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Paint Forge runs natively in mobile browsers without a dedicated app — the editor adapts its UI to the screen size and input device. Touch gestures replace many keyboard shortcuts; the toolbar collapses into a configurable hotbar; panels become bottom sheets that swipe away. This page is the reference for everything mobile- specific.
Multi-touch on the canvas drives camera + history. Single-finger gestures drive the active tool (drawing, selecting, etc.) so they don't conflict.
| Gesture | Action |
|---|---|
| Two-finger pinch | Zoom canvas (centered between fingers) |
| Two-finger rotate | Rotate canvas view (1° per gesture tick) |
| Two-finger tap | Undo (faster than tapping the toolbar button) |
| Three-finger tap | Redo. Also cancels QuickShape during the snap-to-shape moment. |
| Hold ½s mid-stroke | QuickShape — freehand input snaps to the closest clean shape (line, ellipse, rect, polygon). The recognized shape's outline shows; release to keep, lift to commit. |
| Hold ~1.2s after snap | QuickShape vector commit — converts the snapped shape into an editable vector object instead of a raster stroke. |
| Long-press (500ms) on hotbar slot | Open the tool grid to assign a different tool to that slot. |
| Swipe down on a panel | Dismiss the panel without reaching for an X button. Works on Layers, Colors, Properties, etc. |
| Two-finger drag on canvas | Pan the viewport (when not actively zooming/rotating). |
On phones the left toolbar collapses to the bottom of the screen. By default it's a horizontally-scrollable strip of every tool; switching Mobile Toolbar Mode to Hotbar (Preferences > Tools) instead shows a fixed set of your most-used tools as quick-access slots whose count auto-fits the viewport so tools never get cut off.
| Behavior | Detail |
|---|---|
| Slot count | Auto-computed from viewport width (portrait) or height (landscape). Range: 4-9 slots. Re-fits on orientation change and resize. |
| Reassign a slot | Long-press the slot for 500ms; tool grid opens; tap any tool to bind it. |
| Persistence | Slot configuration saves to localStorage (HOTBAR_SLOTS_KEY). Carries across sessions on the same device. |
| Layout modes | Two options in Preferences > Tools > Mobile Toolbar Mode: Scroll (default; a horizontally-scrollable strip of every tool) and Hotbar (user-configurable fixed slots only). |
Landscape orientation
Paint Forge picks up pressure from any device that exposes a PointerEvent with pointerType === 'pen' — Apple Pencil on iPad, S-Pen on Android, Wacom tablets via stylus, Microsoft Surface Pen, etc. Pressure is a value between 0 and 1; mouse input always reports 1.0.
| Modulator | What it drives |
|---|---|
| Pressure → Size | Stroke radius scales with pen pressure. Light touch = thin line, hard press = full size. |
| Pressure → Opacity | Alpha scales with pen pressure. Light touch = faded, hard press = full opacity. Common for inking. |
| Tilt → Opacity | Alpha scales with pen tilt magnitude. Perpendicular pen = full alpha; flat pen ≈ 40% — natural pencil-shading behavior. Requires Apple Pencil 2 / S-Pen / similar tilt-aware stylus. |
| Velocity → Size | Stroke radius scales inversely with drag speed. Slow drag = full width, fast = tapered. Works on mouse and pen. |
Toggle each modulator independently from the active brush's options panel. Save a brush preset to capture your preferred combination across sessions. Each modulator respects the per-tool pressure curve (Linear / Soft / Firm / S-Curve / Custom).
On phones, the right sidebar (Layers, Colors, Objects, Library, Canvas) becomes a bottom sheet. The active panel slides up from the screen bottom; swipe down to dismiss. Tabs at the top of the sheet switch between panels without closing.
On tablets in landscape, the sidebar reverts to its full-width docked form on the right edge. The breakpoint is determined by viewport width — aim for ≥768px to keep the desktop layout.
The mobile canvas surface ships a small floating-pill bar with the most-used controls: Undo, Redo, current Tool indicator (tap to open the tool grid), Color Picker (with active brush color preview), Layer Cycle (tap forward, long-press backward), Fit to Screen, Fullscreen toggle, Delete Selected (when active), Zoom + and − with current zoom %, plus a rotation badge that shows the canvas angle and resets on tap when rotated.
The pill respects the safe-area inset (notch / Dynamic Island on iOS) and the software keyboard height — it stays usable when the on-screen keyboard pushes other content up.
Mobile GPUs and CPUs vary 10× across consumer devices. Paint Forge ships several knobs to tune for slower hardware:
| Knob | When to lower |
|---|---|
| Painting Frame Rate (Preferences > Tools) | Drop from 60fps to 30fps if brush strokes feel laggy on 2-3 year old budget phones. Saves ~50% paint-time CPU. |
| Canvas dimensions (File > Canvas Resize) | Anything over 4000×4000px starts to chug on midrange Android. 2048×2048 is the comfort floor for most filter operations. |
| Max Undo Steps (Preferences > General) | Default 50 steps. Dropping to 25 halves the per-frame undo bookkeeping. |
| Adjustment layer count | Each adjustment layer re-runs its filter on every render. Consider Flatten when an edit chain stops being editable. |