ubuntu-touch-coreapps-reviewers team mailing list archive

[David Planella <david.planella@xxxxxxxxxx>]

David Planella has proposed merging lp:~ubuntu-docviewer-dev/ubuntu-docviewer-app/lo-viewer into lp:ubuntu-docviewer-app.

Requested reviews:
  Ubuntu Document Viewer Developers (ubuntu-docviewer-dev)

For more details, see:
https://code.launchpad.net/~ubuntu-docviewer-dev/ubuntu-docviewer-app/lo-viewer/+merge/262686

Added sample code as the first step to the LibreOffice viewer feature of docviewer. The code was provided by Bjoern Michaelsen, the Ubuntu LO maintaner, as a way to use the LO Toolkit API.

Right now the sample code uses the LO Toolkit API to read a given document into a buffer and then it writes a .png file using libpng.

For docviewer, we can probably convert the C++ code to Qt and assess whether it's needed to do the .png writing (I guess docviewer can use the buffer directly?), and create a QML plugin.

The requirement for this to work is to have LibreOffice 5.0 installed (easily available from a PPA as described in the .cxx's file comments).

I believe the easiest way to start experimenting is to develop on the desktop, prove that it works for Qt/QML and then we can worry about converting it to a .click once we've done that step.


-- 
Your team Ubuntu Document Viewer Developers is requested to review the proposed merge of lp:~ubuntu-docviewer-dev/ubuntu-docviewer-app/lo-viewer into lp:ubuntu-docviewer-app.

=== added directory 'src/plugin/libreofficetoolkit-qml-plugin'
=== added file 'src/plugin/libreofficetoolkit-qml-plugin/libreoffice2png.cxx'
--- src/plugin/libreofficetoolkit-qml-plugin/libreoffice2png.cxx	1970-01-01 00:00:00 +0000
+++ src/plugin/libreofficetoolkit-qml-plugin/libreoffice2png.cxx	2015-06-23 11:22:09 +0000
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+// This short example shows how to use LibreOfficeKit to render (parts of) a
+// document. As-is, it renders a full view of a document into a 250x250 pixel
+// png, ignoring aspect ratio. Its using hardcoded Ubuntu/Debian paths to find
+// the LibreOffice installation.
+//
+// Please install prerequisites if you havent done so:
+//
+//     sudo apt install libreofficekit-dev libreoffice libpng12-dev
+//
+// Note that you need LibreOffice 5.0 -- a prerelease is currently available 
+// at the prereleases ppa:
+//
+//     https://launchpad.net/~libreoffice/+archive/ubuntu/libreoffice-prereleases
+//
+// That ppa has versions for Ubuntu 15.10, 15.04, 14.04 LTS and 12.04 LTS.
+// Although this should work on all releases, it has only been tested on Ubuntu
+// 15.04 (vivid) so far.
+//
+// This example comes without a build system as presumably you would want to
+// use a different one anyway.
+// To compile/link this, save this file as libreoffice2png.cxx and run:
+/*
+        g++ --std=c++11 -I/usr/include/LibreOfficeKit/ `pkg-config --cflags libpng` libreoffice2png.cxx `pkg-config --libs libpng` -ldl -o ./libreoffice2png
+        # or run this sh pipe : grep g++ ./libreoffice2png.cxx | sh
+*/
+// You should be able to easily teach your build system of choice how to build
+// based on the above.
+
+
+#include <iostream>
+#include <memory>
+#include "png.h"
+#include "assert.h"
+#define LOK_USE_UNSTABLE_API
+#include "LibreOfficeKitInit.h"
+#include "LibreOfficeKit.hxx"
+
+constexpr png_uint_32 nCanvasHeight = 256;
+constexpr png_uint_32 nCanvasWidth = 256;
+constexpr png_uint_32 nCanvasDepth = 8;
+constexpr png_uint_32 nBytesPerPixel = 4;
+
+// a simple RGBA buffer to render a document to
+png_byte image[nCanvasHeight][nCanvasWidth*nBytesPerPixel];
+void write_png(const char*);
+
+int main(int argc, char** argv)
+{
+	long nDocWidth(0);
+	long nDocHeight(0);
+	if(argc != 3)
+	{
+		std::cerr << "libreoffice2png renders a document to a png file." << std::endl;
+		std::cerr << "usage: ./libreoffice2png <input-document> <output-png>" << std::endl;
+		return -1;
+	}
+	std::unique_ptr<lok::Office> pOffice(lok::lok_cpp_init("/usr/lib/libreoffice/program/"));
+	std::unique_ptr<lok::Document> pDocument(pOffice->documentLoad(argv[1]));
+	pDocument->initializeForRendering();
+	std::cout << "Document type: " << pDocument->getDocumentType() << std::endl;
+	pDocument->getDocumentSize(&nDocWidth, &nDocHeight);
+	std::cout << "Document size: " << nDocWidth << "x" << nDocHeight << " twips" << std::endl;
+	pDocument->paintTile(&image[0][0], nCanvasHeight, nCanvasWidth, 0, 0, nDocWidth, nDocHeight);
+	write_png(argv[2]);
+	pDocument.reset(nullptr);
+	pOffice.reset(nullptr);
+	return 0;
+}
+
+// only png writer code below this
+#ifndef png_jmpbuf
+#  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+#endif
+
+void write_png(const char* file_name)
+{
+
+	FILE* fp = fopen(file_name, "wb");
+	if (!fp)
+		return;
+
+	png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
+
+	if (!png_ptr)
+	{
+		fclose(fp);
+		return;
+	}
+
+	png_infop info_ptr = png_create_info_struct(png_ptr);
+	if (!info_ptr)
+	{
+		fclose(fp);
+		png_destroy_write_struct(&png_ptr, nullptr);
+		return;
+	}
+
+	if (setjmp(png_jmpbuf(png_ptr)))
+	{
+		fclose(fp);
+		png_destroy_write_struct(&png_ptr, &info_ptr);
+		return;
+	}
+
+	png_init_io(png_ptr, fp);
+
+	png_set_IHDR(png_ptr, info_ptr, nCanvasWidth, nCanvasHeight, nCanvasDepth, PNG_COLOR_TYPE_RGB_ALPHA,
+			PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+	png_write_info(png_ptr, info_ptr);
+
+	assert(nCanvasHeight <= PNG_UINT_32_MAX/png_sizeof(png_bytep));
+	png_bytep row_pointers[nCanvasHeight];
+
+	for (png_uint_32 row = 0; row < nCanvasHeight; ++row)
+		row_pointers[row] = &(image[row][0]);
+
+	png_write_image(png_ptr, row_pointers);
+	png_write_end(png_ptr, info_ptr);
+
+	png_destroy_write_struct(&png_ptr, &info_ptr);
+	fclose(fp);
+}
+/* vim: set noet sw=4 ts=4: */