TP a écrit :
> I'm using Windows XP, Python 2.6.4, and PyQt 4.7.1.
>
> While trying out the example
> C:\Python26\Lib\site-packages\PyQt4\examples\widgets\imageviewer.pyw,
> I notice that the more I zoom into an 1553x2653 B&W PNG image, the
> longer it takes to display. This becomes unacceptably long (on the
> order of a few seconds) at the not so high 3x zoom factor.
>
> Intuitively, I would have thought it would be *faster* since the more
> I zoom in the fewer image pixels need to be displayed. I think what's
> happening is the entire QLabel widget is getting enlarged then
> cropped, rather than just displaying a sub-portion of the image:
>
> def scaleImage(self, factor):
> self.scaleFactor *= factor
> self.imageLabel.resize(self.scaleFactor *
> self.imageLabel.pixmap().size())
>
> I want to create an app to help people explore various image
> processing operations. Fast & flexible image display is essential.
>
> Some features I like to have:
>
> * Zoom In/Out quickly. I can see zooming *out* being slower since more
> image pixels would be involved. Once past the 1x zoom-in factor, I'd
> rather have the pixels as raw as possible to avoid blurring edges
> like the Image Viewer example currently does.
>
> * Compare transformations by having multiple views of images that are
> synchronized as to pan position and zoom factor. Dragging the mouse
> in any of the views should pan all the views.
>
> * Multi-screen support.
>
> I started off by modifying the PyQt4 Image Viewer example, but now I'm
> having second thoughts. Should I really be basing my Image Viewer on a
> QLabel?
>
> Should I instead be using a QGraphicsView (even though I'll probably
> only have a single image, not lots of 2D objects)?
>
> Maybe I should use a QGLWidget (I'd rather not).
>
> Or perhaps I have to write my own custom widget and draw using a
> QPainter object?
>
> Any tips or pointers to other PyQt-based Image Viewers would be
> appreciated.
> _______________________________________________
> PyQt mailing list PyQt@riverbankcomputing.com
> http://www.riverbankcomputing.com/mailman/listinfo/pyqt
>
>
See attachement, it's an images viewer + zoom with QGraphicScene.
Before use, change the line 63
Vincent
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Example of an image viewer with zoom
#
# Created: Thu Feb 25 19:54:49 2010
# by: PyQt4 UI code generator 4.4.4
#
# Author: Vincent Vande Vyvre <v...@swing.be>
#
# Note: before use, change the line 63
import os
import time
import glob
from PyQt4 import QtCore, QtGui
class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.resize(900, 600)
self.centralwidget = QtGui.QWidget(MainWindow)
self.gridLayout = QtGui.QGridLayout(self.centralwidget)
self.verticalLayout = QtGui.QVBoxLayout()
self.scene = QtGui.QGraphicsScene()
self.view = QtGui.QGraphicsView(self.scene)
self.verticalLayout.addWidget(self.view)
self.horizontalLayout = QtGui.QHBoxLayout()
spacerItem = QtGui.QSpacerItem(150, 20, QtGui.QSizePolicy.Expanding,
QtGui.QSizePolicy.Minimum)
self.horizontalLayout.addItem(spacerItem)
self.toolButton_3 = QtGui.QToolButton(self.centralwidget)
self.toolButton_3.setIconSize(QtCore.QSize(48, 24))
self.toolButton_3.setText("Previous")
self.horizontalLayout.addWidget(self.toolButton_3)
self.toolButton_4 = QtGui.QToolButton(self.centralwidget)
self.toolButton_4.setIconSize(QtCore.QSize(48, 24))
self.toolButton_4.setText("Next")
self.horizontalLayout.addWidget(self.toolButton_4)
spacerItem1 = QtGui.QSpacerItem(100, 20, QtGui.QSizePolicy.Expanding,
QtGui.QSizePolicy.Minimum)
self.horizontalLayout.addItem(spacerItem1)
self.toolButton_6 = QtGui.QToolButton(self.centralwidget)
self.toolButton_6.setText("Quit")
self.horizontalLayout.addWidget(self.toolButton_6)
self.verticalLayout.addLayout(self.horizontalLayout)
self.gridLayout.addLayout(self.verticalLayout, 0, 0, 1, 1)
MainWindow.setCentralWidget(self.centralwidget)
MainWindow.setWindowTitle("speedyView")
MainWindow.show()
QtCore.QCoreApplication.processEvents()
QtCore.QObject.connect(ui.toolButton_3, QtCore.SIGNAL("clicked()"), self.prec)
QtCore.QObject.connect(ui.toolButton_4, QtCore.SIGNAL("clicked()"), self.next)
QtCore.QObject.connect(ui.toolButton_6, QtCore.SIGNAL("clicked()"), exit)
QtCore.QMetaObject.connectSlotsByName(MainWindow)
self.centralwidget.wheelEvent = self.wheel_event
self.set_view()
def set_view(self):
in_folder = "/folder/with/images/"
chain = in_folder + "/*"
self.images = glob.glob(chain)
self.images.sort(cmp=lambda x, y: cmp(x.lower(), y.lower()))
self.zoom_step = 0.04
self.w_vsize = self.view.size().width()
self.h_vsize = self.view.size().height()
if self.w_vsize <= self.h_vsize:
self.max_vsize = self.w_vsize
else:
self.max_vsize = self.h_vsize
self.l_pix = ["", "", ""]
self.i_pointer = 0
self.p_pointer = 0
self.load_current()
self.p_pointer = 1
self.load_next()
self.p_pointer = 2
self.load_prec()
self.p_pointer = 0
def next(self):
self.i_pointer += 1
if self.i_pointer == len(self.images):
self.i_pointer = 0
self.p_view = self.c_view
self.c_view = self.n_view
self.view_current()
if self.p_pointer == 0:
self.p_pointer = 2
self.load_next()
self.p_pointer = 1
elif self.p_pointer == 1:
self.p_pointer = 0
self.load_next()
self.p_pointer = 2
else:
self.p_pointer = 1
self.load_next()
self.p_pointer = 0
def prec(self):
self.i_pointer -= 1
if self.i_pointer <= 0:
self.i_pointer = len(self.images)-1
self.n_view = self.c_view
self.c_view = self.p_view
self.view_current()
if self.p_pointer == 0:
self.p_pointer = 1
self.load_prec()
self.p_pointer = 2
elif self.p_pointer == 1:
self.p_pointer = 2
self.load_prec()
self.p_pointer = 0
else:
self.p_pointer = 0
self.load_prec()
self.p_pointer = 1
def view_current(self):
size_img = self.c_view.size()
wth, hgt = QtCore.QSize.width(size_img), QtCore.QSize.height(size_img)
self.scene.clear()
self.scene.setSceneRect(0, 0, wth, hgt)
self.scene.addPixmap(self.c_view)
QtCore.QCoreApplication.processEvents()
def load_current(self):
self.l_pix[self.p_pointer] = QtGui.QPixmap(self.images[self.i_pointer])
self.c_view = self.l_pix[self.p_pointer].scaled(self.max_vsize, self.max_vsize,
QtCore.Qt.KeepAspectRatio,
QtCore.Qt.FastTransformation)
#change the previous line with QtCore.Qt.SmoothTransformation eventually
self.view_current()
def load_next(self):
if self.i_pointer == len(self.images)-1:
p = 0
else:
p = self.i_pointer + 1
self.l_pix[self.p_pointer] = QtGui.QPixmap(self.images[p])
self.n_view = self.l_pix[self.p_pointer].scaled(self.max_vsize,
self.max_vsize,
QtCore.Qt.KeepAspectRatio,
QtCore.Qt.FastTransformation)
def load_prec(self):
if self.i_pointer == 0:
p = len(self.images)-1
else:
p = self.i_pointer - 1
self.l_pix[self.p_pointer] = QtGui.QPixmap(self.images[p])
self.p_view = self.l_pix[self.p_pointer].scaled(self.max_vsize,
self.max_vsize,
QtCore.Qt.KeepAspectRatio,
QtCore.Qt.FastTransformation)
def wheel_event (self, event):
numDegrees = event.delta() / 8
numSteps = numDegrees / 15.0
self.zoom(numSteps)
event.accept()
def zoom(self, step):
self.scene.clear()
w = self.c_view.size().width()
h = self.c_view.size().height()
w, h = w * (1 + self.zoom_step*step), h * (1 + self.zoom_step*step)
self.c_view = self.l_pix[self.p_pointer].scaled(w, h,
QtCore.Qt.KeepAspectRatio,
QtCore.Qt.FastTransformation)
self.view_current()
if __name__ == "__main__":
import sys
app = QtGui.QApplication(sys.argv)
MainWindow = QtGui.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())
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