Touchscreen Tester

What each number on screen means

Active points is the count of fingers the digitizer senses at that instant. Maximum (maxTouchPoints) is the ceiling of simultaneous contacts the browser claims to support, usually 5 or 10 on recent phones, and 10 on many PC touch monitors. Type shows the pointerType of the last event, which is handy for confirming that a stylus is being recognized as a pen and not as a finger.

Pressure comes from the PointerEvent.pressure property, which ranges from 0 to 1. Few devices have a real force sensor: per the W3C specification, a device with no pressure hardware reports 0.5 while a contact is active and 0 when there is none. So a fixed 0.5 is normal, not a fault.

• Active points: fingers recognized right now.
• Maximum: multitouch ceiling reported by the browser.
• Type: touch, pen or mouse (pointerType).
• Pressure: 0 to 1; a fixed 0.5 means no force sensor.

Two real scenarios

Example 1, checking multitouch on a used tablet before buying: rest all five fingers of one hand on the area. If Active points reaches 5 and Maximum reads 5 or 10, the digitizer registers pinch and rotate gestures without dropping contacts. If a finger vanishes or flickers, the digitizer is suspect.

Example 2, validating a stylus: press the tip down and drag. The Type field should switch to pen and, on a device with a force sensor, Pressure should swing (say, between 0.15 and 0.9) as you press harder. If Type stays on touch, the system is not treating the pen as a pen.

When to use it and how to read the symptoms

This is the quick test after a screen replacement, when evaluating a second-hand phone or tablet, when signing off a kiosk or totem that relies on gestures, or when you suspect a "dead zone" after a drop. Dragging one finger slowly across the entire surface is the most reliable way to expose regions that draw no trail.

How to read it: a strip that never registers touch suggests a digitizer dead spot or a poorly applied screen protector interfering. Phantom touches that appear on their own point to a faulty digitizer, a cracked panel or moisture. A Maximum of 0 on a device that is normally touch-capable usually means the browser or driver is not exposing touch input, not that the glass is broken.

• Unresponsive region: possible dead spot or protector interference.
• Phantom touches: faulty digitizer, crack or moisture.
• Maximum = 0 on a touch screen: browser/driver not exposing touch.
• Fewer fingers than expected: hardware, driver or browser limit.