package com.vci.client.workflow.editor;

import java.awt.Color;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;

import com.mxgraph.canvas.mxGraphics2DCanvas;
import com.mxgraph.canvas.mxICanvas;
import com.mxgraph.canvas.mxImageCanvas;
import com.mxgraph.util.mxPoint;
import com.mxgraph.util.mxRectangle;
import com.mxgraph.view.mxGraph;
import com.mxgraph.view.mxGraphView;
import com.mxgraph.view.mxTemporaryCellStates;

public class FlowCellRenderer {
	// static class, 参照 mxCellRenderer class

	/**
	 * Draws the given cells using a Graphics2D canvas and returns the buffered image
	 * that represents the cells.
	 * 
	 * @param graph Graph to be painted onto the canvas.
	 * @return Returns the image that represents the canvas.
	 */
	public static mxICanvas drawCells(mxGraph graph, Object[] cells,
			double scale, CanvasFactory factory)
	{
		mxICanvas canvas = null;

		if (cells == null)
		{
			cells = new Object[] { graph.getModel().getRoot() };
		}

		// Gets the current state of the view
		mxGraphView view = graph.getView();

		// Keeps the existing translation as the cells might
		// be aligned to the grid in a different way in a graph
		// that has a translation other than zero
		boolean eventsEnabled = view.isEventsEnabled();

		// Disables firing of scale events so that there is no
		// repaint or update of the original graph
		view.setEventsEnabled(false);

		// Uses the view to create temporary cell states for each cell
		mxTemporaryCellStates temp = new mxTemporaryCellStates(view, scale,
				cells);

		try {
			mxRectangle clip = graph.getPaintBounds(cells);
			//将clip扩展到左上角(0, 0)
			clip.setWidth(clip.getWidth() + clip.getX());
			clip.setHeight(clip.getHeight() + clip.getY());
			clip.setX(0);
			clip.setY(0);

			if (clip != null && clip.getWidth() > 0 && clip.getHeight() > 0) {
				Rectangle rect = clip.getRectangle();
				canvas = factory.createCanvas(rect.width + 4, rect.height + 4);//增加一点富裕空间

				if (canvas != null) {
					double previousScale = canvas.getScale();
					//mxPoint previousTranslate = canvas.getTranslate();
					Point previousTranslate = canvas.getTranslate();

					try {
//						canvas.setTranslate(-rect.x, -rect.y);
						canvas.setScale(view.getScale());

						for (int i = 0; i < cells.length; i++)
						{
							graph.drawCell(canvas, cells[i]);
						}
					} finally {
						canvas.setScale(previousScale);
						canvas.setTranslate(previousTranslate.x,
								previousTranslate.y);
					}
				}
			}
		} finally {
			temp.destroy();
			view.setEventsEnabled(eventsEnabled);
		}

		return canvas;
	}

	/**
	 * 
	 */
	public static BufferedImage createBufferedImage(mxGraph graph,
			Object[] cells, double scale, final Color background,
			final boolean antiAlias, final mxGraphics2DCanvas graphicsCanvas)
	{
		mxImageCanvas canvas = (mxImageCanvas) drawCells(graph, cells, scale,
				new CanvasFactory()
				{
					public mxICanvas createCanvas(int width, int height)
					{
						return new mxImageCanvas(graphicsCanvas, width, height,
								background, antiAlias);
					}

				});

		return (canvas != null) ? canvas.destroy() : null;
	}


	/**
	 * 
	 */
	public static abstract class CanvasFactory
	{

		/**
		 * Separates the creation of the canvas from its initialization, when the
		 * size of the required graphics buffer / document / container is known.
		 */
		public abstract mxICanvas createCanvas(int width, int height);

	}

}