Remove support of Xdbe

--dbe does not seem to have an effect on tearing, as noted in the old
manpage, and confirmed by my own testing.

So remove it, since it complicates the logic of painting.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/common.h

@@ -83,7 +83,6 @@
 
 #include <X11/Xlib-xcb.h>
 #include <X11/Xlib.h>
-#include <X11/extensions/Xdbe.h>
 #ifdef CONFIG_XSYNC
 #include <X11/extensions/sync.h>
 #endif
@@ -531,8 +530,6 @@ typedef struct options_t {
   bool sw_opti;
   /// VSync method to use;
   vsync_t vsync;
-  /// Whether to enable double buffer.
-  bool dbe;
   /// Whether to do VSync aggressively.
   bool vsync_aggressive;
   /// Whether to use glFinish() instead of glFlush() for (possibly) better
@@ -745,8 +742,6 @@ typedef struct session {
 #ifdef CONFIG_XSYNC
   XSyncFence tgt_buffer_fence;
 #endif
-  /// DBE back buffer for root window. Used in DBE painting mode.
-  XdbeBackBuffer root_dbe;
   /// Window ID of the window we register as a symbol.
   Window reg_win;
 #ifdef CONFIG_OPENGL
@@ -899,8 +894,6 @@ typedef struct session {
   /// Error base number for X GLX extension.
   int glx_error;
 #endif
-  /// Whether X DBE extension exists.
-  bool dbe_exists;
 #ifdef CONFIG_XINERAMA
   /// Whether X Xinerama extension exists.
   bool xinerama_exists;

src/compton.c

@@ -1675,14 +1675,6 @@ paint_all(session_t *ps, region_t *region, const region_t *region_real, win * co
   ps->tgt_buffer.pict = ps->tgt_picture;
 #else
   if (!paint_isvalid(ps, &ps->tgt_buffer)) {
-    // DBE painting mode: Directly paint to a Picture of the back buffer
-    if (BKEND_XRENDER == ps->o.backend && ps->o.dbe) {
-      ps->tgt_buffer.pict = x_create_picture_with_visual_and_pixmap(
-        ps, ps->vis, ps->root_dbe, 0, 0);
-    }
-    // No-DBE painting mode: Paint to an intermediate Picture then paint
-    // the Picture to root window
-    else {
     if (!ps->tgt_buffer.pixmap) {
       free_paint(ps, &ps->tgt_buffer);
       ps->tgt_buffer.pixmap = x_create_pixmap(ps, ps->depth, ps->root, ps->root_width, ps->root_height);
@@ -1696,7 +1688,6 @@ paint_all(session_t *ps, region_t *region, const region_t *region_real, win * co
       ps->tgt_buffer.pict = x_create_picture_with_visual_and_pixmap(
         ps, ps->vis, ps->tgt_buffer.pixmap, 0, 0);
   }
-  }
 #endif
 
   if (BKEND_XRENDER == ps->o.backend) {
@@ -1807,7 +1798,6 @@ paint_all(session_t *ps, region_t *region, const region_t *region_real, win * co
   pixman_region32_fini(&reg_tmp);
 
   // Do this as early as possible
-  if (!ps->o.dbe)
   set_tgt_clip(ps, &ps->screen_reg);
 
   if (ps->o.vsync) {
@@ -1833,17 +1823,7 @@ paint_all(session_t *ps, region_t *region, const region_t *region_real, win * co
 
   switch (ps->o.backend) {
     case BKEND_XRENDER:
-      // DBE painting mode, only need to swap the buffer
+      if (ps->tgt_buffer.pict != ps->tgt_picture) {
-      if (ps->o.dbe) {
-        XdbeSwapInfo swap_info = {
-          .swap_window = get_tgt_window(ps),
-          // Is it safe to use XdbeUndefined?
-          .swap_action = XdbeCopied
-        };
-        XdbeSwapBuffers(ps->dpy, &swap_info, 1);
-      }
-      // No-DBE painting mode
-      else if (ps->tgt_buffer.pict != ps->tgt_picture) {
         xcb_render_composite(
           ps->c, XCB_RENDER_PICT_OP_SRC, ps->tgt_buffer.pict, None,
           ps->tgt_picture, 0, 0, 0, 0,
@@ -3299,10 +3279,6 @@ usage(int ret) {
     "  X Render backend: Step for pregenerating alpha pictures. \n"
     "  0.01 - 1.0. Defaults to 0.03.\n"
     "\n"
-    "--dbe\n"
-    "  Enable DBE painting mode, intended to use with VSync to\n"
-    "  (hopefully) eliminate tearing.\n"
-    "\n"
     "--paint-on-overlay\n"
     "  Painting on X Composite overlay window.\n"
     "\n"
@@ -3909,7 +3885,9 @@ get_cfg(session_t *ps, int argc, char *const *argv, bool first_pass) {
         // --alpha-step
         ps->o.alpha_step = atof(optarg);
         break;
-      P_CASEBOOL(272, dbe);
+      case 272:
+        printf_errf("(): use of --dbe is deprecated");
+        break;
       P_CASEBOOL(273, paint_on_overlay);
       P_CASEBOOL(274, sw_opti);
       P_CASEBOOL(275, vsync_aggressive);
@@ -4486,21 +4464,6 @@ init_alpha_picts(session_t *ps) {
   }
 }
 
-/**
- * Initialize double buffer.
- */
-static bool
-init_dbe(session_t *ps) {
-  if (!(ps->root_dbe = XdbeAllocateBackBufferName(ps->dpy,
-          (ps->o.paint_on_overlay ? ps->overlay: ps->root), XdbeCopied))) {
-    printf_errf("(): Failed to create double buffer. Double buffering "
-        "cannot work.");
-    return false;
-  }
-
-  return true;
-}
-
 /**
  * Initialize X composite overlay window.
  */
@@ -4880,7 +4843,6 @@ session_init(session_t *ps_old, int argc, char **argv) {
     .root_tile_paint = PAINT_INIT,
     .tgt_picture = None,
     .tgt_buffer = PAINT_INIT,
-    .root_dbe = None,
     .reg_win = None,
     .o = {
       .config_file = NULL,
@@ -4910,7 +4872,6 @@ session_init(session_t *ps_old, int argc, char **argv) {
       .refresh_rate = 0,
       .sw_opti = false,
       .vsync = VSYNC_NONE,
-      .dbe = false,
       .vsync_aggressive = false,
 
       .wintype_shadow = { false },
@@ -5017,7 +4978,6 @@ session_init(session_t *ps_old, int argc, char **argv) {
     .glx_event = 0,
     .glx_error = 0,
 #endif
-    .dbe_exists = false,
     .xrfilter_convolution_exists = false,
 
     .atom_opacity = None,
@@ -5222,22 +5182,6 @@ session_init(session_t *ps_old, int argc, char **argv) {
           "detection impossible.");
   }
 
-  // Query X DBE extension
-  if (ps->o.dbe) {
-    int dbe_ver_major = 0, dbe_ver_minor = 0;
-    if (XdbeQueryExtension(ps->dpy, &dbe_ver_major, &dbe_ver_minor))
-      if (dbe_ver_major >= 1)
-        ps->dbe_exists = true;
-      else
-        fprintf(stderr, "DBE extension version too low. Double buffering "
-            "impossible.\n");
-    else {
-      fprintf(stderr, "No DBE extension. Double buffering impossible.\n");
-    }
-    if (!ps->dbe_exists)
-      ps->o.dbe = false;
-  }
-
   // Query X Xinerama extension
   if (ps->o.xinerama_shadow_crop) {
 #ifdef CONFIG_XINERAMA
@@ -5255,15 +5199,6 @@ session_init(session_t *ps_old, int argc, char **argv) {
   if (ps->o.paint_on_overlay)
     init_overlay(ps);
 
-  // Initialize DBE
-  if (ps->o.dbe && BKEND_XRENDER != ps->o.backend) {
-    printf_errf("(): DBE couldn't be used on GLX backend.");
-    ps->o.dbe = false;
-  }
-
-  if (ps->o.dbe && !init_dbe(ps))
-    exit(1);
-
   // Initialize OpenGL as early as possible
   if (bkend_use_glx(ps)) {
 #ifdef CONFIG_OPENGL
@@ -5581,12 +5516,6 @@ session_destroy(session_t *ps) {
   glx_destroy(ps);
 #endif
 
-  // Free double buffer
-  if (ps->root_dbe) {
-    XdbeDeallocateBackBufferName(ps->dpy, ps->root_dbe);
-    ps->root_dbe = None;
-  }
-
 #ifdef CONFIG_VSYNC_DRM
   // Close file opened for DRM VSync
   if (ps->drm_fd >= 0) {

src/config_libconfig.c

@@ -297,8 +297,6 @@ parse_config(session_t *ps, struct options_tmp *pcfgtmp) {
     exit(1);
   // --alpha-step
   config_lookup_float(&cfg, "alpha-step", &ps->o.alpha_step);
-  // --dbe
-  lcfg_lookup_bool(&cfg, "dbe", &ps->o.dbe);
   // --paint-on-overlay
   lcfg_lookup_bool(&cfg, "paint-on-overlay", &ps->o.paint_on_overlay);
   // --sw-opti

src/dbus.c

@@ -910,7 +910,7 @@ cdbus_process_opts_get(session_t *ps, DBusMessage *msg) {
     cdbus_reply_string(ps, msg, BACKEND_STRS[ps->o.backend]);
     return true;
   }
-  cdbus_m_opts_get_do(dbe, cdbus_reply_bool);
+  cdbus_m_opts_get_stub(dbe, cdbus_reply_bool, false);
   cdbus_m_opts_get_do(vsync_aggressive, cdbus_reply_bool);
 
   cdbus_m_opts_get_do(shadow_red, cdbus_reply_double);