asrpdirectory.java

openmap java写的开源数字地图程序. 用applet实现,可以像google map 那样放大缩小地图.

        // Get image data.
        if (tsi != null) {

            int index = y * numHorBlocks_N + x;

            // Check for not blowing the list end...
            if (index >= tsi.size()) {
                return null;
            }

            // Subtracting one because the values look like they start
            // with 1.
            int blockOffset = ((DDFSubfield) tsi.get(index)).intValue() - 1;

            if (Debug.debugging("asrp")) {
                Debug.output("ASRPDirectory.getBlock: index of (" + x + ", "
                        + y + ") is " + blockOffset);
            }

            if (blockOffset < 0) {
                // Can't have a negative offset...
                if (Debug.debugging("asrp")) {
                    Debug.output("     skipping...");
                }

                return null;
            }

            DDFModule mod = img.getInfo();
            mod.seek(tileDataOffset + blockOffset);

            int byteCount = 0; // Which data byte is being set
            int numBlockPixels = numHorPixels_Q * numVerPixels_P;
            byte[] data = new byte[numBlockPixels]; // image byte data

            int rowCount = 0; // the per row count, should equal 128 (
                              // numHorPixels_Q) at the end of every
                              // row
            int cpc = 0; // current pixel count for file pointer
            int cpv = 0; // current pixel value for file pointer
            while (byteCount < numBlockPixels) {
                switch (pixelCountBits) {
                case 8:
                    cpc = mod.read();
                    break;
                case 4:
                    cpc = mod.read() >> 4;
                    // need to back pointer up 4 bits before reading
                    // cpv??
                    Debug.output("CAUTION:  4 bit count");
                    break;
                default:
                    cpc = 1;
                }

                cpv = mod.read();

                // OK, cpv has value, cpc says how many pixels that
                // goes in.

                try {
                    for (int c = 0; c < cpc; c++) {
                        rowCount++;
                        if (colors != null && cpv > colors.length) {
                            if (Debug.debugging("asrpdetail")) {
                                Debug.output("Got value that is too big for colortable");
                            }
                        }
                        data[byteCount + c] = (byte) cpv;
                    }
                } catch (ArrayIndexOutOfBoundsException aioobe) {
                    if (Debug.debugging("asrp")) {
                        Debug.output("ASRPDirectory.getBlock(): bad index for setting byte value: "
                                + aioobe.getMessage());
                    }
                    // This try/catch block is really for the data[]
                    // array indexing.

                    // if byteCount + x was greater than
                    // numBlockPixels,
                    // we should be at the end of the image bytes, so
                    // we
                    // shouldn't have to worry about rowCount not
                    // being
                    // properly updated.
                }

                byteCount += cpc;
                if (rowCount == numHorPixels_Q) {
                    rowCount = 0;
                }
            }

            if (Debug.debugging("asrpdetail")) {
                Debug.output("ASRPDirectory creating image covering (" + ullat
                        + ", " + ullon + "), (" + lrlat + ", " + lrlon + ")");
            }

            return new OMScalingRaster(ullat, ullon, lrlat, lrlon, numHorPixels_Q, numVerPixels_P, data, getColors(), 255);
        }

        return null;
    }

    /**
     * Get the colors from the QAL file.
     */
    protected Color[] getColors() {
        if (colors == null) {
            DDFField col = qal.getField(QualityFile.COLOUR_CODE_ID);

            List reds = col.getSubfields("NSR");
            List greens = col.getSubfields("NSG");
            List blues = col.getSubfields("NSB");

            int numColors = reds.size();
            colors = new Color[numColors];

            for (int count = 0; count < numColors; count++) {
                int red = ((DDFSubfield) reds.get(count)).intValue();
                int green = ((DDFSubfield) greens.get(count)).intValue();
                int blue = ((DDFSubfield) blues.get(count)).intValue();
                //                 Debug.output("Created color " + count + " with " +
                // red + ", " + green + ", " + blue);
                // The zero color is supposed to tbe null color, and
                // clear. Doesn't seem to be working.
                colors[count] = new Color(red, green, blue, (count == 0 ? 0
                        : 255));
            }

        }
        return colors;
    }

    /**
     * Read in the attribute information about the data.
     * 
     * @param dirPath path to the ASRP directory.
     * @param root name of all of the files, usually the same as the
     *        ASRP directory itself.
     * @param DD the occurance number, usually '01' of the files.
     */
    protected void initialize(String dirPath, String root, String DD)
            throws IOException {
        String rootPath = dirPath + "/" + root + DD + ".";

        gen = new GeneralInformationFile(rootPath + GEN_NAME);
        ger = new GeoReferenceFile(rootPath + GER_NAME);
        qal = new QualityFile(rootPath + QAL_NAME);
        sou = new SourceFile(rootPath + SOURCE_NAME);
        img = new RasterGeoDataFile(rootPath + IMAGE_NAME);

        DDFField sprInfo = gen.getField(GeneralInformationFile.DATA_SET_PARAMETERS);
        numHorBlocks_N = sprInfo.getSubfield("NFC").intValue();
        numVerBlocks_M = sprInfo.getSubfield("NFL").intValue();
        numHorPixels_Q = sprInfo.getSubfield("PNC").intValue();
        numVerPixels_P = sprInfo.getSubfield("PNL").intValue();
        pixelCountBits = sprInfo.getSubfield("PCB").intValue();
        pixelValueBits = sprInfo.getSubfield("PVB").intValue();

        //assume there is a tile index map

        DDFField genInfo = gen.getField(GeneralInformationFile.GENERAL_INFORMATION);
        swo = genInfo.getSubfield("SWO").floatValue() / 3600f;
        neo = genInfo.getSubfield("NEO").floatValue() / 3600f;
        nea = genInfo.getSubfield("NEA").floatValue() / 3600f;
        swa = genInfo.getSubfield("SWA").floatValue() / 3600f;
        lso = genInfo.getSubfield("LSO").floatValue() / 3600f;
        pso = genInfo.getSubfield("PSO").floatValue() / 3600f;

        arv = genInfo.getSubfield("ARV").intValue();
        brv = genInfo.getSubfield("BRV").intValue();

        DDFField timInfo = gen.getField(GeneralInformationFile.TILE_INDEX_MAP);
        tsi = timInfo.getSubfields("TSI");

        DDFField pixelInfo = img.getField(RasterGeoDataFile.PIXEL);
        // Finding this out lets you use the tile index map to access
        // pixel data. This offset points to the start of the tile
        // data.
        tileDataOffset = pixelInfo.getHeaderOffset()
                + pixelInfo.getDataPosition();

        degPerHorBlock = 360f / (float) arv * (float) numHorPixels_Q;
        degPerVerBlock = 360f / (float) brv * (float) numVerPixels_P;

        if (Debug.debugging("asrp")) {
            Debug.output("For " + rootPath + "\n\thave blocks ("
                    + numHorBlocks_N + ", " + numVerBlocks_M
                    + ")\n\twith pixels (" + numHorPixels_Q + ", "
                    + numVerPixels_P + ")");
            Debug.output("\tCoverage from (" + nea + ", " + swo + ") to ("
                    + swa + ", " + neo + ")");
            Debug.output("\tPadded coverage starting at (" + pso + ", " + lso
                    + ")");
            Debug.output("\tNumber of pixels 360 e-w (" + arv + ") , n-s ("
                    + brv + ")");
            Debug.output("\tdegrees per horizontal block: " + degPerHorBlock
                    + ", vertical: " + degPerVerBlock);
            Debug.output("\tImage Data made up of count bits: "
                    + pixelCountBits + ", value bits: " + pixelValueBits);

            if (Debug.debugging("asrpdetail")) {
                Debug.output("Checking...");

                float latdiff = nea - swa;
                float londiff = neo - swo;

                float horPixels = arv * (londiff / 360f);
                float verPixels = brv * (latdiff / 360f);

                Debug.output("\tCalculating " + (horPixels / numHorPixels_Q)
                        + " hor blocks");
                Debug.output("\tCalculating " + (verPixels / numVerPixels_P)
                        + " hor blocks");
                Debug.output("\tCalculating "
                        + (lso + degPerHorBlock * numHorBlocks_N)
                        + " end latitude");
                Debug.output("\tCalculating "
                        + (pso - degPerVerBlock * numVerBlocks_M)
                        + " end latitude");
            }

        }

        getColors();

        gen.close();
        ger.close();
        qal.close();
        sou.close();
        img.close();
    }

    /**
     * A private class to store cached images.
     */
    private static class ASRPBlockCacheObject extends CacheObject {
        /**
         * @param id passed to superclass
         * @param obj passed to superclass
         */
        public ASRPBlockCacheObject(String id, OMGraphic obj) {
            super(id, obj);
        }

        /**
         * Calls dispose() on the contained frame, to make it eligible
         * for garbage collection.
         */
        public void finalize() {}
    }

    /**
     * Load a block image into the cache, based on the relative
     * coordintes of the block as a key.
     * 
     * @param xAndY String of form 'x,y' identifying the relative location
     *        of the subframe image.
     * @return Block image, hidden as a CacheObject.
     */
    public CacheObject load(String xAndY) {
        if (xAndY != null) {

            int commaIndex = xAndY.indexOf(',');
            int x = Integer.parseInt(xAndY.substring(0, commaIndex));
            int y = Integer.parseInt(xAndY.substring(commaIndex + 1));

            if (Debug.debugging("asrpdetail")) {
                Debug.output("Getting tiled image " + x + ", " + y + " (from "
                        + xAndY + ")");
            }

            try {
                OMGraphic block = getBlock(x, y);
                if (block != null) {
                    return new ASRPBlockCacheObject(xAndY.intern(), block);
                }
            } catch (IOException ioe) {
                Debug.error("ASRPDirectory caught exception creating tiled image for "
                        + xAndY);
            }
        }
        return null;
    }

    public static void main(String[] argv) {
        Debug.init();

        if (argv.length < 1) {
            Debug.output("Usage: ASRPDirectory dir_pathname");
        } else {
            new ASRPDirectory(argv[0]);
        }

        System.exit(0);
    }

}