Converting from dips to pixels

In some cases, you will need to express dimensions in dip and then convert them to pixels. Imagine an application in which a scroll gesture is recognized after the user's finger has moved by at least 16 pixels. On a baseline HVGA screen, the user will have to move his finger by 16 pixels / 160 dpi = 1/10th of an inch (or 2.5 mm) before the gesture is recognized. On a device with a high (240) density display, the user will move his finger by only 16 pixels / 240 dpi = 1/15th of an inch (or 1.7 mm.) The distance is much shorter and the application thus appears more sensitive to the user. To fix this issue, the gesture threshold must be expressed in the code in dip and then converted to actual pixels.

// The gesture threshold expressed in dip
private static final float GESTURE_THRESHOLD_DIP = 16.0f;

// Convert the dips to pixels
final float scale = getContext().getResources().getDisplayMetrics().density;
mGestureThreshold = (int) (GESTURE_THRESHOLD_DIP * scale + 0.5f);

// Use mGestureThreshold as a distance in pixels