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# This file is part of the Frescobaldi project, http://www.frescobaldi.org/
#
# Copyright (c) 2008 - 2014 by Wilbert Berendsen
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
# See http://www.gnu.org/licenses/ for more information.
"""
A simple scrollarea that can display an image.
"""
from PyQt5.QtCore import pyqtSignal, QMimeData, QSize, QRect, Qt
from PyQt5.QtGui import QColor, QDrag, QImage, QPainter, QPalette, QPixmap
from PyQt5.QtWidgets import QApplication, QScrollArea, QSizePolicy, QWidget
__all__ = ['ImageViewer']
# internal constants
MOVE = 1
DRAG = 2
class ImageViewer(QScrollArea):
actualSizeChanged = pyqtSignal(bool)
def __init__(self, parent=None):
super(ImageViewer, self).__init__(parent, alignment=Qt.AlignCenter)
self._actualsize = True
self._image = QImage()
self.setBackgroundRole(QPalette.Dark)
self.setWidget(ImageWidget(self))
def setActualSize(self, enabled=True):
if enabled == self._actualsize:
return
self.setWidgetResizable(not enabled)
if enabled and not self._image.isNull():
self.widget().resize(self._image.size())
self._actualsize = enabled
self.actualSizeChanged.emit(enabled)
def actualSize(self):
return self._actualsize
def setImage(self, image):
self._image = image
self._pixmap = None
self._pixmapsize = None
if self._actualsize:
self.widget().resize(image.size())
self.widget().update()
def image(self):
return self._image
def pixmap(self, size):
"""Returns (and caches) a scaled pixmap for the image."""
if self._pixmapsize == size:
return self._pixmap
self._pixmap = QPixmap.fromImage(
self._image.scaled(size, Qt.KeepAspectRatio, Qt.SmoothTransformation))
self._pixmapsize = size
return self._pixmap
def startDrag(self):
image = self.image()
data = QMimeData()
data.setImageData(image)
drag = QDrag(self)
drag.setMimeData(data)
if max(image.width(), image.height()) > 256:
image = image.scaled(QSize(256, 256), Qt.KeepAspectRatio, Qt.SmoothTransformation)
p = QPainter()
p.begin(image)
p.setCompositionMode(QPainter.CompositionMode_DestinationIn)
p.fillRect(image.rect(), QColor(0, 0, 0, 160))
p.end()
pixmap = QPixmap.fromImage(image)
drag.setPixmap(pixmap)
drag.setHotSpot(pixmap.rect().center())
drag.exec_(Qt.CopyAction)
class ImageWidget(QWidget):
def __init__(self, viewer):
super(ImageWidget, self).__init__()
self.viewer = viewer
self.setBackgroundRole(QPalette.Dark)
self.setSizePolicy(QSizePolicy.Ignored, QSizePolicy.Ignored)
self._mode = None
self._startpos = None
def paintEvent(self, ev):
image = self.viewer.image()
painter = QPainter(self)
if self.size() == image.size():
painter.drawImage(ev.rect(), image, ev.rect())
else:
s = image.size()
s.scale(self.size(), Qt.KeepAspectRatio)
r = QRect()
r.setSize(s)
r.moveCenter(self.rect().center())
painter.drawPixmap(r, self.viewer.pixmap(s))
def mousePressEvent(self, ev):
if ev.button() == Qt.LeftButton:
if ev.modifiers() & Qt.ControlModifier:
self._mode = MOVE
else:
self._mode = DRAG
self._startpos = ev.globalPos()
def mouseMoveEvent(self, ev):
diff = self._startpos - ev.globalPos()
if self._mode == MOVE:
self._startpos = ev.globalPos()
h = self.viewer.horizontalScrollBar()
v = self.viewer.verticalScrollBar()
h.setValue(h.value() + diff.x())
v.setValue(v.value() + diff.y())
elif self._mode == DRAG and diff.manhattanLength() >= QApplication.startDragDistance():
self.viewer.startDrag()
def mouseReleaseEvent(self, ev):
mode, self._mode = self._mode, None
if (ev.button() == Qt.LeftButton and
mode == DRAG and ev.globalPos() == self._startpos):
self.viewer.setActualSize(not self.viewer.actualSize())
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