Class Canvas

    • Constructor Detail

      • Canvas

        public Canvas​(Composite parent,
                      int style)
        Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.

        The style value is either one of the style constants defined in class SWT which is applicable to instances of this class, or must be built by bitwise OR'ing together (that is, using the int "|" operator) two or more of those SWT style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses.

        Parameters:
        parent - a composite control which will be the parent of the new instance (cannot be null)
        style - the style of control to construct
        Throws:
        IllegalArgumentException -
        • ERROR_NULL_ARGUMENT - if the parent is null
        SWTException -
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
        See Also:
        SWT, Widget.getStyle()
    • Method Detail

      • drawBackground

        public void drawBackground​(GC gc,
                                   int x,
                                   int y,
                                   int width,
                                   int height)
        Fills the interior of the rectangle specified by the arguments, with the receiver's background.
        Parameters:
        gc - the gc where the rectangle is to be filled
        x - the x coordinate of the rectangle to be filled
        y - the y coordinate of the rectangle to be filled
        width - the width of the rectangle to be filled
        height - the height of the rectangle to be filled
        Throws:
        IllegalArgumentException -
        • ERROR_NULL_ARGUMENT - if the gc is null
        • ERROR_INVALID_ARGUMENT - if the gc has been disposed
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.2
      • getCaret

        public Caret getCaret()
        Returns the caret.

        The caret for the control is automatically hidden and shown when the control is painted or resized, when focus is gained or lost and when an the control is scrolled. To avoid drawing on top of the caret, the programmer must hide and show the caret when drawing in the window any other time.

        Returns:
        the caret for the receiver, may be null
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
      • getIME

        public IME getIME()
        Returns the IME.
        Returns:
        the IME
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.4
      • scroll

        public void scroll​(int destX,
                           int destY,
                           int x,
                           int y,
                           int width,
                           int height,
                           boolean all)
        Scrolls a rectangular area of the receiver by first copying the source area to the destination and then causing the area of the source which is not covered by the destination to be repainted. Children that intersect the rectangle are optionally moved during the operation. In addition, all outstanding paint events are flushed before the source area is copied to ensure that the contents of the canvas are drawn correctly.
        Parameters:
        destX - the x coordinate of the destination
        destY - the y coordinate of the destination
        x - the x coordinate of the source
        y - the y coordinate of the source
        width - the width of the area
        height - the height of the area
        all - trueif children should be scrolled, and false otherwise
        Throws:
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
      • setCaret

        public void setCaret​(Caret caret)
        Sets the receiver's caret.

        The caret for the control is automatically hidden and shown when the control is painted or resized, when focus is gained or lost and when an the control is scrolled. To avoid drawing on top of the caret, the programmer must hide and show the caret when drawing in the window any other time.

        Parameters:
        caret - the new caret for the receiver, may be null
        Throws:
        IllegalArgumentException -
        • ERROR_INVALID_ARGUMENT - if the caret has been disposed
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
      • setFont

        public void setFont​(Font font)
        Description copied from class: Control
        Sets the font that the receiver will use to paint textual information to the font specified by the argument, or to the default font for that kind of control if the argument is null.
        Overrides:
        setFont in class Control
        Parameters:
        font - the new font (or null)
      • setIME

        public void setIME​(IME ime)
        Sets the receiver's IME.
        Parameters:
        ime - the new IME for the receiver, may be null
        Throws:
        IllegalArgumentException -
        • ERROR_INVALID_ARGUMENT - if the IME has been disposed
        SWTException -
        • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
        • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
        Since:
        3.4