Add drag-resize to uiTemplatePreview (mat/tex/etc. preview widget).

This is done by adding a new button type, GRIP, similar to other numbuttons
(scroll, slider, ...), which here controls the preview height.

Then, we add a new DNA struct to be able to save that height in Blend files
(note I choose not to use Panel struct for this, because we would then have the
same limitation we used to have with uiLists, only one preview per panel
and no preview outside panel).

This implies a change to template_preview UI RNA/py API (each preview needs an ID),
but this is backward compatible, as by default datablock type will be used if no ID is
given (which means e.g. all material previews with no ID will have same height).

Reviewers: brecht

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D342

1 files changed, 3 insertions, 1 deletions

diff --git a/source/blender/editors/include/UI_interface.h b/source/blender/editors/include/UI_interface.h
index 2177b066c1f..7eb39fd4b3c 100644
--- a/source/blender/editors/include/UI_interface.h
+++ b/source/blender/editors/include/UI_interface.h
@@ -270,6 +270,7 @@ typedef enum {
 	SEARCH_MENU_UNLINK   = (52 << 9),
 	NODESOCKET    = (53 << 9),
 	SEPRLINE      = (54 << 9),
+	GRIP          = (55 << 9),
 } eButType;
 
 #define BUTTYPE     (63 << 9)
@@ -832,7 +833,8 @@ void uiTemplatePathBuilder(uiLayout *layout, struct PointerRNA *ptr, const char
                            struct PointerRNA *root_ptr, const char *text);
 uiLayout *uiTemplateModifier(uiLayout *layout, struct bContext *C, struct PointerRNA *ptr);
 uiLayout *uiTemplateConstraint(uiLayout *layout, struct PointerRNA *ptr);
-void uiTemplatePreview(uiLayout *layout, struct ID *id, int show_buttons, struct ID *parent, struct MTex *slot);
+void uiTemplatePreview(uiLayout *layout, struct bContext *C, struct ID *id, int show_buttons, struct ID *parent,
+                       struct MTex *slot, const char *preview_id);
 void uiTemplateColorRamp(uiLayout *layout, struct PointerRNA *ptr, const char *propname, int expand);
 void uiTemplateIconView(uiLayout *layout, struct PointerRNA *ptr, const char *propname);
 void uiTemplateHistogram(uiLayout *layout, struct PointerRNA *ptr, const char *propname);