Drag and drop in the editor improvements

[michalis]

A few improvements to the drag-and-drop experience in our editor:

1. You can drag-and-drop from “Files” to “Hierarchy” panel. This will add a child to the currently selected item in the tree view.

2. You can drag-and-drop images from “Files” to the central design area even when you’re not over a viewport. From such image, we will create TCastleImageControl. You can also drag-and-drop with Shift pressed to force creating a TCastleImageControl (instead of the default TCastleImageTransform) even when dragging over a viewport.

3. You can drag-and-drop also .castle-user-interface files (will create a TCastleDesign that references them) or .castle-transform files (will create TCastleTransformDesign that references them). If you want to test it out, see e.g. examples/advanced_editor/advanced_loading_designs project.

4. I also reported drag-and-drop bug with cursor on Lazarus GTK2 widgetset that affects us.

In effect (summing up previous and new features):

You can drag-and-drop various files from “Files” to “Hierarchy” or central design area.

• You can drag-and-drop scene files (like glTF or X3D files) on the viewport to create TCastleScene.

• You can drag-and-drop sound files (like WAV or OggVorbis) on the viewport to create TCastleTransform with TCastleSoundSource.

• You can drag-and-drop images (like PNG or JPG) on the viewport to create TCastleImageTransform or on anything else (or hold Shift) to create TCastleImageControl.

• You can drag-and-drop UI designs (.castle-user-interface) to create TCastleDesign.

• You can drag-and-drop transform designs (.castle-transform) to create TCastleTransformDesign.

Enjoy, happy dragging and dropping 🙂