dix/pixmap: track dirty pixmaps in server. (v4)

This adds two functions for drivers to use directly to keep a
linked list of slave pixmaps to do damage tracking on and keep
updated. It also adds a helper function that drivers may optionally
call to do a simple copy area damage update.

v2: use damage.h not damagestr.h, fixes ephyr build.

v3: address ajax review: use slave_dst, drop unused dst member.

v4: check DamageCreate return, add SourceValidate comment,
add a comment addressing possible optimisation possibility

Reviewed-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

dix/dispatch.c

@@ -3742,6 +3742,7 @@ static int init_screen(ScreenPtr pScreen, int i, Bool gpu)
     pScreen->ClipNotify = 0;    /* for R4 ddx compatibility */
     pScreen->CreateScreenResources = 0;
 
+    xorg_list_init(&pScreen->pixmap_dirty_list);
     xorg_list_init(&pScreen->unattached_list);
     xorg_list_init(&pScreen->output_slave_list);
 

dix/pixmap.c

@@ -158,3 +158,109 @@ PixmapPtr PixmapShareToSlave(PixmapPtr pixmap, ScreenPtr slave)
 
     return spix;
 }
+
+Bool
+PixmapStartDirtyTracking(PixmapPtr src,
+                         PixmapPtr slave_dst,
+                         int x, int y)
+{
+    ScreenPtr screen = src->drawable.pScreen;
+    PixmapDirtyUpdatePtr dirty_update;
+
+    dirty_update = calloc(1, sizeof(PixmapDirtyUpdateRec));
+    if (!dirty_update)
+        return FALSE;
+
+    dirty_update->src = src;
+    dirty_update->slave_dst = slave_dst;
+    dirty_update->x = x;
+    dirty_update->y = y;
+
+    dirty_update->damage = DamageCreate(NULL, NULL,
+                                        DamageReportNone,
+                                        TRUE, src->drawable.pScreen,
+                                        src->drawable.pScreen);
+    if (!dirty_update->damage) {
+        free(dirty_update);
+        return FALSE;
+    }
+
+    DamageRegister(&src->drawable, dirty_update->damage);
+    xorg_list_add(&dirty_update->ent, &screen->pixmap_dirty_list);
+    return TRUE;
+}
+
+Bool
+PixmapStopDirtyTracking(PixmapPtr src, PixmapPtr slave_dst)
+{
+    ScreenPtr screen = src->drawable.pScreen;
+    PixmapDirtyUpdatePtr ent, safe;
+
+    xorg_list_for_each_entry_safe(ent, safe, &screen->pixmap_dirty_list, ent) {
+        if (ent->src == src && ent->slave_dst == slave_dst) {
+            DamageUnregister(&src->drawable, ent->damage);
+            DamageDestroy(ent->damage);
+            xorg_list_del(&ent->ent);
+            free(ent);
+        }
+    }
+    return TRUE;
+}
+
+/*
+ * this function can possibly be improved and optimised, by clipping
+ * instead of iterating
+ */
+Bool PixmapSyncDirtyHelper(PixmapDirtyUpdatePtr dirty, RegionPtr dirty_region)
+{
+    ScreenPtr pScreen = dirty->src->drawable.pScreen;
+    int n;
+    BoxPtr b;
+    RegionPtr region = DamageRegion(dirty->damage);
+    GCPtr pGC;
+    PixmapPtr dst;
+    SourceValidateProcPtr SourceValidate;
+
+    /*
+     * SourceValidate is used by the software cursor code
+     * to pull the cursor off of the screen when reading
+     * bits from the frame buffer. Bypassing this function
+     * leaves the software cursor in place
+     */
+    SourceValidate = pScreen->SourceValidate;
+    pScreen->SourceValidate = NULL;
+
+    RegionTranslate(dirty_region, dirty->x, dirty->y);
+    RegionIntersect(dirty_region, dirty_region, region);
+
+    if (RegionNil(dirty_region)) {
+        RegionUninit(dirty_region);
+        return FALSE;
+    }
+
+    dst = dirty->slave_dst->master_pixmap;
+
+    RegionTranslate(dirty_region, -dirty->x, -dirty->y);
+    n = RegionNumRects(dirty_region);
+    b = RegionRects(dirty_region);
+
+    pGC = GetScratchGC(dirty->src->drawable.depth, pScreen);
+    ValidateGC(&dst->drawable, pGC);
+
+    while (n--) {
+        BoxRec dst_box;
+        int w, h;
+
+        dst_box = *b;
+        w = dst_box.x2 - dst_box.x1;
+        h = dst_box.y2 - dst_box.y1;
+
+        pGC->ops->CopyArea(&dirty->src->drawable, &dst->drawable, pGC,
+                           dirty->x + dst_box.x1, dirty->y + dst_box.y1, w, h, dst_box.x1, dst_box.y1);
+        b++;
+    }
+    FreeScratchGC(pGC);
+
+    pScreen->SourceValidate = SourceValidate;
+    return TRUE;
+}

include/pixmap.h

@@ -49,6 +49,7 @@ SOFTWARE.
 
 #include "misc.h"
 #include "screenint.h"
+#include "regionstr.h"
 
 /* types for Drawable */
 #define DRAWABLE_WINDOW 0
@@ -73,6 +74,8 @@ SOFTWARE.
 typedef struct _Drawable *DrawablePtr;
 typedef struct _Pixmap *PixmapPtr;
 
+typedef struct _PixmapDirtyUpdate *PixmapDirtyUpdatePtr;
+
 typedef union _PixUnion {
     PixmapPtr pixmap;
     unsigned long pixel;
@@ -112,4 +115,17 @@ extern _X_EXPORT void FreePixmap(PixmapPtr /*pPixmap */ );
 extern _X_EXPORT PixmapPtr
 PixmapShareToSlave(PixmapPtr pixmap, ScreenPtr slave);
 
+extern _X_EXPORT Bool
+PixmapStartDirtyTracking(PixmapPtr src,
+                         PixmapPtr slave_dst,
+                         int x, int y);
+
+extern _X_EXPORT Bool
+PixmapStopDirtyTracking(PixmapPtr src, PixmapPtr slave_dst);
+
+/* helper function, drivers can do this themselves if they can do it more
+   efficently */
+extern _X_EXPORT Bool
+PixmapSyncDirtyHelper(PixmapDirtyUpdatePtr dirty, RegionPtr dirty_region);
+
 #endif                          /* PIXMAP_H */

include/pixmapstr.h

@@ -50,6 +50,7 @@ SOFTWARE.
 #include "screenint.h"
 #include "regionstr.h"
 #include "privates.h"
+#include "damage.h"
 
 typedef struct _Drawable {
     unsigned char type;         /* DRAWABLE_<type> */
@@ -84,6 +85,13 @@ typedef struct _Pixmap {
     PixmapPtr master_pixmap;    /* pointer to master copy of pixmap for pixmap sharing */
 } PixmapRec;
 
+typedef struct _PixmapDirtyUpdate {
+    PixmapPtr src, slave_dst;
+    int x, y;
+    DamagePtr damage;
+    struct xorg_list ent;
+} PixmapDirtyUpdateRec;
+
 static inline void
 PixmapBox(BoxPtr box, PixmapPtr pixmap)
 {

include/scrnintstr.h

@@ -505,6 +505,8 @@ typedef struct _Screen {
 
     StartPixmapTrackingProcPtr StartPixmapTracking;
     StopPixmapTrackingProcPtr StopPixmapTracking;
+
+    struct xorg_list pixmap_dirty_list;
 } ScreenRec;
 
 static inline RegionPtr