Class

DesktopButton


Description

A Button is the standard button used in desktop apps. Examples are a Default button, a Cancel button or a standard button.

Enumerations

DesktopButton.MacButtonStyles

MacButtonStyles

Specifies the various styles that can be used with the MacButtonStyle property which is only supported for macOS.

Enum

Push

Gradient

Recessed

Textured

RoundedTextured

Square

Bevel

Round

Help (Caption property not used)

Property descriptions


DesktopButton.Active

Active As Boolean

Indicates whether the control is active.

This property is read-only.

Active is False when the control's window is not in the foreground. When a DesktopWindow is deactivated, its controls are automatically deactivated unless AllowAutoDeactivate is set to False.


DesktopButton.AllowAutoDeactivate

AllowAutoDeactivate As Boolean

Determines whether the control should be deactivated (on macOS) when the parent window is deactivated. The default is True.


DesktopButton.AllowTabStop

AllowTabStop As Boolean

If True, the control is in the Tab Order and accepts the focus when the user tabs into it. The default is True. If False, the user cannot tab into it to give it the focus. However, the control can gain the focus by other means, such as the user's clicking on it or by setting the focus in code.

This example removes the control from the Tab Order:

Me.AllowTabStop = False

DesktopButton.Bold

Bold As Boolean

If True, applies the bold style to the control's caption and/or its text content if any.

Mac apps can only display font styles that are available. You cannot force a font to display in bold or italic if it does not have bold or italic variations available. In this situation, the Bold property will not affect the font.

This example sets the text to Bold.

Me.Bold = True

DesktopButton.Cancel

Cancel As Boolean

If True, the Escape key and Command-Period key sequence are mapped to the button. The default is False.

This example makes the PushButton a cancel button. It is in the Opening event of the control.

Me.Cancel = True

DesktopButton.Caption

Caption As String

The caption of a control.

To set an accelerator character, precede the character in the Caption with an ampersand. In order to show an ampersand in the Caption, use two ampersands in a row.

This code sets the caption of the control to "OK".

Me.Caption = "OK"

This code in the Pressed event handler for a DesktopButton changes the text of the button each time it is pressed:

If Me.Caption = "Blue" Then
  Me.Caption = "Red"
Else
  Me.Caption = "Blue"
End If

DesktopButton.Default

Default As Boolean

If True, the default button indicator is added to the button and the Return and Enter keys are mapped to the button. The default is False.

This code sets the PushButton as the default button. It is in the Open event of the control.

Me.Default = True

DesktopButton.Enabled

Enabled As Boolean

Determines if the control should be enabled when the owning window is opened.

A disabled control cannot be clicked and cannot receive the focus.

This example disables the control.

Me.Enabled = False

DesktopButton.FontName

FontName As String

Name of the font used to display the caption.

You can enter any font that is installed on the computer or the names of the two metafonts, "System" and "SmallSystem".

The System font is the font used by the system software as its default font. Different operating systems use different default fonts. If the system software supports both a large and small System font, you can also specify the "SmallSystem" font as your TextFont.

On Macintosh, "SmallSystem" specifies the OS's smaller system font and may make the control smaller in size as well. On Windows and Linux, "SmallSystem" is the same as "System".

This code sets the FontName property.

Me.FontName = "Helvetica"

DesktopButton.FontSize

FontSize As Single

Point size of the font used to display the caption.

If you enter zero as the FontSize, your app will use the font size that works best for the platform on which it is running.

This code sets the font size to 16 points.

Me.FontSize = 16

DesktopButton.FontUnit

FontUnit As FontUnits

The units in which FontSize is measured.


DesktopButton.Handle

Handle As Ptr

Returns a handle to the control.

This property is read-only.

For interfacing with Mac APIs using Declares, DesktopControl.Handle returns NSViews (except for DesktopToolbar).

On Windows returns the HWND of the control.

On Linux it returns a GtkWidget.

The following gets a handle to the control.

Var p As Ptr = Me.Handle

DesktopButton.Height

Height As Integer

The height (in points) of the control.

This example sets the height of the control to 100:

Me.Height = 100

DesktopButton.Index

Index As Integer

If the control is used in a control set, this specifies the control's index in the set.

This property is read-only.


DesktopButton.Italic

Italic As Boolean

If True, applies the italic style to the control's caption and/or its text content if any.

Mac apps can only display font styles that are available. You cannot force a font to display in bold or italic if it does not have bold or italic variations available. In this situation, the Italic property will not affect the font.

The following sets the Italic property for the control.

Me.Italic = True

DesktopButton.Left

Left As Integer

The distance from the left side of the control to the left side of its containing window or container.

The following example moves the control 100 points from the left side of the window:

Me.Left = 150

DesktopButton.LockBottom

LockBottom As Boolean

Determines whether the bottom edge of the control should stay at a set distance from the bottom edge of the parent control, if there is one, or the owning window.

This property can be set in the control's Inspector. The following example sets it in code.

Me.LockBottom = True

DesktopButton.LockLeft

LockLeft As Boolean

Determines whether the left edge of the control should stay at a set distance from the left edge of the parent control, if there is one, or the owning window.

LockLeft and Locktop default to True when you add a new control to a window. Existing controls will be altered only if LockRight and/or LockBottom are not set. LockLeft has no effect unless LockRight is True.

This property can be set in the control's Inspector. The following example sets it in code.

Me.LockLeft = True

DesktopButton.LockRight

LockRight As Boolean

Determines whether the right edge of the control should stay at a set distance from the right edge of the parent control, if there is one, or the owning window.

This property can be set in the control's Inspector. The following example sets it in code.

Me.LockRight = True

DesktopButton.LockTop

LockTop As Boolean

Determines whether the top edge of the control should stay at a set distance from the top edge of the parent control, if there is one, or the owning window.

LockTop and LockLeft default to True when you add a control to a window. Existing controls will be altered only if LockRight and/or LockBottom are not set. LockTop has no effect unless LockBottom is True.

This property can be set in the control's Inspector. The following example sets it in code.

Me.LockTop = True

DesktopButton.MacButtonStyle

MacButtonStyle As MacButtonStyles

Applies the selected button style to the DesktopButton. This is a macOS-only property. You can only set the MacButtonStyle Property in the IDE, not in code.

The styles are not shown in the Layout Editor in the IDE, but you'll see them in your macOS app when you run it.

You can determine which style is set by comparing it with DesktopButton.


DesktopButton.MouseCursor

MouseCursor As MouseCursor

The cursor to be displayed while the mouse is within the control and both the DesktopApplication and DesktopWindow class's MouseCursor properties are Nil.

If the DesktopApplication class's MouseCursor property is not Nil or the DesktopWindow's MouseCursor property is not Nil, then any control's MouseCursor property is ignored. You can use a cursor stored in the Cursors module. On Macintosh, you can also obtain a MouseCursor from a resource file.

This line in the Opening event of the control sets the default cursor to the finger pointer.

Me.MouseCursor = System.Cursors.FingerPointer

DesktopButton.Name

Name As String

The name of the control. Set the name of the control in the Inspector.

This property is read-only.


DesktopButton.PanelIndex

PanelIndex As Integer

If the control has been placed on a DesktopTabPanel or DesktopPagePanel control, this is the panel (page/tab) that the control is on. If the control is not on a panel, it returns -1.

The first panel is numbered zero. If the control has been placed on a panel of a DesktopTabPanel or DesktopPagePanel control, it returns the panel number. If the control is not on a DesktopPagePanel or DesktopTabPanel, it returns -1. If you change the PanelIndex to a nonexistent panel, the control will disappear until you give it a PanelIndex value that corresponds to a panel that exists.

If you are looking to change the currently selected panel (page/tab), use DesktopPagePanel.

This code displays the panel index of the control that is on the page.

MessageBox(Me.SelectedPanelIndex.ToString)

DesktopButton.Parent

Parent As Object

Used to get and set the control's parent control or window.

If the control is on the window, the Parent will be the Window. If the control is on the container, the Parent will be the container. If the control is completed enclosed by another control, the Parent will be that control.

If you do not want the enclosing control to be the parent, set the Parent property of that control to Nil to make it the Window.

If the parent control is somehow in another window, an InvalidParentException will occur.

The following example sets the parent of the control to the window.

Me.Parent = Nil

DesktopButton.Scope

Scope As Integer

Used to determine whether access to the control is Public (0) or Private (2). The default is Public.

This property is read-only.

Note

This is a designtime-only property and thus can only be set in the Inspector and is not accessible via code.

If the Scope of a control is set to Private, it cannot be accessed from outside its parent window.


DesktopButton.TabIndex

TabIndex As Integer

The control's position in the Tab Order. The control with whose TabIndex is 0 will get the focus first.

On macOS, only controls where you enter data from the keyboard typically get the focus. In order to manually set focus to controls that don't allow keyboard entry, go to System Preferences, click on the Keyboard icon then on the Shortcuts tab and then check the Use keyboard navigation to move focus between controls checkbox.

This example sets the control's TabIndex.

Me.TabIndex = 2

DesktopButton.Tooltip

Tooltip As String

Text of help message displayed as a Windows or Linux "tooltip" or macOS help tag.

The tip/tag is displayed when the user hovers the mouse cursor over the control.

This example adds a tooltip to a control:

Me.Tooltip = "Click to bark."

DesktopButton.Top

Top As Integer

The distance from the top of the control to the top of its containing window or container.

This example sets the top of the control to 140 points from the top of the window:

Me.Top = 140

DesktopButton.Transparent

Transparent As Boolean

Determines whether the control is transparent on Windows. The default is False. Has no effect on macOS or Linux.

Transparent controls draw more slowly and use more memory in order to cache the background. Unless you absolutely require transparency, leave this set to False.

For projects that were created prior to 2018r1, this property defaults to True to emulate previous behavior. Consider changing it to False to improve performance if you do not require transparency.


DesktopButton.Underline

Underline As Boolean

If True, applies the underline style to the control's caption and/or its text content if any.

This code underlines the control's text or caption property.

Me.Underline = True

This code underlines the Caption property:

Me.Underline = True
Me.Caption = "underlined"

DesktopButton.Visible

Visible As Boolean

Determines whether the control is visible when its owning window is opened. The default is True: the control is visible.

The following code makes the control invisible:

Me.Visible = False

DesktopButton.Width

Width As Integer

The width (in points) of the control.

The following example resizes the control:

Me.Width = 200

DesktopButton.Window

Window As DesktopWindow

The control's parent window.

This property is read-only.

This code gets the parent window's Title property.

MessageBox(Me.Window.Title)

Method descriptions


DesktopButton.AcceptFileDrop

AcceptFileDrop(FileType As String)

Permits documents of type FileType to be dropped on the control. FileType must be a file type that you defined in via the FileType class or the File Type Sets Editor.

This code in the Opening event makes it possible for the user to drop either a picture or a file that is a jpeg image. The File Type Sets editor was used to define the “image/jpeg” file type. It is one of the “Common File Types” that is available in the editor.

Me.AcceptPictureDrop
Me.AcceptFileDrop("image/jpeg")

To restrict file drops to just folders (and not files), you can put this code in the DragEnter event:

If Not obj.FolderItem.IsFolder Then Return True

DesktopButton.AcceptPictureDrop

AcceptPictureDrop

Permits pictures to be dropped on the control.

If a control should accept pictures in a drag and drop, then AcceptPictureDrop needs to be called prior to the drop. Typically, it is in the Opening event of the control itself. For example, the line:

Me.AcceptPictureDrop

in the Opening event of the control that will receive the dragged pictures is needed. When the picture is dropped, the DropObject event is called and this is where you will put your code to handle the drop.

Opening Event:

Me.AcceptPictureDrop

DropObject Event:

If obj.PictureAvailable Then
  Me.Backdrop = obj.Picture
End If

DesktopButton.AcceptRawDataDrop

AcceptRawDataDrop(Type As String)

Permits data (of the Type specified) to be dropped on the control.

The following specfies a generic file type defined in the File Type Sets editor.

Me.AcceptRawDataDrop("????")

DesktopButton.AcceptTextDrop

AcceptTextDrop

Permits text to be dropped on the control.

This line in the Opening event of a control that can accept dragged text.

Me.AcceptTextDrop

DesktopButton.AddActionNotificationReceiver

AddActionNotificationReceiver(theReceiver As ActionNotificationReceiver)

Registers an ActionNotificationReceiver.


DesktopButton.Close

Close

Closes a control.

Closing a control permanently removes the control from memory, making it impossible to access. You can close both non-indexed controls and indexed controls. When you close an indexed control, the indexes for the remaining controls will shift downward so that the indexes start with zero and are consecutive.

The following code closes the control. When this is executed from a visible control, the control disappears from the window.

Me.Close

DesktopButton.DrawInto

DrawInto(g As Graphics, x As Integer, y As Integer)

Draws the contents of the control into the specified Graphics context. The parameters x and y are the coordinates of the top, left corner.

This example draws the current control into the Graphics of a Picture and then displays it as the Backdrop of a Canvas:

Var p As New Picture(Me.Width, Me.Height)
Me.DrawInto(p.Graphics, 0, 0)
Canvas1.Backdrop = p

DesktopButton.Press

Press

Causes the button to be visually pressed, as well as triggering the Pressed event.

Call Press when the user has pressed the keyboard equivalent for the button to give the appropriate visual feedback.

This example presses Button1. It is called from another control.

Button1.Press

DesktopButton.Refresh

Refresh(immediately As Boolean = False)

Redraws the portion specified of the contents of the control the next time the OS redraws the control or immediately if True is passed.

If you are calling this so frequently that you experience a slowdown in your code, pass True for the immediately parameter.

Calling this method causes the Render event to fire.

Refresh the entire area immediately:

Me.Refresh(True)

Refresh a portion of the area the next time the OS redraws the control:

Me.Refresh(100, 150, 200, 300)

DesktopButton.RemoveActionNotificationReceiver

RemoveActionNotificationReceiver(theReceiver As ActionNotificationReceiver)

Unregisters an ActionNotificationReceiver.


DesktopButton.SetFocus

SetFocus

If applicable, sets the focus to the DesktopUIControl. KeyDown events are directed to the control.

If the control cannot get the focus on the platform on which the application is running, SetFocus does nothing. The SetFocus method of the DesktopWindow class or the ClearFocus method can be used to remove the focus from the control that currently has the focus, leaving no control with the focus.

Note

On the Mac you need Full Keyboard Access turned on in System Preferences (Keyboard->Shortcuts) in order to manually set focus to non-text controls.

The following example in the Opening event sets the focus to the that control. If another control has the focus when this line is executed, then the user sees this control gets the focus.

Me.SetFocus

Event descriptions


DesktopButton.Closing

Closing

The control is closing.


DesktopButton.ConstructContextualMenu

ConstructContextualMenu(Base As DesktopMenuItem, x As Integer, y As Integer) As Boolean

This event is called when it is appropriate to display a contextual menu for the control.

This event handler is the recommended way to handle contextual menus because this event figures out whether the user has requested the contextual menu, regardless of how they did it. Depending on platform, it might be in the MouseUp or MouseDown event and it might be a right+click or by pressing the contextual menu key on the keyboard, for example.

Base is analogous to the menu bar for the contextual menu. Any items you add to Base will be shown as menu items. If you return False, the event is passed up the parent hierarchy.

If you return True, the contextual menu is displayed. The parameters x and y are the mouse locations. If the event was fired because of a non-mouse event, then x and y are both set to -1. See the example of a contextual menu in the following section.

The following ConstructContextualMenu event handler builds a menu with three menu items plus a submenu with three additional menu items.

// Add some items
base.AddMenu(New DesktopMenuItem("Test 1"))
base.AddMenu(New DesktopMenuItem("Test 2"))
base.AddMenu(New DesktopMenuItem("Test 3"))

// Add a Separator
base.AddMenu(New DesktopMenuItem(DesktopMenuItem.TextSeparator))

// Add a sub menu
Var submenu As New DesktopMenuItem("SubMenu")
submenu.AddMenu(New DesktopMenuItem("SubMenu Test 1"))
submenu.AddMenu(New DesktopMenuItem("SubMenu Test 2"))
submenu.AddMenu(New DesktopMenuItem("SubMenu Test 3"))
base.AddMenu(submenu)

// Add a Separator
base.AddMenu(New DesktopMenuItem(DesktopMenuItem.TextSeparator))

Return True

DesktopButton.ContextualMenuItemSelected

ContextualMenuItemSelected(HitItem As DesktopMenuItem) As Boolean

Fires when a contextual menuitem selectedItem was selected but the MenuItemSelected event and the MenuHandler for the DesktopMenuItem did not handle the menu selection.

This event gives you a chance to handle the menu selection by inspecting the menuitem's Text or Tag properties to see which item was selected. Use this in conjunction with ConstructContextualMenu if you have not specified the MenuItemSelected event or the Menu Handler for the items on the contextual menu. See the example of a contextual menu in the examples for the DesktopUIControl class.

Return True if this event has handled the item the user chose from the contextual menu. Returning False will cause the control's parent to execute its ContextualMenuAction event. This can be handy if you have the same contextual menu for several controls who share the same Parent (several on the same window for example). By returning False you can handle them all in a single event.

This simple event handler displays the value of the selected menu item.

If selectedItem <> Nil Then MessageBox(selectedItem.Text)
Return True

DesktopButton.DragEnter

DragEnter(obj As DragItem, Action As DragItem.Types) As Boolean

Fires when the passed DragItem enters the DesktopUIControl.

Returns a Boolean. Return True from this event to prevent the drop from occurring.

The Action parameter specifies the type of drag action.

To restrict file drops to just folders (and not files), you can put this code in the DragEnter event:

If Not obj.FolderItem.IsFolder Then Return True

DesktopButton.DragExit

DragExit(obj As DragItem, Action As DragItem.Types)

Fires when the passed DragItem exits the DesktopUIControl.

The Obj parameter is the item being dragged. The Action parameter specifies the type of drag action.


DesktopButton.DragOver

DragOver(x As Integer, y As Integer, obj As DragItem, Action As DragItem.Types) As Boolean

Fires when the DragItem is over the DesktopUIControl.

The Obj parameter is the object being dragged. The coordinates x and y are relative to the DesktopUIControl. Returns a Boolean. Return True from this event to prevent the drop from occurring.

The Action parameter specifies the type of drag action, which is typically done by holding down a modifier key (Shift, Alt, Option, Command, etc.) while doing the drag.


DesktopButton.DropObject

DropObject(Obj As DragItem Action As DragItem.Types)

The item represented by Obj has been dropped on the control.

The Obj parameter is the object being dragged. The Action parameter specifies the type of drag action.

The following DropObject event handler can handle either a dropped picture or a dropped file. The type of file that it can handle needs to have been specified in a call to AcceptFileDrop prior to the drop, for example, in the Opening event.

If Obj.PictureAvailable Then
  Me.Image = obj.Picture
ElseIf Obj.FolderItemAvailable Then
  Me.Image = Picture.Open(obj.FolderItem)
End If

DesktopButton.FocusLost

FocusLost

The control has lost the focus.

This property must be set to True for the control to be capable of getting then losing the focus.

Note

On macOS, controls other than text fields and lists will accept and lose focus only if the full keyboard access option is enabled in System Preferences/Keyboard.


DesktopButton.FocusReceived

FocusReceived

The control has received the focus and has a selection rectangle around it.

This property must be set to True for the control to be capable of getting the focus.

Note

On macOS, controls other than text fields and lists will accept focus only if the full keyboard access option is enabled in System Preferences/Keyboard.


DesktopButton.KeyDown

KeyDown(Key As String) As Boolean

The user has pressed the Key passed while the control has the focus.

Returning True prevents the KeyDown event on the parent control (usually the window) from executing. Returning False results in the execution of the KeyDown event of the parent control.


DesktopButton.KeyUp

KeyUp(Key As String)

Fires when the passed Key is released in the control that has the focus.

It is not guaranteed to be the same key that received the KeyDown event.


DesktopButton.MouseDown

MouseDown(X As Integer, Y As Integer) As Boolean

The mouse button was pressed inside the control's region at the location passed in to x, y.

This event fires repeatedly while the mouse button is being held down.

The coordinates x and y are local to the control, i.e. they represent the position of the mouse click relative to the upper-left corner or the control.

Return True if you are going to handle the MouseDown. In such a case:

  • The Pressed event, if any, will not execute and the state of the object will not change.

  • You will receive the MouseUp event.

If you return False, the system handles the MouseDown so the MouseUp event handler do not get called.

The MouseDown event uses the DragItem constructor when the user drags the contents of the control. It is:

Var d As DragItem
d = New DragItem(Self, Me.Left, Me.Top, Me.Width, Me.Height)
d.Picture = Me.Image
d.Drag // Allow the drag

DesktopButton.MouseDrag

MouseDrag(X As Integer, Y As Integer)

The mouse button was pressed inside the control and moved (dragged) at the location local to the control passed in to x, y.

This event fires repeatedly while the mouse button is down regardless of whether or not the mouse coordinates are changing.

This event will not occur unless you return True in the MouseDown event.


DesktopButton.MouseEnter

MouseEnter

The mouse has entered the area of the control.


DesktopButton.MouseExit

MouseExit

The mouse has left the area of the control.


DesktopButton.MouseMove

MouseMove(X As Integer, Y As Integer)

The mouse has moved within the control to the coordinates passed. The coordinates are local to the control, not to the window.


DesktopButton.MouseUp

MouseUp(X As Integer, Y As Integer)

The mouse button was released. Use the x and y parameters to determine if the mouse button was released within the control's boundaries.

Note

This event will not occur unless you return True in the MouseDown event. The return value is ignored.

The parameters x and y are local coordinates, i.e. they represent the position of the mouse click relative to the upper-left corner or the control. Mouse clicks that are released to the left or above a control are negative.


DesktopButton.MouseWheel

MouseWheel(X As Integer, Y As Integer, DeltaX As Integer, DeltaY As Integer) As Boolean

The mouse wheel has been moved.

The parameters X and Y are the mouse coordinates relative to the control that has received the event. The parameters DeltaX and DeltaY hold the number of scroll lines the wheel has been moved horizontally and vertically, as defined by the operating system. DeltaX is positive when the user scrolls right and negative when scrolling to the left. DeltaY is positive when the user scrolls down and negative when scrolling up.

Returns a Boolean. Return True to prevent the event from propagating further.


DesktopButton.Opening

Opening

The control is about to be displayed. Use this event to initialize a control.

The Opening event is called after the Constructor.

Be warned that initializing control property values using the Constructor instead of the Opening event may result in those property values being overwritten by what is set in the Inspector. For best results, use the Opening event for control initialization rather than the control Constructor.

If the control is supposed to handle drag and drop, you need to tell it which type of item it needs to be able to handle. The following example informs the control that pictures and files can be dropped on it. The type of the file it needs to support is specified via the File Types Editor.

Sub Opening()
  Me.AcceptPictureDrop
  Me.AcceptFileDrop("JPEG")
End Sub

DesktopButton.Pressed

Pressed

The button has been clicked. A right- or middle-click does not trigger the Pressed event.

This code in the Pressed event handler displays a message when the button is clicked:

MessageBox("You clicked the button.")

Notes

To set an accelerator character, precede the character in the Caption with an ampersand. In order to show an ampersand in the Caption, use two ampersands in a row. The sets the accelerator to the "D" character:

Calculate &Data

The DesktopButton's Caption property can show a caption that uses an encoding that doesn't match the application's region code (or while running within the IDE, the IDE's region code). For example, an English application can set a Japanese caption, as long as it first sets the button's FontName to Osaka.

If your button has a height greater than 22 pixels, on macOS it will not have the standard rounded appearance and will instead be drawn as a square button. This is a restriction of macOS.


Linux and pi button height

On Linux and Pi you may find that the button height is not large enough to fit the text. This is because some themes will drastically increase the default font size for buttons causing it to exceed the size of the button. There are a couple things you can do to fix this. In the Opening event of the Button you can choose to make the button larger:

Me.Height = 32

Or you can choose to make its font smaller:

Me.FontSize = 10

The above numbers are for example. You will want to adjust them as appropriate for the theme being used.

You can also look up the best size to use based on the theme by using Declares. Refer to this example project to see how it is done:

Examples/Platform-Specific/Linux/GetDefaultControlSize

Compatibility

Desktop projects on all supported operating systems.