Recalculating path's array after modification - fabricjs - fabricjs

After moving, rescaling or rotating a path in fabricjs, I would like to recalculate the path's array coordinates in order to use them later to draw the exact same path on a plain HTML5 canvas.
I have gotten around rotation by storing the angle and then performing a transformation of the whole html canvas. For translation I tried recalculating the points like so:
point[1] = (point[1] + modifiedObject.left - oldState.left);
point[2] = (point[2] + modifiedObject.top - oldState.top);
but this messes up with rescaling on fabric.
I also tried using the transformation matrix on the points, but this didn't work either and I think it's because I am missing some steps in between.
Any help would be appreciated.
Here's a simple demo of what I'm trying to do in essence: https://jsfiddle.net/1b68eLdr/86688/

Related

Creating THREE js extrudeGeometry from svg path

I'm trying to generate a 3d map of the boroughs of London using Three js. I've reverse engineered this example: http://threejs.org/examples/webgl_geometry_extrude_shapes2.html
using this svg file: https://upload.wikimedia.org/wikipedia/commons/2/29/London-boroughs.svg
So, I'm passing svg path strings such as:
M130.833,250.833L135.5,262.5l14,42.667l-6.333,4l-4.667,3.667l1,3.666l-14.333,3 c0,0,0.333,3.334,4.667,5.667s16,2.667,17,3.667s0.667,6.333,0.667,6.333l-5.667,6.333l-0.667,6.667l-1.667,2l-3.333,1.333l-4.667,6 l-1.333,10l-2.667,8l-4-0.333c0,0,0.667,6.001-0.333,9.667s-2,9.666-5,11.333S112.5,396,112.5,396"
into the transformSVGPath function, and it kind of works except the vertices seem to be interpolated badly.
I get the console error "three.js:34023 THREE.ShapeUtils: Unable to triangulate polygon! in triangulate()" and it looks like this:
On examination of the SVG, it is a collection of lines over a primary closed shape. The primary shape is the first element in the SVG file and encompasses all of London. The rest of the paths are simply lineTo and bezier curves which define the borders. This is done so that the svg file size will be efficient and that shared edges of boroughs are not doubled - a classic 2d mapping issue. 3d is a different problem space - extrude path in Three.js requires discrete outline shapes to form a complete closed shape. This SVG file is unusable for 3d or polygons. You're better off finding each borough as a single SVG/polygon and importing them each individually if you can find them.
I believe you will find this file more usable as each borough is a discrete shape, but it will still need tayloring to remove the strokes: https://commons.wikimedia.org/wiki/File:London_boroughs.svg

Applying rotation to Graphics object

I have very little experience programming with graphics objects. I am currently tasked with exporting a document (.tiff image) with redacted annotations. The redacted annotation is just a black rectangle object. I am able to get the x coordinates, y coordinates, width and height properties through the .XMP data. There is also a property called rotatation. This is where I am getting stuck, applying the rotation.
So, imagine a document with a redaction on it blacking out the first paragraph. Then, using a tool in the editor the user rotates the document so that it is now laying on it's side. The client is able to render the redaction correctly because we are using the Atalasoft controls to get and display annotations. Now we have a web service that will go and retrieve that image with redactions. We are not able to use the Atalasoft controls in this service due to licensing issues so we just extract the .XMP data from the .tiff image and manually draw the redactions. The problem is, if the user rotates the document when the redaction is already on the document I am having a hard time getting the redaction to rotate correctly (due to my lack of knowledge on graphics programming). If I do not apply any rotation, the redaction is displayed where it was BEFORE the document had been rotated, thus redacting the wrong area of the document.
Here is what I have tried:
Dim rectangle As New Rectangle(xCoordinate, yCoordinate, width, height)
graphics.RotateTransform(rotation)
graphics.FillRectangle(Brushes.Black, rectangle)
When I do this, the redaction does not show up at all on the final document. I have read that I may need to call the following before applying the rotation:
graphics.TranslateTransform(x,y)
But I have no idea what I should be passing in as x and y. It seems like I just need to get the rotation to apply from the upper left corner of the rectangle, but I have yet to figure out a way to properly do this.
Thank you so much for any help or pushes in the right direction!
EDIT 1:
I have also tried this (taken from How can I rotate an RectangleF at a specific degree using Graphics object?).
Dim rectangle As New Rectangle(xCoordinate, yCoordinate, width, height)
Using rotationMatrix As New Matrix
rotationMatrix.RotateAt(rotation, New PointF(rectangle.Left + (rectangle.Width / 2), rectangle.Top + (rectangle.Height / 2)))
graphics.Transform = rotationMatrix
graphics.FillRectangle(Brushes.Black, rectangle)
graphics.ResetTransform()
End Using
Which does rotate the rectangle, but it ends up in the wrong spot so it is not redacting the correct portion of the document. Once again, when I display the document without any rotation transform, it looks like the redaction simply needs to be rotated using the upper left corner as an axis but I'm not quite sure how to accomplish that.
Figured it out. Here is how I am rotating a rectangle using the upper left-hand corner as the axis:
Dim rectangle As New Rectangle(xCoordinate, yCoordinate, width, height)
Using rotationMatrix As New Matrix
rotationMatrix.RotateAt(rotation, New PointF(rectangle.Left, rectangle.Top))
graphics.Transform = rotationMatrix
graphics.FillRectangle(Brushes.Black, rectangle)
graphics.ResetTransform()
End Using

Add BullsEye to Image (changing pixels)

I am trying to add a target (bullseye) to an image without the use of importing python functions, it is proving to be rather difficult however I believe I need to define a circle through use of code. It should be done by changing the pixels as opposed to importing functions.
Thanks
Needs to be in the centre of an image
You will need to add more information here - how is your image represnted in Python? Normally for porduction code, dealing with images is done through 3rd party modules, each of which have a way to draw or change different pixels. If you are using none you have to define your image reading and writting code (or a way to display the image on the screen).
Anyway, doing all of that without any "importing" will be quite artificial, though feasible.
Maybe you should use pnm files which have a minimum of encoding required.
That said, you could represent the image in memory as a bytesarray object, and use math.sin and math.cos (you will have to import those, or resort to a "raytracing" approach which can render the circle based on x**2 + y * 2 = r ** 2 ) to draw your circle.

How do I rotate or scale (transform) an SVG path relative to its center point?

I'm trying to rotate and scale shapes within an SVG around their center point. I've looked into several libraries, including Jquery, Greensock, D3, RaphaelJS, but I haven't been able to find any that provide a straightforward way to accomplish this. Each animates the shape from the origin point (which I understand is the default). I want to be able to spin a shape around its center point or scale it up or down from the center point.
Here are a couple examples using Greensock and D3 that illustrate the default behavior: http://jsbin.com/AHEXiPa/1/edit?html,js,output
Each of these examples bounce in and out from the top left as opposed to remaining stationary and expanding from the center of the triangle out in all directions.
Can one of the libraries I mentioned accomplish this, or is there another library or method I should consider?
Ideally, I need to be able to apply the animation/transform to an existing object in the DOM. D3 is good at this for instance, but Raphael seems to require converting an SVG to Raphael first prior to injecting it into the DOM.
Really its a case of pick the library that suits your needs, and then you will figure a way. As BigBadaboom says, if you do a search, there are lots of solutions.
To try and combine your questions, as sometimes the tricky bit is using an existing DOM object, I've included an example in Snap.svg. You can often do something similar in most libraries.
jsfiddle here Fiddle using your existing html.
s = Snap("#mySVGContainer1"); // create a canvas from existing svg
var triangle1 = s.select("#myShape1").transform("r90"); //select&transform existing object
p = Snap("#mySVGContainer2");
var triangle2 = p.select("#myShape2");
var bbox = triangle2.getBBox(); //bounding box, centre cx/cy
//rotate and scale with transform string (raphael/snap format)
triangle2.animate({ transform: "r180," + bbox.cx + ',' + bbox.cy + "s3,3," + bbox.cx + "," + bbox.cy }, 2000);
For rotations, as #Ian points out, you can specify the center of rotation. For other transformations, changes are defined relative to the path's (0,0) point.
The easiest way to get transformations to work relative to the path's center is to either:
Define the path so that it is centered around the (0,0) point; or
Wrap the path in a <g> element, and then translate it so it is centered on the (0,0) point of the <g> element's coordinate system.
Then, you can apply rotations, scales and transforms (on the <g> element, if using) and they will all be nicely centred.
The trickiest part is figuring out the "center" of an arbitrary shape. #Ian's approach of using the center of the bounding box will usually give decent results. If your shape is a polygon there are d3 functions you could use.
Example showing a shape moving with the mouse, rotating and changing scale, all centered around the center of the bounding box:
http://fiddle.jshell.net/LgfE3/
Edit: simplier jsfiddle
I've been looking for a long time, and will settle for the following.
1. Design your svg shape at coordinate x:0,y:0.
2. Identify by hand the center of rotation, by example, center = [ x:50,y:100].
3. Build a spinIt() function such :
function spinIt() {
needle.transition()
.duration(2000)
.attrTween("transform", tween);
function tween() {
return d3.interpolateString("rotate(-180, 50, 100)", "rotate(90, 50, 100)");
}
}
4. Use it on a triger:
svg.on("click", spinIt);
http://jsfiddle.net/SHF2M/79/

D3 Sunburst clip path of text

I am trying to implement a d3 visualization based on the sunburst diagram, and i have found an almost perfect online example of this which i have got working http://tributary.io/inlet/4127332/:
My main issue is that I need to also Clip the text to the segment,I have tried using the svg clip path but my meager d3 skills have let me down. Any help with this is appreciated.
So my first attempt to clip the text did not work and I think this is because the arc's coordinate space does not line up with the text's coordinate space in the way that you want if you are using the arc generator, as you are.
I found that if I apply the clip to the groups you make for each node then it worked like a charm. There was one caveat. When I tried generating my clip path and then applying them the order that the nodes were joined to the elements differed and so the wrong path were clipping the wrong text. I got around this by adding an id to each data element. You can see the final version here
The important parts are adding the clip paths (note the use of the new id field):
svg.append('defs')
.selectAll("clipPath")
.data(partition.nodes)
.enter().append('svg:clipPath')
.attr('id', function(d,i) { return d.id;})
.append('path').attr('d', arc);
Then you simply have to reference them on your node groups (again using the id):
group =
svg.selectAll("g")
.data(partition.nodes)
.enter().append('svg:g')
.attr('clip-path', function(d,i) { return 'url(#' + d.id + ')';});
In the tributary I put the svg data join first so that the "defs" node would appear in the usual place (first after the svg tag), but I do not think this is technically necessary.

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