Viewport Class Reference

A Viewport is used to contain a larger child component, and allows the child to be automatically scrolled around. More...

#include <juce_Viewport.h>

Inheritance diagram for Viewport:

Public Types
enum class	ScrollOnDragMode { never , nonHover , all }
Public Types inherited from Component
enum class	FocusContainerType { none , focusContainer , keyboardFocusContainer }
	A focus container type that can be passed to setFocusContainerType(). More...
enum	FocusChangeType { focusChangedByMouseClick , focusChangedByTabKey , focusChangedDirectly }
	Enumeration used by the focusGained() and focusLost() methods. More...
enum class	FocusChangeDirection { unknown , forward , backward }
	Enumeration used by the focusGainedWithDirection() method. More...

Public Member Functions
	Viewport (const String &componentName=String())
	Creates a Viewport.
	~Viewport () override
	Destructor.
void	setViewedComponent (Component *newViewedComponent, bool deleteComponentWhenNoLongerNeeded=true)
	Sets the component that this viewport will contain and scroll around.
Component *	getViewedComponent () const noexcept
	Returns the component that's currently being used inside the Viewport.
void	setViewPosition (int xPixelsOffset, int yPixelsOffset)
	Changes the position of the viewed component.
void	setViewPosition (Point< int > newPosition)
	Changes the position of the viewed component.
void	setViewPositionProportionately (double proportionX, double proportionY)
	Changes the view position as a proportion of the distance it can move.
bool	autoScroll (int mouseX, int mouseY, int distanceFromEdge, int maximumSpeed)
	If the specified position is at the edges of the viewport, this method scrolls the viewport to bring that position nearer to the centre.
Point< int >	getViewPosition () const noexcept
	Returns the position within the child component of the top-left of its visible area.
Rectangle< int >	getViewArea () const noexcept
	Returns the visible area of the child component, relative to its top-left.
int	getViewPositionX () const noexcept
	Returns the position within the child component of the top-left of its visible area.
int	getViewPositionY () const noexcept
	Returns the position within the child component of the top-left of its visible area.
int	getViewWidth () const noexcept
	Returns the width of the visible area of the child component.
int	getViewHeight () const noexcept
	Returns the height of the visible area of the child component.
int	getMaximumVisibleWidth () const
	Returns the width available within this component for the contents.
int	getMaximumVisibleHeight () const
	Returns the height available within this component for the contents.
virtual void	visibleAreaChanged (const Rectangle< int > &newVisibleArea)
	Callback method that is called when the visible area changes.
virtual void	viewedComponentChanged (Component *newComponent)
	Callback method that is called when the viewed component is added, removed or swapped.
void	setScrollBarsShown (bool showVerticalScrollbarIfNeeded, bool showHorizontalScrollbarIfNeeded, bool allowVerticalScrollingWithoutScrollbar=false, bool allowHorizontalScrollingWithoutScrollbar=false)
	Turns scrollbars on or off.
void	setScrollBarPosition (bool verticalScrollbarOnRight, bool horizontalScrollbarAtBottom)
	Changes where the scroll bars are positioned.
bool	isVerticalScrollbarOnTheRight () const noexcept
	True if the vertical scrollbar will appear on the right side of the content.
bool	isHorizontalScrollbarAtBottom () const noexcept
	True if the horizontal scrollbar will appear at the bottom of the content.
bool	isVerticalScrollBarShown () const noexcept
	True if the vertical scrollbar is enabled.
bool	isHorizontalScrollBarShown () const noexcept
	True if the horizontal scrollbar is enabled.
void	setScrollBarThickness (int thickness)
	Changes the width of the scrollbars.
int	getScrollBarThickness () const
	Returns the thickness of the scrollbars.
void	setSingleStepSizes (int stepX, int stepY)
	Changes the distance that a single-step click on a scrollbar button will move the viewport.
ScrollBar &	getVerticalScrollBar () noexcept
	Returns a reference to the scrollbar component being used.
ScrollBar &	getHorizontalScrollBar () noexcept
	Returns a reference to the scrollbar component being used.
void	recreateScrollbars ()
	Re-instantiates the scrollbars, which is only really useful if you've overridden createScrollBarComponent().
bool	canScrollVertically () const noexcept
	True if there's any off-screen content that could be scrolled vertically, or false if everything is currently visible.
bool	canScrollHorizontally () const noexcept
	True if there's any off-screen content that could be scrolled horizontally, or false if everything is currently visible.
void	setScrollOnDragEnabled (bool shouldScrollOnDrag)
	Enables or disables drag-to-scroll functionality for mouse sources in the viewport.
bool	isScrollOnDragEnabled () const noexcept
	Returns true if drag-to-scroll functionality is enabled for mouse input sources.
void	setScrollOnDragMode (ScrollOnDragMode scrollOnDragMode)
	Sets the current scroll-on-drag mode.
ScrollOnDragMode	getScrollOnDragMode () const
	Returns the current scroll-on-drag mode.
bool	isCurrentlyScrollingOnDrag () const noexcept
	Returns true if the user is currently dragging-to-scroll.
void	resized () override
	Called when this component's size has been changed.
void	scrollBarMoved (ScrollBar *, double newRangeStart) override
	Called when a ScrollBar is moved.
void	mouseWheelMove (const MouseEvent &, const MouseWheelDetails &) override
	Called when the mouse-wheel is moved.
void	mouseDown (const MouseEvent &e) override
	Called when a mouse button is pressed.
bool	keyPressed (const KeyPress &) override
	Called when a key is pressed.
void	componentMovedOrResized (Component &, bool wasMoved, bool wasResized) override
	Called when the component's position or size changes.
void	lookAndFeelChanged () override
	Called to let the component react to a change in the look-and-feel setting.
bool	useMouseWheelMoveIfNeeded (const MouseEvent &, const MouseWheelDetails &)
Public Member Functions inherited from Component
	Component () noexcept
	Creates a component.
	~Component () override
	Destructor.
	Component (const String &componentName) noexcept
	Creates a component, setting its name at the same time.
String	getName () const noexcept
	Returns the name of this component.
virtual void	setName (const String &newName)
	Sets the name of this component.
String	getComponentID () const noexcept
	Returns the ID string that was set by setComponentID().
void	setComponentID (const String &newID)
	Sets the component's ID string.
virtual void	setVisible (bool shouldBeVisible)
	Makes the component visible or invisible.
bool	isVisible () const noexcept
	Tests whether the component is visible or not.
virtual void	visibilityChanged ()
	Called when this component's visibility changes.
bool	isShowing () const
	Tests whether this component and all its parents are visible.
virtual void	addToDesktop (int windowStyleFlags, void *nativeWindowToAttachTo=nullptr)
	Makes this component appear as a window on the desktop.
void	removeFromDesktop ()
	If the component is currently showing on the desktop, this will hide it.
bool	isOnDesktop () const noexcept
	Returns true if this component is currently showing on the desktop.
ComponentPeer *	getPeer () const
	Returns the heavyweight window that contains this component.
virtual void	userTriedToCloseWindow ()
	For components on the desktop, this is called if the system wants to close the window.
virtual void	minimisationStateChanged (bool isNowMinimised)
	Called for a desktop component which has just been minimised or un-minimised.
virtual float	getDesktopScaleFactor () const
	Returns the default scale factor to use for this component when it is placed on the desktop.
void	toFront (bool shouldAlsoGainKeyboardFocus)
	Brings the component to the front of its siblings.
void	toBack ()
	Changes this component's z-order to be at the back of all its siblings.
void	toBehind (Component *other)
	Changes this component's z-order so that it's just behind another component.
void	setAlwaysOnTop (bool shouldStayOnTop)
	Sets whether the component should always be kept at the front of its siblings.
bool	isAlwaysOnTop () const noexcept
	Returns true if this component is set to always stay in front of its siblings.
int	getX () const noexcept
	Returns the x coordinate of the component's left edge.
int	getY () const noexcept
	Returns the y coordinate of the top of this component.
int	getWidth () const noexcept
	Returns the component's width in pixels.
int	getHeight () const noexcept
	Returns the component's height in pixels.
int	getRight () const noexcept
	Returns the x coordinate of the component's right-hand edge.
Point< int >	getPosition () const noexcept
	Returns the component's top-left position as a Point.
int	getBottom () const noexcept
	Returns the y coordinate of the bottom edge of this component.
Rectangle< int >	getBounds () const noexcept
	Returns this component's bounding box.
Rectangle< int >	getLocalBounds () const noexcept
	Returns the component's bounds, relative to its own origin.
Rectangle< int >	getBoundsInParent () const noexcept
	Returns the area of this component's parent which this component covers.
int	getScreenX () const
	Returns this component's x coordinate relative the screen's top-left origin.
int	getScreenY () const
	Returns this component's y coordinate relative the screen's top-left origin.
Point< int >	getScreenPosition () const
	Returns the position of this component's top-left corner relative to the screen's top-left.
Rectangle< int >	getScreenBounds () const
	Returns the bounds of this component, relative to the screen's top-left.
Point< int >	getLocalPoint (const Component *sourceComponent, Point< int > pointRelativeToSourceComponent) const
	Converts a point to be relative to this component's coordinate space.
Point< float >	getLocalPoint (const Component *sourceComponent, Point< float > pointRelativeToSourceComponent) const
	Converts a point to be relative to this component's coordinate space.
Rectangle< int >	getLocalArea (const Component *sourceComponent, Rectangle< int > areaRelativeToSourceComponent) const
	Converts a rectangle to be relative to this component's coordinate space.
Rectangle< float >	getLocalArea (const Component *sourceComponent, Rectangle< float > areaRelativeToSourceComponent) const
	Converts a rectangle to be relative to this component's coordinate space.
Point< int >	localPointToGlobal (Point< int > localPoint) const
	Converts a point relative to this component's top-left into a screen coordinate.
Point< float >	localPointToGlobal (Point< float > localPoint) const
	Converts a point relative to this component's top-left into a screen coordinate.
Rectangle< int >	localAreaToGlobal (Rectangle< int > localArea) const
	Converts a rectangle from this component's coordinate space to a screen coordinate.
Rectangle< float >	localAreaToGlobal (Rectangle< float > localArea) const
	Converts a rectangle from this component's coordinate space to a screen coordinate.
void	setTopLeftPosition (int x, int y)
	Moves the component to a new position.
void	setTopLeftPosition (Point< int > newTopLeftPosition)
	Moves the component to a new position.
void	setTopRightPosition (int x, int y)
	Moves the component to a new position.
void	setSize (int newWidth, int newHeight)
	Changes the size of the component.
void	setBounds (int x, int y, int width, int height)
	Changes the component's position and size.
void	setBounds (Rectangle< int > newBounds)
	Changes the component's position and size.
void	setBoundsRelative (float proportionalX, float proportionalY, float proportionalWidth, float proportionalHeight)
	Changes the component's position and size in terms of fractions of its parent's size.
void	setBoundsRelative (Rectangle< float > proportionalArea)
	Changes the component's position and size in terms of fractions of its parent's size.
void	setBoundsInset (BorderSize< int > borders)
	Changes the component's position and size based on the amount of space to leave around it.
void	setBoundsToFit (Rectangle< int > targetArea, Justification justification, bool onlyReduceInSize)
	Positions the component within a given rectangle, keeping its proportions unchanged.
void	setCentrePosition (int x, int y)
	Changes the position of the component's centre.
void	setCentrePosition (Point< int > newCentrePosition)
	Changes the position of the component's centre.
void	setCentreRelative (float x, float y)
	Changes the position of the component's centre.
void	centreWithSize (int width, int height)
	Changes the component's size and centres it within its parent.
void	setTransform (const AffineTransform &transform)
	Sets a transform matrix to be applied to this component.
AffineTransform	getTransform () const
	Returns the transform that is currently being applied to this component.
bool	isTransformed () const noexcept
	Returns true if a non-identity transform is being applied to this component.
int	proportionOfWidth (float proportion) const noexcept
	Returns a proportion of the component's width.
int	proportionOfHeight (float proportion) const noexcept
	Returns a proportion of the component's height.
int	getParentWidth () const noexcept
	Returns the width of the component's parent.
int	getParentHeight () const noexcept
	Returns the height of the component's parent.
Rectangle< int >	getParentMonitorArea () const
	Returns the screen coordinates of the monitor that contains this component.
int	getNumChildComponents () const noexcept
	Returns the number of child components that this component contains.
Component *	getChildComponent (int index) const noexcept
	Returns one of this component's child components, by it index.
int	getIndexOfChildComponent (const Component *child) const noexcept
	Returns the index of this component in the list of child components.
const Array< Component * > &	getChildren () const noexcept
	Provides access to the underlying array of child components.
Component *	findChildWithID (StringRef componentID) const noexcept
	Looks for a child component with the specified ID.
void	addChildComponent (Component *child, int zOrder=-1)
	Adds a child component to this one.
void	addChildComponent (Component &child, int zOrder=-1)
	Adds a child component to this one.
void	addAndMakeVisible (Component *child, int zOrder=-1)
	Adds a child component to this one, and also makes the child visible if it isn't already.
void	addAndMakeVisible (Component &child, int zOrder=-1)
	Adds a child component to this one, and also makes the child visible if it isn't already.
void	addChildAndSetID (Component *child, const String &componentID)
	Adds a child component to this one, makes it visible, and sets its component ID.
void	removeChildComponent (Component *childToRemove)
	Removes one of this component's child-components.
Component *	removeChildComponent (int childIndexToRemove)
	Removes one of this component's child-components by index.
void	removeAllChildren ()
	Removes all this component's children.
void	deleteAllChildren ()
	Removes and deletes all of this component's children.
Component *	getParentComponent () const noexcept
	Returns the component which this component is inside.
template<class TargetClass >
TargetClass *	findParentComponentOfClass () const
	Searches the parent components for a component of a specified class.
Component *	getTopLevelComponent () const noexcept
	Returns the highest-level component which contains this one or its parents.
bool	isParentOf (const Component *possibleChild) const noexcept
	Checks whether a component is anywhere inside this component or its children.
virtual void	parentHierarchyChanged ()
	Called to indicate that the component's parents have changed.
virtual void	childrenChanged ()
	Subclasses can use this callback to be told when children are added or removed, or when their z-order changes.
virtual bool	hitTest (int x, int y)
	Tests whether a given point is inside the component.
void	setInterceptsMouseClicks (bool allowClicksOnThisComponent, bool allowClicksOnChildComponents) noexcept
	Changes the default return value for the hitTest() method.
void	getInterceptsMouseClicks (bool &allowsClicksOnThisComponent, bool &allowsClicksOnChildComponents) const noexcept
	Retrieves the current state of the mouse-click interception flags.
bool	contains (Point< int > localPoint)
	Returns true if a given point lies within this component or one of its children.
bool	contains (Point< float > localPoint)
	Returns true if a given point lies within this component or one of its children.
bool	reallyContains (Point< int > localPoint, bool returnTrueIfWithinAChild)
	Returns true if a given point lies in this component, taking any overlapping siblings into account.
bool	reallyContains (Point< float > localPoint, bool returnTrueIfWithinAChild)
	Returns true if a given point lies in this component, taking any overlapping siblings into account.
Component *	getComponentAt (int x, int y)
	Returns the component at a certain point within this one.
Component *	getComponentAt (Point< int > position)
	Returns the component at a certain point within this one.
Component *	getComponentAt (Point< float > position)
	Returns the component at a certain point within this one.
void	repaint ()
	Marks the whole component as needing to be redrawn.
void	repaint (int x, int y, int width, int height)
	Marks a subsection of this component as needing to be redrawn.
void	repaint (Rectangle< int > area)
	Marks a subsection of this component as needing to be redrawn.
void	setBufferedToImage (bool shouldBeBuffered)
	Makes the component use an internal buffer to optimise its redrawing.
Image	createComponentSnapshot (Rectangle< int > areaToGrab, bool clipImageToComponentBounds=true, float scaleFactor=1.0f)
	Generates a snapshot of part of this component.
void	paintEntireComponent (Graphics &context, bool ignoreAlphaLevel)
	Draws this component and all its subcomponents onto the specified graphics context.
void	setPaintingIsUnclipped (bool shouldPaintWithoutClipping) noexcept
	This allows you to indicate that this component doesn't require its graphics context to be clipped when it is being painted.
bool	isPaintingUnclipped () const noexcept
	Returns true if this component doesn't require its graphics context to be clipped when it is being painted.
void	setComponentEffect (ImageEffectFilter *newEffect)
	Adds an effect filter to alter the component's appearance.
ImageEffectFilter *	getComponentEffect () const noexcept
	Returns the current component effect.
LookAndFeel &	getLookAndFeel () const noexcept
	Finds the appropriate look-and-feel to use for this component.
void	setLookAndFeel (LookAndFeel *newLookAndFeel)
	Sets the look and feel to use for this component.
void	sendLookAndFeelChange ()
	Calls the methods repaint(), lookAndFeelChanged(), and colourChanged() in this component and all its children recursively.
void	setOpaque (bool shouldBeOpaque)
	Indicates whether any parts of the component might be transparent.
bool	isOpaque () const noexcept
	Returns true if no parts of this component are transparent.
void	setBroughtToFrontOnMouseClick (bool shouldBeBroughtToFront) noexcept
	Indicates whether the component should be brought to the front when clicked.
bool	isBroughtToFrontOnMouseClick () const noexcept
	Indicates whether the component should be brought to the front when clicked-on.
void	setExplicitFocusOrder (int newFocusOrderIndex)
	Sets the focus order of this component.
int	getExplicitFocusOrder () const
	Returns the focus order of this component, if one has been specified.
void	setFocusContainerType (FocusContainerType containerType) noexcept
	Sets whether this component is a container for components that can have their focus traversed, and the type of focus traversal that it supports.
bool	isFocusContainer () const noexcept
	Returns true if this component has been marked as a focus container.
bool	isKeyboardFocusContainer () const noexcept
	Returns true if this component has been marked as a keyboard focus container.
Component *	findFocusContainer () const
	Returns the focus container for this component.
Component *	findKeyboardFocusContainer () const
	Returns the keyboard focus container for this component.
void	setWantsKeyboardFocus (bool wantsFocus) noexcept
	Sets a flag to indicate whether this component wants keyboard focus or not.
bool	getWantsKeyboardFocus () const noexcept
	Returns true if the component is interested in getting keyboard focus.
void	setMouseClickGrabsKeyboardFocus (bool shouldGrabFocus)
	Chooses whether a click on this component automatically grabs the focus.
bool	getMouseClickGrabsKeyboardFocus () const noexcept
	Returns the last value set with setMouseClickGrabsKeyboardFocus().
void	grabKeyboardFocus ()
	Tries to give keyboard focus to this component.
void	giveAwayKeyboardFocus ()
	If this component or any of its children currently have the keyboard focus, this will defocus it, send a focus change notification, and try to pass the focus to the next component.
bool	hasKeyboardFocus (bool trueIfChildIsFocused) const
	Returns true if this component currently has the keyboard focus.
void	moveKeyboardFocusToSibling (bool moveToNext)
	Tries to move the keyboard focus to one of this component's siblings.
virtual std::unique_ptr< ComponentTraverser >	createFocusTraverser ()
	Creates a ComponentTraverser object to determine the logic by which focus should be passed from this component.
virtual std::unique_ptr< ComponentTraverser >	createKeyboardFocusTraverser ()
	Creates a ComponentTraverser object to use to determine the logic by which keyboard focus should be passed from this component.
void	setHasFocusOutline (bool hasFocusOutline) noexcept
	Use this to indicate that the component should have an outline drawn around it when it has keyboard focus.
bool	hasFocusOutline () const noexcept
	Returns true if this component should have a focus outline.
bool	isEnabled () const noexcept
	Returns true if the component (and all its parents) are enabled.
void	setEnabled (bool shouldBeEnabled)
	Enables or disables this component.
virtual void	enablementChanged ()
	Callback to indicate that this component has been enabled or disabled.
float	getAlpha () const noexcept
	Returns the component's current transparency level.
void	setAlpha (float newAlpha)
	Changes the transparency of this component.
virtual void	alphaChanged ()
	Called when setAlpha() is used to change the alpha value of this component.
void	setMouseCursor (const MouseCursor &cursorType)
	Changes the mouse cursor shape to use when the mouse is over this component.
virtual MouseCursor	getMouseCursor ()
	Returns the mouse cursor shape to use when the mouse is over this component.
void	updateMouseCursor () const
	Forces the current mouse cursor to be updated.
virtual void	paint (Graphics &g)
	Components can override this method to draw their content.
virtual void	paintOverChildren (Graphics &g)
	Components can override this method to draw over the top of their children.
void	mouseMove (const MouseEvent &event) override
	Called when the mouse moves inside a component.
void	mouseEnter (const MouseEvent &event) override
	Called when the mouse first enters a component.
void	mouseExit (const MouseEvent &event) override
	Called when the mouse moves out of a component.
void	mouseDrag (const MouseEvent &event) override
	Called when the mouse is moved while a button is held down.
void	mouseUp (const MouseEvent &event) override
	Called when a mouse button is released.
void	mouseDoubleClick (const MouseEvent &event) override
	Called when a mouse button has been double-clicked on a component.
void	mouseMagnify (const MouseEvent &event, float scaleFactor) override
	Called when a pinch-to-zoom mouse-gesture is used.
void	setRepaintsOnMouseActivity (bool shouldRepaint) noexcept
	Causes automatic repaints when the mouse enters or exits this component.
void	addMouseListener (MouseListener *newListener, bool wantsEventsForAllNestedChildComponents)
	Registers a listener to be told when mouse events occur in this component.
void	removeMouseListener (MouseListener *listenerToRemove)
	Deregisters a mouse listener.
void	addKeyListener (KeyListener *newListener)
	Adds a listener that wants to hear about keypresses that this component receives.
void	removeKeyListener (KeyListener *listenerToRemove)
	Removes a previously-registered key listener.
virtual bool	keyStateChanged (bool isKeyDown)
	Called when a key is pressed or released.
virtual void	modifierKeysChanged (const ModifierKeys &modifiers)
	Called when a modifier key is pressed or released.
virtual void	focusGained (FocusChangeType cause)
	Called to indicate that this component has just acquired the keyboard focus.
virtual void	focusGainedWithDirection (FocusChangeType cause, FocusChangeDirection direction)
	Called to indicate that this component has just acquired the keyboard focus.
virtual void	focusLost (FocusChangeType cause)
	Called to indicate that this component has just lost the keyboard focus.
virtual void	focusOfChildComponentChanged (FocusChangeType cause)
	Called to indicate a change in whether or not this component is the parent of the currently-focused component.
bool	isMouseOver (bool includeChildren=false) const
	Returns true if the mouse is currently over this component.
bool	isMouseButtonDown (bool includeChildren=false) const
	Returns true if the mouse button is currently held down in this component.
bool	isMouseOverOrDragging (bool includeChildren=false) const
	True if the mouse is over this component, or if it's being dragged in this component.
Point< int >	getMouseXYRelative () const
	Returns the mouse's current position, relative to this component.
virtual void	moved ()
	Called when this component's position has been changed.
virtual void	childBoundsChanged (Component *child)
	Called when one of this component's children is moved or resized.
virtual void	parentSizeChanged ()
	Called when this component's immediate parent has been resized.
virtual void	broughtToFront ()
	Called when this component has been moved to the front of its siblings.
void	addComponentListener (ComponentListener *newListener)
	Adds a listener to be told about changes to the component hierarchy or position.
void	removeComponentListener (ComponentListener *listenerToRemove)
	Removes a component listener.
void	postCommandMessage (int commandId)
	Dispatches a numbered message to this component.
virtual void	handleCommandMessage (int commandId)
	Called to handle a command that was sent by postCommandMessage().
int	runModalLoop ()
	Runs a component modally, waiting until the loop terminates.
void	enterModalState (bool takeKeyboardFocus=true, ModalComponentManager::Callback *callback=nullptr, bool deleteWhenDismissed=false)
	Puts the component into a modal state.
void	exitModalState (int returnValue=0)
	Ends a component's modal state.
bool	isCurrentlyModal (bool onlyConsiderForemostModalComponent=true) const noexcept
	Returns true if this component is the modal one.
bool	isCurrentlyBlockedByAnotherModalComponent () const
	Checks whether there's a modal component somewhere that's stopping this one from receiving messages.
virtual bool	canModalEventBeSentToComponent (const Component *targetComponent)
	When a component is modal, this callback allows it to choose which other components can still receive events.
virtual void	inputAttemptWhenModal ()
	Called when the user tries to click on a component that is blocked by another modal component.
NamedValueSet &	getProperties () noexcept
	Returns the set of properties that belong to this component.
const NamedValueSet &	getProperties () const noexcept
	Returns the set of properties that belong to this component.
Colour	findColour (int colourID, bool inheritFromParent=false) const
	Looks for a colour that has been registered with the given colour ID number.
void	setColour (int colourID, Colour newColour)
	Registers a colour to be used for a particular purpose.
void	removeColour (int colourID)
	If a colour has been set with setColour(), this will remove it.
bool	isColourSpecified (int colourID) const
	Returns true if the specified colour ID has been explicitly set for this component using the setColour() method.
void	copyAllExplicitColoursTo (Component &target) const
	This looks for any colours that have been specified for this component, and copies them to the specified target component.
virtual void	colourChanged ()
	This method is called when a colour is changed by the setColour() method, or when the look-and-feel is changed by the setLookAndFeel() or sendLookAndFeelChanged() methods.
void *	getWindowHandle () const
	Returns the underlying native window handle for this component.
Positioner *	getPositioner () const noexcept
	Returns the Positioner object that has been set for this component.
void	setPositioner (Positioner *newPositioner)
	Sets a new Positioner object for this component.
void	setCachedComponentImage (CachedComponentImage *newCachedImage)
	Gives the component a CachedComponentImage that should be used to buffer its painting.
CachedComponentImage *	getCachedComponentImage () const noexcept
	Returns the object that was set by setCachedComponentImage().
void	setViewportIgnoreDragFlag (bool ignoreDrag) noexcept
	Sets a flag to indicate whether mouse drag events on this Component should be ignored when it is inside a Viewport with drag-to-scroll functionality enabled.
bool	getViewportIgnoreDragFlag () const noexcept
	Retrieves the current state of the Viewport drag-to-scroll functionality flag.
String	getTitle () const noexcept
	Returns the title text for this component.
void	setTitle (const String &newTitle)
	Sets the title for this component.
String	getDescription () const noexcept
	Returns the description for this component.
void	setDescription (const String &newDescription)
	Sets the description for this component.
String	getHelpText () const noexcept
	Returns the help text for this component.
void	setHelpText (const String &newHelpText)
	Sets the help text for this component.
void	setAccessible (bool shouldBeAccessible)
	Sets whether this component and its children are visible to accessibility clients.
bool	isAccessible () const noexcept
	Returns true if this component and its children are visible to accessibility clients.
AccessibilityHandler *	getAccessibilityHandler ()
	Returns the accessibility handler for this component, or nullptr if this component is not accessible.
void	invalidateAccessibilityHandler ()
	Invalidates the AccessibilityHandler that is currently being used for this component.
virtual std::unique_ptr< AccessibilityHandler >	createAccessibilityHandler ()
	Override this method to return a custom AccessibilityHandler for this component.
Public Member Functions inherited from MouseListener
virtual	~MouseListener ()=default
	Destructor.

Static Public Member Functions
static bool	respondsToKey (const KeyPress &)
Static Public Member Functions inherited from Component
static float JUCE_CALLTYPE	getApproximateScaleFactorForComponent (const Component *targetComponent)
	Returns the approximate scale factor for a given component by traversing its parent hierarchy and applying each transform and finally scaling this by the global scale factor.
static Component *JUCE_CALLTYPE	getCurrentlyFocusedComponent () noexcept
	Returns the component that currently has the keyboard focus.
static void JUCE_CALLTYPE	unfocusAllComponents ()
	If any component has keyboard focus, this will defocus it.
static void JUCE_CALLTYPE	beginDragAutoRepeat (int millisecondsBetweenCallbacks)
	Ensures that a non-stop stream of mouse-drag events will be sent during the current mouse-drag operation.
static bool JUCE_CALLTYPE	isMouseButtonDownAnywhere () noexcept
	Returns true if a mouse button is currently down.
static int JUCE_CALLTYPE	getNumCurrentlyModalComponents () noexcept
	Returns the number of components that are currently in a modal state.
static Component *JUCE_CALLTYPE	getCurrentlyModalComponent (int index=0) noexcept
	Returns one of the components that are currently modal.

Protected Member Functions
virtual ScrollBar *	createScrollBarComponent (bool isVertical)
	Creates the Scrollbar components that will be added to the Viewport.

Detailed Description

A Viewport is used to contain a larger child component, and allows the child to be automatically scrolled around.

To use a Viewport, just create one and set the component that goes inside it using the setViewedComponent() method. When the child component changes size, the Viewport will adjust its scrollbars accordingly.

A subclass of the viewport can be created which will receive calls to its visibleAreaChanged() method when the subcomponent changes position or size.

Member Enumeration Documentation

ScrollOnDragMode

enum class Viewport::ScrollOnDragMode

strong

Enumerator
never	Dragging will never scroll the viewport.
nonHover	Dragging will only scroll the viewport if the input source cannot hover.
all	Dragging will always scroll the viewport.

Constructor & Destructor Documentation

Viewport()

Viewport::Viewport ( const String & componentName = String() )

explicit

Creates a Viewport.

The viewport is initially empty - use the setViewedComponent() method to add a child component for it to manage.

~Viewport()

Viewport::~Viewport ( )

override

Destructor.

Member Function Documentation

setViewedComponent()

void Viewport::setViewedComponent	(	Component *	newViewedComponent,
		bool	deleteComponentWhenNoLongerNeeded = true )

Sets the component that this viewport will contain and scroll around.

This will add the given component to this Viewport and position it at (0, 0).

(Don't add or remove any child components directly using the normal Component::addChildComponent() methods).

Parameters

newViewedComponent	the component to add to this viewport, or null to remove the current component.
deleteComponentWhenNoLongerNeeded	if true, the component will be deleted automatically when the viewport is deleted or when a different component is added. If false, the caller must manage the lifetime of the component

See also

getViewedComponent

getViewedComponent()

Component * Viewport::getViewedComponent ( ) const

noexcept

Returns the component that's currently being used inside the Viewport.

See also

setViewedComponent

setViewPosition() [1/2]

void Viewport::setViewPosition	(	int	xPixelsOffset,
		int	yPixelsOffset )

Changes the position of the viewed component.

The inner component will be moved so that the pixel at the top left of the viewport will be the pixel at position (xPixelsOffset, yPixelsOffset) within the inner component.

This will update the scrollbars and might cause a call to visibleAreaChanged().

See also

getViewPositionX, getViewPositionY, setViewPositionProportionately

setViewPosition() [2/2]

void Viewport::setViewPosition

(

Point< int >

newPosition

)

Changes the position of the viewed component.

The inner component will be moved so that the pixel at the top left of the viewport will be the pixel at the specified coordinates within the inner component.

This will update the scrollbars and might cause a call to visibleAreaChanged().

See also

getViewPositionX, getViewPositionY, setViewPositionProportionately

setViewPositionProportionately()

void Viewport::setViewPositionProportionately	(	double	proportionX,
		double	proportionY )

Changes the view position as a proportion of the distance it can move.

The values here are from 0.0 to 1.0 - where (0, 0) would put the visible area in the top-left, and (1, 1) would put it as far down and to the right as it's possible to go whilst keeping the child component on-screen.

autoScroll()

bool Viewport::autoScroll	(	int	mouseX,
		int	mouseY,
		int	distanceFromEdge,
		int	maximumSpeed )

If the specified position is at the edges of the viewport, this method scrolls the viewport to bring that position nearer to the centre.

Call this if you're dragging an object inside a viewport and want to make it scroll when the user approaches an edge. You might also find Component::beginDragAutoRepeat() useful when auto-scrolling.

Parameters

mouseX	the x position, relative to the Viewport's top-left
mouseY	the y position, relative to the Viewport's top-left
distanceFromEdge	specifies how close to an edge the position needs to be before the viewport should scroll in that direction
maximumSpeed	the maximum number of pixels that the viewport is allowed to scroll by.

Returns

true if the viewport was scrolled

getViewPosition()

Point< int > Viewport::getViewPosition ( ) const

noexcept

Returns the position within the child component of the top-left of its visible area.

getViewArea()

Rectangle< int > Viewport::getViewArea ( ) const

noexcept

Returns the visible area of the child component, relative to its top-left.

getViewPositionX()

int Viewport::getViewPositionX ( ) const

noexcept

Returns the position within the child component of the top-left of its visible area.

See also

getViewWidth, setViewPosition

getViewPositionY()

int Viewport::getViewPositionY ( ) const

noexcept

Returns the position within the child component of the top-left of its visible area.

See also

getViewHeight, setViewPosition

getViewWidth()

int Viewport::getViewWidth ( ) const

noexcept

Returns the width of the visible area of the child component.

This may be less than the width of this Viewport if there's a vertical scrollbar or if the child component is itself smaller.

getViewHeight()

int Viewport::getViewHeight ( ) const

noexcept

Returns the height of the visible area of the child component.

This may be less than the height of this Viewport if there's a horizontal scrollbar or if the child component is itself smaller.

getMaximumVisibleWidth()

int Viewport::getMaximumVisibleWidth

(

)

const

Returns the width available within this component for the contents.

This will be the width of the viewport component minus the width of a vertical scrollbar (if visible).

getMaximumVisibleHeight()

int Viewport::getMaximumVisibleHeight

(

)

const

Returns the height available within this component for the contents.

This will be the height of the viewport component minus the space taken up by a horizontal scrollbar (if visible).

visibleAreaChanged()

virtual void Viewport::visibleAreaChanged ( const Rectangle< int > & newVisibleArea )

virtual

Callback method that is called when the visible area changes.

This will be called when the visible area is moved either be scrolling or by calls to setViewPosition(), etc.

viewedComponentChanged()

virtual void Viewport::viewedComponentChanged ( Component * newComponent )

virtual

Callback method that is called when the viewed component is added, removed or swapped.

setScrollBarsShown()

void Viewport::setScrollBarsShown	(	bool	showVerticalScrollbarIfNeeded,
		bool	showHorizontalScrollbarIfNeeded,
		bool	allowVerticalScrollingWithoutScrollbar = false,
		bool	allowHorizontalScrollingWithoutScrollbar = false )

Turns scrollbars on or off.

If set to false, the scrollbars won't ever appear. When true (the default) they will appear only when needed.

The allowVerticalScrollingWithoutScrollbar parameters allow you to enable mouse-wheel scrolling even when there the scrollbars are hidden. When the scrollbars are visible, these parameters are ignored.

setScrollBarPosition()

void Viewport::setScrollBarPosition	(	bool	verticalScrollbarOnRight,
		bool	horizontalScrollbarAtBottom )

Changes where the scroll bars are positioned.

If verticalScrollbarOnRight is set to true, then the vertical scrollbar will appear on the right side of the view port's content (this is the default), otherwise it will be on the left side of the content.

If horizontalScrollbarAtBottom is set to true, then the horizontal scrollbar will appear at the bottom of the view port's content (this is the default), otherwise it will be at the top.

isVerticalScrollbarOnTheRight()

bool Viewport::isVerticalScrollbarOnTheRight ( ) const

noexcept

True if the vertical scrollbar will appear on the right side of the content.

isHorizontalScrollbarAtBottom()

bool Viewport::isHorizontalScrollbarAtBottom ( ) const

noexcept

True if the horizontal scrollbar will appear at the bottom of the content.

isVerticalScrollBarShown()

bool Viewport::isVerticalScrollBarShown ( ) const

noexcept

True if the vertical scrollbar is enabled.

See also

setScrollBarsShown

isHorizontalScrollBarShown()

bool Viewport::isHorizontalScrollBarShown ( ) const

noexcept

True if the horizontal scrollbar is enabled.

See also

setScrollBarsShown

setScrollBarThickness()

void Viewport::setScrollBarThickness

(

int

thickness

)

Changes the width of the scrollbars.

If this isn't specified, the default width from the LookAndFeel class will be used.

See also

LookAndFeel::getDefaultScrollbarWidth

getScrollBarThickness()

int Viewport::getScrollBarThickness

(

)

const

Returns the thickness of the scrollbars.

See also

setScrollBarThickness

setSingleStepSizes()

void Viewport::setSingleStepSizes	(	int	stepX,
		int	stepY )

Changes the distance that a single-step click on a scrollbar button will move the viewport.

getVerticalScrollBar()

ScrollBar & Viewport::getVerticalScrollBar ( )

noexcept

Returns a reference to the scrollbar component being used.

Handy if you need to customise the bar somehow.

getHorizontalScrollBar()

ScrollBar & Viewport::getHorizontalScrollBar ( )

noexcept

Returns a reference to the scrollbar component being used.

Handy if you need to customise the bar somehow.

recreateScrollbars()

void Viewport::recreateScrollbars

(

)

Re-instantiates the scrollbars, which is only really useful if you've overridden createScrollBarComponent().

canScrollVertically()

bool Viewport::canScrollVertically ( ) const

noexcept

True if there's any off-screen content that could be scrolled vertically, or false if everything is currently visible.

canScrollHorizontally()

bool Viewport::canScrollHorizontally ( ) const

noexcept

True if there's any off-screen content that could be scrolled horizontally, or false if everything is currently visible.

setScrollOnDragEnabled()

void Viewport::setScrollOnDragEnabled

(

bool

shouldScrollOnDrag

)

Enables or disables drag-to-scroll functionality for mouse sources in the viewport.

If your viewport contains a Component that you don't want to receive mouse events when the user is drag-scrolling, you can disable this with the Component::setViewportIgnoreDragFlag() method.

isScrollOnDragEnabled()

bool Viewport::isScrollOnDragEnabled ( ) const

noexcept

Returns true if drag-to-scroll functionality is enabled for mouse input sources.

setScrollOnDragMode()

void Viewport::setScrollOnDragMode

(

ScrollOnDragMode

scrollOnDragMode

)

Sets the current scroll-on-drag mode.

The default is ScrollOnDragMode::nonHover.

If your viewport contains a Component that you don't want to receive mouse events when the user is drag-scrolling, you can disable this with the Component::setViewportIgnoreDragFlag() method.

getScrollOnDragMode()

ScrollOnDragMode Viewport::getScrollOnDragMode

(

)

const

Returns the current scroll-on-drag mode.

isCurrentlyScrollingOnDrag()

bool Viewport::isCurrentlyScrollingOnDrag ( ) const

noexcept

Returns true if the user is currently dragging-to-scroll.

See also

setScrollOnDragEnabled

resized()

void Viewport::resized ( )

overridevirtual

Called when this component's size has been changed.

A component can implement this method to do things such as laying out its child components when its width or height changes.

The method is called synchronously as a result of the setBounds or setSize methods, so repeatedly changing a components size will repeatedly call its resized method (unlike things like repainting, where multiple calls to repaint are coalesced together).

If the component is a top-level window on the desktop, its size could also be changed by operating-system factors beyond the application's control.

See also

moved, setSize

Reimplemented from Component.

scrollBarMoved()

void Viewport::scrollBarMoved ( ScrollBar * scrollBarThatHasMoved, double newRangeStart )

overridevirtual

Called when a ScrollBar is moved.

Parameters

scrollBarThatHasMoved	the bar that has moved
newRangeStart	the new range start of this bar

Implements ScrollBar::Listener.

mouseWheelMove()

void Viewport::mouseWheelMove ( const MouseEvent & event, const MouseWheelDetails & wheel )

overridevirtual

Called when the mouse-wheel is moved.

This callback is sent to the component that the mouse is over when the wheel is moved.

If not overridden, a component will forward this message to its parent, so that parent components can collect mouse-wheel messages that happen to child components which aren't interested in them. (Bear in mind that if you attach a component as a mouse-listener to other components, then those wheel moves will also end up calling this method and being passed up to the parents, which may not be what you intended to happen).

Parameters

event	details about the mouse event
wheel	details about the mouse wheel movement

Reimplemented from Component.

mouseDown()

void Viewport::mouseDown ( const MouseEvent & event )

overridevirtual

Called when a mouse button is pressed.

The MouseEvent object passed in contains lots of methods for finding out which button was pressed, as well as which modifier keys (e.g. shift, ctrl) were held down at the time.

Once a button is held down, the mouseDrag method will be called when the mouse moves, until the button is released.

Parameters

event

details about the position and status of the mouse event, including the source component in which it occurred

See also

mouseUp, mouseDrag, mouseDoubleClick, contains

Reimplemented from Component.

keyPressed()

bool Viewport::keyPressed ( const KeyPress & key )

overridevirtual

Called when a key is pressed.

When a key is pressed, the component that has the keyboard focus will have this method called. Remember that a component will only be given the focus if its setWantsKeyboardFocus() method has been used to enable this.

If your implementation returns true, the event will be consumed and not passed on to any other listeners. If it returns false, the key will be passed to any KeyListeners that have been registered with this component. As soon as one of these returns true, the process will stop, but if they all return false, the event will be passed upwards to this component's parent, and so on.

The default implementation of this method does nothing and returns false.

See also

keyStateChanged, getCurrentlyFocusedComponent, addKeyListener

Reimplemented from Component.

componentMovedOrResized()

void Viewport::componentMovedOrResized ( Component & component, bool wasMoved, bool wasResized )

overridevirtual

Called when the component's position or size changes.

Parameters

component	the component that was moved or resized
wasMoved	true if the component's top-left corner has just moved
wasResized	true if the component's width or height has just changed

See also

Component::setBounds, Component::resized, Component::moved

Reimplemented from ComponentListener.

lookAndFeelChanged()

void Viewport::lookAndFeelChanged ( )

overridevirtual

Called to let the component react to a change in the look-and-feel setting.

When the look-and-feel is changed for a component, this method, repaint(), and colourChanged() are called on the original component and all its children recursively.

It can also be triggered manually by the sendLookAndFeelChange() method, in case an application uses a LookAndFeel class that might have changed internally.

See also

sendLookAndFeelChange, getLookAndFeel

Reimplemented from Component.

useMouseWheelMoveIfNeeded()

bool Viewport::useMouseWheelMoveIfNeeded	(	const MouseEvent &	,
		const MouseWheelDetails &	)

respondsToKey()

static bool Viewport::respondsToKey ( const KeyPress & )

static

createScrollBarComponent()

virtual ScrollBar * Viewport::createScrollBarComponent ( bool isVertical )

protectedvirtual

Creates the Scrollbar components that will be added to the Viewport.

Subclasses can override this if they need to customise the scrollbars in some way.

References ScrollBar::createAccessibilityHandler(), and Component::forward.

---

The documentation for this class was generated from the following file:

• juce_Viewport.h