Image diffs

Ticket 88: https://dev.gitblit.com/tickets/gitblit.git/88

Based on Lea Verou's pure CSS slider:
http://lea.verou.me/2014/07/image-comparison-slider-with-pure-css/

* Add a callback interface, pass it through DiffUtils to the
  GitBlitDiffFormatter. Is needed because the rendering needs access
  to the repositoryName and other things that are known only at higher
  levels.
  
* New class ImageDiffHandler responsible for rendering an image diff.
  Called for all binary diffs, doesn't do anything if it's not an
  image. HTML is generated via JSoup: no worries about forgetting to
  close a tag, not about HTML escaping, nor about XSS.
  
* The 3 diff pages set up such an ImageDIffHandler and pass it along.

* CSS changes: from Lea Verou, with some minor improvements.

I think in the long run there'll be no way around rewriting the
HTML diff formatter from scratch, not using the standard JGit
DiffFormatter at all.

1 files changed, 96 insertions, 0 deletions

diff --git a/src/main/java/com/gitblit/utils/HtmlBuilder.java b/src/main/java/com/gitblit/utils/HtmlBuilder.java
new file mode 100644
index 00000000..6208ea82
--- /dev/null
+++ b/src/main/java/com/gitblit/utils/HtmlBuilder.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2014 Tom <tw201207@gmail.com>
+ *
+ * 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.gitblit.utils;
+
+import org.jsoup.nodes.Document;
+import org.jsoup.nodes.Element;
+import org.jsoup.parser.Tag;
+
+/**
+ * Simple helper class to hide some common setup needed to use JSoup as an HTML generator.
+ * A {@link HtmlBuilder} has a root element that can be manipulated in all the usual JSoup
+ * ways (but not added to some {@link Document}); to generate HTML for that root element,
+ * the builder's {@link #toString()} method can be used. (Or one can invoke toString()
+ * directly on the root element.) By default, a HTML builder does not pretty-print the HTML.
+ *
+ * @author Tom <tw201207@gmail.com>
+ */
+public class HtmlBuilder {
+
+	private final Document shell;
+	private final Element root;
+
+	/**
+	 * Creates a new HTML builder with a root element with the given {@code tagName}.
+	 *
+	 * @param tagName
+	 *            of the {@link Element} to set as the root element.
+	 */
+	public HtmlBuilder(String tagName) {
+		this(new Element(Tag.valueOf(tagName), ""));
+	}
+
+	/**
+	 * Creates a new HTML builder for the given element.
+	 *
+	 * @param element
+	 *            to set as the root element of this HTML builder.
+	 */
+	public HtmlBuilder(Element element) {
+		shell = Document.createShell("");
+		shell.outputSettings().prettyPrint(false);
+		shell.body().appendChild(element);
+		root = element;
+	}
+
+	/** @return the root element of this HTML builder */
+	public Element getRoot() {
+		return root;
+	}
+
+	/** @return the root element of this HTML builder */
+	public Element root() {
+		return root;
+	}
+
+	/** @return whether this HTML builder will pretty-print the HTML generated by {@link #toString()} */
+	public boolean prettyPrint() {
+		return shell.outputSettings().prettyPrint();
+	}
+
+	/**
+	 * Sets whether this HTML builder will produce pretty-printed HTML in its {@link #toString()} method.
+	 *
+	 * @param pretty
+	 *            whether to pretty-print
+	 * @return the HTML builder itself
+	 */
+	public HtmlBuilder prettyPrint(boolean pretty) {
+		shell.outputSettings().prettyPrint(pretty);
+		return this;
+	}
+
+	/** @return the HTML for the root element. */
+	@Override
+	public String toString() {
+		return root.toString();
+	}
+
+	/** @return the {@link Document} used as generation shell. */
+	protected Document getShell() {
+		return shell;
+	}
+}