Draw on the pad to reveal dead zones — multi-touch trails, zero uploads
👆 Drag one finger slowly across the whole pad — a healthy digitizer draws an unbroken glowing line. Gaps or jumps mean dead zones. Then press 2–5 fingers at once: each gets its own color and label. On desktop, draw with the mouse.
This test uses the browser's standard PointerEvent and Touch Events APIs to track every contact point on the pad in real time. Each simultaneous touch is assigned a distinct color and drawn as a glowing trail, so you can see exactly where the digitizer reports contact — and, more importantly, where it doesn't. The counters show how many touches are active right now, the maximum your screen registered at once, and the total number of contact points since the last clear.
Finding dead zones and ghost touches: draw slow, deliberate lines across the entire surface, edge to edge and corner to corner. A line that stops mid-stroke while your finger keeps moving marks a dead zone — an area where the digitizer no longer registers input. A line that appears where you never touched indicates ghost touches, a classic symptom of a failing digitizer or a swollen battery pressing against the screen from below.
How many touch points should my screen support? Almost every modern phone supports at least 5 simultaneous touches (most support 10). If the "Max simultaneous" counter stops at 1 or 2 when you have more fingers down, either the digitizer is degraded or the device only advertises a low touch count — common on very cheap tablets and aging screens.
Part of my screen doesn't draw — is the phone broken? Not necessarily. First clean the screen and remove the case or screen protector, then retest. If a persistent patch still refuses to register while drawing gentle figure-eights, the digitizer layer under that area is likely damaged and a repair is usually the only fix.