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Classes | Public Types | Public Member Functions | List of all members
ScrollBar Class Reference
juce_gui_basics » layout

A scrollbar component. More...

`#include <juce_ScrollBar.h>`

Inheritance diagram for ScrollBar:

## Classes
class | Listener
| A class for receiving events from a ScrollBar. More...
struct | LookAndFeelMethods
| This abstract base class is implemented by LookAndFeel classes to provide scrollbar-drawing functionality. More...

## Public Types
enum | ColourIds { backgroundColourId = 0x1000300 , thumbColourId = 0x1000400 , trackColourId = 0x1000401 }
| A set of colour IDs to use to change the colour of various aspects of the component. More...
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
| ScrollBar (bool isVertical)
| Creates a Scrollbar.
| ~ScrollBar () override
| Destructor.
bool | isVertical () const noexcept
| Returns true if the scrollbar is vertical, false if it's horizontal.
void | setOrientation (bool shouldBeVertical)
| Changes the scrollbar's direction.
void | setAutoHide (bool shouldHideWhenFullRange)
| Tells the scrollbar whether to make itself invisible when not needed.
bool | autoHides () const noexcept
| Returns true if this scrollbar is set to auto-hide when its thumb is as big as its maximum range.
void | setRangeLimits (Range< double > newRangeLimit, NotificationType notification=sendNotificationAsync)
| Sets the minimum and maximum values that the bar will move between.
void | setRangeLimits (double minimum, double maximum, NotificationType notification=sendNotificationAsync)
| Sets the minimum and maximum values that the bar will move between.
Range< double > | getRangeLimit () const noexcept
| Returns the current limits on the thumb position.
double | getMinimumRangeLimit () const noexcept
| Returns the lower value that the thumb can be set to.
double | getMaximumRangeLimit () const noexcept
| Returns the upper value that the thumb can be set to.
bool | setCurrentRange (Range< double > newRange, NotificationType notification=sendNotificationAsync)
| Changes the position of the scrollbar's 'thumb'.
void | setCurrentRange (double newStart, double newSize, NotificationType notification=sendNotificationAsync)
| Changes the position of the scrollbar's 'thumb'.
void | setCurrentRangeStart (double newStart, NotificationType notification=sendNotificationAsync)
| Moves the bar's thumb position.
Range< double > | getCurrentRange () const noexcept
| Returns the current thumb range.
double | getCurrentRangeStart () const noexcept
| Returns the position of the top of the thumb.
double | getCurrentRangeSize () const noexcept
| Returns the current size of the thumb.
void | setSingleStepSize (double newSingleStepSize) noexcept
| Sets the amount by which the up and down buttons will move the bar.
double | getSingleStepSize () const noexcept
| Returns the current step size.
bool | moveScrollbarInSteps (int howManySteps, NotificationType notification=sendNotificationAsync)
| Moves the scrollbar by a number of single-steps.
bool | moveScrollbarInPages (int howManyPages, NotificationType notification=sendNotificationAsync)
| Moves the scroll bar up or down in pages.
bool | scrollToTop (NotificationType notification=sendNotificationAsync)
| Scrolls to the top (or left).
bool | scrollToBottom (NotificationType notification=sendNotificationAsync)
| Scrolls to the bottom (or right).
void | setButtonRepeatSpeed (int initialDelayInMillisecs, int repeatDelayInMillisecs, int minimumDelayInMillisecs=-1)
| Changes the delay before the up and down buttons autorepeat when they are held down.
void | addListener (Listener *listener)
| Registers a listener that will be called when the scrollbar is moved.
void | removeListener (Listener *listener)
| Deregisters a previously-registered listener.
bool | keyPressed (const KeyPress &) override
| Called when a key is pressed.
void | mouseWheelMove (const MouseEvent &, const MouseWheelDetails &) override
| Called when the mouse-wheel is moved.
void | lookAndFeelChanged () override
| Called to let the component react to a change in the look-and-feel setting.
void | mouseDown (const MouseEvent &) override
| Called when a mouse button is pressed.
void | mouseDrag (const MouseEvent &) override
| Called when the mouse is moved while a button is held down.
void | mouseUp (const MouseEvent &) override
| Called when a mouse button is released.
void | paint (Graphics &) override
| Components can override this method to draw their content.
void | resized () override
| Called when this component's size has been changed.
void | parentHierarchyChanged () override
| Called to indicate that the component's parents have changed.
void | setVisible (bool) override
| Makes the component visible or invisible.
std::unique_ptr< AccessibilityHandler > | createAccessibilityHandler () override
| Override this method to return a custom AccessibilityHandler for this component.
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.
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 | 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 | 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 | 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.
Public Member Functions inherited from MouseListener
virtual | ~MouseListener ()=default
| Destructor.
Public Member Functions inherited from AsyncUpdater
| AsyncUpdater ()
| Creates an AsyncUpdater object.
virtual | ~AsyncUpdater ()
| Destructor.
void | triggerAsyncUpdate ()
| Causes the callback to be triggered at a later time.
void | cancelPendingUpdate () noexcept
| This will stop any pending updates from happening.
void | handleUpdateNowIfNeeded ()
| If an update has been triggered and is pending, this will invoke it synchronously.
bool | isUpdatePending () const noexcept
| Returns true if there's an update callback in the pipeline.

## Additional Inherited Members
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.

## Detailed Description

A scrollbar component.

To use a scrollbar, set up its total range using the setRangeLimits() method - this sets the range of values it can represent. Then you can use setCurrentRange() to change the position and size of the scrollbar's 'thumb'.

Registering a ScrollBar::Listener with the scrollbar will allow you to find out when the user moves it, and you can use the getCurrentRangeStart() to find out where they moved it to.

The scrollbar will adjust its own visibility according to whether its thumb size allows it to actually be scrolled.

For most purposes, it's probably easier to use a Viewport or ListBox instead of handling a scrollbar directly.

See also
  ScrollBar::Listener

## Member Enumeration Documentation

## ◆ ColourIds

enum ScrollBar::ColourIds

A set of colour IDs to use to change the colour of various aspects of the component.

These constants can be used either via the Component::setColour(), or LookAndFeel::setColour() methods.

See also
  Component::setColour, Component::findColour, LookAndFeel::setColour, LookAndFeel::findColour

Enumerator
backgroundColourId | The background colour of the scrollbar.
thumbColourId | A base colour to use for the thumb. The look and feel will probably use variations on this colour.
trackColourId | A base colour to use for the slot area of the bar. The look and feel will probably use variations on this colour.

## Constructor & Destructor Documentation

## ◆ ScrollBar()

ScrollBar::ScrollBar | ( | bool | isVertical | ) |

Creates a Scrollbar.

Parameters

  isVertical | specifies whether the bar should be a vertical or horizontal

## ◆ ~ScrollBar()

ScrollBar::~ScrollBar | ( |  | ) |
| override

Destructor.

## Member Function Documentation

## ◆ isVertical()

bool ScrollBar::isVertical | ( |  | ) | const
| noexcept

Returns true if the scrollbar is vertical, false if it's horizontal.

## ◆ setOrientation()

void ScrollBar::setOrientation | ( | bool | shouldBeVertical | ) |

Changes the scrollbar's direction.

You'll also need to resize the bar appropriately - this just changes its internal layout.

Parameters

  shouldBeVertical | true makes it vertical; false makes it horizontal.

## ◆ setAutoHide()

void ScrollBar::setAutoHide | ( | bool | shouldHideWhenFullRange | ) |

Tells the scrollbar whether to make itself invisible when not needed.

The default behaviour is for a scrollbar to become invisible when the thumb fills the whole of its range (i.e. when it can't be moved). Setting this value to false forces the bar to always be visible.

See also
  autoHides()

## ◆ autoHides()

bool ScrollBar::autoHides | ( |  | ) | const
| noexcept

Returns true if this scrollbar is set to auto-hide when its thumb is as big as its maximum range.

See also
  setAutoHide

## ◆ setRangeLimits() [1/2]

void ScrollBar::setRangeLimits | ( | Range< double > | newRangeLimit,
|  | NotificationType | notification = sendNotificationAsync )

Sets the minimum and maximum values that the bar will move between.

The bar's thumb will always be constrained so that the entire thumb lies within this range.

Parameters

  newRangeLimit | the new range.
  notification | whether to send a notification of the change to listeners. A notification will only be sent if the range has changed.

See also
  setCurrentRange

## ◆ setRangeLimits() [2/2]

void ScrollBar::setRangeLimits | ( | double | minimum,
|  | double | maximum,
|  | NotificationType | notification = sendNotificationAsync )

Sets the minimum and maximum values that the bar will move between.

The bar's thumb will always be constrained so that the entire thumb lies within this range.

Parameters

  minimum | the new range minimum.
  maximum | the new range maximum.
  notification | whether to send a notification of the change to listeners. A notification will only be sent if the range has changed.

See also
  setCurrentRange

## ◆ getRangeLimit()

Range< double > ScrollBar::getRangeLimit | ( |  | ) | const
| noexcept

Returns the current limits on the thumb position.

See also
  setRangeLimits

## ◆ getMinimumRangeLimit()

double ScrollBar::getMinimumRangeLimit | ( |  | ) | const
| noexcept

Returns the lower value that the thumb can be set to.

This is the value set by setRangeLimits().

## ◆ getMaximumRangeLimit()

double ScrollBar::getMaximumRangeLimit | ( |  | ) | const
| noexcept

Returns the upper value that the thumb can be set to.

This is the value set by setRangeLimits().

## ◆ setCurrentRange() [1/2]

bool ScrollBar::setCurrentRange | ( | Range< double > | newRange,
|  | NotificationType | notification = sendNotificationAsync )

Changes the position of the scrollbar's 'thumb'.

This sets both the position and size of the thumb - to just set the position without changing the size, you can use setCurrentRangeStart().

If this method call actually changes the scrollbar's position, it will trigger an asynchronous call to ScrollBar::Listener::scrollBarMoved() for all the listeners that are registered.

The notification parameter can be used to optionally send or inhibit a callback to any scrollbar listeners.

Returns
  true if the range was changed, or false if nothing was changed.

See also
  getCurrentRange. setCurrentRangeStart

## ◆ setCurrentRange() [2/2]

void ScrollBar::setCurrentRange | ( | double | newStart,
|  | double | newSize,
|  | NotificationType | notification = sendNotificationAsync )

Changes the position of the scrollbar's 'thumb'.

This sets both the position and size of the thumb - to just set the position without changing the size, you can use setCurrentRangeStart().

Parameters

  newStart | the top (or left) of the thumb, in the range getMinimumRangeLimit() <= newStart <= getMaximumRangeLimit(). If the value is beyond these limits, it will be clipped.
  newSize | the size of the thumb, such that getMinimumRangeLimit() <= newStart + newSize <= getMaximumRangeLimit(). If the size is beyond these limits, it will be clipped.
  notification | specifies if and how a callback should be made to any listeners if the range actually changes

See also
  setCurrentRangeStart, getCurrentRangeStart, getCurrentRangeSize

## ◆ setCurrentRangeStart()

void ScrollBar::setCurrentRangeStart | ( | double | newStart,
|  | NotificationType | notification = sendNotificationAsync )

Moves the bar's thumb position.

This will move the thumb position without changing the thumb size. Note that the maximum thumb start position is (getMaximumRangeLimit() - getCurrentRangeSize()).

If this method call actually changes the scrollbar's position, it will trigger an asynchronous call to ScrollBar::Listener::scrollBarMoved() for all the listeners that are registered.

See also
  setCurrentRange

## ◆ getCurrentRange()

Range< double > ScrollBar::getCurrentRange | ( |  | ) | const
| noexcept

Returns the current thumb range.

See also
  getCurrentRange, setCurrentRange

## ◆ getCurrentRangeStart()

double ScrollBar::getCurrentRangeStart | ( |  | ) | const
| noexcept

Returns the position of the top of the thumb.

See also
  getCurrentRange, setCurrentRangeStart

## ◆ getCurrentRangeSize()

double ScrollBar::getCurrentRangeSize | ( |  | ) | const
| noexcept

Returns the current size of the thumb.

See also
  getCurrentRange, setCurrentRange

## ◆ setSingleStepSize()

void ScrollBar::setSingleStepSize | ( | double | newSingleStepSize | ) |
| noexcept

Sets the amount by which the up and down buttons will move the bar.

The value here is in terms of the total range, and is added or subtracted from the thumb position when the user clicks an up/down (or left/right) button.

## ◆ getSingleStepSize()

double ScrollBar::getSingleStepSize | ( |  | ) | const
| noexcept

Returns the current step size.

See also
  setSingleStepSize

## ◆ moveScrollbarInSteps()

bool ScrollBar::moveScrollbarInSteps | ( | int | howManySteps,
|  | NotificationType | notification = sendNotificationAsync )

Moves the scrollbar by a number of single-steps.

This will move the bar by a multiple of its single-step interval (as specified using the setSingleStepSize() method).

A positive value here will move the bar down or to the right, a negative value moves it up or to the left.

Parameters

  howManySteps | the number of steps to move the scrollbar
  notification | whether to send a notification of the change to listeners. A notification will only be sent if the position has changed.

Returns
  true if the scrollbar's position actually changed.

## ◆ moveScrollbarInPages()

bool ScrollBar::moveScrollbarInPages | ( | int | howManyPages,
|  | NotificationType | notification = sendNotificationAsync )

Moves the scroll bar up or down in pages.

This will move the bar by a multiple of its current thumb size, effectively doing a page-up or down.

A positive value here will move the bar down or to the right, a negative value moves it up or to the left.

Parameters

  howManyPages | the number of pages to move the scrollbar
  notification | whether to send a notification of the change to listeners. A notification will only be sent if the position has changed.

Returns
  true if the scrollbar's position actually changed.

## ◆ scrollToTop()

bool ScrollBar::scrollToTop | ( | NotificationType | notification = sendNotificationAsync | ) |

Scrolls to the top (or left).

This is the same as calling setCurrentRangeStart (getMinimumRangeLimit());

Parameters

  notification | whether to send a notification of the change to listeners. A notification will only be sent if the position has changed.

Returns
  true if the scrollbar's position actually changed.

## ◆ scrollToBottom()

bool ScrollBar::scrollToBottom | ( | NotificationType | notification = sendNotificationAsync | ) |

Scrolls to the bottom (or right).

This is the same as calling setCurrentRangeStart (getMaximumRangeLimit() - getCurrentRangeSize());

Parameters

  notification | whether to send a notification of the change to listeners. A notification will only be sent if the position has changed.

Returns
  true if the scrollbar's position actually changed.

## ◆ setButtonRepeatSpeed()

void ScrollBar::setButtonRepeatSpeed | ( | int | initialDelayInMillisecs,
|  | int | repeatDelayInMillisecs,
|  | int | minimumDelayInMillisecs = -1 )

Changes the delay before the up and down buttons autorepeat when they are held down.

For an explanation of what the parameters are for, see Button::setRepeatSpeed().

See also
  Button::setRepeatSpeed

## ◆ addListener()

void ScrollBar::addListener | ( | Listener * | listener | ) |

Registers a listener that will be called when the scrollbar is moved.

## ◆ removeListener()

void ScrollBar::removeListener | ( | Listener * | listener | ) |

Deregisters a previously-registered listener.

## ◆ keyPressed()

bool ScrollBar::keyPressed | ( | const KeyPress & | key | ) |
| override virtual

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.

## ◆ mouseWheelMove()

void ScrollBar::mouseWheelMove | ( | const MouseEvent & | event,
|  | const MouseWheelDetails & | wheel )
| override virtual

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.

## ◆ lookAndFeelChanged()

void ScrollBar::lookAndFeelChanged | ( |  | ) |
| override virtual

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.

## ◆ mouseDown()

void ScrollBar::mouseDown | ( | const MouseEvent & | event | ) |
| override virtual

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.

## ◆ mouseDrag()

void ScrollBar::mouseDrag | ( | const MouseEvent & | event | ) |
| override virtual

Called when the mouse is moved while a button is held down.

When a mouse button is pressed inside a component, that component receives mouseDrag callbacks each time the mouse moves, even if the mouse strays outside the component's bounds.

Parameters

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

See also
  mouseDown, mouseUp, mouseMove, contains, setDragRepeatInterval

Reimplemented from Component.

## ◆ mouseUp()

void ScrollBar::mouseUp | ( | const MouseEvent & | event | ) |
| override virtual

Called when a mouse button is released.

A mouseUp callback is sent to the component in which a button was pressed even if the mouse is actually over a different component when the button is released.

The MouseEvent object passed in contains lots of methods for finding out which buttons were down just before they were released.

Parameters

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

See also
  mouseDown, mouseDrag, mouseDoubleClick, contains

Reimplemented from Component.

## ◆ paint()

void ScrollBar::paint | ( | Graphics & | g | ) |
| override virtual

Components can override this method to draw their content.

The paint() method gets called when a region of a component needs redrawing, either because the component's repaint() method has been called, or because something has happened on the screen that means a section of a window needs to be redrawn.

Any child components will draw themselves over whatever this method draws. If you need to paint over the top of your child components, you can also implement the paintOverChildren() method to do this.

If you want to cause a component to redraw itself, this is done asynchronously - calling the repaint() method marks a region of the component as "dirty", and the paint() method will automatically be called sometime later, by the message thread, to paint any bits that need refreshing. In JUCE (and almost all modern UI frameworks), you never redraw something synchronously.

You should never need to call this method directly - to take a snapshot of the component you could use createComponentSnapshot() or paintEntireComponent().

Parameters

  g | the graphics context that must be used to do the drawing operations.

See also
  repaint, paintOverChildren, Graphics

Reimplemented from Component.

## ◆ resized()

void ScrollBar::resized | ( |  | ) |
| override virtual

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.

## ◆ parentHierarchyChanged()

void ScrollBar::parentHierarchyChanged | ( |  | ) |
| override virtual

Called to indicate that the component's parents have changed.

When a component is added or removed from its parent, this method will be called on all of its children (recursively - so all children of its children will also be called as well).

Subclasses can override this if they need to react to this in some way.

See also
  getParentComponent, isShowing, ComponentListener::componentParentHierarchyChanged

Reimplemented from Component.

## ◆ setVisible()

void ScrollBar::setVisible | ( | bool | shouldBeVisible | ) |
| override virtual

Makes the component visible or invisible.

This method will show or hide the component. Note that components default to being non-visible when first created. Also note that visible components won't be seen unless all their parent components are also visible.

This method will call visibilityChanged() and also componentVisibilityChanged() for any component listeners that are interested in this component.

Parameters

  shouldBeVisible | whether to show or hide the component

See also
  isVisible, isShowing, visibilityChanged, ComponentListener::componentVisibilityChanged

Reimplemented from Component.

## ◆ createAccessibilityHandler()

std::unique_ptr< AccessibilityHandler > ScrollBar::createAccessibilityHandler | ( |  | ) |
| override virtual

Override this method to return a custom AccessibilityHandler for this component.

The default implementation creates and returns a AccessibilityHandler object with an unspecified role, meaning that it will be visible to accessibility clients but without a specific role, action callbacks or interfaces. To control how accessibility clients see and interact with your component subclass AccessibilityHandler, implement the desired behaviours, and return an instance of it from this method in your component subclass.

The accessibility handler you return here is guaranteed to be destroyed before its Component, so it's safe to store and use a reference back to the Component inside the AccessibilityHandler if necessary.

This function should rarely be called directly. If you need to query a component's accessibility handler, it's normally better to call getAccessibilityHandler(). The exception to this rule is derived implementations of createAccessibilityHandler(), which may find it useful to call the base class implementation, and then wrap or modify the result.

See also
  getAccessibilityHandler

Reimplemented from Component.

Referenced by Viewport::createScrollBarComponent().

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

- juce_ScrollBar.h