GradientRail

Remarks

⚠ The keyboard came before the role, which is #420's whole ordering. This was pointer-only and roleless together, and the pairing was deliberate: announcing a rail a mouse alone can reach converts "not available to me" into "available and does nothing". So the arrows landed with the role, in one change, and neither is correct alone.

⚠ Two axes and two meanings, because a rail is a list and not a value. Left and Right move the selected stop along the gradient — a hundredth a press, a tenth with Page, the ends with Home and End, which is ColorStrip's contract. Up and Down select the previous and next stop, which on a horizontal rail is an axis with nothing else to mean. Any of the six with nothing selected selects the first stop rather than doing nothing: a keyboard user who has just tabbed in has no selection and would otherwise be stuck in a control that answers no key.

⚠ One tab stop for the whole rail, not one per stop. A stop is drawn rather than built — see GradientRail.OnDraw — so there is no element to focus, and a gradient of sixteen stops would otherwise be sixteen tab stops between the bar and the picker.

Fields and properties (11)

• public const float KeyStep

  How far one arrow press moves the selected stop. ColorStrip.KeyStep's value.

• protected override string TagName

  The element name this type answers to when a caller does not choose one.

• protected override bool AcceptsFocus

  Whether the focus can rest on this kind of control at all.

• protected override AccessibleRole NativeRole
• protected override string? NativeAccessibleName
• protected override string? NativeAccessibleValue
• public GradientEditor? Owner

  The editor it belongs to.

• public bool IsAlpha

  Whether it carries the alpha stops rather than the colour ones.

• public int Count

  How many stops this rail carries.

• public int SelectedIndex

  Where the selected stop is on this rail, or -1 when none of them is.

• public float SelectedPosition

  Where the selected stop sits along the gradient, or zero when none is selected.

Methods (4)

• protected override void OnCreated()

  Builds whatever this element is made of, once, as it joins a document.

• public void SelectAt(int index)

  Selects the stop at an index of this rail's list, or nothing for an index outside it.

• public void MoveSelected(float position)

  Moves the selected stop to a position along the gradient.

• protected override void OnDraw(DrawContext context)

  Draws whatever this element is, beyond what a stylesheet can describe.

Used by (2)

• GradientEditorVixen.Ui.Controls.Advanced
• GradientRailKeyboardTestsVixen.Ui.Controls.Advanced.Tests