Class TCastleUserInterface

Container sizes.

Warning: this symbol is deprecated: better override VisibleChange and watch for chCursor in Changes

Called when Cursor changed. In TCastleUserInterface class, just calls OnCursorChange.

Controls that have a preferred size should override this. By default this contains values derived from Width, WidthFraction, Height, HeightFraction, with Border subtracted.

Note that the arguments should be already scaled, i.e. multiplied by UIScale, i.e. expressed in final device pixels.

Note that the returned PreferredWidth and PreferredHeight must not include the space for Border. Border size will be added later.

Called right before calculating size. This is your only chance to adjust e.g. children size, if you need them to be synchronized with something, and you may use AutoSizeToChildren.

In most use-cases, you rather adjust preferred size by overriding PreferredSize.

Theme that should be used by this control. Either CustomTheme or global Theme.

Handle press or release of a key, mouse button or mouse wheel. Return True if the event was somehow handled, which prevents from passing this event to other UI controls.

When implementing in descendants it is best to override it like this:

function TMyControl.Press(const Event: TInputPressRelease): boolean;
begin
  Result := inherited;
  if Result then Exit; // exit if ancestor already handled event

  if Event.IsKey(keyEnter) then
  begin
    // do something in reaction on Enter
    Exit(ExclusiveEvents); // ExclusiveEvents is true by default
  end;

  if Event.IsMouseButton(buttonLeft) then
  begin
    // do something in reaction on Enter
    Exit(ExclusiveEvents); // ExclusiveEvents is true by default
  end;
end;

Note that releasing of the mouse wheel is not reported now by any backend. Only releasing of keys and mouse buttons is reported.

The events PreviewPress and PreviewRelease are passed first to the parent control, before children have a chance to process this event. Overriding them makes sense if you draw something in TCastleUserInterface.RenderOverChildren.

The events Press and Release are passed to the parent only after the children had a chance to process this event. Overriding them makes sense if you draw something in TCastleUserInterface.Render. This is usually more natural, and adviced.

Motion of mouse or touch.

Rotation detected by 3D sensor. Used for example by 3Dconnexion devices.

Parameters

X

X axis (tilt forward/backwards)

Y

Y axis (rotate)

Z

Z axis (tilt sidewards)

Angle

Angle of rotation (in radians)

SecondsPassed

The time passed since last SensorRotation call. This is necessary because some sensors, e.g. 3Dconnexion, may *not* reported as often as normal Update calls.

Translation detected by 3D sensor. Used for example by 3Dconnexion devices.

Parameters

X

X axis (move left/right)

Y

Y axis (move up/down)

Z

Z axis (move forward/backwards)

Length

Length of the vector consisting of the above

SecondsPassed

The time passed since last SensorRotation call. This is necessary because some sensors, e.g. 3Dconnexion, may *not* reported as often as normal Update calls.

Warning: this symbol is deprecated: use event Joysticks.OnAxisMove, or just observe Joysticks[0].Axis

Axis movement detected by joystick.

Parameters

JoyID

ID of joystick with pressed button

Axis

Number of moved axis

Warning: this symbol is deprecated: use Joysticks.OnButtonDown or Joysticks.OnButtonPress

Joystick button pressed.

Parameters

JoyID

ID of joystick with pressed button

Button

Number of pressed button

Control may do here anything that must be continuously repeated. E.g. camera handles here falling down due to gravity, rotating model in Examine mode, and many more.

This method may be used, among many other things, to continuously react to the fact that user pressed some key (or mouse button). For example, if holding some key should move some 3D object, you should do something like:

if HandleInput then
begin
  if Container.Pressed[keyArrowRight] then
    Transform.Position := Transform.Position + Vector3(SecondsPassed * 10, 0, 0);
  HandleInput := not ExclusiveEvents;
end;

Instead of directly using a key code, consider also using TInputShortcut that makes the input key nicely configurable. See engine tutorial about handling inputs.

Multiplying movement by SecondsPassed makes your operation frame-rate independent. Object will move by 10 units in a second, regardless of how many FPS your game has.

The code related to HandleInput is important if you write a generally-useful control that should nicely cooperate with all other controls, even when placed on top of them or under them. The correct approach is to only look at pressed keys/mouse buttons if HandleInput is True. Moreover, if you did check that HandleInput is True, and you did actually handle some keys, then you have to set HandleInput := not ExclusiveEvents. As ExclusiveEvents is True in normal circumstances, this will prevent the other controls (behind the current control) from handling the keys (they will get HandleInput = False). And this is important to avoid doubly-processing the same key press, e.g. if two controls react to the same key, only the one on top should process it.

Note that to handle a single press / release (like "switch light on when pressing a key") you should rather use Press and Release methods. Use this method only for continuous handling (like "holding this key makes the light brighter and brighter").

To understand why such HandleInput approach is needed, realize that the "Update" events are called differently than simple mouse and key events like "Press" and "Release". "Press" and "Release" events return whether the event was somehow "handled", and the container passes them only to the controls under the mouse (decided by TCastleUserInterface.CapturesEventsAtPosition). And as soon as some control says it "handled" the event, other controls (even if under the mouse) will not receive the event.

This approach is not suitable for Update events. Some controls need to do the Update job all the time, regardless of whether the control is under the mouse and regardless of what other controls already did. So all controls (well, all controls that exist, in case of TCastleUserInterface, see TCastleUserInterface.Exists) receive Update calls.

So the "handled" status is passed through HandleInput. If a control is not under the mouse, it will receive HandleInput = False. If a control is under the mouse, it will receive HandleInput = True as long as no other control on top of it didn't already change it to False.

Parameters

SecondsPassed

Should be calculated like TFramesPerSecond.SecondsPassed, and usually it's in fact just taken from TCastleWindow.Fps.SecondsPassed.

Called always when something important inside this control (or it's children) changed. To be more precise, this is called when something mentioned among the TCastleUserInterfaceChange enumerated items changed.

This is always called with Changes <> [] (non-empty set).

Allow window containing this control to suspend waiting for user input. Typically you want to override this to return False when you do something in the overridden Update method.

In this class, this simply returns always True.

See also

TCastleWindow.AllowSuspendForInput

Is it allowed to suspend (for an indefinite amount of time) waiting for user input.

Event called when the container (component or window with OpenGL context) size changes.

You can resize/reposition your component here, for example set TCastleUserInterface.Left or TCastleUserInterface.Bottom, to react to parent size changes. This is called only when the OpenGL context of the container is initialized, so you can be sure that this is called only between GLContextOpen and GLContextClose.

We also call this once when inserting into the controls list (like TCastleWindow.Controls or TCastleControl.Controls or inside parent TCastleUserInterface), if inserting into the container/parent with already initialized OpenGL context. If inserting into the container/parent without OpenGL context initialized, it will be called later, when OpenGL context will get initialized, right after GLContextOpen.

In other words, this is always called to let the control know the size of the container, if and only if the OpenGL context is initialized.

Warning: this symbol is deprecated: use Resize

Add child control, at the front of other children.

Add child control, at the back of other children.

Add child control at specified position. It is usually easier to use InsertFront or InsertBack, if possible.

Remove control added by InsertFront or InsertBack.

Note that this method does not free the Item instance. This method merely removes Item from our controls, so that Item is no longer rendered as part of this parent. It is still the caller's responsibility to make sure the Item is freed at some point.

See https://castle-engine.io/modern_pascal_introduction.html#_freeing_classes for description how to free instances in Pascal. As TCastleUserInterface descends from TComponent, a simple and proper solution is often just to create it with some "owner" (like TUIState.FreeAtStop or Application) that will take care of freeing it.

Index of child control, or -1 if not present.

Remove all child controls added by InsertFront or InsertBack.

Note that, just like RemoveControl, this method does not free the children controls. This method merely removes children controls, so they are no longer rendered as part of the parent. It is still the caller's responsibility to make sure the children controls are freed at some point.

See https://castle-engine.io/modern_pascal_introduction.html#_freeing_classes for description how to free instances in Pascal. As TCastleUserInterface descends from TComponent, a simple and proper solution is often just to create it with some "owner" (like TUIState.FreeAtStop or Application) that will take care of freeing it.

Does this control capture events under this container position. The default implementation simply checks whether Position is inside RenderRect. It also checks whether CapturesEvents is True.

Always treated like False when Exists returns False, so the implementation of this method only needs to make checks assuming that Exists = True.

Prepare your resources, right before drawing. Called only when Exists and GLInitialized.

Do not explicitly call this method. Instead, render controls by adding them to the TCastleContainer.Controls list, or render them explicitly (for off-screen rendering) by TCastleContainer.RenderControl.

Render a control. Called only when Exists and GLInitialized, you can depend on it in the implementation of this method.

Do not explicitly call this method. Instead, render controls by adding them to the TCastleContainer.Controls list, or render them explicitly (for off-screen rendering) by TCastleContainer.RenderControl. This is method should only be overridden in your own code.

Before calling this method we always set some OpenGL state, and you can depend on it (and you can carelessly change it, as it will be reset again before rendering other control).

OpenGL state always set:

• Viewport is set to include whole container.

• Depth test is off.

• (For fixed-function pipeline:) The 2D orthographic projection is always set at the beginning. Useful for 2D controls, 3D controls can just override projection matrix, e.g. use CastleRenderContext.PerspectiveProjection.

• (For fixed-function pipeline:) The modelview matrix is set to identity. The matrix mode is always modelview.

• (For fixed-function pipeline:) The raster position is set to (0,0). The (deprecated) WindowPos is also set to (0,0).

• (For fixed-function pipeline:) Texturing, lighting, fog is off.

Beware that GLSL RenderContext.CurrentProgram has undefined value when this is called. You should always set it, before making direct OpenGL drawing calls (all the engine drawing routines of course do it already, this is only a concern if you make direct OpenGL / OpenGLES calls).

Render a control contents over the children controls. This is analogous to Render, but it executes after children are drawn. You should usually prefer to override Render instead of this method, as the convention is that the parent is underneath children.

Render a tooltip of this control. If you want to have tooltip for this control detected, you have to override TooltipExists. Then the TooltipRender will be called.

TooltipRender is called in the same way as Render. TooltipRender is always called as a last (front-most) control. Argument TooltipPosition is the left-bottom (in screen space, regardless of UIScaling) suggested position of the tooltip.

It is simplest to descend from TCastleUserInterfaceFont, that implements simple TCastleUserInterfaceFont.Tooltip property and overrides these two methods as necessary.

Initialize your OpenGL resources.

This is called when OpenGL context of the container is created, or when the control is added to the already existing context. In other words, this is the moment when you can initialize OpenGL resources, like display lists, VBOs, OpenGL texture names, etc.

As an exception, this is called regardless of the Exists value. This way a control can prepare it's resources, regardless if it exists now.

Destroy your OpenGL resources.

Called when OpenGL context of the container is destroyed. Also called when controls is removed from the container Controls list. Also called from the destructor.

You should release here any resources that are tied to the OpenGL context. In particular, the ones created in GLContextOpen.

As an exception, this is called regardless of the Exists value. This way a control can release it's resources, regardless if it exists now.

Called when this control becomes or stops being focused, that is: under the mouse cursor and will receive events.

This updates Focused property. This also calls OnInternalMouseEnter / OnInternalMouseLeave.

Control position and size. Use this to base other controls size/position on this control's calculated size/position.

The algorithm that determines control position and size is like this:

• When AutoSizeToChildren is True:

  The control size is adjusted to children, to surround them. Left and Bottom and our anchors still matter, but our Width and Height do not matter. See the AutoSizeToChildren documentation for details.

• Otherwise, when FullSize is True:

  The control always fills the whole parent. If the control is added directly to the container, it will fill the whole container (TCastleWindow or TCastleControl).

• Otherwise (when FullSize and AutoSizeToChildren are both False):

  The position and size of the control is determined by the Left, Bottom, Width, Height properties.

  Moreover, WidthFraction, if non-zero, specifies the control width as a fraction of the parent width. E.g. WidthFraction = 1.0 means that width equals parent, 0.5 means it's half the width of the parent etc. In this case the explicit Width is ignored.

  Similarly you can use HeightFraction to express height as a fraction of parent. When HeightFraction is not zero, then the explicit Height is ignored.

  If at least one of the resulting sizes is zero, the rectangle is empty (it is TFloatRectangle.Empty).

The above describes the size of the content and border, summed. The content itself may be a little smaller, when the Border is used. The size of the "content itself" is returned only by RenderRect (in already-scaled coordinates, i.e. using final device pixels).

The anchors (see Anchor) also affect the final position of the control.

Note that some descendants do auto-sizing by default. This means that some of these properties may be ignored, and instead the calculated size (EffectiveWidth, EffectiveHeight) depends on some core values of the control.

For example:

• TCastleImageControl adjusts to image (unless you set TCastleImageControl.Stretch to True),

• TCastleLabel adjusts to caption (unless you set TCastleLabel.AutoSize to False),

• TCastleButton adjusts to caption and icon (unless you set TCastleButton.AutoSize to False),

• TCastleVerticalGroup adjusts to children sizes,

• ... and so on.

Consult the documentation of each descendant for the exact specification of the size behavior.

This method returns the rectangle in local coordinates (relative to the parent 2D control). The returned rectangle size includes the border size. The returned rectangle size uses "unscaled" coordinates, which means that they correspond to the sizes you set e.g. in TCastleUserInterface.Width, TCastleUserInterface.Height, and translation units you use with e.g. TCastleUserInterface.Anchor.

If you're looking for a way to query the size of the control in final scaled coordinates (in real device pixels), and not relative to the parent position, use RenderRect or RenderRectWithBorder instead.

This method ignores the current value of the Exists method and Exists property, that is: the result of this function assumes that control does exist.

See also

TCastleUserInterface.EffectiveWidth

Calculated width of the control, without UI scaling.

TCastleUserInterface.EffectiveHeight

Calculated height of the control, without UI scaling.

Calculated width of the control, without UI scaling. Useful if you want to base other controls size/position on this control calculated size.

Unlike the Width property, this is the effective size, not the desired size. So this is already processed by any auto-sizing mechanism (e.g. TCastleImageControl may adjust it's own size to the underlying image, depending on settings), it is changed by FullSize and so on.

It is always equal to just EffectiveRect.Width. It is 0 when EffectiveRect is empty.

See also

EffectiveRect

Control position and size.

Calculated height of the control, without UI scaling. Useful if you want to base other controls size/position on this control calculated size.

Unlike the Height property, this is the effective size, not the desired size. So this is already processed by any auto-sizing mechanism (e.g. TCastleImageControl may adjust it's own size to the underlying image, depending on settings), it is changed by FullSize and so on.

It is always equal to just EffectiveRect.Height. It is 0 when EffectiveRect is empty.

See also

EffectiveRect

Control position and size.

EffectiveWidth without Border size.

EffectiveHeight without Border size.

Warning: this symbol is deprecated: use EffectiveWidth

Warning: this symbol is deprecated: use EffectiveHeight

Warning: this symbol is deprecated: use EffectiveRect

Position and size of this control, assuming it exists, in container coordinates (in final device pixels). The primary use of this is inside Render. A proper UI control should adjust to draw precisely in this rectangle.

Warning: this symbol is deprecated: use RenderRect

Convert position relative to container (in final device coordinates, without UI scaling, by default) into position relative to this UI control (in coordinates with UI scaling). Useful e.g. to convert mouse/touch position from TInputPressRelease.Position into position useful for children of this UI control.

The exact definition is that using the result of this to set our child AnchorDelta, assuming the child is anchored to the left-bottom (the default state) and child has Left = Bottom = 0, sets child position exactly to the indicated point on the container.

Parameters

ContainerPositionScaled

If True (default) then the container position (the ContainerPosition parameter) is assumed to be in final device pixels, i.e. the window area in X is from 0 to TCastleContainer.Width, in Y from 0 and TCastleContainer.Height. This is useful when the parameter comes e.g. from TInputPressRelease.Position.

If False then the container position (the ContainerPosition parameter) is assumed to be in unscaled device pixels, i.e. the window area in X is from 0 to TCastleContainer.UnscaledWidth, in Y from 0 and TCastleContainer.UnscaledHeight.

Convert position relative to this UI control (in coordinates with UI scaling) into relative to container (in final device coordinates, without UI scaling, by default). Reverses ContainerToLocalPosition.

Parameters

ContainerPositionScaled

If True (default) then the container position (the result of this method) is assumed to be in final device pixels, i.e. the window area in X is from 0 to TCastleContainer.Width, in Y from 0 and TCastleContainer.Height.

If False then the container position (the result of this method) is assumed to be in unscaled device pixels, i.e. the window area in X is from 0 to TCastleContainer.UnscaledWidth, in Y from 0 and TCastleContainer.UnscaledHeight.

Rectangle filling the parent control (or container), in local coordinates. Since this is in local coordinates, the returned rectangle Left and Bottom are always zero, unless parent has Border (the returned rectangle is shrunk by Parent.Border). This is already scaled by UI scaling.

Quick way to enable horizontal anchor, to automatically keep this control aligned to parent. Sets HorizontalAnchorSelf, HorizontalAnchorParent, HorizontalAnchorDelta.

Quick way to enable horizontal anchor, to automatically keep this control aligned to parent. Sets HorizontalAnchorSelf, HorizontalAnchorParent, HorizontalAnchorDelta.

Quick way to enable vertical anchor, to automatically keep this control aligned to parent. Sets VerticalAnchorSelf, VerticalAnchorParent, VerticalAnchorDelta.

Quick way to enable vertical anchor, to automatically keep this control aligned to parent. Sets VerticalAnchorSelf, VerticalAnchorParent, VerticalAnchorDelta.

Warning: this symbol is deprecated: use Anchor

Immediately position the control with respect to the parent by adjusting Left. Deprecated, use Align with THorizontalPosition.

Warning: this symbol is deprecated: use Anchor

Immediately position the control with respect to the parent by adjusting Left.

Note that using Anchor is often more comfortable than this method, since you only need to set anchor once (for example, right after creating the control). In contract, adjusting position using this method will typically need to be repeated at each window on resize, like in TCastleWindow.OnResize.

Warning: this symbol is deprecated: use Anchor

Immediately position the control with respect to the parent by adjusting Bottom. Deprecated, use Align with TVerticalPosition.

Warning: this symbol is deprecated: use Anchor

Immediately position the control with respect to the parent by adjusting Bottom.

Note that using Anchor is often more comfortable than this method, since you only need to set anchor once (for example, right after creating the control). In contract, adjusting position using this method will typically need to be repeated at each window on resize, like in TCastleWindow.OnResize.

Warning: this symbol is deprecated: use Anchor(hpMiddle); Anchor(vpMiddle); to reliably center the control

Immediately center the control within the parent, both horizontally and vertically.

Note that using Anchor is often more comfortable than this method, since you only need to set anchor once. For example, right after creating the control call Anchor(hpMiddle); Anchor(vpMiddle);. In contrast, adjusting position using this method will typically need to be repeated at each window on resize, like in TCastleWindow.OnResize.

UI scale of this control, derived from container (see TCastleContainer.UIScaling and EnableUIScaling).

Override this to prevent resizing some dimension in CGE editor.

Called always when something important inside this control (or it's children) changed. See VisibleChange for details about when and how this is called.

Be careful when handling this event. Various changes may cause this, so be prepared to handle it at any moment, even in the middle when UI control is changing. It may also occur very often. It's usually safest to only set a boolean flag like "something should be recalculated" when this event happens, and do the actual recalculation later.

Container of this control. When adding control to container's Controls list (like TCastleWindow.Controls) container will automatically set itself here, and when removing from container this will be changed back to Nil.

May be Nil if this control is not yet inserted into any container.

Warning: this symbol is deprecated: use OnVisibleChange (or override VisibleChange) and watch for Changes that include chCursor

Event called when the Cursor property changes. This event is, in normal circumstances, used by the Container, so you should not use it in your own programs.

Should we disable further mouse / keys handling for events that we already handled in this control. If True, then our events will return True for mouse and key events handled.

This means that events will not be simultaneously handled by both this control and some other (or camera or normal window callbacks), which is usually more sensible, but sometimes somewhat limiting.

Warning: this symbol is deprecated: use Exists

See SetFocused.

Visual parent control. This control is rendered within the parent, and it's anchors and coordinates are relative to the parent. Parent may be Nil, which means that the Container (if set) is our direct parent.

Warning: this symbol is deprecated: use Width

Warning: this symbol is deprecated: use Height

A simple shortcut to modify HorizontalAnchorDelta/VerticalAnchorDelta as TVector2

Keep the control in front of other controls (with KeepInFront=False) when inserting.

TODO: Do not change this property while the control is already a child of something.

Color of the Border, by default completely transparent black.

Warning: this symbol is deprecated: this property does not do anything anymore, anchors are always active

Warning: this symbol is deprecated: this property does not do anything anymore, anchors are always active

Is the control possibly visible. This is always True when Culling is False (the default).

Enable or disable UI scaling for this particular control. See more about UI scaling on TCastleContainer.UIScaling and TCastleUserInterface.UIScale. Setting this to False forces TCastleUserInterface.UIScale to always return 1.0.

Note that this does not work recursively, i.e. it does not affect the children of this control. Setting this to False does not prevent UI scaling on children (you have to turn it off explicitly for children too, if you need to disable UI scaling recursively).

The use-cases for changing this property to "false" are very rare. Usually you should use UI scaling for 100% of your UI.

Capture input events (keyboard, mouse, joystick). If False, then the methods like Press and Release will never be called, and Update will always be called with HandleInput = False. The control will never behave like focused.

The only exception is when this control is set as TCastleContainer.ForceCaptureInput. In this case, the control will receive inputs. In other words, TCastleContainer.ForceCaptureInput overrides the intent of this property.

This property may be replaced by something like "CaptureInput" or just universal "Enabled" in the future.

Called when control starts being under the mouse cursor and will receive events. See SetFocused, this is called when Focused changes from False to True.

This is called "Internal" now, because we do not guarantee it's 100% always paired with OnInternalMouseLeave. A different approach to this may be done in the future releases.

Called when control stops being under the mouse cursor and will receive events. See SetFocused, this is called when Focused changes from True to False.

This is called "Internal" now, because we do not guarantee it's 100% always paired with OnInternalMouseEnter. A different approach to this may be done in the future releases.

Mouse cursor over this control. When user moves mouse over the Container, the currently focused (topmost under the cursor) control determines the mouse cursor look.

Event that occurs continuously on each control. See Update for details.

An input (key, mouse button, mouse wheel) was pressed. See Press for details.

An input (key, mouse button, mouse wheel) was released. See Release for details.

Pointer (mouse or finger) moved. See Motion for details.

Control is being displayed. See Render for details. This event it called after the Render method of this control finished.

Not existing control is not visible, it doesn't receive input and generally doesn't exist from the point of view of user. This is mostly equivalent to just removing this control from parent list.

Non-existing controls still receive GLContextOpen, GLContextClose, Resize events.

Position from the left side of the parent control.

It's usually better to use anchors instead of this property. For example, instead of setting Control.Left := 10, you can call Control.Anchor(hpLeft, 10), or just change HorizontalAnchorDelta.

Note that the effects of this property and HorizontalAnchorDelta are summed, if you set both.

Position from the bottom side of the parent control.

It's usually better to use anchors instead of this property. For example, instead of setting Control.Bottom := 10, you can call Control.Anchor(vpBottom, 10), or just change VerticalAnchorDelta.

Note that the effects of this property and VerticalAnchorDelta are summed, if you set both.

When FullSize, the control will always fill the whole parent area.

See also

TCastleUserInterface.EffectiveRect

Control position and size.

TCastleUserInterface.EffectiveWidth

Calculated width of the control, without UI scaling.

TCastleUserInterface.EffectiveHeight

Calculated height of the control, without UI scaling.

These properties determine the control size. See the EffectiveRect documentation for details how the size is calculated.

See also

TCastleUserInterface.EffectiveRect

Control position and size.

TCastleUserInterface.EffectiveWidth

Calculated width of the control, without UI scaling.

TCastleUserInterface.EffectiveHeight

Calculated height of the control, without UI scaling.

Adjust size to encompass all the children. The properties FullSize, Width, Height are ignored in this case. Our Left and Bottom still matter.

Our size is adjusted to all existing children sizes and positions.

We add AutoSizeToChildrenPaddingTop to the resulting height, and AutoSizeToChildrenPaddingRight to the resulting width.

Padding added when AutoSizeToChildren is used. TODO: Should be AutoSizeToChildrenPaddingHorizontal, there's nothing that makes it specific to "right" or "left" side now.

Padding added when AutoSizeToChildren is used. TODO: Should be AutoSizeToChildrenPaddingVertical, there's nothing that makes it specific to "top" or "bottom" side now.

Adjust position to align us to the parent horizontally. The resulting EffectiveRect and RenderRect and RenderRectWithBorder will immediately reflect the new position.

Note that HorizontalAnchorDelta is summed with Left. It's usually most natural to leave Left as zero when using anchors.

Note that anchors (as well as Left and Bottom) are ignored when FullSize is set to true. In case of FullSize, the control fills the parent perfectly.

Anchor distance is automatically affected by TCastleContainer.UIScaling.

Which our border to align (it's aligned to parent HorizontalAnchorParent border).

Which parent border is aligned to our HorizontalAnchorSelf border.

Delta between our border and parent.

Adjust position to align us to the parent vertically. The resulting EffectiveRect and RenderRect and RenderRectWithBorder will immediately reflect the new position.

Note that VerticalAnchorDelta is summed with Bottom. It's usually most natural to leave Bottom as zero when using anchors.

Note that anchors (as well as Left and Bottom) are ignored when FullSize is set to true. In case of FullSize, the control fills the parent perfectly.

Anchor distance is automatically affected by TCastleContainer.UIScaling.

Which our border to align (it's aligned to parent VerticalAnchorParent border).

Which parent border is aligned to our VerticalAnchorSelf border.

Delta between our border and parent.

Optimize rendering and event processing by checking whether the control can be visible. The visibility is checked by looking at container rectangle, and all possible clipping parents (set by TCastleScrollView, or any other control with ClipChildren).

This is useful for UI controls that have expensive rendering or other events (e.g. they do something non-trivial in Render or RenderOverChildren, or they include a lot of children controls). And they may be placed off-screen, or they may be outside of a parent with clipping, which is often the case when the parent is TCastleScrollView.

Clip the rendering of children.

By default this is False and so the control can draw outside of it's designated rectangle (RenderRect). Although all the standard UI controls are carefully implemented such that their Render and RenderOverChildren draw only within their RenderRect. But it is easy to place children controls outside of this rectangle.

When this property is True, the rendering is clipped, so the "overflowing" parts are never visible. This affects both Render and RenderOverChildren of this control, as well as all children rendering.

Border (by default transparent) of the control. Border adds a space from the control content (drawn within RenderRect) to the control rectangle (returned by RenderRectWithBorder) (scaled), or EffectiveRect (unscaled) and friends).

It is transparent by default, but you can change it by BorderColor.

Border works always, regardless of FullSize or AutoSizeToChildren.

One obvious use-case is to use this for visual space (empty space or a colorful frame, separating this control from the rest).

Another use-case is to reserve a predictable space for as additional (sibling) control within the same parent. E.g. you can set FullSize=true and Border.Top=100, and this way there is always a strip with Height=100 at the top of the parent, where you can insert another control (with Height=100, anchored to the top).

Use a custom instance of TCastleTheme to determine the look of this control.

BorderColor that can be visually edited in Castle Game Engine Editor, Lazarus and Delphi. Normal user code does not need to deal with this, instead read or write BorderColor directly.

See also

BorderColor

Color of the Border, by default completely transparent black.