1 files changed, 94 insertions, 0 deletions
diff --git a/examples/org.eclipse.swt.examples.paint/src/org/eclipse/swt/examples/paint/ContainerFigure.java b/examples/org.eclipse.swt.examples.paint/src/org/eclipse/swt/examples/paint/ContainerFigure.java
new file mode 100755
index 0000000000..ac36901c7c
--- /dev/null
+++ b/examples/org.eclipse.swt.examples.paint/src/org/eclipse/swt/examples/paint/ContainerFigure.java
@@ -0,0 +1,94 @@
+package org.eclipse.swt.examples.paint;
+
+/*
+ * (c) Copyright IBM Corp. 2000, 2001.
+ * All Rights Reserved
+ */
+
+import org.eclipse.swt.graphics.*;
+
+/**
+ * Container for Figure objects with stacking preview mechanism.
+ */
+public class ContainerFigure extends Figure {
+	private static final int INITIAL_ARRAY_SIZE = 16;
+	
+	Figure[]   objectStack = null;
+	int      nextIndex = 0;
+
+	/**
+	 * Constructs an empty Container
+	 */
+	public ContainerFigure() {
+	}
+	/**
+	 * Adds an object to the container for later drawing.
+	 * 
+	 * @param object the object to add to the drawing list
+	 */
+	public void add(Figure object) {
+		if (objectStack == null) {
+			objectStack = new Figure[INITIAL_ARRAY_SIZE];
+		} else if (objectStack.length <= nextIndex) {
+			Figure[] newObjectStack = new Figure[objectStack.length * 2];
+			System.arraycopy(objectStack, 0, newObjectStack, 0, objectStack.length);
+			objectStack = newObjectStack;
+		}
+		objectStack[nextIndex] = object;
+		++nextIndex;
+	}
+	/**
+	 * Adds an object to the container and draws its preview then updates the supplied preview state.
+	 * 
+	 * @param object the object to add to the drawing list
+	 * @param gc the GC to draw on
+	 * @param offset the offset to add to virtual coordinates to get display coordinates
+	 * @param rememberedState the state returned by a previous drawPreview() or addAndPreview()
+	 *        using this Container, may be null if there was no such previous call
+	 * @return object state that must be passed to erasePreview() later to erase this object
+	 */
+	public Object addAndPreview(Figure object, GC gc, Point offset, Object rememberedState) {
+		Object[] stateStack = (Object[]) rememberedState;
+		if (stateStack == null) {
+			stateStack = new Object[INITIAL_ARRAY_SIZE];
+		} else if (stateStack.length <= nextIndex) {
+			Object[] newStateStack = new Object[stateStack.length * 2];
+			System.arraycopy(stateStack, 0, newStateStack, 0, stateStack.length);
+			stateStack = newStateStack;
+		}
+		add(object);
+		stateStack[nextIndex - 1] = object.drawPreview(gc, offset);
+		return stateStack;
+	}
+	/**
+	 * Clears the container.
+	 * <p>
+	 * Note that erasePreview() cannot be called after this point to erase any previous
+	 * drawPreview()'s.
+	 * </p>
+	 */
+	public void clear() {
+		while (--nextIndex > 0) objectStack[nextIndex] = null;
+		nextIndex = 0;
+	}
+	public void draw(GC gc, Point offset) {
+		for (int i = 0; i < nextIndex; ++i) objectStack[i].draw(gc, offset);
+	}
+	public Object drawPreview(GC gc, Point offset) {
+		if (nextIndex == 0) return null;
+		
+		Object[] stateStack = new Object[nextIndex];
+		for (int i = 0; i < nextIndex; ++i) stateStack[i] = objectStack[i].drawPreview(gc, offset);
+		return stateStack;
+	}
+	public void erasePreview(GC gc, Point offset, Object rememberedState) {
+		if (rememberedState == null) return;
+		
+		final Object[] stateStack = (Object[]) rememberedState;
+		int i = nextIndex;
+		while (--i >= 0) {
+			objectStack[i].erasePreview(gc, offset, stateStack[i]);
+			stateStack[i] = null;
+		}
+	}	
+}