Commit: ee6507f2b1d776099e199a31a3af0f09d2fbba74
Author: Campbell Barton
Date: Wed Jan 19 14:04:32 2022 +1100
Branches: master
https://developer.blender.org/rBee6507f2b1d776099e199a31a3af0f09d2fbba74
Docs: notes on thumbnail sizes
The rationale for storing thumbnails at different sizes wasn't obvious.
===================================================================
M source/blender/blenkernel/BKE_main.h
M source/blender/windowmanager/intern/wm_files.c
===================================================================
diff --git a/source/blender/blenkernel/BKE_main.h
b/source/blender/blenkernel/BKE_main.h
index b7f675e4e97..4c6eb31db4b 100644
--- a/source/blender/blenkernel/BKE_main.h
+++ b/source/blender/blenkernel/BKE_main.h
@@ -406,6 +406,13 @@ int set_listbasepointers(struct Main *main, struct
ListBase *lb[]);
((main)->versionfile < (ver) || \
((main)->versionfile == (ver) && (main)->subversionfile < (subver)))
+/**
+ * The size of thumbnails (optionally) stored in the `.blend` files header.
+ *
+ * NOTE(@campbellbarton): This is kept small as it's stored uncompressed in
the `.blend` file,
+ * where a larger size would increase the size of every `.blend` file
unreasonably.
+ * If we wanted to increase the size, we'd want to use compression (JPEG or
similar).
+ */
#define BLEN_THUMB_SIZE 128
#define BLEN_THUMB_MEMSIZE(_x, _y) \
diff --git a/source/blender/windowmanager/intern/wm_files.c
b/source/blender/windowmanager/intern/wm_files.c
index 344f4959a93..1478712c3cd 100644
--- a/source/blender/windowmanager/intern/wm_files.c
+++ b/source/blender/windowmanager/intern/wm_files.c
@@ -1521,11 +1521,29 @@ static void wm_history_file_update(void)
/** \} */
/* -------------------------------------------------------------------- */
-/** \name Save Main Blend-File (internal) Screen-Shot
+/** \name Thumbnail Generation: Screen-Shot / Camera View
+ *
+ * Thumbnail Sizes
+ * ===============
+ *
+ * - `PREVIEW_RENDER_LARGE_HEIGHT * 2` is used to render a large thumbnail,
+ * giving some over-sampling when scaled down:
+ *
+ * - There are two outputs for this thumbnail:
+ *
+ * - An image is saved to the thumbnail cache, sized at
#PREVIEW_RENDER_LARGE_HEIGHT.
+ *
+ * - A smaller thumbnail is stored in the `.blend` file it's self, sized at
#BLEN_THUMB_SIZE.
+ * The size is kept small to prevent thumbnails bloating the size of
`.blend` files.
+ *
+ * The this thumbnail will be extracted if the file is shared or the local
thumbnail cache
+ * is cleared. see: `blendthumb_extract.cc` for logic that extracts the
thumbnail.
*
- * Screen-shot the active window.
* \{ */
+/**
+ * Screen-shot the active window.
+ */
static ImBuf *blend_file_thumb_from_screenshot(bContext *C, BlendThumbnail
**r_thumb)
{
*r_thumb = NULL;
@@ -1571,15 +1589,11 @@ static ImBuf *blend_file_thumb_from_screenshot(bContext
*C, BlendThumbnail **r_t
return ibuf;
}
-/** \} */
-
-/* -------------------------------------------------------------------- */
-/** \name Save Main Blend-File (internal) Camera View
- *
+/**
* Render the current scene with the active camera.
- * \{ */
-
-/* screen can be NULL */
+ *
+ * \param screen: can be NULL.
+ */
static ImBuf *blend_file_thumb_from_camera(const bContext *C,
Scene *scene,
bScreen *screen,
@@ -1617,7 +1631,6 @@ static ImBuf *blend_file_thumb_from_camera(const bContext
*C,
return NULL;
}
- /* gets scaled to BLEN_THUMB_SIZE */
Depsgraph *depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
/* Note that with scaling, this ends up being 0.5,
@@ -1689,6 +1702,12 @@ static ImBuf *blend_file_thumb_from_camera(const
bContext *C,
return ibuf;
}
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Write Main Blend-File (internal)
+ * \{ */
+
bool write_crash_blend(void)
{
char path[FILE_MAX];
@@ -2017,7 +2036,7 @@ void wm_autosave_delete(void)
/** \} */
/* -------------------------------------------------------------------- */
-/** \name Initialize WM_OT_open_xxx properties
+/** \name Initialize `WM_OT_open_*` Properties
*
* Check if load_ui was set by the caller.
* Fall back to user preference when file flags not specified.
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