This post shows a form control widget that performs validation on its input. The invalid input is highlighted in red and the error message is display below the input. The input is validated in real-time (as the text is changed) when invalid the submit button is disabled and when valid it is enabled. The desired effect is shown below:
This post demonstrates how to create custom tabs using QPushButtons in a QButtonGroup. The code below is self explanatory, the button group ensures that only a single button can be selected at one time. The buttons are made to look more like tabs using QT style sheet and the final result is shown below
There is no API to insert a checkbox into the header of a QTableView. The recommended way of achieving this is to subclass the QHeaderView and draw the checkbox in the paintSection() method which is in my opinion overkill for such a simple feature.
In this post, I show how to achieve a similar effect by simply adding icons in the header. The desired effect is shown below:
import cv2
from math import atan, pi, ceil
img = cv2.imread('mask3.jpg', 0)
h,w = img.shape[:2]
cv2.imshow('original', img)
m = cv2.moments(img)
# You can read about Image Moments
# Chapter 18 Shape analysis - Page 633
# Digital Image Processing 4th Edition By William K. Pratt
# OR http://en.wikipedia.org/wiki/Image_moment
x = m['m10']/m['m00']
y = m['m01']/m['m00']
mu02 = m['mu02']
mu20 = m['mu20']
mu11 = m['mu11']
lambda1 = 0.5*( mu20 + mu02 ) + 0.5*( mu20**2 + mu02**2 - 2*mu20*mu02 + 4*mu11**2 )**0.5
lambda2 = 0.5*( mu20 + mu02 ) - 0.5*( mu20**2 + mu02**2 - 2*mu20*mu02 + 4*mu11**2 )**0.5
lambda_m = max(lambda1, lambda2)
# Convert from radians to degrees
angle = atan((lambda_m - mu20)/mu11)*180/pi
print angle
# Create a rotation matrix and use it to de-skew the image.
center = tuple(map(int, (x, y)))
rotmat = cv2.getRotationMatrix2D(center, angle , 1)
rotatedImg = cv2.warpAffine(img, rotmat, (w, h), flags = cv2.INTER_CUBIC)
cv2.imshow('final', rotatedImg)
cv2.waitKey()
| Original Image | De-skewed Image | Orientation (degree) |
|---|---|---|
 |
 |
-89.99 |
 |
|
-0.0 |
 |
 |
-39.03 |
 |
 |
46.95 |
 |
 |
3.57 |
# Install python cd $OPENSHIFT_TMP_DIR wget http://python.org/ftp/python/2.7.3/Python-2.7.3.tar.bz2 tar jxf Python-2.7.3.tar.bz2 cd Python-2.7.3 ./configure --prefix=$OPENSHIFT_DATA_DIR --enable-shared make make altinstall export PATH=$OPENSHIFT_DATA_DIR/bin:$PATH export LD_LIBRARY_PATH=$OPENSHIFT_DATA_DIR/lib # Install setuptools cd $OPENSHIFT_TMP_DIR wget --no-check-certificate https://pypi.python.org/packages/2.7/s/setuptools/setuptools-0.6c11-py2.7.egg#md5=fe1f997bc722265116870bc7919059ea sh setuptools-0.6c11-py2.7.egg export PATH=$OPENSHIFT_DATA_DIR/bin:$PATH export LD_LIBRARY_PATH=$OPENSHIFT_DATA_DIR/lib # Install pip cd $OPENSHIFT_TMP_DIR wget --no-check-certificate http://pypi.python.org/packages/source/p/pip/pip-1.1.tar.gz tar zxf pip-1.1.tar.gz cd pip-1.1 python2.7 setup.py install --prefix=$OPENSHIFT_DATA_DIR/lib/python2.7/site-packages/ python2.7 setup.py install export PATH=$OPENSHIFT_DATA_DIR/bin:$PATH export LD_LIBRARY_PATH=$OPENSHIFT_DATA_DIR/lib # Install numpy $OPENSHIFT_DATA_DIR/bin/pip install numpy # House-cleaning cd $OPENSHIFT_TMP_DIR rm -r Python-2.7.3 rm Python-2.7.3.tar.bz2 rm -r pip-1.1/ rm pip-1.1.tar.gz rm setuptools-0.6c11-py2.7.egg # Install CMake cd $OPENSHIFT_TMP_DIR wget http://www.cmake.org/files/v2.8/cmake-2.8.10.2.tar.gz tar xvf cmake-2.8.10.2.tar.gz cd cmake-2.8.10.2 ./configure --prefix=$OPENSHIFT_DATA_DIR gmake gmake install # Download OPenCV cd $OPENSHIFT_TMP_DIR wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.4.3/OpenCV-2.4.3.tar.bz2/download tar xvf OpenCV-2.4.3.tar.bz2 # More House-cleaning rm cmake-2.8.10.2.tar.gz rm OpenCV-2.4.3.tar.bz2 cd OpenCV-2.4.3/ rm -r 3rdparty/ rm -r android rm -r doc rm -r data rm -r ios rm -r samples rm -r apps rm README rm -r ../cmake-2.8.10.2/Tests rm -r ../cmake-2.8.10.2/Testing rm -r ../cmake-2.8.10.2/Example rm -r ../cmake-2.8.10.2/Docs rm -r ../cmake-2.8.10.2/Source
mkdir release cd release $OPENSHIFT_DATA_DIR/bin/cmake cmake ../OpenCV-2.4.3 -D BUILD_NEW_PYTHON_SUPPORT=ON -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=$OPENSHIFT_DATA_DIR -D PYTHON_LIBRARY=$OPENSHIFT_DATA_DIR/lib/libpython2.7.so -D CMAKE_INCLUDE_PATH=$OPENSHIFT_DATA_DIR/include/python2.7 -D PYTHON_INCLUDE_DIR=$OPENSHIFT_DATA_DIR/include/python2.7 -D PYTHON_PACKAGES_PATH=$OPENSHIFT_DATA_DIR/lib/python2.7/site-packages -D PYTHON_EXECUTABLE=$OPENSHIFT_DATA_DIR/bin/python2.7 -D WITH_OPENEXR=OFF -D BUILD_DOCS=OFF -DBUILD_SHARED_LIBS=ON .. make make install
Python 2.7.3 (default, May 28 2013, 07:58:37)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> A = cv2.imread("A.jpg")
>>> print A
None