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Java example source code file (render.py)

This example Java source code file (render.py) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

add, make, none, pil, png, render, rendering, rgba

The render.py Java example source code

"""
Render t-SNE text labels.
Requires PIL (Python Imaging Library) and ImageMagick "convert" command.
"""

import sys
import Image, ImageFont, ImageDraw, ImageChops, string

import os.path
#DEFAULT_FONT=os.path.join(os.path.expanduser('~'), "fonts/Vera.ttf")
DEFAULT_FONT=None

import tempfile

def render(points, filename, width=3000, height=1800, fontfile=DEFAULT_FONT, fontsize=12, margin=0.05, transparency=0.5):
    """
    Render t-SNE text points to an image file.
    points is a list of tuples of the form (title, x, y).
    filename should be a .png, typically.
    margin is the amount of extra whitespace added at the edges.
    transparency is the amount of transparency in the text.
    @warning: Make sure you open the PNG in Gimp, or something that supports alpha channels. Otherwise, it will just look completely black.
    """
    W = width
    H = height

    #im = Image.new("L", (W, H), 255)
    im = Image.new("RGBA", (W, H), (0,0,0))

    # use a bitmap font
    #font = ImageFont.load("/usr/share/fonts/liberation/LiberationSans-Italic.ttf")

    if fontfile is not None:
        assert os.path.exists(fontfile)
        font = ImageFont.truetype(fontfile, fontsize)
    
    #draw = ImageDraw.Draw(im)
    #draw.text((10, 10), "hello", font=font)
    
    minx = 0
    maxx = 0
    miny = 0
    maxy = 0
    for (title, x, y) in points:
        if minx > x: minx = x
        if maxx < x: maxx = x
        if miny > y: miny = y
        if maxy < y: maxy = y

    dx = maxx - minx
    dy = maxy - miny
    assert dx > 0
    assert dy > 0
    minx -= dx * margin
    miny -= dy * margin
    maxx += dx * margin
    maxy += dy * margin


    alpha = Image.new("L", im.size, "black")

    for (idx, pt) in enumerate(points):
        (title, x, y) = pt
    #    print x, minx
    #    print 1. * (x - minx) / (maxx - minx)
    #    print y, miny
    #    print 1. * (y - miny) / (maxy - miny)
        x = 1. * (x - minx) / (maxx - minx) * W
        y = 1. * (y - miny) / (maxy - miny) * H
    #    draw.text((x, y), w, fill=255, font=font)

    # Make a grayscale image of the font, white on black.
        pos = (x, y)
        imtext = Image.new("L", im.size, 0)
        drtext = ImageDraw.Draw(imtext)
        print >> sys.stderr, "Rendering title (#%d):" % idx, repr(title)
        if fontfile is not None:
            drtext.text(pos, title, font=font, fill=(256-256*transparency))
        else:
            drtext.text(pos, title, fill=(256-256*transparency))
#        drtext.text(pos, title, font=font, fill=128)

    # Add the white text to our collected alpha channel. Gray pixels around
    # the edge of the text will eventually become partially transparent
    # pixels in the alpha channel.
    #    alpha = ImageChops.lighter(alpha, imtext)
        alpha = ImageChops.add(alpha, imtext)
            
    # Make a solid color, and add it to the color layer on every pixel
    # that has even a little bit of alpha showing.
    #    solidcolor = Image.new("RGBA", im.size, "#ffffff")
    #    immask = Image.eval(imtext, lambda p: 120 * (int(p != 0)))
    #    im = Image.composite(solidcolor, im, immask)
    #    draw.text((x, y), w, fill=0, font=font)
    
        print >> sys.stderr, "Rendered word #%d" % idx
    #    if idx % 100 == 99:
    #        break
    
    # Add the alpha channel to the image, and save it out.
    im.putalpha(alpha)

    tmpf = tempfile.NamedTemporaryFile(suffix=".png")

    #im.save("transtext.png", "PNG")
    print >> sys.stderr, "Rendering alpha image to file", tmpf.name
    im.save(tmpf.name)

    cmd = "convert %s -background white -flatten %s" % (tmpf.name, filename)
    print >> sys.stderr, "Flattening image", tmpf.name, "to", filename, "using command:", cmd
    os.system(cmd)

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