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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);
 
    }
 
}