Politically correct terrible consequencer changes

This patch includes the work done in the terrible consequencer branch
that hasn't been merged to master minus a few controversial and WIP
stuff, like strip parenting, new sequence data structs and cuddly
widgets.

What is included:

* Strip extensions only when slipping. It can very easily be made an
option but with a few strips with overlapping durations it makes view
too crowded and difficult to make out.
* Threaded waveform loading + code that restores waveforms on undo (not
used though, since sound_load recreates everything. There's a patch for
review D876)
* Toggle to enable backdrop in the strip sequence editor
* Toggle to easily turn on/off waveform display
* Snapping during transform on sequence boundaries. Snapping to start or
end of selection depends on position of mouse when invoking the operator
* Snapping of timeline indicator in sequencer to strip boundaries. To
use just press and hold ctrl while dragging.

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D904

3 files changed, 20 insertions, 6 deletions

diff --git a/source/blender/makesdna/DNA_sequence_types.h b/source/blender/makesdna/DNA_sequence_types.h
index af33ae80ed9..a7288b95a7a 100644
--- a/source/blender/makesdna/DNA_sequence_types.h
+++ b/source/blender/makesdna/DNA_sequence_types.h
@@ -131,10 +131,11 @@ typedef struct Sequence {
 
 	int flag, type; /*flags bitmap (see below) and the type of sequence*/
 	int len; /* the length of the contents of this strip - before handles are applied */
-	int start, startofs, endofs;
-	int startstill, endstill;
+	int start; /* start frame of contents of strip in absolute frame coordinates. For metastrips start of first strip startdisp */
+	int startofs, endofs; /* frames after the first frame where display starts, frames before the last frame where display ends */
+	int startstill, endstill; /* frames that use the first frame before data begins, frames that use the last frame after data ends */
 	int machine, depth; /*machine - the strip channel, depth - the depth in the sequence when dealing with metastrips */
-	int startdisp, enddisp; /*starting and ending points in the sequence*/
+	int startdisp, enddisp; /* starting and ending points of the strip in the sequence*/
 	float sat;
 	float mul, handsize;
 
diff --git a/source/blender/makesdna/DNA_sound_types.h b/source/blender/makesdna/DNA_sound_types.h
index d7a51359777..4ab22e4f7b7 100644
--- a/source/blender/makesdna/DNA_sound_types.h
+++ b/source/blender/makesdna/DNA_sound_types.h
@@ -95,6 +95,8 @@ typedef struct bSound {
 	 */
 	void *playback_handle;
 
+	/* mutex for asynchronous loading of sounds */
+	void *mutex;
 	/* XXX unused currently	(SOUND_TYPE_LIMITER) */
 	/* float start, end; */
 } bSound;
@@ -116,9 +118,10 @@ enum {
 };
 
 enum {
-	SOUND_FLAGS_3D          = (1 << 3),  /* deprecated! used for sound actuator loading */
-	SOUND_FLAGS_CACHING     = (1 << 4),
-	SOUND_FLAGS_MONO        = (1 << 5),
+	SOUND_FLAGS_3D                   = (1 << 3),  /* deprecated! used for sound actuator loading */
+	SOUND_FLAGS_CACHING              = (1 << 4),
+	SOUND_FLAGS_MONO                 = (1 << 5),
+	SOUND_FLAGS_WAVEFORM_LOADING     = (1 << 6),
 };
 
 #if (DNA_DEPRECATED_GCC_POISON == 1)
diff --git a/source/blender/makesdna/DNA_space_types.h b/source/blender/makesdna/DNA_space_types.h
index a8fe8ceb6b0..dd661d00d54 100644
--- a/source/blender/makesdna/DNA_space_types.h
+++ b/source/blender/makesdna/DNA_space_types.h
@@ -497,6 +497,8 @@ typedef struct SpaceSeq {
 	float zoom DNA_DEPRECATED;  /* deprecated, handled by View2D now */
 	int view; /* see SEQ_VIEW_* below */
 	int overlay_type;
+	int draw_flag; /* overlay an image of the editing on below the strips */
+	int pad;
 
 	struct bGPdata *gpd;        /* grease-pencil data */
 
@@ -513,6 +515,12 @@ typedef enum eSpaceSeq_RegionType {
 	SEQ_DRAW_IMG_HISTOGRAM = 4,
 } eSpaceSeq_RegionType;
 
+/* sseq->draw_flag */
+typedef enum eSpaceSeq_DrawFlag {
+	SEQ_DRAW_BACKDROP              = (1 << 0),
+} eSpaceSeq_DrawFlag;
+
+
 /* sseq->flag */
 typedef enum eSpaceSeq_Flag {
 	SEQ_DRAWFRAMES              = (1 << 0),
@@ -522,6 +530,8 @@ typedef enum eSpaceSeq_Flag {
 	SEQ_SHOW_GPENCIL            = (1 << 4),
 	SEQ_NO_DRAW_CFRANUM         = (1 << 5),
 	SEQ_USE_ALPHA               = (1 << 6), /* use RGBA display mode for preview */
+	SEQ_ALL_WAVEFORMS           = (1 << 7), /* draw all waveforms */
+	SEQ_NO_WAVEFORMS            = (1 << 8), /* draw no waveforms */
 } eSpaceSeq_Flag;
 
 /* sseq->view */