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Use binary search to find the right file size

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This commit is contained in:
hunbernd 2017-06-11 00:31:20 +02:00
parent c17a8e7d51
commit f434e6559b
3 changed files with 47 additions and 22 deletions
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3
retroshare-gui/src/util/HandleRichText.cpp
View File

@ -1123,7 +1123,8 @@ bool RsHtml::makeEmbeddedImage(const QImage &originalImage, QString &embeddedIma
{
RsScopeTimer s("Embed image");
QImage opt;
ImageUtil::optimizeSize(embeddedImage, originalImage, opt, maxPixels, 6000);
ImageUtil::optimizeSize(embeddedImage, originalImage, opt, maxPixels, 6000-500);
// -500 bytes: keep space for html stuff
}
QString RsHtml::plainText(const QString &text)

64
retroshare-gui/src/util/imageutil.cpp
View File

@ -53,7 +53,7 @@ void ImageUtil::optimizeSize(QString &html, const QImage& original, QImage &opti
//nothing to do if it fits into the limits
optimized = original;
if ((maxPixels <= 0) || (optimized.width()*optimized.height() <= maxPixels)) {
if(checkSize(html, optimized, maxBytes)) {
if(checkSize(html, optimized, maxBytes) <= maxBytes) {
return;
}
}
@ -62,43 +62,67 @@ void ImageUtil::optimizeSize(QString &html, const QImage& original, QImage &opti
quantization(original, ct);
//Downscale the image to fit into maxPixels
qreal scale = qSqrt((qreal)(maxPixels) / original.width() / original.height());
if(scale > 1.0) scale = 1.0;
double whratio = (qreal)original.width() / (qreal)original.height();
int maxwidth;
if(maxPixels > 0)
maxwidth = qSqrt((qreal)(maxPixels) * whratio);
else
maxwidth = original.width();
//Half the resolution until image fits into maxBytes, or width becomes 0
int minwidth = qSqrt(100.0 * whratio);
//Use binary search to find a suitable image size + linear regression to guess the file size
double maxsize = (double)checkSize(html, original.scaledToWidth(maxwidth, Qt::SmoothTransformation).convertToFormat(QImage::Format_Indexed8, ct), maxBytes);
if(maxsize <= maxBytes) return; //success
double minsize = (double)checkSize(html, original.scaledToWidth(minwidth, Qt::SmoothTransformation).convertToFormat(QImage::Format_Indexed8, ct), maxBytes);
if(minsize > maxBytes) return; //impossible
// std::cout << "maxS: " << maxsize << " minS: " << minsize << std::endl;
// std::cout << "maxW: " << maxwidth << " minW: " << minwidth << std::endl;
int region = 500;
bool success = false;
do {
optimized = original.scaledToWidth((int)(original.width() * scale), Qt::SmoothTransformation).convertToFormat(QImage::Format_Indexed8, ct);
success = checkSize(html, optimized, maxBytes);
scale = scale / 2.0;
} while((!optimized.isNull()) && !success);
double m = (maxsize - minsize) / ((double)maxwidth * (double)maxwidth / whratio - (double)minwidth * (double)minwidth / whratio);
double b = maxsize - m * ((double)maxwidth * (double)maxwidth / whratio);
double a = ((double)(maxBytes - region/2) - b) / m; //maxBytes - region/2 target the center of the accepted region
int nextwidth = qSqrt((qreal)(a * whratio));
double nextsize = (double)checkSize(html, original.scaledToWidth(nextwidth, Qt::SmoothTransformation).convertToFormat(QImage::Format_Indexed8, ct), maxBytes);
if(nextsize <= maxBytes) {
minsize = nextsize;
minwidth = nextwidth;
if(nextsize >= (maxBytes - region)) //the file size is close anough to the limit
success = true;
} else {
maxsize = nextsize;
maxwidth = nextwidth;
}
// std::cout << "maxS: " << maxsize << " minS: " << minsize << std::endl;
// std::cout << "maxW: " << maxwidth << " minW: " << minwidth << std::endl;
} while(!success);
//html = html.arg(original.width());
//std::cout << html.toStdString() << std::endl;
}
bool ImageUtil::checkSize(QString &embeddedImage, const QImage &img, int maxBytes)
int ImageUtil::checkSize(QString &embeddedImage, const QImage &img, int maxBytes)
{
RsScopeTimer st("Check size");
//0 means no limit
if(maxBytes > 500)
maxBytes -= 500; //make place for html stuff
else if(maxBytes > 0) {
std::cerr << QString("Limit is too small nothing will fit in, limit: %1 bytes\n").arg(maxBytes).toStdString();
return false;
}
QByteArray bytearray;
QBuffer buffer(&bytearray);
bool success = false;
int size = 0;
std::cout << QString("Trying image: format PNG, size %1x%2, colors %3\n").arg(img.width()).arg(img.height()).arg(img.colorCount()).toStdString();
if (buffer.open(QIODevice::WriteOnly)) {
if (img.save(&buffer, "PNG", 0)) {
if((maxBytes > 0) && (bytearray.length() * 4/3 > maxBytes)) // *4/3 for base64
size = bytearray.length() * 4/3;
if((maxBytes > 0) && (size > maxBytes)) // *4/3 for base64
{
std::cout << QString("\tToo large, size: %1, limit: %2 bytes\n").arg(bytearray.length() * 4/3).arg(maxBytes).toStdString();
}else{
std::cout << QString("\tOK, size: %1, limit: %2 bytes\n").arg(bytearray.length() * 4/3).arg(maxBytes).toStdString();
success = true;
QByteArray encodedByteArray = bytearray.toBase64();
//embeddedImage = "<img width=\"%1\" src=\"data:image/png;base64,";
embeddedImage = "<img src=\"data:image/png;base64,";
embeddedImage.append(encodedByteArray);
embeddedImage.append("\">");
@ -111,7 +135,7 @@ bool ImageUtil::checkSize(QString &embeddedImage, const QImage &img, int maxByte
} else {
std::cerr << "ImageUtil: buffer can't be opened" << std::endl;
}
return success;
return size;
}
bool redLessThan(const QRgb &c1, const QRgb &c2)

2
retroshare-gui/src/util/imageutil.h
View File

@ -14,7 +14,7 @@ public:
static void optimizeSize(QString &html, const QImage& original, QImage &optimized, int maxPixels = -1, int maxBytes = -1);
private:
static bool checkSize(QString& embeddedImage, const QImage& img, int maxBytes = -1);
static int checkSize(QString& embeddedImage, const QImage& img, int maxBytes = -1);
static void quantization(const QImage& img, QVector<QRgb>& palette);
static void quantization(QList<QRgb>::iterator begin, QList<QRgb>::iterator end, int depth, QVector<QRgb>& palette);
static void avgbucket(QList<QRgb>::iterator begin, QList<QRgb>::iterator end, QVector<QRgb>& palette);