[Mesa-dev] [PATCH 4/4] drisw/glx: use XShm if possible

Marc-André Lureau marcandre.lureau at gmail.com
Wed Jun 10 09:08:57 PDT 2015


Implements putImageShm from DRIswrastLoaderExtension.

If XShm extension is not available, or fails, it will fallback on
regular XPutImage().

Tested on Linux only with 16bpp and 32bpp visual.
---
 src/glx/drisw_glx.c  | 164 +++++++++++++++++++++++++++++++++++++++++++--------
 src/glx/drisw_priv.h |   3 +
 2 files changed, 143 insertions(+), 24 deletions(-)

diff --git a/src/glx/drisw_glx.c b/src/glx/drisw_glx.c
index 749ceb0..9e0b214 100644
--- a/src/glx/drisw_glx.c
+++ b/src/glx/drisw_glx.c
@@ -28,10 +28,12 @@
 #include <dlfcn.h>
 #include "dri_common.h"
 #include "drisw_priv.h"
+#include <X11/extensions/shmproto.h>
+#include <assert.h>
 
 static Bool
-XCreateDrawable(struct drisw_drawable * pdp,
-                Display * dpy, XID drawable, int visualid)
+XCreateGCs(struct drisw_drawable * pdp,
+           Display * dpy, XID drawable, int visualid)
 {
    XGCValues gcvalues;
    long visMask;
@@ -56,15 +58,78 @@ XCreateDrawable(struct drisw_drawable * pdp,
    if (!pdp->visinfo || num_visuals == 0)
       return False;
 
-   /* create XImage */
-   pdp->ximage = XCreateImage(dpy,
-                              pdp->visinfo->visual,
-                              pdp->visinfo->depth,
-                              ZPixmap, 0,             /* format, offset */
-                              NULL,                   /* data */
-                              0, 0,                   /* width, height */
-                              32,                     /* bitmap_pad */
-                              0);                     /* bytes_per_line */
+   return True;
+}
+
+static int xshm_error = 0;
+static int xshm_opcode = -1;
+
+/**
+ * Catches potential Xlib errors.
+ */
+static int
+handle_xerror(Display *dpy, XErrorEvent *event)
+{
+   (void) dpy;
+
+   assert(xshm_opcode != -1);
+   if (event->request_code != xshm_opcode ||
+       event->minor_code != X_ShmAttach)
+      return 0;
+
+   xshm_error = 1;
+   return 0;
+}
+
+static Bool
+XCreateDrawable(struct drisw_drawable * pdp, int shmid, Display * dpy)
+{
+   if (pdp->ximage) {
+      XDestroyImage(pdp->ximage);
+      pdp->ximage = NULL;
+   }
+
+   if (!xshm_error && shmid >= 0) {
+      pdp->shminfo.shmid = shmid;
+      pdp->ximage = XShmCreateImage(dpy,
+                                    pdp->visinfo->visual,
+                                    pdp->visinfo->depth,
+                                    ZPixmap,              /* format */
+                                    NULL,                 /* data */
+                                    &pdp->shminfo,        /* shminfo */
+                                    0, 0);                /* width, height */
+      if (pdp->ximage == NULL) {
+         int (*old_handler)(Display *, XErrorEvent *);
+
+         /* dispatch pending errors */
+         XSync(dpy, False);
+
+         old_handler = XSetErrorHandler(handle_xerror);
+         /* This may trigger the X protocol error we're ready to catch: */
+         XShmAttach(dpy, &pdp->shminfo);
+         XSync(dpy, False);
+
+         if (xshm_error) {
+         /* we are on a remote display, this error is normal, don't print it */
+            XDestroyImage(pdp->ximage);
+            pdp->ximage = NULL;
+         }
+
+         (void) XSetErrorHandler(old_handler);
+      }
+   }
+
+   if (pdp->ximage == NULL) {
+      pdp->shminfo.shmid = -1;
+      pdp->ximage = XCreateImage(dpy,
+                                 pdp->visinfo->visual,
+                                 pdp->visinfo->depth,
+                                 ZPixmap, 0,             /* format, offset */
+                                 NULL,                   /* data */
+                                 0, 0,                   /* width, height */
+                                 32,                     /* bitmap_pad */
+                                 0);                     /* bytes_per_line */
+   }
 
   /**
    * swrast does not handle 24-bit depth with 24 bpp, so let X do the
@@ -79,7 +144,9 @@ XCreateDrawable(struct drisw_drawable * pdp,
 static void
 XDestroyDrawable(struct drisw_drawable * pdp, Display * dpy, XID drawable)
 {
-   XDestroyImage(pdp->ximage);
+   if (pdp->ximage)
+      XDestroyImage(pdp->ximage);
+
    free(pdp->visinfo);
 
    XFreeGC(dpy, pdp->gc);
@@ -133,9 +200,9 @@ bytes_per_line(unsigned pitch_bits, unsigned mul)
 }
 
 static void
-swrastPutImage2(__DRIdrawable * draw, int op,
+swrastXPutImage(__DRIdrawable * draw, int op,
                 int x, int y, int w, int h, int stride,
-                char *data, void *loaderPrivate)
+                int shmid, char *data, void *loaderPrivate)
 {
    struct drisw_drawable *pdp = loaderPrivate;
    __GLXDRIdrawable *pdraw = &(pdp->base);
@@ -144,6 +211,11 @@ swrastPutImage2(__DRIdrawable * draw, int op,
    XImage *ximage;
    GC gc;
 
+   if (!pdp->ximage || shmid != pdp->shminfo.shmid) {
+      if (!XCreateDrawable(pdp, shmid, dpy))
+         return;
+   }
+
    switch (op) {
    case __DRI_SWRAST_IMAGE_OP_DRAW:
       gc = pdp->gc;
@@ -156,24 +228,51 @@ swrastPutImage2(__DRIdrawable * draw, int op,
    }
 
    drawable = pdraw->xDrawable;
-
    ximage = pdp->ximage;
-   ximage->data = data;
-   ximage->width = w;
-   ximage->height = h;
    ximage->bytes_per_line = stride ? stride : bytes_per_line(w * ximage->bits_per_pixel, 32);
+   ximage->data = data;
 
-   XPutImage(dpy, drawable, gc, ximage, 0, 0, x, y, w, h);
-
+   if (pdp->shminfo.shmid >= 0) {
+      ximage->width = ximage->bytes_per_line / ((ximage->bits_per_pixel + 7)/ 8);
+      ximage->height = h;
+      XShmPutImage(dpy, drawable, gc, ximage, 0, 0, x, y, w, h, False);
+   } else {
+      ximage->width = w;
+      ximage->height = h;
+      XPutImage(dpy, drawable, gc, ximage, 0, 0, x, y, w, h);
+   }
    ximage->data = NULL;
 }
 
 static void
+swrastPutImageShm(__DRIdrawable * draw, int op,
+                  int x, int y, int w, int h, int stride,
+                  int shmid, char *shmaddr, unsigned offset,
+                  void *loaderPrivate)
+{
+   struct drisw_drawable *pdp = loaderPrivate;
+
+   pdp->shminfo.shmaddr = shmaddr;
+   swrastXPutImage(draw, op, x, y, w, h, stride, shmid,
+                   shmaddr + offset, loaderPrivate);
+}
+
+static void
+swrastPutImage2(__DRIdrawable * draw, int op,
+                int x, int y, int w, int h, int stride,
+                char *data, void *loaderPrivate)
+{
+   swrastXPutImage(draw, op, x, y, w, h, stride, -1,
+                   data, loaderPrivate);
+}
+
+static void
 swrastPutImage(__DRIdrawable * draw, int op,
                int x, int y, int w, int h,
                char *data, void *loaderPrivate)
 {
-   swrastPutImage2(draw, op, x, y, w, h, 0, data, loaderPrivate);
+   swrastXPutImage(draw, op, x, y, w, h, 0, -1,
+                   data, loaderPrivate);
 }
 
 static void
@@ -187,6 +286,11 @@ swrastGetImage(__DRIdrawable * read,
    Drawable readable;
    XImage *ximage;
 
+   if (!prp->ximage || prp->shminfo.shmid >= 0) {
+      if (!XCreateDrawable(prp, -1, dpy))
+         return;
+   }
+
    readable = pread->xDrawable;
 
    ximage = prp->ximage;
@@ -200,13 +304,14 @@ swrastGetImage(__DRIdrawable * read,
    ximage->data = NULL;
 }
 
-static const __DRIswrastLoaderExtension swrastLoaderExtension = {
-   .base = {__DRI_SWRAST_LOADER, 2 },
+static __DRIswrastLoaderExtension swrastLoaderExtension = {
+   .base = {__DRI_SWRAST_LOADER, 3 },
 
    .getDrawableInfo     = swrastGetDrawableInfo,
    .putImage            = swrastPutImage,
    .getImage            = swrastGetImage,
    .putImage2           = swrastPutImage2,
+   .putImageShm         = swrastPutImageShm,
 };
 
 static const __DRIextension *loader_extensions[] = {
@@ -512,7 +617,7 @@ driswCreateDrawable(struct glx_screen *base, XID xDrawable,
    pdp->base.drawable = drawable;
    pdp->base.psc = &psc->base;
 
-   ret = XCreateDrawable(pdp, psc->base.dpy, xDrawable, modes->visualID);
+   ret = XCreateGCs(pdp, psc->base.dpy, xDrawable, modes->visualID);
    if (!ret) {
       free(pdp);
       return NULL;
@@ -640,6 +745,14 @@ driswBindExtensions(struct drisw_screen *psc, const __DRIextension **extensions)
    }
 }
 
+static int
+check_xshm(Display *dpy)
+{
+   int ignore;
+
+   return XQueryExtension(dpy, "MIT-SHM", &xshm_opcode, &ignore, &ignore);
+}
+
 static struct glx_screen *
 driswCreateScreen(int screen, struct glx_display *priv)
 {
@@ -667,6 +780,9 @@ driswCreateScreen(int screen, struct glx_display *priv)
    if (extensions == NULL)
       goto handle_error;
 
+   if (!check_xshm(psc->base.dpy))
+      swrastLoaderExtension.putImageShm = NULL;
+
    for (i = 0; extensions[i]; i++) {
       if (strcmp(extensions[i]->name, __DRI_CORE) == 0)
 	 psc->core = (__DRIcoreExtension *) extensions[i];
diff --git a/src/glx/drisw_priv.h b/src/glx/drisw_priv.h
index 5d47900..a670da2 100644
--- a/src/glx/drisw_priv.h
+++ b/src/glx/drisw_priv.h
@@ -23,6 +23,8 @@
  * SOFTWARE.
  */
 
+#include <X11/extensions/XShm.h>
+
 struct drisw_display
 {
    __GLXDRIdisplay base;
@@ -62,6 +64,7 @@ struct drisw_drawable
    __DRIdrawable *driDrawable;
    XVisualInfo *visinfo;
    XImage *ximage;
+   XShmSegmentInfo shminfo;
 };
 
 _X_HIDDEN int
-- 
2.4.2



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