Scaling -and positioning of controls

Interface elements -a user has to select and manipulate should not be smaller than the smallest -average finger pad, that is, no smaller than 1 cm (0.4") in diameter or a -1 cm × 1 cm square.

In the Symbian platform, UI style defines the minimum -sizes for a UI element considered as finger usable:

7 x 7 mm with 1 mm gaps for index finger usage
8 x 8 mm with 2 mm gaps for thumb usage
List type of components should have minimum of 5 mm line spacing

The width of a finger limits the density of items on screen. If the -items are too close, the user will not be able to choose a single one.

As -the probability of the user touching the higher end of the button (than on -the either side of the key) is high, button and icon sizes can be increased -vertically.

Essential information or features, such as a label, instructions, -or sub-controls should never be placed below an interface element that can -be touched, as it may be hidden by the user's finger.

- -Following are some useful tips that can be used while placing essential -information or features on interface element:

With interfaces having input devices, it makes sense to place targets -like menu items on the edges of screens because the cursor movement stops -at the edge of the screen.
When using a touch screen, a user seldom drags the finger across the -screen like a cursor. Instead, they most likely lift their finger and place -it on a new target. Users may have difficulties in reaching the objects located -on the edges of the screen, especially if the physical device has protruding -edges around the touch screen panel. Additionally, with some devices, the -screen edges may be less sensitive to register the touch input.

+ + + + + +Scaling +and positioning of controls +

Interface elements +a user has to select and manipulate should not be smaller than the smallest +average finger pad, that is, no smaller than 1 cm (0.4") in diameter or a +1 cm × 1 cm square.

In the Symbian platform, UI style defines the minimum +sizes for a UI element considered as finger usable:

7 x 7 mm with 1 mm gaps for index finger usage
8 x 8 mm with 2 mm gaps for thumb usage
List type of components should have minimum of 5 mm line spacing

The width of a finger limits the density of items on screen. If the +items are too close, the user will not be able to choose a single one.

As +the probability of the user touching the higher end of the button (than on +the either side of the key) is high, button and icon sizes can be increased +vertically.

Essential information or features, such as a label, instructions, +or sub-controls should never be placed below an interface element that can +be touched, as it may be hidden by the user's finger.

+ +Following are some useful tips that can be used while placing essential +information or features on interface element:

With interfaces having input devices, it makes sense to place targets +like menu items on the edges of screens because the cursor movement stops +at the edge of the screen.
When using a touch screen, a user seldom drags the finger across the +screen like a cursor. Instead, they most likely lift their finger and place +it on a new target. Users may have difficulties in reaching the objects located +on the edges of the screen, especially if the physical device has protruding +edges around the touch screen panel. Additionally, with some devices, the +screen edges may be less sensitive to register the touch input.

Finger usable UI

Sylus can be used as +the input method with touch UI, but events apply to finger use also. However, +in some cases the components may not be finger optimized due to the size of +objects, for example, virtual keyboard or text field.

In Symbian, UI +style defines the target minimum sizes for a UI element considered as finger +usable:

7 x 7 mm with 1 mm gaps for index finger usage
8 x 8 mm with 2 mm gaps for thumb usage
List type of components should have minimum of 5 mm line spacing

Targets are general as in practice sizes can be use case dependent, +for example, due to frequency of use, efficiency vs. error criticality or +ease of error correction, location of the button (edge of screen vs. center).

The +visible area of the component and the component's active area should be identical. +There are exception cases to this rule though:

When components are located near the edge of the display, the touchable +area should extend fully to the edge of the display (beyond the components +visible graphics).
Visible area is smaller than the active area in order to keep the balance +in look and feel of the UI. For example, scrollbar has wider touch area than +visible area.
Active area is smaller than the visible area in order to avoid unwanted +presses to contiguous active areas. In this case, there it should be graphically +indicated where the user should tap. Example: fixed toolbar buttons in landscape +layout.

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