BinaryComboBox

Sets up the owner-drawn, flat painting and the default colours shared by the Hypernova combo boxes.

The defaults: CustomPaintingColor and CustomControlBorderColor are SystemColors.Highlight, ControlArrowColor is SystemColors.WindowText, ShowBorderAlways and ShouldDisplayColumnHeadersWhenInMultiColumnMode are true, the drop-down list's border and item borders are transparent, and the text is left-aligned.

Gets or sets the blend weight used for the background of the flat drop-down button's arrow area.

It does not involve CustomPaintingColor, so it changes only how grey the arrow area looks. EmulateThisXPTheme sets it to 100.

Gets or sets how strongly CustomPaintingColor shows in the drop-down button while the list is open.

The pressed colour is CustomPaintingColor blended over the button's ordinary face (itself CustomPaintingColor blended with the window colour by AlphaBlendFactorForItemSelectionColor). EmulateThisXPTheme sets it to 75.

Gets or sets how strongly CustomPaintingColor shows in the highlighted item and the drop-down button face.

The same colour fills the highlighted item, in the list and on the closed control, and the drop-down button while the list is closed, so the two always match. EmulateThisXPTheme sets it to 135.

Gets or sets the colour of the arrow (chevron) on the drop-down button.

The disabled control draws its arrow in SystemColors.ControlDark whatever this is set to. With ShouldDrawExtendedDropdownButton on, the built-in arrow image is recoloured to this colour; an image of your own in ExtendedDropdownButtonInternalImage is drawn as it is.

Gets or sets the colour of the control's border and of the outline round its drop-down button.

The border is drawn in this colour whenever it is shown – always, with ShowBorderAlways on, or while the pointer is over the control or it has the focus, with it off. To use a different colour while the control does not have the focus, set CustomControlBorderColorWhenNotInFocus.

EmulateThisXPTheme replaces the value.

Gets or sets the colour of the border, and of the drop-down button, while the control does not have the focus.

Used only while ShowBorderAlways is true, and not in the designer. When the control gets the focus, or the pointer moves over it, the border goes back to CustomControlBorderColor.

The drop-down button is filled with this colour too, unless CustomControlDropDownButtonFillColorWhenNotInFocus gives it one of its own.

// Grey until the user arrives, then the accent colour.
customerPicker.ShowBorderAlways = true;
customerPicker.CustomControlBorderColor = Color.SteelBlue;
customerPicker.CustomControlBorderColorWhenNotInFocus = Color.Gainsboro;
customerPicker.CustomControlDropDownButtonFillColorWhenNotInFocus = Color.WhiteSmoke;

Gets or sets the colour that fills the drop-down button while the control does not have the focus.

Used only when CustomControlBorderColorWhenNotInFocus is set and ShowBorderAlways is true. The control does not repaint when it changes; set it before the control is shown, or call Control.Invalidate.

Gets or sets the accent colour the control blends to fill its drop-down button and the highlighted item.

The colour is not used as it stands. It is blended with SystemColors.Window by AlphaBlendFactorForItemSelectionColor to fill the drop-down button and the highlighted item, and blended again by AlphaBlendFactorForDropDownPressedColor for the button while the list is open. Lower factors give paler tints.

EmulateThisXPTheme replaces the value.

Gets or sets the colour of the rectangle drawn round each item in the single-column drop-down list.

One pixel wide; a coloured value gives the list a ruled, table-like look. The multi-column drop-down uses BinaryTextComboBox.MultiColumnDropListGridLines instead.

Gets or sets how the item text is aligned in the drop-down list.

In the single-column list of BinaryTextComboBox it applies to items that come from a DataSource; items added to ComboBox.Items are drawn left-aligned.

In the multi-column drop-down it aligns every column and its heading; a column given its own alignment in MultiColumnWindowColumnsHorizontalAlignments uses that instead.

Gets or sets whether the user can type into the control (DropDown) or can only pick from the list (DropDownList).

Simple is not supported: setting it is ignored and the style stays as it was.

Gets or sets the background colour of the single-column drop-down list.

BinaryTextComboBox hides this property with its own, which also sets the background of the multi-column drop-down.

Gets or sets the colour of the border drawn round the single-column drop-down list.

The border is drawn DropDownWindowBorderThickness wide, along the outer edges of the list's items, and only while the list has items. The multi-column drop-down of BinaryTextComboBox draws its own frame and does not use it.

Gets or sets the width of the border drawn round the single-column drop-down list.

Used only when DropDownWindowBorderColor is not transparent. The width is applied as given and is not scaled to the display.

Gets or sets a picture that replaces the whole push-button style drop-down button.

Used only while ShouldDrawExtendedDropdownButton is true. The picture is stretched over the button's whole area – DropDownButtonExtent wide and the control's height – and drawn as it is, with no arrow added; draw the arrow into the picture. The same picture is used when the control is disabled.

Gets or sets the small arrow image drawn on the push-button style drop-down button, in place of the built-in arrow.

Used only while ShouldDrawExtendedDropdownButton is true and ExtendedDropdownButtonImage is null. The image is drawn into a 6 by 6 pixel box, centred vertically on the button and not scaled to the display, and is not recoloured to ControlArrowColor.

Gets or sets whether a read-only text combo box also refuses changes to its selection, not just to its text.

This works together with BinaryTextComboBox.ComboBoxIsReadOnly, and only while that is true. A read-only combo box on its own refuses typing, Delete and Backspace but still lets the user pick another item. In extended read-only mode it also ignores every key in its text area, puts back the previous item when the user picks one from the drop-down list, and does not let the selection move in the multi-column drop-down. The user can still open the list and look.

BinaryImageComboBox has no read-only mode, so the property has no effect there.

// Show the account's region, but do not let it be changed on this screen.
regionPicker.ComboBoxIsReadOnly = true;
regionPicker.IsInExtendedReadOnlyMode = true;

Gets or sets the width of the frame round the multi-column drop-down when it shows a header and footer.

The frame belongs to the header and footer area, so it is drawn only while BinaryTextComboBox.EnableDrawingHeaderFooterWhenInMultiColumnMode is true, in the colour of MultiColumnDropDownWindowConfiguration.HeaderControlRenderingStartColor.

Gets or sets the alignment of each column in the multi-column drop-down, in column order.

The first entry aligns the first column and its heading, the second the second, and so on. Columns beyond the end of the list keep DropDownItemTextAlignment. Change the list itself, or assign a new one; do not assign null on a BinaryTextComboBox, which expects a list when it opens the drop-down.

With ShouldApplyMultiColumnWindowColumnsAlignmentsToAutoCompleteDropDown on, the typing suggestion list follows the same alignments.

// Account and customer on the left, the balance on the right.
accountPicker.ColumnsToDisplay = new[] { "AccountNo", "Name", "Balance" };
accountPicker.MultiColumnWindowColumnsHorizontalAlignments = new List<HorizontalAlignment>
{
    HorizontalAlignment.Left, HorizontalAlignment.Left, HorizontalAlignment.Right
};

Gets or sets whether the control takes its colours from the current Windows colour scheme when its window is created.

The control reads the name of the current visual style's colour scheme and calls EmulateThisXPTheme: Olive Green for the XP "HomeStead" scheme, Silver for "Metallic", and Blue for any other – which on current versions of Windows means Blue. The colours you set yourself for the five properties that method sets are overwritten when the window is created.

Applies only while the control uses its flat drawing.

Gets the control's right-to-left setting, which is always No: right-to-left layout is not supported.

Gets or sets whether the per-column alignments in MultiColumnWindowColumnsHorizontalAlignments are also applied to the multi-column suggestion list shown while the user types.

The suggestion list is the one BinaryTextComboBox.AutoCompleteStyleForMultiColumnModeIsMultiColumn turns on.

Gets or sets whether the multi-column drop-down shows its row of column headings.

Without headings the user cannot sort by clicking a column, whatever BinaryTextComboBox.EnableColumnSorting says. The heading text comes from BinaryTextComboBox.HeadersToDisplay, or from the column names.

Gets or sets whether the drop-down button is drawn as a separate, push-button style button beside the text area, instead of the flat button inside the border.

The button is drawn with the Windows visual style for a push button, as wide as DropDownButtonExtent and outside the border, with a small arrow image on it: the built-in arrow recoloured to ControlArrowColor, or ExtendedDropdownButtonInternalImage if you set one. To draw the whole button from a picture of your own, set ExtendedDropdownButtonImage.

The space round the button is filled with the parent's background colour, read when the control's window is created.

departmentPicker.ShouldDrawExtendedDropdownButton = true;
departmentPicker.ControlArrowColor = Color.DarkSlateGray;

Gets or sets whether the border is drawn all the time, or only while the pointer is over the control or it has the focus.

With it on, the border is drawn in CustomControlBorderColor, or in CustomControlBorderColorWhenNotInFocus while the control does not have the focus if that is set. With it off, the control rests without a visible border, which appears when the pointer arrives or the control gets the focus – the hover look of a toolbar control.

Gets or sets how the selected item's text is aligned on the closed control.

Only a DropDownList combo box draws its own text, so only it can align it. In DropDown style the value is always HorizontalAlignment.Left: setting another is ignored, and switching to that style puts it back to left.

BinaryTextComboBox uses it. The items in the drop-down list are aligned by DropDownItemTextAlignment.

Gets or sets whether the control applies the current Windows colour scheme again whenever the system colours change.

When the user changes the Windows colours, the control picks the matching scheme exactly as ReflectCurrentXPThemeColorOnLoad does, overwriting the colours set on it.

Returns the width of the drop-down button strip at the right of the control, in device pixels.

The larger of the system's vertical scroll bar width and one and a quarter times the height of the control's Control.Font.

The button grows with the font, so a combo box given a large font keeps a button in proportion to its text. Every part of the control that needs the button's width reads it here, so the button, the text area beside it and the drop-down's position stay in agreement.

Colours the control to match one of the Windows XP colour schemes: Blue, Olive Green or Silver.

The control is still drawn by its own flat painting; only the colours change. CustomControlBorderColor becomes blue, olive or dark grey, CustomPaintingColor becomes the scheme's Explorer bar colour, and the alpha-blending factors become 100 (AlphaBlendFactorForControlPainting), 75 (AlphaBlendFactorForDropDownPressedColor) and 135 (AlphaBlendFactorForItemSelectionColor).

The values you had set for those five properties are overwritten. Keep them first if you want to go back to them later, and set them again yourself; any value set after the call is used as it is.

productPicker.EmulateThisXPTheme(XPTheme.Silver);

Clears the selection, so the control shows no item.

ComboBox.SelectedIndex becomes -1 and the text area is emptied. The control sets it twice, because a single assignment does not always clear a Windows combo box.

private void clearButton_Click(object sender, EventArgs e)
{
    customerPicker.MakeBlank();
    orderNumberBox.Clear();
}

Measures text the way GDI draws it, for laying out text that the control draws.

The width and height the text occupies on a single line, in device pixels; an empty size if it cannot be measured.

GDI and GDI+ (Graphics.MeasureString) measure the same text differently. A derived control centring text vertically in an item uses this so its rows line up with the built-in ones.

Draws one item of the list, or the selected item on the closed control, by calling PaintControlWithData.

Raises the Control.GotFocus event and redraws the border and drop-down button in their highlighted colours.

Prepares the new window: turns off its visual style so the control's own drawing stays in place, applies the current Windows colour scheme when ReflectCurrentXPThemeColorOnLoad is set, and attaches to the edit box of a DropDown combo box so the border follows the pointer over it.

Raises the Control.KeyPress event; an exception thrown by a handler is absorbed rather than propagated, so a faulty handler cannot close the form.

Raises the Control.LostFocus event and redraws the border and drop-down button in their resting state.

Raises the Control.MouseEnter event and shows the border and drop-down button in their highlighted colours.

Raises the Control.MouseLeave event and, unless the control has the focus, returns the border to its resting state: hidden with ShowBorderAlways off, or drawn in CustomControlBorderColorWhenNotInFocus when that is set.

Paints the closed control when it draws itself – the face, the selected item and the border – in the colours set on the control.

A combo box in DropDown style leaves its face to its edit box, and a disabled one is drawn greyed by SetData.

Raises the ComboBox.SelectedIndexChanged event; an exception thrown by a handler is absorbed rather than propagated.

Raises the Control.SystemColorsChanged event and, when UpdateWhenSystemColorsChanges is set, applies the colour scheme of the current Windows theme again.

Draws one item, either in the drop-down list or as the selected item on the closed control.

The base fills the background – the highlight colour for the highlighted item, otherwise DropDownWindowBackgroundColor in the open list – and draws the list's border lines and item borders. The derived combo boxes call it and then draw the item's text, or image and text, on top.

Redraws the selected item on the closed control, without waiting for a full repaint.

The base fills the face, leaving the push-style drop-down button clear, and redraws the drop-down button of the closed control; the derived combo boxes draw the item over it.

Draws the control in its disabled state: a plain face, a dark grey border and a dimmed drop-down button, with the selected item's text in the dimmed system colour.

Called while the control is disabled, when it paints. The base draws the frame and the button; the derived combo boxes override it to draw their item – text, or image and text – over it. Call the base implementation from an override.

Processes Windows messages, redrawing the flat border and drop-down button after the control has painted itself.

The width, in logical pixels, of the area the flat drop-down button's arrow is drawn in; it is 12.

A derived control drawing its own drop-down button can use it to line its arrow up with the built-in one. It is scaled to the display at the point of drawing. The whole button strip is wider; see DropDownButtonExtent.