SVG gaussian blur on text under Google Chrome - text

I'm trying to make a text effect with a drop shadow gaussian blur on my svg.
Under firefox it's look good, but under chrome it's horrible, as you can see below.
What is strange is taht when zooming (ctrl + mousewheel) at the max level possible, it's suddenly looks good, but at intermediate zooming level, it's still horrible.
My code to generate this example is:
<html>
<head>
</head>
<body>
<svg width="200px" heigth="200px">
<filter id="dropshadow" height="130%">
<feGaussianBlur in="SourceAlpha" stdDeviation="3" />
<feOffset dx="2" dy="2" result="offsetblur" />
<feMerge>
<feMergeNode />
<feMergeNode in="SourceGraphic" />
</feMerge>
</filter>
<text x="50" y="50" style="filter:url(#dropshadow)">This is a test</text>
</svg>
</body>
</html>
I've taken the drop shadow code from this question.
Note that I'm using one of the last version of Firefox (33.1) and of Chrome (Version 38.0.2125.122 m).

This isn't correct behaviour at all. It looks like Chrome is failing to render the alpha channel correctly for text at small font sizes.
This is what I get if I just extract the alpha channel from text sized at 18, 36 and 72pt:
<svg width="200" height="200" viewBox="0 0 200 200">
<defs>
<filter id="f" width="200%" height="200%">
<feMerge>
<feMergeNode in="SourceAlpha" />
</feMerge>
</filter>
</defs>
<rect x="0" y="0" width="200" height="200" fill="#eee" />
<text font-size="18" x="5" y="25" style="filter:url(#f)">Small</text>
<text font-size="36" x="5" y="75" style="filter:url(#f)">Medium</text>
<text font-size="72" x="5" y="165" style="filter:url(#f)">Large</text>
</svg>
EDIT: This isn't an answer, so I've flagged as community wiki.

Related

SVG filter lightsources not working in Firefox

I have the following SVG to render checkers on a board where both the board and checkers have a nice bevelled effect. I'm very happy with the effect on Chrome (and Safari) but Firefox seems to ignore the effect.
Would appreciate help understanding why it doesn't work as all the primitives show as supported in Firefox (caniuse.com).
<svg width="800" height="200" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<filter id="counter" filterUnits="objectBoundingBox">
<feGaussianBlur in="SourceAlpha" stdDeviation="2" result="blur" />
<feSpecularLighting in="blur" surfaceScale="2" specularConstant="0.3" specularExponent="10" result="lightingOut" lightingColor="white">
<fePointLight x="-2000" y="-2000" z="500" />
</feSpecularLighting>
<feComposite in="lightingOut" in2="SourceAlpha" operator="in" result="composite1" />
<feComposite in="SourceGraphic" in2="composite1" operator="arithmetic" k1="0" k2="1" k3="1" />
</filter>
<rect width="400" height="200" fill="#ffffff" />
<rect x="50" y="10" width="300" rx="10" ry="10" height="180" fill="#666666" filter="url(#counter)" />
<circle cx="120" cy="100" r="20" filter="url(#counter)" fill="black" />
<circle cx="250" cy="100" r="20" filter="url(#counter)" fill="#3333ff" />
</svg>
Codepen: https://codepen.io/jugglingcats/pen/RwWLQjJ
Many thanks
Firefox is not ignoring the effect, it's just very faint. If you increase surfaceScale and bring the point light nearer to the drawing surface, you'll be able to see it more clearly.
There are a lot of inconsistencies in lightsource implementations cross-browser - for example FireFox uses sRGB color space by default for lightsources, so you have to set Chrome to use it explicitly. Then, you need to tweak things until you have something that looks the same. For example, specularConstant doesn't seem to be doing the same thing in each browser at 0.3 - but setting it to "1" seems to be consistent. Here is a filter that looks mostly the same. I had to switch out the fePointLight for a feDistantLight to avoid positioning calculation inconsistencies.
<filter id="counter2" color-interpolation-filters="sRGB">
<feGaussianBlur in="SourceAlpha" stdDeviation="2" result="blur" />
<feSpecularLighting in="blur" surfaceScale="10" specularConstant="1" specularExponent="10" result="lightingOut" lightingColor="white">
<feDistantLight azimuth="225" elevation="0" />
</feSpecularLighting>
<feComposite in="lightingOut" in2="SourceAlpha" operator="in" result="composite1" />
<feComposite in="SourceGraphic" in2="composite1" operator="arithmetic" k1="0" k2="1" k3="1" />
</filter>

SVG text edges change color when scaling

I've created an SVG filter and applied it to some text. When I scale the text smaller by resizing the browser window, some of the edges of the text have a colored line down one side.
<svg
class="tstx" viewBox="0 0 160 160"
height="160" width="160"
style="width: 100%; height: 100%">
<defs>
<filter id="innershadow" x0="-50%" y0="-50%" width="200%" height="200%">
<feGaussianBlur in="SourceAlpha" stdDeviation="2" result="blur"/>
<feOffset dy="3" dx="3"/>
<feComposite in2="SourceAlpha" operator="arithmetic"
k2="-1" k3="1" result="shadowDiff"/>
<feFlood flood-color="grey" flood-opacity="1"/>
<feComposite in2="shadowDiff" operator="in"/>
<feComposite in2="SourceGraphic" operator="over"/>
</filter>
</defs>
<g
font-family="Verdana" font-size="80" font-weight="bold"
stroke="none" fill="#fff" filter="url(#innershadow)">
<text x="10" y="70">A</text>
<text x="80" y="70">B</text>
</g>
</svg>
How can I fix this?
Codepen Example
Move the middle margin right to scale text.
EDIT: It looks like I may have fixed the problem - I just don't know why it worked or if it will cause problems later on. I removed the following:
<feComposite in2="SourceGraphic" operator="over"/>
And the lines disappeared. Is anyone able to explain why?

Matching SVG fill pattern with repeated background image on containing element?

I am trying to create some ornate page dividers using SVGs with a fill pattern using the same image as the containing element's background image but I am having difficulty getting the SVG pattern to match the repeated background image of the containing element. I found a few similar questions on StackOverflow which mentioned using preserveAspectRatio but none of the solutions I've found are creating the desired effect.
Here's what my SVG code looks like:
<svg id="Layer_1" class="divider" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1400 150" >
<defs>
<pattern id="imgpattern" patternUnits="userSpaceOnUse" width="576" height="576" preserveAspectRatio="xMinYMin slice">
<image width="576" height="576" xlink:href="http://s12.postimg.org/730a258rx/pattern2.jpg"/>
</pattern>
<filter id="dropshadow" height="130%">
<feGaussianBlur in="SourceAlpha" stdDeviation="3"/>
<feOffset dx="0" dy="2" result="offsetblur"/>
<feMerge>
<feMergeNode/>
<feMergeNode in="SourceGraphic"/>
</feMerge>
</filter>
</defs>
<path d="M-394.09,367.9V295.34l1400,0v70s-3.39.9-4.92,1.38c-56.68,17.79-114.85,25.72-174.22,26.17-36.9.27-73.6-2.7-110.25-6.28q-67.4-6.59-134.7-14.08c-49.65-5.51-99.28-8.74-149-1.64-35.12,5-68.54,15.05-99.24,33.08-6,3.53-12.09,7-18.13,10.48-8.94,5.18-17.93,5.51-27,.36-3.47-2-7.14-3.6-10.51-5.71-48.22-30.22-101-43.79-157.83-41.84-29.13,1-58.27,2.45-87.3,4.94-40.49,3.48-80.88,8.18-121.32,12.27-24.37,2.46-48.71,5.26-73.14,7a714.52,714.52,0,0,1-96.42.34,605.73,605.73,0,0,1-96.81-13.9C-368.07,374.88-394.09,367.9-394.09,367.9Z" transform="translate(394.09 -295.32)" stroke="none" fill="url(#imgpattern)" filter="url(#dropshadow)" />
</svg>
And here's a JSFiddle which recreates my issue. Notice how the background pattern of the SVG appears more stretched and because of that does not completely match the repeated background image of the container.
One option is just to move the pattern fill into the filter like so - although there is a small problem that your texture has a one pixel black border, so the tiling isn't perfect.
<filter id="dropshadowandfill" height="130%" >
<feImage x="0" y="0" width="575" height="575" xlink:href="http://s12.postimg.org/730a258rx/pattern2.jpg"></feImage>
<feTile/>
<feComposite operator="in" in2="SourceGraphic" result="filledOriginal"/>
<feGaussianBlur in="SourceAlpha" stdDeviation="3"/>
<feOffset dx="0" dy="2" result="offsetblur"/>
<feMerge>
<feMergeNode/>
<feMergeNode in="filledOriginal"/>
</feMerge>
</filter>
</defs>
<path d="M-394.09,367.9V295.34l1400,0v70s-3.39.9-4.92,1.38c-56.68,17.79-114.85,25.72-174.22,26.17-36.9.27-73.6-2.7-110.25-6.28q-67.4-6.59-134.7-14.08c-49.65-5.51-99.28-8.74-149-1.64-35.12,5-68.54,15.05-99.24,33.08-6,3.53-12.09,7-18.13,10.48-8.94,5.18-17.93,5.51-27,.36-3.47-2-7.14-3.6-10.51-5.71-48.22-30.22-101-43.79-157.83-41.84-29.13,1-58.27,2.45-87.3,4.94-40.49,3.48-80.88,8.18-121.32,12.27-24.37,2.46-48.71,5.26-73.14,7a714.52,714.52,0,0,1-96.42.34,605.73,605.73,0,0,1-96.81-13.9C-368.07,374.88-394.09,367.9-394.09,367.9Z" transform="translate(394.09 -295.32)" stroke="none" filter="url(#dropshadowandfill)" />

Rectangle with looming border

I want to create rectangle with smoothed border. Important part that size of it's solid part should be certain. To clarify I'll give an example:
I can achieve desired effect with Gaussian filter:
<svg id="svg-root" width="800" height="600"
xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink">
<g id="test-body-content">
<defs>
<filter id="blur" filterUnits="userSpaceOnUse">
<feGaussianBlur in="SourceGraphic" stdDeviation="10" result="blur" />
<feMerge>
<feMergeNode in="blur" />
</feMerge>
</filter>
</defs>
<rect x="50" y="50" width="200" height="100" fill="black" filter="url(#blur)"/>
</g>
</svg>
Result:
But it doesn't meet requirements because it is not fully solid within given dimensions (width="200" height="100"):
Also I thought about applying gradient perpendicular to stroke, but SVG doesn't support such thing.
As #ABFORCE wrote you can provide the width and height you want via the filter element.
For example:
<filter id="blur" filterUnits="objectBoundingBox"
x="0" y="0" width="100%" height="100%">
...
</filter>
Note that this means that above filter will be clipped to the boundingbox of the filtered element.
If you want the original shape in the filter output you could add another feMergeNode like this:
<svg id="svg-root" width="800" height="600"
xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink">
<g id="test-body-content">
<defs>
<filter id="blur" filterUnits="userSpaceOnUse">
<feGaussianBlur in="SourceGraphic" stdDeviation="10" result="blur" />
<feMerge>
<feMergeNode in="blur" />
<feMergeNode in="SourceGraphic"/>
</feMerge>
</filter>
</defs>
<rect x="50" y="50" width="200" height="100" fill="black" filter="url(#blur)"/>
</g>
</svg>
Live example.

Why does a filter break the half-pixel trick for crisp 1px strokes?

I'm using the "offset everything by half a pixel" trick discussed in the second answer to this question to get a crisp 1px stroke on a shape.
(There are rounded edges involved, so the shape-rendering: crispEdges solution isn't viable here -- it makes the curved parts of strokes look terrible.)
How come adding a filter (I'm using a gaussian blur + offset filter to implement a drop shadow) breaks the half-pixel offset hack?
You can play with the jsfiddle.
<svg xmlns="http://www.w3.org/2000/svg" version="1.1">
<defs>
<filter id="f1" x="-20%" y="-20%" width="160%" height="160%">
<feOffset result="offOut" in="SourceAlpha" dx="10" dy="10" />
<feGaussianBlur result="blurOut" in="offOut" stdDeviation="2" />
<feBlend in="SourceGraphic" in2="blurOut" mode="normal" />
</filter>
</defs>
<g transform="translate(5.5,5.5)">
<!-- This one has a blurry stroke -->
<rect width="50" height="50" rx="5" ry="5" stroke="black" stroke-width="1" fill="steelblue" filter="url(#f1)" />
<!-- This one has a crisp stroke -->
<rect x="150" width="50" height="50" rx="5" ry="5" stroke="black" stroke-width="1" fill="steelblue" />
</g>
</svg>
Apparently I can't post inline images as a new user, but you can this is an image of how the svg looks for me.
If you don't like the blurry edges, you can always experiment with adding an feComponentTransfer with feFuncA to manually manipulate the edge blur. Aka:
<filter id="fee" x="-20%" y="-20%" width="160%" height="160%">
<feComponentTransfer>
<feFuncA type="table" tableValues="0 0 1" />
</feComponentTransfer>
</filter>

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