I want to combine two SVG paths such that
1.Both paths will be there but, at the area of intersection, there will be no strokes.
2.Second path will be excluded and there will be a complete stroke
See image at http://s18.postimg.org/et4m803rd/shape_combinations.jpg
I want similar function also in HTML5 canvas.
The purpose of this scenario is to implement a lasso selection tool (freehand selection) similar to that of photoshop, with Ctrl and Alt options for adding and subtracting selection [ + some other functions ].
What have you tried? This sounds a little bit like a homework assignment.
The first one is easy to replicate. Just draw the two circles with the stroke, then draw them again in the same place without the stroke.
You can achieve the second shape (the "pacman") by drawing a purple circle on the right that is clipped by a circle that is in the same position as the left (black) circle.
Related
In a webpage created with node/webpack, vega-lite, and vegaEmbed, I have a layer with rect marks with short annotations inside them using text marks. I'd like to clip the text to its surrounding rect but haven't figured out a way to do this and hope someone can point me in the right direction.
I realize text has a limit property in pixel units. If I could determine the pixel units of my rect marks (I don't know how to do this), using limit seems like a reasonable approach.
Also, if I knew the pixel extents of my rectangle, I can then write code to align the text within the rect which would be desirable. Currently I just use the same x as the rect, with a dx offset.
I've read about background for text which is a similar problem, but not the same.
Me and my team have problems with generating bitmaps out of polygons. We've tried a few different solutions in order to generate polygons sufficiently fast and have found generating SVG paths and then using CairoSVG to be the best solution for us. We are using the even-odd rule to fill the polygons. I apologies if I'm describing everything in an incorrect way in terms of vocabulary, I'm new to SVG. The pathes are created as:
path_entry = f'<path fill="rgb{rgb_color}" fill-rule="evenodd" d="{svg_path}"/>'
With header
<svg
xmlnsXlink="http://www.w3.org/2000/svg"
preserveAspectRatio="xMinYMin meet"
style="color:green;"
>
We only allow the bitmap to have a set of color values. The value of a pixel should be that of the polygon which it's inside. A problem we've encountered is that the edges of the polygons "splits" pixels, i.e a pixel can be both on the edge/inside of polygon A and polygon B. See the image below where the edge between the black, green and grey area gets a mixed color.
We've currently solved this by finding each pixel that doesn't have an allowed color. We then use numpy roll to fill the value of these pixels with the value of its neighbours according to a solution found on this site.
for shift in (-1,1):
for axis in (0,1):
a_shifted=np.roll(bitmap_only_correct_colors,shift=shift,axis=axis)
idx=~a_shifted.mask * bitmap_only_correct_colors.mask
bitmap_only_correct_colors[idx]=a_shifted[idx]
The problem with this solution is thin diagonal polygons, 1-2 pixels thick. All pixels of these polygons get the mixed value and are therefor removed. This causes the thin polygons to be partly removed creating dotted lines instead of full lines, see the image below.
My question is: Can we solve this problem with the edges of the polygons not getting fixed values in another way? The best solution would be to add some kind of setting to the SVG-Document before generating the images.
Thank you!
Turn off anti-aliasing i.e. set shape-rendering="crispEdges" See the SVG specification for more details about this CSS property.
By default, the anchor for the text element in SVG is at the bottom left, but I want it to be at the top left, since I am also creating a rectangle to act as the background for the text, but it is displayed incorrectly since the text is higher than the rectangle (because rectangle anchor/offset is at the top left). Is there a way to fix this, so both text and rectangle can be drawn at same coordinates and be displayed in the same location.
The dominant-baseline property/attribute worked for me:
svg {
dominant-baseline: hanging;
}
The coordinates (x and y) you supply for text elements is used as the baseline of the text. This makes sense because if there is text with varying font sizes on the same line, you would want their baselines to line up.
There is no "automatic" way to do what you want. SVG elements are always absolutely positioned.
You will just have to move the text down a bit by making the y coordinate a bit larger.
Alternatively, you could add a dy attribute to shift the text down a bit. Or even use a transform attribute to do the same. But using either of those methods wouldn't really be simplifying the process for you.
I am trying to mimic the behavior of markers on white boards and was wondering if it I can do it with svg polylines. I know the stroke width can be set but can be it changed to vary depending on the velocity of the mouse which I can figure out or is it just a constant value for the stroke?
Or if you wanted to use SVG, instead of using a <polyline>, use a series of connected <line>s
You can't have multiple stroke widths in a single polyline element. I think canvas is probably a better fit for this task.
This question already has answers here:
How can I cut one shape inside another?
(4 answers)
Closed 6 years ago.
So basically as my title says, I want to "cut a hole" in a rect element.
I have two rect elements, one on top of the other. The one on the bottom has a fill colour of white, and the one on the top has a fill colour of grey.
What I want to do is cut a triangle out of the top rect element so that the rect element below shows through.
This svg element is going to be used as an audio button for a media player on a page. In other words, you'll be able to click (or drag) your mouse left/right and the change in audio level will be represented by a change in the width of the rect element on the bottom, which shows through the triangle cut out of the top rect element.
I hope that's not too confusing. :P
Here is a quick mockup of what it should look like: http://forboden.com/coding/s1.png
Here is my code: http://forboden.com/coding/svgClipTest.html
Where am I going wrong here?
You should be able to use the fill-rule: evenodd(default) property to achieve this effect, if you want to prevent the fill of the rectangle from painting where the circle is. See this example from the SVG specification:
The key point is draw outer shape and inner shapes(holes) in different direction (clockwise vs anti-clockwise).
Draw the outer shape clockwise and draw the inner(holes) shapes anti-clockwise.
Or conversely, draw the outer shape(holes) anti-clockwise and draw the inner shapes clockwise.
Concat the path datas of outer shape and inner shapes(holes).
You can cut more holes by concat more hole path data.
This image explain how to cut a hole:
I see that you have it solved already, just wanted to add that if you want something more advanced then it's often quite easy to use a <mask>, see http://dev.w3.org/SVG/profiles/1.1F2/test/svg/masking-path-11-b.svg for example.
However, if you can avoid masking and clipping (e.g by just drawing things on top) that usually leads to better performance/user-experience.
Easiest way is to use <path> with the hole, and set pointer-events to none so events can pass through to the <rect> under. Of course there are many other ways to handle events such as wrapping them with a <g> and handling events on it.
You don't need to limit yourself to the basic shapes and use complicated clipping. Make things felxible enough so you can copy&paste path data generated by tools like inkscape.