender_data *xd = (void *)base;
-
-	// Paint the root pixmap (i.e. wallpaper)
-	// Limit the paint area
-	x_set_picture_clip_region(base->c, xd->back[xd->curr_back], 0, 0, reg_paint);
-
-	xcb_render_composite(base->c, XCB_RENDER_PICT_OP_SRC, xd->root_pict, XCB_NONE,
-	                     xd->back[xd->curr_back], 0, 0, 0, 0, 0, 0, xd->target_width,
-	                     xd->target_height);
-}
-
 static void present(backend_t *base) {
 	struct _xrender_data *xd = (void *)base;
 
@@ -457,7 +445,6 @@ static struct backend_operations xrender_ops = {
     .deinit = deinit,
     .blur = blur,
     .present = present,
-    .prepare = prepare,
     .compose = compose,
     .bind_pixmap = bind_pixmap,
     .release_image = release_image,