org.eclipse.jface.text/src/org/eclipse/jface/text/IPainter.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jface.text;


/**
 * A painter is responsible for creating, managing, updating, and removing visual decorations on an
 * <code>ITextViewer</code>'s text widget. Examples are the highlighting of the caret line, the
 * print margin, or the highlighting of matching peer characters such as pairs of brackets.
 * <p>
 * Clients may implement this interface.
 * </p>
 * <p>
 * Painters should be registered with a {@link org.eclipse.jface.text.PaintManager}. The paint
 * manager tracks several classes of events issued by an <code>ITextViewer</code> and reacts by
 * appropriately invoking the registered painters.
 * </p>
 * <p>
 * Painters are either active or inactive. Usually, painters are initially inactive and are
 * activated by the first call to their <code>paint</code> method. Painters can be deactivated by
 * calling <code>deactivate</code>. Inactive painter can be reactivated by calling
 * <code>paint</code>.
 * </p>
 * <p>
 * Painters usually have to manage state information. E.g., a painter painting a caret line
 * highlight must redraw the previous and the actual caret line in the advent of a change of the
 * caret position. This state information must be adapted to changes of the viewer's content. In
 * order to support this common scenario, the <code>PaintManager</code> gives a painter access to a
 * {@link org.eclipse.jface.text.IPaintPositionManager}. The painter can use this updater to manage
 * its state information.
 * </p>
 *
 * @see org.eclipse.jface.text.PaintManager
 * @see org.eclipse.jface.text.IPaintPositionManager
 * @since 2.1
 */
public interface IPainter {

	/**
	 * Constant describing the reason of a repaint request: selection changed.
	 */
	int SELECTION= 0;
	/**
	 * Constant describing the reason of a repaint request: text changed.
	 */
	int TEXT_CHANGE= 1;
	/**
	 * Constant describing the reason of a repaint request: key pressed.
	 */
	int KEY_STROKE= 2;
	/**
	 * Constant describing the reason of a repaint request: mouse button pressed.
	 */
	int MOUSE_BUTTON= 4;
	/**
	 * Constant describing the reason of a repaint request: paint manager internal change.
	 */
	int INTERNAL= 8;
	/**
	 * Constant describing the reason of a repaint request: paint manager or painter configuration changed.
	 */
	int CONFIGURATION= 16;


	/**
	 * Disposes this painter. Prior to disposing, a painter should be deactivated. A disposed
	 * painter can not be reactivated.
	 *
	 * @see #deactivate(boolean)
	 */
	void dispose();

	/**
	 * Requests this painter to repaint because of the given reason. Based on
	 * the given reason the painter can decide whether it will repaint or not.
	 * If it repaints and is inactive, it will activate itself.
	 *
	 * @param reason the repaint reason, value is one of the constants defined
	 *            in this interface
	 */
	void paint(int reason);

	/**
	 * Deactivates this painter. If the painter is inactive, this call does not
	 * have any effect. <code>redraw</code> indicates whether the painter
	 * should remove any decoration it previously applied. A deactivated painter
	 * can be reactivated by calling <code>paint</code>.
	 *
	 * @param redraw <code>true</code> if any previously applied decoration
	 *            should be removed
	 * @see #paint(int)
	 */
	void deactivate(boolean redraw);

	/**
	 * Sets the paint position manager that can be used by this painter or removes any previously
	 * set paint position manager.
	 *
	 * @param manager the paint position manager or <code>null</code>
	 */
	void setPositionManager(IPaintPositionManager manager);
}