gi-gtk-3.0.43: Gtk bindings

Copyright | Will Thompson and Iñaki García Etxebarria
License | LGPL-2.1
Maintainer | Iñaki García Etxebarria
Safe Haskell | None
Language | Haskell2010

GI.Gtk.Objects.DrawingArea

Contents

- Exported types
- Methods
  - new

Description

The `DrawingArea` widget is used for creating custom user interface elements. It’s essentially a blank widget; you can draw on it. After creating a drawing area, the application may want to connect to:

- Mouse and button press signals to respond to input from the user. (Use `widgetAddEvents` to enable events you wish to receive.)
- The Widget::realize signal to take any necessary actions when the widget is instantiated on a particular display. (Create GDK resources in response to this signal.)
- The Widget::sizeAllocate signal to take any necessary actions when the widget changes size.
- The Widget::draw signal to handle redrawing the contents of the widget.

The following code portion demonstrates using a drawing area to display a circle in the normal widget foreground color.

Note that GDK automatically clears the exposed area before sending the expose event, and that drawing is implicitly clipped to the exposed area. If you want to have a theme-provided background, you need to call `renderBackground` in your draw method.

## Simple GtkDrawingArea usage

### C code

    gboolean
    draw_callback (GtkWidget *widget, cairo_t *cr, gpointer data)
    {
      guint width, height;
      GdkRGBA color;
      GtkStyleContext *context;

      context = gtk_widget_get_style_context (widget);

      width = gtk_widget_get_allocated_width (widget);
      height = gtk_widget_get_allocated_height (widget);

      gtk_render_background (context, cr, 0, 0, width, height);

      cairo_arc (cr,
                 width / 2.0, height / 2.0,
                 MIN (width, height) / 2.0,
                 0, 2 * G_PI);

      gtk_style_context_get_color (context,
                                   gtk_style_context_get_state (context),
                                   &color);
      gdk_cairo_set_source_rgba (cr, &color);

      cairo_fill (cr);

     return FALSE;
    }
    [...]
      GtkWidget *drawing_area = gtk_drawing_area_new ();
      gtk_widget_set_size_request (drawing_area, 100, 100);
      g_signal_connect (G_OBJECT (drawing_area), "draw",
                        G_CALLBACK (draw_callback), NULL);

Draw signals are normally delivered when a drawing area first comes onscreen, or when it’s covered by another window and then uncovered. You can also force an expose event by adding to the “damage region” of the drawing area’s window; `widgetQueueDrawArea` and `windowInvalidateRect` are equally good ways to do this. You’ll then get a draw signal for the invalid region.

The available routines for drawing are documented on the [GDK Drawing Primitives][gdk3-Cairo-Interaction] page and the cairo documentation.

To receive mouse events on a drawing area, you will need to enable them with `widgetAddEvents`. To receive keyboard events, you will need to set the “can-focus” property on the drawing area, and you should probably draw some user-visible indication that the drawing area is focused. Use `widgetHasFocus` in your expose event handler to decide whether to draw the focus indicator. See `renderFocus` for one way to draw focus.

Synopsis

- newtype DrawingArea = DrawingArea (ManagedPtr DrawingArea)
- class (GObject o, IsDescendantOf DrawingArea o) => IsDrawingArea o
- toDrawingArea :: (MonadIO m, IsDrawingArea o) => o -> m DrawingArea
- drawingAreaNew :: (HasCallStack, MonadIO m) => m DrawingArea

# Exported types

newtype DrawingArea Source #

Memory-managed wrapper type.

Constructors

DrawingArea (ManagedPtr DrawingArea) |

#### Instances

Instances details

Eq DrawingArea Source # |
Instance details Defined in GI.Gtk.Objects.DrawingArea Methods (==) :: DrawingArea -> DrawingArea -> Bool Source # (/=) :: DrawingArea -> DrawingArea -> Bool Source #
GObject DrawingArea Source # |
Instance details Defined in GI.Gtk.Objects.DrawingArea
ManagedPtrNewtype DrawingArea Source # |
Instance details Defined in GI.Gtk.Objects.DrawingArea Methods toManagedPtr :: DrawingArea -> ManagedPtr DrawingArea Source #
TypedObject DrawingArea Source # |
Instance details Defined in GI.Gtk.Objects.DrawingArea Methods glibType :: IO GType Source #
HasParentTypes DrawingArea Source # |
Instance details Defined in GI.Gtk.Objects.DrawingArea
IsGValue (Maybe DrawingArea) Source # | Convert `DrawingArea` to and from `GValue`. See `toGValue` and `fromGValue`.
Instance details Defined in GI.Gtk.Objects.DrawingArea Methods gvalueGType_ :: IO GType Source # gvalueSet_ :: Ptr GValue -> Maybe DrawingArea -> IO () Source # gvalueGet_ :: Ptr GValue -> IO (Maybe DrawingArea) Source #
type ParentTypes DrawingArea Source # |
Instance details Defined in GI.Gtk.Objects.DrawingArea type ParentTypes DrawingArea = '[Widget, Object, ImplementorIface, Buildable]

class (GObject o, IsDescendantOf DrawingArea o) => IsDrawingArea o Source #

Type class for types which can be safely cast to `DrawingArea`, for instance with `toDrawingArea`.

#### Instances

Instances details

(GObject o, IsDescendantOf DrawingArea o) => IsDrawingArea o Source # |
Instance details Defined in GI.Gtk.Objects.DrawingArea

toDrawingArea :: (MonadIO m, IsDrawingArea o) => o -> m DrawingArea Source #

Cast to `DrawingArea`, for types for which this is known to be safe. For general casts, use `castTo`.

# Methods

### Click to display all available methods, including inherited ones

Expand

#### Methods

activate, addAccelerator, addChild, addDeviceEvents, addEvents, addMnemonicLabel, addTickCallback, bindProperty, bindPropertyFull, canActivateAccel, childFocus, childNotify, classPath, computeExpand, constructChild, createPangoContext, createPangoLayout, customFinished, customTagEnd, customTagStart, destroy, destroyed, deviceIsShadowed, dragBegin, dragBeginWithCoordinates, dragCheckThreshold, dragDestAddImageTargets, dragDestAddTextTargets, dragDestAddUriTargets, dragDestFindTarget, dragDestGetTargetList, dragDestGetTrackMotion, dragDestSet, dragDestSetProxy, dragDestSetTargetList, dragDestSetTrackMotion, dragDestUnset, dragGetData, dragHighlight, dragSourceAddImageTargets, dragSourceAddTextTargets, dragSourceAddUriTargets, dragSourceGetTargetList, dragSourceSet, dragSourceSetIconGicon, dragSourceSetIconName, dragSourceSetIconPixbuf, dragSourceSetIconStock, dragSourceSetTargetList, dragSourceUnset, dragUnhighlight, draw, ensureStyle, errorBell, event, forceFloating, freezeChildNotify, freezeNotify, getv, grabAdd, grabDefault, grabFocus, grabRemove, hasDefault, hasFocus, hasGrab, hasRcStyle, hasScreen, hasVisibleFocus, hide, hideOnDelete, inDestruction, initTemplate, inputShapeCombineRegion, insertActionGroup, intersect, isAncestor, isComposited, isDrawable, isFloating, isFocus, isSensitive, isToplevel, isVisible, keynavFailed, listAccelClosures, listActionPrefixes, listMnemonicLabels, map, mnemonicActivate, modifyBase, modifyBg, modifyCursor, modifyFg, modifyFont, modifyStyle, modifyText, notify, notifyByPspec, overrideBackgroundColor, overrideColor, overrideCursor, overrideFont, overrideSymbolicColor, parserFinished, path, queueAllocate, queueComputeExpand, queueDraw, queueDrawArea, queueDrawRegion, queueResize, queueResizeNoRedraw, realize, ref, refSink, regionIntersect, registerWindow, removeAccelerator, removeMnemonicLabel, removeTickCallback, renderIcon, renderIconPixbuf, reparent, resetRcStyles, resetStyle, runDispose, sendExpose, sendFocusChange, shapeCombineRegion, show, showAll, showNow, sizeAllocate, sizeAllocateWithBaseline, sizeRequest, stealData, stealQdata, styleAttach, styleGetProperty, thawChildNotify, thawNotify, translateCoordinates, triggerTooltipQuery, unmap, unparent, unrealize, unref, unregisterWindow, unsetStateFlags, watchClosure.

#### Getters

getAccessible, getActionGroup, getAllocatedBaseline, getAllocatedHeight, getAllocatedSize, getAllocatedWidth, getAllocation, getAncestor, getAppPaintable, getCanDefault, getCanFocus, getChildRequisition, getChildVisible, getClip, getClipboard, getCompositeName, getData, getDeviceEnabled, getDeviceEvents, getDirection, getDisplay, getDoubleBuffered, getEvents, getFocusOnClick, getFontMap, getFontOptions, getFrameClock, getHalign, getHasTooltip, getHasWindow, getHexpand, getHexpandSet, getInternalChild, getMapped, getMarginBottom, getMarginEnd, getMarginLeft, getMarginRight, getMarginStart, getMarginTop, getModifierMask, getModifierStyle, getName, getNoShowAll, getOpacity, getPangoContext, getParent, getParentWindow, getPath, getPointer, getPreferredHeight, getPreferredHeightAndBaselineForWidth, getPreferredHeightForWidth, getPreferredSize, getPreferredWidth, getPreferredWidthForHeight, getProperty, getQdata, getRealized, getReceivesDefault, getRequestMode, getRequisition, getRootWindow, getScaleFactor, getScreen, getSensitive, getSettings, getSizeRequest, getState, getStateFlags, getStyle, getStyleContext, getSupportMultidevice, getTemplateChild, getTooltipMarkup, getTooltipText, getTooltipWindow, getToplevel, getValign, getValignWithBaseline, getVexpand, getVexpandSet, getVisible, getVisual, getWindow.

#### Setters

setAccelPath, setAllocation, setAppPaintable, setBuildableProperty, setCanDefault, setCanFocus, setChildVisible, setClip, setCompositeName, setData, setDataFull, setDeviceEnabled, setDeviceEvents, setDirection, setDoubleBuffered, setEvents, setFocusOnClick, setFontMap, setFontOptions, setHalign, setHasTooltip, setHasWindow, setHexpand, setHexpandSet, setMapped, setMarginBottom, setMarginEnd, setMarginLeft, setMarginRight, setMarginStart, setMarginTop, setName, setNoShowAll, setOpacity, setParent, setParentWindow, setProperty, setRealized, setReceivesDefault, setRedrawOnAllocate, setSensitive, setSizeRequest, setState, setStateFlags, setStyle, setSupportMultidevice, setTooltipMarkup, setTooltipText, setTooltipWindow, setValign, setVexpand, setVexpandSet, setVisible, setVisual, setWindow.

## new

drawingAreaNew Source #

Arguments

:: (HasCallStack, MonadIO m) |
=> m DrawingArea | Returns: a new `DrawingArea`

Creates a new drawing area.