[Python编程(第4版)].(Programming.Python.4th.Edition).Mark.Lutz.文字版

hbar.pack(side=BOTTOM, fill=X) # so clipped first

canvas.pack(side=TOP, fill=BOTH, expand=YES)

vbar.config(command=canvas.yview) # call on scroll move

hbar.config(command=canvas.xview)

canvas.config(yscrollcommand=vbar.set) # call on canvas move

canvas.config(xscrollcommand=hbar.set)

canvas.config(height=height, width=width) # init viewable area size

# changes if user resizes

thumbs = makeThumbs(imgdir) # [(imgfile, imgobj)]

numthumbs = len(thumbs)

if not numcols:

numcols = int(math.ceil(math.sqrt(numthumbs))) # fixed or N x N

numrows = int(math.ceil(numthumbs / numcols)) # 3.x true div

linksize = max(thumbs[0][1].size) # (width, height)

fullsize = (0, 0, # upper left X,Y

(linksize * numcols), (linksize * numrows) ) # lower right X,Y

canvas.config(scrollregion=fullsize) # scrollable area size

rowpos = 0

savephotos = []

while thumbs:

thumbsrow, thumbs = thumbs[:numcols], thumbs[numcols:]

colpos = 0

for (imgfile, imgobj) in thumbsrow:

photo = PhotoImage(imgobj)

link = Button(canvas, image=photo)

handler = lambda savefile=imgfile: ViewOne(imgdir, savefile)

link.config(command=handler, width=linksize, height=linksize)

link.pack(side=LEFT, expand=YES)

canvas.create_window(colpos, rowpos, anchor=NW,

window=link, width=linksize, height=linksize)

colpos += linksize

savephotos.append(photo)

rowpos += linksize

return win, savephotos

if __name__ == '__main__':

imgdir = 'images' if len(sys.argv) < 2 else sys.argv[1]

main, save = viewer(imgdir, kind=Tk)

main.mainloop()

To see this program in action, make sure you’ve installed the PIL extension described

near the end of Chapter 8 and launch the script from a command line, passing the name

of the image directory to be viewed as a command-line argument:

...\PP4E\Gui\PIL> viewer_thumbs_scrolled.py C:\Users\mark\temp\101MSDCF

As before, clicking on a thumbnail image opens the corresponding image at its full size

in a new pop-up window. Figure 9-25 shows the viewer at work on a large directory

copied from my digital camera; the initial run must create and cache thumbnails, but

later runs start quickly.

558 | Chapter 9: A tkinter Tour, Part 2

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