com.google.gitiles.doc.ImageLoader.java Source code

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Here is the source code for com.google.gitiles.doc.ImageLoader.java

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// Copyright 2015 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gitiles.doc;

import com.google.common.collect.ImmutableMap;
import com.google.common.io.BaseEncoding;
import com.google.gitiles.GitilesView;
import com.google.template.soy.shared.restricted.EscapingConventions.FilterImageDataUri;

import org.eclipse.jgit.errors.LargeObjectException;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.FileMode;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;

/** Reads an image from Git and converts to {@code data:image/*;base64,...} */
public class ImageLoader {
    private static final Logger log = LoggerFactory.getLogger(ImageLoader.class);

    private final ObjectReader reader;
    private final GitilesView view;
    private final RevTree root;
    private final String path;
    private final int imageLimit;

    public ImageLoader(ObjectReader reader, GitilesView view, RevTree root, String path, int maxImageSize) {
        this.reader = reader;
        this.view = view;
        this.root = root;
        this.path = path;
        this.imageLimit = maxImageSize;
    }

    String loadImage(String src) {
        if (src.startsWith("/")) {
            return readAndBase64Encode(src.substring(1));
        }

        String base = directory();
        while (src.startsWith("../")) {
            int s = base.lastIndexOf('/');
            if (s == -1) {
                return FilterImageDataUri.INSTANCE.getInnocuousOutput();
            }
            base = base.substring(0, s + 1);
            src = src.substring("../".length());
        }
        return readAndBase64Encode(base + src);
    }

    private String directory() {
        int s = path.lastIndexOf('/');
        if (s > 0) {
            return path.substring(0, s + 1);
        }
        return "";
    }

    private String readAndBase64Encode(String path) {
        String type = getMimeType(path);
        if (type == null) {
            return FilterImageDataUri.INSTANCE.getInnocuousOutput();
        }

        try {
            TreeWalk tw = TreeWalk.forPath(reader, path, root);
            if (tw == null || tw.getFileMode(0) != FileMode.REGULAR_FILE) {
                return FilterImageDataUri.INSTANCE.getInnocuousOutput();
            }

            ObjectId id = tw.getObjectId(0);
            byte[] raw = reader.open(id, Constants.OBJ_BLOB).getCachedBytes(imageLimit);
            if (raw.length > imageLimit) {
                return FilterImageDataUri.INSTANCE.getInnocuousOutput();
            }

            return "data:" + type + ";base64," + BaseEncoding.base64().encode(raw);
        } catch (LargeObjectException.ExceedsLimit e) {
            return FilterImageDataUri.INSTANCE.getInnocuousOutput();
        } catch (IOException e) {
            log.error(String.format("cannot read repo %s image %s from %s", view.getRepositoryName(), path,
                    root.name()), e);
            return FilterImageDataUri.INSTANCE.getInnocuousOutput();
        }
    }

    private static final ImmutableMap<String, String> TYPES = ImmutableMap.of("png", "image/png", "gif",
            "image/gif", "jpg", "image/jpeg", "jpeg", "image/jpeg");

    private static String getMimeType(String path) {
        int d = path.lastIndexOf('.');
        if (d == -1) {
            return null;
        }
        String ext = path.substring(d + 1);
        return TYPES.get(ext.toLowerCase());
    }
}