VSE: Implement the bounding box (xform) tool in the seq preview window

Make the "xform" tool/gizmo available for strip transformations in the
sequencer preview window.

Because of the amount of hacks needed to make the gizmo work nicely with
multiple strips at the same time, it was decided to only show the
translate gizmo when multiple strips are selected.

This is because the transforms with multiple strips would appear buggy
because of our lack of shearing support in the transform system.
There is also currently no way to properly sync the gizmo drawing with
the transform when using multiple strips.

Reviewed By: Richard Antalik, Campbell Barton

Differential Revision: http://developer.blender.org/D12729

1 files changed, 33 insertions, 2 deletions

diff --git a/source/blender/editors/transform/transform_mode_resize.c b/source/blender/editors/transform/transform_mode_resize.c
index 65f4623b3be..28323460626 100644
--- a/source/blender/editors/transform/transform_mode_resize.c
+++ b/source/blender/editors/transform/transform_mode_resize.c
@@ -201,14 +201,45 @@ static void applyResize(TransInfo *t, const int UNUSED(mval[2]))
   ED_area_status_text(t->area, str);
 }
 
-void initResize(TransInfo *t)
+void initResize(TransInfo *t, float mouse_dir_constraint[3])
 {
   t->mode = TFM_RESIZE;
   t->transform = applyResize;
   t->tsnap.applySnap = ApplySnapResize;
   t->tsnap.distance = ResizeBetween;
 
-  initMouseInputMode(t, &t->mouse, INPUT_SPRING_FLIP);
+  if (is_zero_v3(mouse_dir_constraint)) {
+    initMouseInputMode(t, &t->mouse, INPUT_SPRING_FLIP);
+  }
+  else {
+    int mval_start[2], mval_end[2];
+    float mval_dir[3], t_mval[2];
+    float viewmat[3][3];
+
+    copy_m3_m4(viewmat, t->viewmat);
+    mul_v3_m3v3(mval_dir, viewmat, mouse_dir_constraint);
+    normalize_v2(mval_dir);
+    if (is_zero_v2(mval_dir)) {
+      /* The screen space direction is orthogonal to the view.
+       * Fall back to constraining on the Y axis. */
+      mval_dir[0] = 0;
+      mval_dir[1] = 1;
+    }
+
+    mval_start[0] = t->center2d[0];
+    mval_start[1] = t->center2d[1];
+
+    t_mval[0] = t->mval[0] - mval_start[0];
+    t_mval[1] = t->mval[1] - mval_start[1];
+    project_v2_v2v2(mval_dir, t_mval, mval_dir);
+
+    mval_end[0] = t->center2d[0] + mval_dir[0];
+    mval_end[1] = t->center2d[1] + mval_dir[1];
+
+    setCustomPoints(t, &t->mouse, mval_end, mval_start);
+
+    initMouseInputMode(t, &t->mouse, INPUT_CUSTOM_RATIO);
+  }
 
   t->flag |= T_NULL_ONE;
   t->num.val_flag[0] |= NUM_NULL_ONE;