package ij.plugin;
import ij.*;
import ij.process.*;
import java.awt.*;
import java.awt.image.*;
import javax.imageio.ImageIO;

/** Saves in PNG format using the ImageIO classes.  RGB images are saved
    as RGB PNGs. All other image types are saved as 8-bit PNGs. With 8-bit images,
    the value of the transparent index can be set in the Edit/Options/Input-Output dialog,
    or by calling Prefs.setTransparentIndex(index), where 0<=index<=255. */
public class PNG_Writer implements PlugIn {
    ImagePlus imp;

    public void run(String path) {
        imp = WindowManager.getCurrentImage();
        if (imp==null) {
        if (path.equals("")) {
            SaveDialog sd = new SaveDialog("Save as PNG...", imp.getTitle(), ".png");
            String name = sd.getFileName();
            if (name==null)
            String dir = sd.getDirectory();
            path = dir + name;
        try {
            writeImage(imp, path, Prefs.getTransparentIndex());
        } catch (Exception e) {
            String msg = e.getMessage();
            if (msg==null || msg.equals(""))
                msg = ""+e;
            msg = "An error occured writing the file.\n \n" + msg;
            if (msg.contains("NullPointerException"))
                msg = "Incorrect file path:";
            msg += "\n \n"+path;
            IJ.error("PNG Writer", msg);

    public void writeImage(ImagePlus imp, String path, int transparentIndex) throws Exception {
        if (imp.getType()==ImagePlus.COLOR_256) {
            imp = imp.duplicate();
            new ImageConverter(imp).convertToRGB();
        if (imp.getStackSize()==4 && imp.getBitDepth()==8 && "alpha".equalsIgnoreCase(imp.getStack().getSliceLabel(4)))
            writeFourChannelsWithAlpha(imp, path);
        else if (transparentIndex>=0 && transparentIndex<=255 && imp.getBitDepth()==8)
            writeImageWithTransparency(imp, path, transparentIndex);
        else if (imp.getOverlay()!=null && !imp.getHideOverlay() && !imp.tempOverlay())
            ImageIO.write(imp.flatten().getBufferedImage(), "png", new File(path));
        else if (imp.getBitDepth()==16 && !imp.isComposite() && imp.getProcessor().isDefaultLut())
            write16gs(imp, path);
            ImageIO.write(imp.getBufferedImage(), "png", new File(path));
    private void writeFourChannelsWithAlpha(ImagePlus imp, String path) throws Exception {
        ImageStack stack = imp.getStack();
        int w=imp.getWidth(), h=imp.getHeight();
        ImagePlus imp2 = new ImagePlus("", new ColorProcessor(w,h));
        ColorProcessor cp = (ColorProcessor)imp2.getProcessor();
        for (int channel=1; channel<=4; channel++)
            cp.setChannel(channel, (ByteProcessor)stack.getProcessor(channel));
        BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
        WritableRaster raster = bi.getRaster();
        raster.setDataElements(0, 0, w, h, cp.getPixels());
        ImageIO.write(bi, "png", new File(path));
    void writeImageWithTransparency(ImagePlus imp, String path, int transparentIndex) throws Exception {
        int width = imp.getWidth();
        int  height = imp.getHeight();
        ImageProcessor ip = imp.getProcessor();
        IndexColorModel cm = (IndexColorModel)ip.getColorModel();
        int size = cm.getMapSize();
        byte[] reds = new byte[256];
        byte[] greens = new byte[256];
        byte[] blues = new byte[256];   
        cm = new IndexColorModel(8, 256, reds, greens, blues, transparentIndex);
        WritableRaster wr = cm.createCompatibleWritableRaster(width, height);
        DataBufferByte db = (DataBufferByte)wr.getDataBuffer();
        byte[] biPixels = db.getData();
        System.arraycopy(ip.getPixels(), 0, biPixels, 0, biPixels.length);
        BufferedImage bi = new BufferedImage(cm, wr, false, null);
        ImageIO.write(bi, "png", new File(path));

    void write16gs(ImagePlus imp, String path) throws Exception {
        ShortProcessor sp = (ShortProcessor)imp.getProcessor();
        BufferedImage bi = sp.get16BitBufferedImage();
        File f = new File(path);
        ImageIO.write(bi, "png", f);