paintsurface.java

eclipse 的程序源码

	 *         might be)
	 */
	public PaintTool getPaintTool() {
		return (paintSession != null && paintSession instanceof PaintTool) ?
			(PaintTool)paintSession : null;
	}

	/**
	 * Returns the current position in an interactive operation.
	 *
	 * @return the last known position of the pointer
	 */
	public Point getCurrentPosition() {
		return currentPosition;
	}

	/**
	 * Draws a Figure object to the screen and to the backing store permanently.
	 * 
	 * @param object the object to draw onscreen
	 */
	public void drawFigure(Figure object) {
		object.draw(imageFDC);
		object.draw(displayFDC);
	}

	/**
	 * Adds a Figure object to the active rubberband selection.
	 * <p>
	 * This object will be drawn to the screen as a preview and refreshed appropriately
	 * until the selection is either cleared or committed.
	 * </p>
	 * 
	 * @param object the object to add to the selection
	 */
	public void addRubberbandSelection(Figure object) {
		rubberband.add(object);
		if (! isRubberbandHidden()) object.draw(displayFDC);
	}

	/**
	 * Clears the active rubberband selection.
	 * <p>
	 * Erases any rubberband objects on the screen then clears the selection.
	 * </p>
	 */
	public void clearRubberbandSelection() {
		if (! isRubberbandHidden()) {
			Region region = new Region();
			rubberband.addDamagedRegion(displayFDC, region);
			Rectangle r = region.getBounds();
			paintCanvas.redraw(r.x, r.y, r.width, r.height, true);
			region.dispose();
		}
		rubberband.clear();

	}

	/**
	 * Commits the active rubberband selection.
	 * <p>
	 * Redraws any rubberband objects on the screen as permanent objects then clears the selection.
	 * </p>
	 */
	public void commitRubberbandSelection() {
		rubberband.draw(imageFDC);
		if (isRubberbandHidden()) rubberband.draw(displayFDC);
		rubberband.clear();
	}
	
	/**
	 * Hides the rubberband (but does not eliminate it).
	 * <p>
	 * Increments by one the rubberband "hide" nesting count.  The rubberband
	 * is hidden from view (but remains active) if it wasn't already hidden.
	 * </p>
	 */
	public void hideRubberband() {
		if (rubberbandHiddenNestingCount++ <= 0) {
			Region region = new Region();
			rubberband.addDamagedRegion(displayFDC, region);
			Rectangle r = region.getBounds();
			paintCanvas.redraw(r.x, r.y, r.width, r.height, true);
			region.dispose();
		}
	}		

	/**
	 * Shows (un-hides) the rubberband.
	 * <p>
	 * Decrements by one the rubberband "hide" nesting count.  The rubberband
	 * is only made visible when showRubberband() has been called once for each
	 * previous hideRubberband().  It is not permitted to call showRubberband() if
	 * the rubber band is not presently hidden.
	 * </p>
	 */
	public void showRubberband() {
		if (rubberbandHiddenNestingCount <= 0)
			throw new IllegalStateException("rubberbandHiddenNestingCount > 0");
		if (--rubberbandHiddenNestingCount == 0) {
			rubberband.draw(displayFDC);
		}
	}
	
	/**
	 * Determines if the rubberband is hidden.
	 * 
	 * @return true iff the rubber is hidden
	 */
	public boolean isRubberbandHidden() {
		return rubberbandHiddenNestingCount > 0;
	}

	/**
	 * Handles a horizontal scroll event
	 * 
	 * @param scrollbar the horizontal scroll bar that posted this event
	 */
	public void scrollHorizontally(ScrollBar scrollBar) {
		if (image == null) return;
		if (imageWidth > visibleWidth) {
			final int oldOffset = displayFDC.xOffset;
			final int newOffset = Math.min(scrollBar.getSelection(), imageWidth - visibleWidth);
			if (oldOffset != newOffset) {
				paintCanvas.update();
				displayFDC.xOffset = newOffset;
				paintCanvas.scroll(Math.max(oldOffset - newOffset, 0), 0, Math.max(newOffset - oldOffset, 0), 0,
					visibleWidth, visibleHeight, false);
			}
		}
	}

	/**
	 * Handles a vertical scroll event
	 * 
	 * @param scrollbar the vertical scroll bar that posted this event
	 */
	public void scrollVertically(ScrollBar scrollBar) {
		if (image == null) return;
		if (imageHeight > visibleHeight) {
			final int oldOffset = displayFDC.yOffset;
			final int newOffset = Math.min(scrollBar.getSelection(), imageHeight - visibleHeight);
			if (oldOffset != newOffset) {
				paintCanvas.update();
				displayFDC.yOffset = newOffset;
				paintCanvas.scroll(0, Math.max(oldOffset - newOffset, 0), 0, Math.max(newOffset - oldOffset, 0),
					visibleWidth, visibleHeight, false);
			}
		}
	}
	
	/**
	 * Handles resize events
	 */
	private void handleResize() {
		paintCanvas.update();

		Rectangle visibleRect = paintCanvas.getClientArea();
		visibleWidth = visibleRect.width;
		visibleHeight = visibleRect.height;

		ScrollBar horizontal = paintCanvas.getHorizontalBar();
		if (horizontal != null) {
			displayFDC.xOffset = Math.min(horizontal.getSelection(), imageWidth - visibleWidth);
			if (imageWidth <= visibleWidth) {
				horizontal.setEnabled(false);
				horizontal.setSelection(0);
			} else {
				horizontal.setEnabled(true);
				horizontal.setValues(displayFDC.xOffset, 0, imageWidth, visibleWidth,
					8, visibleWidth);
			}
		}

		ScrollBar vertical = paintCanvas.getVerticalBar();
		if (vertical != null) {
			displayFDC.yOffset = Math.min(vertical.getSelection(), imageHeight - visibleHeight);
			if (imageHeight <= visibleHeight) {
				vertical.setEnabled(false);
				vertical.setSelection(0);
			} else {
				vertical.setEnabled(true);
				vertical.setValues(displayFDC.yOffset, 0, imageHeight, visibleHeight,
					8, visibleHeight);
			}
		}
	}

	/**
	 * Virtualizes MouseEvent coordinates and stores the current position.
	 */
	private void processMouseEventCoordinates(MouseEvent event) {
		currentPosition.x = event.x =
			Math.min(Math.max(event.x, 0), visibleWidth - 1) + displayFDC.xOffset;
		currentPosition.y = event.y =
			Math.min(Math.max(event.y, 0), visibleHeight - 1) + displayFDC.yOffset;
	}
	
	/**
	 * Clears the status bar.
	 */
	public void clearStatus() {
		statusActionInfo = "";
		statusMessageInfo = "";
		statusCoordInfo = "";
		updateStatus();
	}

	/**
	 * Sets the status bar action text.
	 *
	 * @param action the action in progress, null to clear
	 */
	public void setStatusAction(String action) {
		statusActionInfo = (action != null) ? action : "";
		updateStatus();
	}
	
	/**
	 * Sets the status bar message text.
	 * 
	 * @param message the message to display, null to clear
	 */
	public void setStatusMessage(String message) {
		statusMessageInfo = (message != null) ? message : "";
		updateStatus();
	}

	/**
	 * Sets the coordinates in the status bar.
	 * 
	 * @param coord the coordinates to display, null to clear
	 */
	public void setStatusCoord(Point coord) {
		statusCoordInfo = (coord != null) ? PaintExample.getResourceString("status.Coord.format", new Object[]
			{ new Integer(coord.x), new Integer(coord.y)}) : "";
		updateStatus();
	}

	/**
	 * Sets the coordinate range in the status bar.
	 * 
	 * @param a the "from" coordinate, must not be null
	 * @param b the "to" coordinate, must not be null
	 */
	public void setStatusCoordRange(Point a, Point b) {
		statusCoordInfo = PaintExample.getResourceString("status.CoordRange.format", new Object[]
			{ new Integer(a.x), new Integer(a.y), new Integer(b.x), new Integer(b.y)});
		updateStatus();
	}

	/**
	 * Updates the display.
	 */
	private void updateStatus() {
		statusText.setText(
			PaintExample.getResourceString("status.Bar.format", new Object[]
			{ statusActionInfo, statusMessageInfo, statusCoordInfo }));
	}
}