Replace the overflow:auto + scrollTo zoom approach with a CSS transform
model to fix the scroll-to-zoom cursor targeting bug in dual-pane layouts.
Root cause: flex centering (justify-content:center) and overflow:auto
conflict -- when content fits, flex positions it; when zoomed (overflow),
scrollLeft=0 jumps to the left edge. The zoom-to-cursor formula used
scrollLeft as reference without accounting for the centering offset,
causing systematic drift toward the right pane.
Changes:
- Host CSS: overflow:hidden, display:block, position:relative
- New #wrapper div with transform:translate(x,y) for pan positioning
- New #transform = { x, y, scale } as single source of truth
- #zoomByRatio(cx,cy,ratio) uses panzoom formula: x = cx - ratio*(cx - x)
- #render() centers via transform.x/y = (hostSize - contentSize) / 2
- #updateFrameScales() handles iframe size/scale separately from centering
- Simplified drag: tracks startTX/startTY, updates transform directly
- Simplified attributeChangedCallback: detects external vs internal zoom
changes and zooms from viewport center for external ones
- Remove all scrollLeft/scrollTop/scrollTo usage
- Remove marginBlock:auto, long-press drag detection, debug console.logs
- Preserve external API: zoom attribute, dragOffset, toggleMagnifier(),
load/relocate events
This commit enhances the FixedLayout component by including additional
contextual information when zoom or pan operations occur:
- scrollLeft and scrollTop: Current scroll position of the viewport
- source: Origin of the zoom/pan action (e.g., mouse wheel, pinch zoom, button)
- leftWidth: Width of the left page/panel in dual-page layouts
These parameters provide downstream handlers with complete state information
needed to implement sophisticated zoom behaviors, such as:
- Preserving scroll position during zoom operations
- Differentiating between user-initiated and programmatic zoom changes
- Handling asymmetric layouts with different panel widths
This change is part of the ongoing zoom control implementation for
fixed-layout e-books.
This commit addresses several issues with zoom and pan functionality,
particularly when zooming from the right iframe in a two-page spread:
- Add source iframe tracking to wheel and mouse events
* Pass frameId parameter through frame creation pipeline
* Tag events with sourceIframe and sourceFrame properties
* Enable proper cursor position calculation regardless of event source
- Fix zoom cursor calculation for two-page spreads
* Calculate cursor position relative to spread viewport, not individual pages
* Simplify scroll position calculation to work uniformly for both left and right pages
* Add debug logging for cursor calculation verification
- Improve drag/pan behavior across zoom modes
* Add draggable state property to control drag availability
* Handle fit-page mode differently with dragOffset tracking
* Direct scroll manipulation for zoom levels above 1
* Add console logging for ignored drag scenarios
- Prevent native image drag interference
* Set draggable="false" on all images in iframe documents
* Disable user select and webkit drag on images
* Prevent default behavior on iframe mouse events
These changes ensure that zoom operations work correctly from both left and
right iframes, maintaining proper cursor focus and scroll position.
This commit fixes several issues with the drag functionality in the FixedLayout
component to ensure smooth and accurate dragging behavior:
Changes:
- Initialize dragOffset to (0, 0) instead of scroll position when drag starts
- Fix drag offset calculation direction (changed from -= to +=)
- Add proper scroll position updates during drag operations
- Ensure dragOffset is reset to (0, 0) when drag completes
The previous implementation was incorrectly initializing dragOffset with the
current scroll position, which caused the drag offset to compound with scroll
position and led to incorrect rendering. The new approach starts drag offset
at zero and directly updates the scroll position during drag operations.
This ensures that:
1. Drag movements are accurately tracked relative to the drag start point
2. Scroll position is properly synchronized with drag movements
3. Drag state is cleanly reset when drag operations complete
This commit adds comprehensive zoom control capabilities for fixed-layout
e-book content, allowing users to zoom in, out, and reset zoom levels for
better readability and content inspection.
Key features added:
- Zoom control UI with +/- buttons and percentage display
- Keyboard shortcuts for zoom operations (Ctrl/Cmd +, -, 0)
- Mouse wheel zoom with Ctrl/Cmd modifier key
- Drag-to-pan functionality when zoomed in
- Smooth zoom transitions and state management
- Zoom constraints (min/max limits) to prevent over-zooming
Changes include:
- FixedLayout: Enhanced with zoom state management, drag handlers,
and keyboard/mouse event listeners for intuitive zoom control
- Reader UI: Added zoom control toolbar with visual feedback
- FixedLayout renderer integration with reader zoom controls
The zoom controls provide a seamless experience for users who need to
examine fixed-layout content more closely or adjust content size for
their preferred reading experience.
john-okeefe