* Add a workspace drag surface that blocks and bubble get moved to during a workspace drag.
The surface is translated using translate3d instead of svg's translate attribute so that
the browser does not have to repaint the entire workspace on every mouse move.
This is very similar to the block drag surface.
* Address code review comments
* add back hasClass_ utility removed in #748 and stop using contains since it is not supported in IE
* Split the scrollbar and flyout out into their own SVG elements. They
are siblings of the workpsace SVG. This paves the way to make performance
improvements to workspace dragging.
Before, touchpads would give "smoother" scrolling by delivering lots of
mousewheel events with small distance changes. Because the code only
looked at the sign of deltaY, ten 5px scrolls would zoom 10x more than
one 50px scroll.
This change makes zooming with a touchpad more like zooming with a
mousewheel. On my laptop, a full-scale zoom (fully out to fully in) was
about a 5mm finger movement before, and is now about 3cm.
Fixes#758.
Improve performance of block dragging. This is a backport of the block drag surface from scratch-blocks. At the beginning of a block drag, blocks get moved to a drag surface which then translates using translate3d to avoid repainting the entire svg on every mouse move. At the end of the drag, the blocks are dropped back in the svg in their new position.
Add a isMutator member similar to isFlyout to workspace_svg so it knows whether
it is mutator or not. Allow blocks to access that property so that they can recalculate
coordinates appropriately.
screen transformation matrix) when a scroll happened.
This is not done using a scroll handler since the update
is expensive (getScreenCTM and getClientBoundingRect) and we don't need to do it
until the scroll is done and the user is interacting with blocks again.
We also have to record startFlyout_ on background scrolls - before
dragMode_ wasn't being reset by terminateDrag() for background scrolls,
which would suppress clicks from that point on.
Fixes#476.
* Record whether the workspace has been dragged
This fixes#473 by differentiating between a touch on an unmovable block
and using it to drag the workspace.
* Remove isScrolling and add DRAG_BEGIN
Applied after PR review.
This comment made sense [before multiple workspace support](67140282a0/core/blockly.js (L297)), where it was near a (Blockly.readOnly || isTargetSvg) check. Now, this logic is implemented in BlockSvg.onMouseDown_() instead.
