Cache transform buffer to avoid per-frame malloc

include/twin.h

@@ -253,6 +253,10 @@ typedef struct _twin_pixmap {
 #endif
 
     twin_window_t *window; /**< Associated window (if any) */
+
+    /* Transform buffer cache for compositing operations */
+    void *xform_cache;       /**< Cached xform buffer */
+    size_t xform_cache_size; /**< Cached xform buffer size in bytes */
 } twin_pixmap_t;
 
 /**

src/draw-builtin.c

@@ -633,10 +633,22 @@ static twin_xform_t *twin_pixmap_init_xform(twin_pixmap_t *pixmap,
     if (fmt == TWIN_RGB16)
         fmt = TWIN_ARGB32;
 
-    twin_xform_t *xform =
-        calloc(1, sizeof(twin_xform_t) + width * twin_bytes_per_pixel(fmt));
-    if (!xform)
-        return NULL;
+    size_t required_size =
+        sizeof(twin_xform_t) + (size_t) width * twin_bytes_per_pixel(fmt);
+
+    /* Reuse cached xform buffer if large enough */
+    twin_xform_t *xform;
+    if (pixmap->xform_cache && pixmap->xform_cache_size >= required_size) {
+        xform = (twin_xform_t *) pixmap->xform_cache;
+    } else {
+        /* Need larger cache - reallocate */
+        void *new_cache = realloc(pixmap->xform_cache, required_size);
+        if (!new_cache)
+            return NULL;
+        pixmap->xform_cache = new_cache;
+        pixmap->xform_cache_size = required_size;
+        xform = (twin_xform_t *) new_cache;
+    }
 
     xform->span.v = (twin_argb32_t *) (char *) (xform + 1);
     xform->pixmap = pixmap;
@@ -650,7 +662,9 @@ static twin_xform_t *twin_pixmap_init_xform(twin_pixmap_t *pixmap,
 
 static void twin_pixmap_free_xform(twin_xform_t *xform)
 {
-    free(xform);
+    /* Xform buffer is now cached in pixmap - don't free */
+    /* This function is kept for API compatibility but does nothing */
+    (void) xform;
 }
 
 #define FX(x) twin_int_to_fixed(x)

src/pixmap.c

@@ -52,6 +52,8 @@ twin_pixmap_t *twin_pixmap_create(twin_format_t format,
     pixmap->shadow = false;
 #endif
     pixmap->window = NULL; /* Initialize window field */
+    pixmap->xform_cache = NULL;
+    pixmap->xform_cache_size = 0;
     pixmap->p.v = pixmap + 1;
     memset(pixmap->p.v, '\0', space);
     return pixmap;
@@ -82,6 +84,8 @@ twin_pixmap_t *twin_pixmap_create_const(twin_format_t format,
     pixmap->stride = stride;
     pixmap->disable = 0;
     pixmap->window = NULL; /* Initialize window field */
+    pixmap->xform_cache = NULL;
+    pixmap->xform_cache_size = 0;
     pixmap->p = pixels;
     return pixmap;
 }
@@ -90,6 +94,7 @@ void twin_pixmap_destroy(twin_pixmap_t *pixmap)
 {
     if (pixmap->screen)
         twin_pixmap_hide(pixmap);
+    free(pixmap->xform_cache); /* Free xform buffer cache */
     free(pixmap);
 }