[RaffaelFerro]

Part 1 of 5. Series: #202 zoom → #203 Aa's Auto → #204 strip stacks → #205 Shortcuts → #206 Full Screen. Each part builds on the one before; this one stands alone.

What

Zoom the picture on an iPhone held upright, on the device alone, with the Mac's pointer held in the middle (as macOS's own Zoom does).

• Tap Aa to turn the zoom on (2×, or the last zoom used) or off. Hold Aa and move up for the zoom's ruler (1×, 1.5×, 2×, 3×, 4×) above Aa's own. Two-finger double tap on the picture toggles it too. Aa's label shows the zoom while on ("1× 🔍2×").
• The pointer stays in the middle; the view stops at the frame's edges.
• Touches, scrolls and the Pencil map back through the zoom, so a click lands under the finger. The trackpad slows by the zoom, so the pointer moves as far on the glass as without it.
• The picture holds still while a finger is on it (otherwise a drag on the Mac would chase itself), and a finger's click is followed only after the double-click time, so a double click stays one.
• Each source keeps its zoom (a window, the Desktop).
• Only on a phone held upright; sideways and on an iPad nothing changes. Nothing new on the wire.

How

• PictureZoom (new, pure geometry): where the magnified frame is drawn, the focus, the hold under a finger, the per-source memory.
• HEVCDisplayView: the AVSampleBufferDisplayLayer now lives in a subview, so the zoom transforms the picture while the pointer sprite and the HUD keep their size; the sprite is placed in the zoomed frame.
• InputOverlay maps through zoom.rect; a two-finger double-tap recognizer that holds nothing back (cancelsTouchesInView = false).
• TrackpadView divides its motion by the zoom.
• TextScaleControl takes an optional zoom: a quick tap toggles it, a hold or a move opens the rulers.

Checks

• Tests/checks/picture-zoom (new, in CI's matrix): 45 checks, 20,000 random zooms against the geometry's rules; 19 of 19 mutants caught.
• phone-portrait, tour, pointer-presence unchanged and passing. iOS app built with Xcode 27.1, Debug for the simulator and Release for a device.

Tested

Tried by Raffael on an iPhone 12 Pro (Release build) against Sill for Mac 0.5.1: the zoom and the pointer in the middle work. Not tried on an iPad (unchanged there by design) or a Duo; the double click while zoomed and the two-finger double tap not yet confirmed on the device.

🤖 Generated with Claude Code

[Saffsanity]

Heads-up: pinch to zoom on the picture is merged into main (#196), so an Aa-driven zoom would now sit beside it. If you keep this one, please rebase on main so the two agree on who owns two fingers (StreamZoom.Stroke).