is there a way to fill everything outside of a closed path (polygon)?
Background: I'd like to render some maps with coastlines - so sometimes I need to fill the sea with blue color, so I thought it would be the easiest and in my situation the most efficient to fill everything outside of this coastline polygon with blue color.
Thanks in advance!
You can add a rectangle covering the whole drawing area to your coastline path and set the fill rule to cairo.FILL_RULE_EVEN_ODD. Calling fill() after this fills the area outside your original path. (If you choose the correct orientation for your rectangle you can skip setting the fill rule.)
Draw a big blue rectangle over the entire cairo surface and then draw your coastline on top of that?
While you could create a closed path the size of the surface and then fill it with a solidpattern (the fill rule won't matter for a simple rectangle), it would be easier to just use the context paint() method which will fill the current clip region (that is initially set to the entire surface). It's important to do this before drawing the map/coastline boundaries and filling them so they will be on top of the background.
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It appears that in Python graphics.py, new objects are drawn behind existing objects. So if I draw a blue circle and THEN place a rectangular box over half the circle, you find the circle in on top of the rectangular box. The box, even though it was written last, is appearing behind the circle. Is there a way to control this behavior so the rectangle would appear on top of the circle and not behind it? I want to avoid having to undraw the circle, draw the rectangle, then redraw the circle, so that the rectangle is on top of the circle instead of behind it.
Certainly, this becomes more cumbersome as you have more and more overlapped objects.
Its my first time to use python code to display ds9 images.I just display black and white image but I wanted to get a color image with two or more slit positioned on the image which passes at the center,plus the position angle and coordinates should not be manually typed coz I have many images.I expect something like this.As you see the slits are not at the center I need them all at the center but they are at different angle.I need your help as usual,thanks!
I'm using matplotlib for visualizing some data on a world map, and I would like to fill the regions with a custom pattern, which may be of multiple colors.
I have two main patterns that I would like to obtain:
fill each region with stripes, but those stripes have multiple colors and different thickness depending on the region. For example, one region may be totally red, another may be half red and half green, and another may have red and blue lines, but red lines are much thicker than the blue ones.
fill with different colors in a pie-chart sliced fashion: some rays depart from the centroid of the region toward the borders,
More generally, I would like to understand how to draw a custom image and use it as a repeated pattern. Each region I've got is a set of lines, so I can assume that I can compute its centroid, size and borders before drawing the pattern.
For example, I may want to draw an histogram for each region and plot the histogram inside the region, but for doing that I need a general way for using custom images as patterns.
So, how do I do that? I tried looking at matplotlib gallery, but didn't see anything like that.
EDIT: I saw the hatch demo, but as far as I understand, has just one color, and I cannot use custom images in it http://matplotlib.org/examples/pylab_examples/hatch_demo.html
I have a panoramic one shot lens from here: http://www.0-360.com/ and I wrote a script using the python image library to "unwrap" the image into a panorama. I want to automate this process though, as currently I have to specify the center of the image. Also, getting the radius of the circle would be good too. The input image looks like this:
And the "unwrapped" image looks like this:
So far I have been trying the Hough Circle detection. The issues I have is selecting the correct values to use. Also, sometimes, dark objects near the center circle seem to throw it off.
Other Ideas I had:
Hough Line detection of the unwrapped image. Basically, choose center pixel as center, then unwrap and see if the lines on the top and bottom are straight or "curvy". If not straight, then keep trying with different centers.
Moments/blob detection. Maybe I can find the center blob and find the center of that. The problem is sometimes I get a bright ring in the center of the dark disk as seen in the image above. Also, the issue with dark objects near the center.
Paint the top bevel of the mirror a distinct color like green to make circle detection easier? If I use green and only use the green channel, would the detection be easier?
Whats the best method I should try and use to get the center of this image and possibly the radius of the outer and inner rings.
As your image have multiple circle with common centre you can move that way, like
Detect circle with Hough circle and consider circle with common centre.
Now check the ratio for co-centred circle, as your image keep that ratio constant.
I guess don't make it too fancy. The black center is at the center of the image, right? Cut a square ROI close to the image center and look for 'black' region there. Store all the 'black' pixel locations and find their center. You may consider using CMYK color space for detecting the black region.
I have got some surfaces in Pygame with a transparent background. They're all the same size. But there's a different sized circle drawn on each of them, so the circle doesn't exactly fit the image.
Here are some example images (I took a screenshot in Photoshop so you can clearly see the transparency and the size of the images):
Now I want to remove the transparent border around the image so the circle exactly fits into the image. I don't want the surface to be circle shaped, I don't think that's possible, but I want that the surface doesn't have blank columns on the left and right and that it doesn't have any blank rows on the top and the bottom. The wanted results:
The circle on the surfaces changes size every frame so I have to recalculate the new surfaces every frame.
I already Googled it, but I haven't found anything for Pygame surfaces yet. I also tried making my own function but it looks ugly and much worse: the framerate drops from 50 (if I don't call the function) to 30 fps (if I do call the function). I tested it a little bit and I found out that smaller circles take longer to process than bigger circles. How can I do this, but faster. If you want I can show the function I made.
The surface object has a method called get_bounding_rect which is where we will start. The function returns the smallest rect possible which contains all of the non-transparent pixels on the surface.
pixel_rect = image.get_bounding_rect()
With the size of this rect, we can create a new surface:
trimmed_surface = pygame.Surface(pixel_rect.size)
Now blit the portion of image contained within pixel_rect onto trimmed_surface:
trimmed_surface.blit(image, (0,0), pixel_rect)
At this point, trimmed_surface should be a surface the same size as pixel_rect, with the unwanted transparent rows and columns "trimmed" off of the original surface.
Documentation for Surface.get_bounding_rect: http://www.pygame.org/docs/ref/surface.html#Surface.get_bounding_rect