VSE: Media transform redesign

This patch changes behavior of strip transform and crop feature.

Purpose of this change is to allow display arbitrary portion of input
image, simplify user interface and workflow.
Offset and Crop values in old files are converted in versioning.
Offset animation is also converted. Crop animation and animation of
crop or offset enable properties is not taken into account

Changes in behavior and interface:
- If image is added to timeline it is scaled to fit inside preview area
while maintaining aspect ratio. Image is centered. This is considered
as a baseline for further transformation.
- Scale and rotation was added, so it is possible to transform image at
it's original resolution.
- Crop will not affect image transformation (does not move image).
- Values of Crop and Transform Position are in pixels, these values are
corrected if preview is fraction of project resolution.
- Transform and Mirror panel has been removed and new Transform panel
and Crop panel is moved to Adjust panel. Mirror is now part of new
Transform panel.

Technical changes:
- Preprocessing stage must work on duplicated image, because original is
cached. Previously Crop and Offset could run at once and required only
one duplication of image. This is not the case with new algorithms, so
duplication on demand is implemented. Transformation can read original
image and will output new image that is safe to modify. It should be
possible to add crop step to transform algorithm, so that Crop won't
require previous duplication though.
- Use Crop and Use Translation checkboxes were removed. Individual
values are compared to default values to check if image needs to be
processed. In case of transform this will be done also if resolution of
source.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8393

1 files changed, 2 insertions, 0 deletions

diff --git a/source/blender/imbuf/IMB_imbuf.h b/source/blender/imbuf/IMB_imbuf.h
index 839b0b12b83..2f848b5be08 100644
--- a/source/blender/imbuf/IMB_imbuf.h
+++ b/source/blender/imbuf/IMB_imbuf.h
@@ -684,6 +684,8 @@ void IMB_rectfill_area(struct ImBuf *ibuf,
                        int x2,
                        int y2,
                        struct ColorManagedDisplay *display);
+void IMB_rectfill_area_replace(
+    const struct ImBuf *ibuf, const float col[4], int x1, int y1, int x2, int y2);
 void IMB_rectfill_alpha(struct ImBuf *ibuf, const float value);
 
 /* This should not be here, really,