Feature: circular magnifying glass - #572
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luisangelsm merged 7 commits intoJul 29, 2026
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Introduce an optional circular loupe for the magnifying glass, toggled from the Options window (General tab). The circle's diameter is the wider of the two configured rectangle dimensions, derived at display time only: the rectangle size setting (MAG_GLASS_SIZE) is never overwritten, so switching modes restores the exact saved size. MagnifyingGlass now separates its logical rectangle (the source of truth for size gestures and the persisted setting) from its display geometry, which grows to a max(w, h) square while circular. The shape is realised with a widget mask for corner transparency plus a custom paintEvent for antialiased interior scaling. A secondary bezel-ring option (default on, enabled only when circular is active) draws an antialiased filled annulus inset just inside the mask so its outer edge forms a smooth silhouette that blends into the page, hiding the aliased mask edge.
The loupe's sampled content is pushed outward toward the viewport edges so edge content is reachable without moving the cursor all the way to the edge, while tracking the cursor 1:1 in the middle. - Viewer::easeViewerPos normalizes the cursor about the viewport center (the region the page is actually drawn in — the top-level window would fold in the toolbar/chrome and ease too hard), runs it through a smoothstep ramp, and scales it by the loupe half-extent. The half-size cap keeps the cursor's point inside the loupe view and ties the strength to loupe size: a minimum loupe is nearly linear, a large one eases hard. Rectangular loupes cap per axis; circular loupes cap the displacement vector radially. - Two tuning knobs: edgeReach saturates the ramp before the cursor reaches the border, and edgeStrength scales the peak push below the half-extent. - Per-axis letterbox gate: easing only helps where there is off-page content to bring toward the cursor, so it is skipped on an axis once the page is letterboxed by more than minLetterboxFraction (10%) of its own size there. Overflow, an exact fit, or a thin margin still ease, so the effect does not vanish the instant a page is a hair smaller than the viewport. In continuous view the horizontal extent is the page under the cursor, so the gate can vary per row. - Only the content is eased; the loupe widget follows the cursor, so the zoomed image swims a little toward the edge inside the loupe. - MouseHandler's mouse-move path routes through updateImage so both update paths share the eased positioning. - New MAG_GLASS_EDGE_EASE config (default on) with an Options toggle, applied live via Viewer::updateConfig().
… delta) Resizing the magnifying glass by scrolling used to step on the mere sign of each wheel event, so a trackpad's many tiny high-resolution events each fired a full step and the faintest two-finger brush resized the loupe. Accumulate the active gesture's signed angleDelta and only take a step once the running total crosses a 120-unit threshold (looping so a fast multi-notch event still steps several times). A real mouse wheel delivers 120 per notch in one event, so it still steps once per notch; the 120 threshold is itself the trackpad/mouse discriminator, so no device-type branching is needed. The accumulator resets when the gesture changes (different modifier) or after ~400ms idle so a stale partial gesture can't leak forward. Applies to the size, height (Ctrl), width (Alt), and zoom (Shift) branches.
The circle's diameter is the wider of the two logical dimensions, so squaring up a wide, short rectangle could exceed the parent on the other axis even though the rectangle itself fit: a logical 800x175 became an 800x800 widget, taller than the viewport it magnifies. The grow steps only ever clamped the logical rectangle, so nothing caught this. Clamp the circle's side to the same fraction of the parent that the grow steps enforce, taken on whichever axis is tighter. The logical size is untouched, so the saved setting and the rectangular mode are unaffected.
It introduced a regression that causes the magnifying glass to start tiny because the size of the parent is not know when the magnifying glass is setup, and it would require to update the clamping for every resize of the parent widget. Clamping ads complexity and some UX inconsistencies that are not really necessary IMO.
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Add an option for a circular magnifying glass.
CHANGELOG updated.
Please let me know if you want any other changes, additions, or removals.
Thank you!