Finder

class Finder

Be aware: Since 1.1.0 the behavior is changed compared to previous versions, to be consistent with Region.find()/findAll().

A Finder object implements an iterator of matches and allows to search for a visual object in an image file that you provide (e.g. a screenshot taken and saved in a file before). After setting up the finder object and doing a find operation, you can iterate through the found matches if any.

Be aware: an iterator can be stepped through only once - it is empty afterwards

Compared with the region based find/findAll operation, no exception FindFailed is raised in case nothing is found at all. Use hasNext() to check.

Note: There is no chance, to get the number of matches in advance. If you iterate through to count, afterwards your finder is empty. So you have to save your matches somehow while counting, if you need them later (one possible solution see example below).

The workflow always is (except for findChanges):
  • setup a Finder
  • do a find or findAll operation
  • check with hasNext(), wether anything was found at all
  • get the available matches with next() if hasNext() says more are available
  • After a complete iteration, the finder object is empty.

You can start a new find or findAll operation on the same Finder object at any time.

class Finder
Finder(path-to-imagefile)

Create a new finder object.

Parameters:path-to-imagefile – filename to a source image to search within
find(path-to-imagefile[, similarity])

Find a given image within a source image previously specified in the constructor of the finder object. If more than one match is possible, yet only one is returned and which one is not predictible.

Parameters:
  • path-to-imagefile – the target image to search for
  • similarity – the minimum similarity a match should have. If omitted, the default is used.
findAll(path-to-imagefile[, similarity])

Find all occurences of the given image within a source image previously specified in the constructor of the finder object.

Parameters:
  • path-to-imagefile – the target image to search for
  • similarity – the minimum similarity a match should have. If omitted, the default is used.
hasNext()

Check whether there are more matches available that satisfy the minimum similarity requirement. A False returned after the first hasNext() signals, that nothing was found at all.

Returns:True if more matches exist.
next()

Get the next match.

Returns:a Match object or None, if empty or no more matches.

The returned reference to a match object is no longer available in the finder object afterwards. So if it is needed later, it has to be saved to another variable.

findChanges(path-to-imagefile)

Find rectangle areas in an image (the one the Finder was created with), that differ from another image. This feature is the image variant of onChange in the Region observe feature for one-time-use.

Parameters:path-to-imagefile – the target image to compare with (exactly same size in pixels)
Returns:a list of Region objects (empty, if no changes where detected).

Example 1: findAll using a Finder

1# create a Finder with your saved screenshot
2f = Finder()
3img=  # the image you are searching
4
5f.findAll(img) # find all matches
6
7while f.hasNext(): # loop as long there is a first and more matches
8        print "found: ", f.next() # access the next match in the row
9
10print f.hasNext() # is False, because f is empty now

Example 2: we want to know how many matches in advance and want to save the matches for later use (based on the previous example).

1# create a Finder with your saved screenshot
2f = Finder()
3img=  # the image you are searching
4
5f.findAll(img) # find all matches
6matches = [] # an empty list to store the matches
7
8while f.hasNext(): # loop as long there is a first and more matches
9        matches.append(f.next())        # access next match and add to matches
10
11print f.hasNext() # is False, because f is empty now
12
13# now we have our matches saved in the list matches
14print len(matches) # the number of matches
15
16# we want to use our matches
17for m in matches:
18        print m