Image: support storing full image buffers for each undo step

Update image undo to store buffers for each step:

- Undo buffers share tiles to avoid using too much memory.
- Undo support for different sized buffers
  allowing operations such as crop or resize.
- Paint tiles have been split into separate API/storage.
- Painting speed wont be impacted significantly
  since storing the extra tiles is done after the stroke & only
  for the first undo step.

Resolves T61263, see D5939 for details.

source/blender/editors/include/ED_paint.h

@@ -42,6 +42,10 @@ void ED_imapaint_bucket_fill(struct bContext *C, float color[3], struct wmOperat
 
 /* paint_image_undo.c */
 void ED_image_undo_push_begin(const char *name, int paint_mode);
+void ED_image_undo_push_begin_with_image(const char *name,
+                                         struct Image *image,
+                                         struct ImBuf *ibuf);
+
 void ED_image_undo_push_end(void);
 void ED_image_undo_restore(struct UndoStep *us);
 

source/blender/editors/sculpt_paint/CMakeLists.txt

@@ -31,6 +31,7 @@ set(INC
   ../../render/extern/include
   ../../windowmanager
   ../../../../intern/atomic
+  ../../../../intern/clog
   ../../../../intern/glew-mx
   ../../../../intern/guardedalloc
 )

source/blender/editors/space_image/image_ops.c

@@ -2765,8 +2765,7 @@ static int image_invert_exec(bContext *C, wmOperator *op)
   Image *ima = image_from_context(C);
   ImBuf *ibuf = BKE_image_acquire_ibuf(ima, NULL, NULL);
   SpaceImage *sima = CTX_wm_space_image(C);
-  /* undo is supported only on image paint mode currently */
-  bool support_undo = ((sima != NULL) && (sima->mode == SI_MODE_PAINT));
+  const bool is_paint = ((sima != NULL) && (sima->mode == SI_MODE_PAINT));
 
   /* flags indicate if this channel should be inverted */
   const bool r = RNA_boolean_get(op->ptr, "invert_r");
@@ -2781,14 +2780,12 @@ static int image_invert_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
 
-  if (support_undo) {
-    ED_image_undo_push_begin(op->type->name, PAINT_MODE_TEXTURE_2D);
-    /* not strictly needed, because we only imapaint_dirty_region to invalidate all tiles
-     * but better do this right in case someone copies this for a tool that uses partial
-     * redraw better */
+  ED_image_undo_push_begin_with_image(op->type->name, ima, ibuf);
+
+  if (is_paint) {
     ED_imapaint_clear_partial_redraw();
-    ED_imapaint_dirty_region(ima, ibuf, 0, 0, ibuf->x, ibuf->y, false);
   }
+
   /* TODO: make this into an IMB_invert_channels(ibuf,r,g,b,a) method!? */
   if (ibuf->rect_float) {
 
@@ -2842,9 +2839,7 @@ static int image_invert_exec(bContext *C, wmOperator *op)
     ibuf->userflags |= IB_MIPMAP_INVALID;
   }
 
-  if (support_undo) {
-    ED_image_undo_push_end();
-  }
+  ED_image_undo_push_end();
 
   /* force GPU reupload, all image is invalid */
   GPU_free_image(ima);
@@ -2880,7 +2875,7 @@ void IMAGE_OT_invert(wmOperatorType *ot)
   RNA_def_property_flag(prop, PROP_SKIP_SAVE);
 
   /* flags */
-  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+  ot->flag = OPTYPE_REGISTER;
 }
 
 /** \} */

source/blender/imbuf/IMB_imbuf.h

@@ -228,6 +228,8 @@ void IMB_blend_color_float(float dst[4],
 
 void IMB_rect_crop(struct ImBuf *ibuf, const struct rcti *crop);
 
+void IMB_rect_size_set(struct ImBuf *ibuf, const uint size[2]);
+
 void IMB_rectclip(struct ImBuf *dbuf,
                   const struct ImBuf *sbuf,
                   int *destx,

source/blender/imbuf/intern/rectop.c

@@ -279,6 +279,45 @@ void IMB_rect_crop(ImBuf *ibuf, const rcti *crop)
   ibuf->y = size_dst[1];
 }
 
+/** Re-alloc buffers at a new size */
+
+static void rect_realloc_4bytes(void **buf_p, const uint size[2])
+{
+  if (*buf_p == NULL) {
+    return;
+  }
+  MEM_freeN(*buf_p);
+  *buf_p = MEM_mallocN(sizeof(uint) * size[0] * size[1], __func__);
+}
+
+static void rect_realloc_16bytes(void **buf_p, const uint size[2])
+{
+  if (*buf_p == NULL) {
+    return;
+  }
+  MEM_freeN(*buf_p);
+  *buf_p = MEM_mallocN(sizeof(uint[4]) * size[0] * size[1], __func__);
+}
+
+/**
+ * In-place size setting (caller must fill in buffer contents).
+ */
+void IMB_rect_size_set(ImBuf *ibuf, const uint size[2])
+{
+  BLI_assert(size[0] > 0 && size[0] > 0);
+  if ((size[0] == ibuf->x) && (size[1] == ibuf->y)) {
+    return;
+  }
+
+  rect_realloc_4bytes((void **)&ibuf->rect, size);
+  rect_realloc_4bytes((void **)&ibuf->zbuf, size);
+  rect_realloc_4bytes((void **)&ibuf->zbuf_float, size);
+  rect_realloc_16bytes((void **)&ibuf->rect_float, size);
+
+  ibuf->x = size[0];
+  ibuf->y = size[1];
+}
+
 /* clipping */
 
 void IMB_rectclip(ImBuf *dbuf,