gwenview/lib/imagescaler.cpp

   1 /*
   2 Gwenview: an image viewer
   3 Copyright 2007 Aurélien Gâteau <aurelien.gateau@free.fr>
   4
   5 This program is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU General Public License
   7 as published by the Free Software Foundation; either version 2
   8 of the License, or (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  18
  19 */
  20 #include "imagescaler.moc"
  21
  22 // Qt
  23 #include <QImage>
  24 #include <QRegion>
  25
  26 // KDE
  27 #include <kdebug.h>
  28
  29 // Local
  30 #include <lib/document/document.h>
  31 #include <lib/paintutils.h>
  32
  33 #undef ENABLE_LOG
  34 #undef LOG
  35 //#define ENABLE_LOG
  36 #ifdef ENABLE_LOG
  37 #define LOG(x) kDebug() << x
  38 #else
  39 #define LOG(x) ;
  40 #endif
  41
  42 namespace Gwenview {
  43
  44 // Amount of pixels to keep so that smooth scale is correct
  45 static const int SMOOTH_MARGIN = 3;
  46
  47 struct ImageScalerPrivate {
  48         Qt::TransformationMode mTransformationMode;
  49         Document::Ptr mDocument;
  50         qreal mZoom;
  51         QRegion mRegion;
  52 };
  53
  54 ImageScaler::ImageScaler(QObject* parent)
  55 : QObject(parent)
  56 , d(new ImageScalerPrivate) {
  57         d->mTransformationMode = Qt::FastTransformation;
  58         d->mZoom = 0;
  59 }
  60
  61 ImageScaler::~ImageScaler() {
  62         delete d;
  63 }
  64
  65 void ImageScaler::setDocument(Document::Ptr document) {
  66         if (d->mDocument) {
  67                 disconnect(d->mDocument.data(), 0, this, 0);
  68         }
  69         d->mDocument = document;
  70         connect(d->mDocument.data(), SIGNAL(downSampledImageReady()),
  71                 SLOT(doScale()) );
  72 }
  73
  74 void ImageScaler::setZoom(qreal zoom) {
  75         d->mZoom = zoom;
  76 }
  77
  78 void ImageScaler::setTransformationMode(Qt::TransformationMode mode) {
  79         d->mTransformationMode = mode;
  80 }
  81
  82 void ImageScaler::setDestinationRegion(const QRegion& region) {
  83         LOG(region);
  84         d->mRegion = region;
  85         if (d->mRegion.isEmpty()) {
  86                 return;
  87         }
  88
  89         if (d->mDocument && d->mZoom > 0) {
  90                 doScale();
  91         }
  92 }
  93
  94
  95 void ImageScaler::doScale() {
  96         if (d->mZoom < Document::maxDownSampledZoom()) {
  97                 if (!d->mDocument->prepareDownSampledImageForZoom(d->mZoom)) {
  98                         LOG("Asked for a down sampled image");
  99                         return;
 100                 }
 101         } else if (d->mDocument->image().isNull()) {
 102                 LOG("Asked for the full image");
 103                 d->mDocument->loadFullImage();
 104                 return;
 105         }
 106
 107         LOG("Starting");
 108         Q_FOREACH(const QRect& rect, d->mRegion.rects()) {
 109                 LOG(rect);
 110                 scaleRect(rect);
 111         }
 112         LOG("Done");
 113 }
 114
 115
 116 void ImageScaler::scaleRect(const QRect& rect) {
 117         const qreal REAL_DELTA = 0.001;
 118         if (qAbs(d->mZoom - 1.0) < REAL_DELTA) {
 119                 QImage tmp = d->mDocument->image().copy(rect);
 120                 tmp.convertToFormat(QImage::Format_ARGB32_Premultiplied);
 121                 scaledRect(rect.left(), rect.top(), tmp);
 122                 return;
 123         }
 124
 125         QImage image;
 126         qreal zoom;
 127         if (d->mZoom < Document::maxDownSampledZoom()) {
 128                 image = d->mDocument->downSampledImageForZoom(d->mZoom);
 129                 Q_ASSERT(!image.isNull());
 130                 qreal zoom1 = qreal(image.width()) / d->mDocument->width();
 131                 zoom = d->mZoom / zoom1;
 132         } else {
 133                 image = d->mDocument->image();
 134                 zoom = d->mZoom;
 135         }
 136         // If rect contains "half" pixels, make sure sourceRect includes them
 137         QRectF sourceRectF(
 138                 rect.left() / zoom,
 139                 rect.top() / zoom,
 140                 rect.width() / zoom,
 141                 rect.height() / zoom);
 142
 143         sourceRectF = sourceRectF.intersected(image.rect());
 144         QRect sourceRect = PaintUtils::containingRect(sourceRectF);
 145         if (sourceRect.isEmpty()) {
 146                 return;
 147         }
 148
 149         // Compute smooth margin
 150         bool needsSmoothMargins = d->mTransformationMode == Qt::SmoothTransformation;
 151
 152         int sourceLeftMargin, sourceRightMargin, sourceTopMargin, sourceBottomMargin;
 153         int destLeftMargin, destRightMargin, destTopMargin, destBottomMargin;
 154         if (needsSmoothMargins) {
 155                 sourceLeftMargin = qMin(sourceRect.left(), SMOOTH_MARGIN);
 156                 sourceTopMargin = qMin(sourceRect.top(), SMOOTH_MARGIN);
 157                 sourceRightMargin = qMin(image.rect().right() - sourceRect.right(), SMOOTH_MARGIN);
 158                 sourceBottomMargin = qMin(image.rect().bottom() - sourceRect.bottom(), SMOOTH_MARGIN);
 159                 sourceRect.adjust(
 160                         -sourceLeftMargin,
 161                         -sourceTopMargin,
 162                         sourceRightMargin,
 163                         sourceBottomMargin);
 164                 destLeftMargin = int(sourceLeftMargin * zoom);
 165                 destTopMargin = int(sourceTopMargin * zoom);
 166                 destRightMargin = int(sourceRightMargin * zoom);
 167                 destBottomMargin = int(sourceBottomMargin * zoom);
 168         } else {
 169                 sourceLeftMargin = sourceRightMargin = sourceTopMargin = sourceBottomMargin = 0;
 170                 destLeftMargin = destRightMargin = destTopMargin = destBottomMargin = 0;
 171         }
 172
 173         // destRect is almost like rect, but it contains only "full" pixels
 174         QRectF destRectF = QRectF(
 175                 sourceRect.left() * zoom,
 176                 sourceRect.top() * zoom,
 177                 sourceRect.width() * zoom,
 178                 sourceRect.height() * zoom
 179                 );
 180         QRect destRect = PaintUtils::containingRect(destRectF);
 181
 182         QImage tmp;
 183         tmp = image.copy(sourceRect);
 184         tmp.convertToFormat(QImage::Format_ARGB32_Premultiplied);
 185         tmp = tmp.scaled(
 186                 destRect.width(),
 187                 destRect.height(),
 188                 Qt::IgnoreAspectRatio, // Do not use KeepAspectRatio, it can lead to skipped rows or columns
 189                 d->mTransformationMode);
 190
 191         if (needsSmoothMargins) {
 192                 tmp = tmp.copy(
 193                         destLeftMargin, destTopMargin,
 194                         destRect.width() - (destLeftMargin + destRightMargin),
 195                         destRect.height() - (destTopMargin + destBottomMargin)
 196                         );
 197         }
 198
 199         scaledRect(destRect.left() + destLeftMargin, destRect.top() + destTopMargin, tmp);
 200 }
 201
 202 } // namespace