#7546 - Canvas does not reset scroll position after using “Clear canvas” - added monomers appear offset

[gitquil07]

How the feature works? / How did you fix the issue?

(Screenshots, videos, or GIFs, if applicable)

Clear canvas: zoom & scrollbars (macromolecules)

Issue

In macromolecules (e.g. popup mode), after adding monomers the canvas could zoom and scroll as expected. After Clear canvas, the view was wrong: custom SVG scrollbars stayed visible on an empty canvas, the pan/zoom state was not reset, and new monomers appeared offset from the usual default position instead of at the normal starting point.

Resolution (code changes)

1. Reset zoom when clearing (ClearTool, ketcher-core)

After the model is cleared and the render is updated, ZoomTool.instance.resetZoom() is invoked so the zoom/pan transform returns to the default state for an empty canvas.

2. Do not draw scrollbars on an empty canvas (ZoomTool.drawScrollBars(), ketcher-core)

If the drawing layer (e.g. <g class="drawn-structures">) has no child nodes, the code skips scrollbar rendering: it removes any existing horizontal/vertical scrollbar elements and returns early. That avoids incorrect scrollbar layout when there is no content and hides scrollbars when nothing is drawn.

3. Unit test (ZoomTool.test.ts, ketcher-core)

A test verifies that after clearing children under .drawn-structures, calling drawScrollBars() leaves no scrollbar rects (e.g. no elements matching rect[data-testid$="-bar"]).

screen-capture.6.webm

Check list

• unit-tests written
• e2e-tests written
• documentation updated
• PR name follows the pattern #1234 – issue name
• branch name doesn't contain '#'
• PR is linked with the issue
• base branch (master or release/xx) is correct
• task status changed to "Code review"
• reviewers are notified about the pull request