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#ifndef INCLUDED_WATERMARK_HPP
#define INCLUDED_WATERMARK_HPP
#define LOK_USE_UNSTABLE_API
#include <LibreOfficeKit/LibreOfficeKitInit.h>
#include <LibreOfficeKit/LibreOfficeKit.hxx>
#include <LibreOfficeKit/LibreOfficeKitEnums.h>
#include <vector>
#include <Log.hpp>
#include <cstdlib>
#include <string>
#include "ChildSession.hpp"
class Watermark
{
public:
Watermark(const std::shared_ptr<lok::Document>& loKitDoc,
const std::shared_ptr<ChildSession> & session)
: _loKitDoc(loKitDoc)
, _text(session->getWatermarkText())
, _font("Liberation Sans")
, _width(0)
, _height(0)
, _alphaLevel(session->getWatermarkOpacity())
{
}
~Watermark()
{
}
void blending(unsigned char* tilePixmap,
int offsetX, int offsetY,
int tilesPixmapWidth, int tilesPixmapHeight,
int tileWidth, int tileHeight,
LibreOfficeKitTileMode /*mode*/)
{
// set requested watermark size a little bit smaller than tile size
int width = tileWidth * 0.9;
int height = tileHeight * 0.9;
const std::vector<unsigned char>* pixmap = getPixmap(width, height);
if (pixmap && tilePixmap)
{
// center watermark
const int maxX = std::min(tileWidth, _width);
const int maxY = std::min(tileHeight, _height);
offsetX += (tileWidth - maxX) / 2;
offsetY += (tileHeight - maxY) / 2;
alphaBlend(*pixmap, _width, _height, offsetX, offsetY, tilePixmap, tilesPixmapWidth, tilesPixmapHeight);
}
}
private:
/// Alpha blend pixels from 'from' over the 'to'.
void alphaBlend(const std::vector<unsigned char>& from, int from_width, int from_height, int from_offset_x, int from_offset_y,
unsigned char* to, int to_width, int to_height)
{
for (int to_y = from_offset_y, from_y = 0; (to_y < to_height) && (from_y < from_height) ; ++to_y, ++from_y)
for (int to_x = from_offset_x, from_x = 0; (to_x < to_width) && (from_x < from_width); ++to_x, ++from_x)
{
const unsigned char* f = from.data() + 4 * (from_y * from_width + from_x);
double src_r = f[0];
double src_g = f[1];
double src_b = f[2];
double src_a = f[3] / 255.0;
unsigned char* t = to + 4 * (to_y * to_width + to_x);
double dst_r = t[0];
double dst_g = t[1];
double dst_b = t[2];
double dst_a = t[3] / 255.0;
double out_a = src_a + dst_a * (1.0 - src_a);
unsigned char out_r = src_r + dst_r * (1.0 - src_a);
unsigned char out_g = src_g + dst_g * (1.0 - src_a);
unsigned char out_b = src_b + dst_b * (1.0 - src_a);
t[0] = out_r;
t[1] = out_g;
t[2] = out_b;
t[3] = static_cast<unsigned char>(out_a * 255.0);
}
}
/// Create bitmap that we later use as the watermark for every tile.
const std::vector<unsigned char>* getPixmap(int width, int height)
{
if (!_pixmap.empty() && width == _width && height == _height)
return &_pixmap;
_pixmap.clear();
_width = width;
_height = height;
if (!_loKitDoc)
{
LOG_ERR("Watermark rendering requested without a valid document.");
return nullptr;
}
// renderFont returns a buffer based on RGBA mode, where r, g, b
// are always set to 0 (black) and the alpha level is 0 everywhere
// except on the text area; the alpha level take into account of
// performing anti-aliasing over the text edges.
unsigned char* textPixels = _loKitDoc->renderFont(_font.c_str(), _text.c_str(), &_width, &_height);
if (!textPixels)
{
LOG_ERR("Watermark: rendering failed.");
}
const unsigned int pixel_count = width * height * 4;
std::vector<unsigned char> text(textPixels, textPixels + pixel_count);
// No longer needed.
std::free(textPixels);
_pixmap.reserve(pixel_count);
// Create the white blurred background
// Use box blur, it's enough for our purposes
const int r = 2;
const double weight = (r+1) * (r+1);
for (int y = 0; y < height; ++y)
{
for (int x = 0; x < width; ++x)
{
double t = 0;
for (int ky = std::max(y - r, 0); ky <= std::min(y + r, height - 1); ++ky)
{
for (int kx = std::max(x - r, 0); kx <= std::min(x + r, width - 1); ++kx)
{
// Pre-multiplied alpha; the text is black, so all the
// information is only in the alpha channel
t += text[4 * (ky * width + kx) + 3];
}
}
// Clamp the result.
double avg = t / weight;
if (avg > 255.0)
avg = 255.0;
// Pre-multiplied alpha, but use white for the resulting color
const double alpha = avg / 255.0;
_pixmap[4 * (y * width + x) + 0] = 0xff * alpha;
_pixmap[4 * (y * width + x) + 1] = 0xff * alpha;
_pixmap[4 * (y * width + x) + 2] = 0xff * alpha;
_pixmap[4 * (y * width + x) + 3] = avg;
}
}
// Now copy the (black) text over the (white) blur
alphaBlend(text, _width, _height, 0, 0, _pixmap.data(), _width, _height);
// Make the resulting pixmap semi-transparent
for (unsigned char* p = _pixmap.data(); p < _pixmap.data() + pixel_count; p++)
{
*p = static_cast<unsigned char>(*p * _alphaLevel);
}
return &_pixmap;
}
private:
std::shared_ptr<lok::Document> _loKitDoc;
std::string _text;
std::string _font;
int _width;
int _height;
double _alphaLevel;
std::vector<unsigned char> _pixmap;
};
#endif
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