RaphaelJS: Ensuring Consistent Size of SVG Path Shapes

Question

RaphaelJS: Ensuring Consistent Size of SVG Path Shapes

I am currently constructing a website that features an SVG map of the United States using the user-friendly usmap jQuery plugin powered by Raphael. An event is triggered when an individual state on the map is clicked.

However, when rendering a single state from the US States object, I encounter an issue with the paths being relative to each other as displayed in the entire map. My goal is to have each state rendered at approximately the same size when viewed individually.

While I am aware that applying a multiplier to the path parameters can scale the overall state, I am seeking a dynamic method to determine this multiplier.

I attempted to utilize setViewBox with the hope that it would resize the <path> element to fit the area but it did not produce the desired effect.

Therefore, my options are to either make the <path> fill the space or find a way to calculate a multiplier to scale the <path>.

// State coordinates extracted from the All states SVG file
var statePolygon = "M 93.573239,6.3617734 L 97.938071,7.8167177..."; // (coordinates truncated for brevity)
var width = 175,
    height = 125,
    paper = Raphael(document.getElementById("statemap"), 350, 250);

paper.setViewBox(0, 0, width, height, true);
//  paper.canvas.setAttribute('preserveAspectRatio', true);
paper.path(statePolygon);

Any suggestions or ideas?

Update

After some research (special mention to Jordan), I discovered that determining a "size" dimension involves capturing the variance between all X coordinates (the same can be done with Y coordinates). By calculating the difference between the lowest and highest X coordinate, you can establish a size reference.

If you identify what a standard size should be, you can then calculate a multiplier to apply to each state based on its size relative to the standard one.

In my scenario, Kansas has a differential of 128 while CT has 29, indicating that CT requires a multiplier of 4.41 to match the relative size of Kansas. TX, with a difference of 242, necessitates a multiplier of 0.53 to adjust its size accordingly.

This process normalizes the sizes of the states. If further adjustments are needed using Raphael, the transform function can come in handy:

p = paper.path(statePolygonNew);
var scale = 1.5;
p.transform("t" + scale*52 + "," + scale*32 + " s" + scale + "");

Thank you, Scott

javascript jquery svg raphael

Answer 1

Answer №1

There are multiple approaches to tackle this issue. Here are a couple of methods you can consider.

Adjusting the viewbox to match the path

Your initial attempt at using this method was incorrect when initially searching for a solution. The viewbox serves as a tool for dynamically scaling the translation of SVG coordinates to screen coordinates. Setting the viewbox to match the dimensions of the SVG in screen units essentially does nothing, as it's the default behavior.

Instead, try aligning the viewbox with the bounding box of the target path:

var statePathString = "..."; // insert your path here
var statePath = paper.path(statePathString).attr({ /* your attributes */ });
var bbox = statePath.getBBox();
paper.setViewBox(bbox.x, bbox.y, bbox.width, bbox.height, true);

This creates the path for the state, calculates its dimensions, and zooms the viewbox to focus solely on that portion of the SVG coordinate system. Additional adjustments may be necessary to maintain aspect ratios and include margins, but this is a straightforward approach.

Adapting the path to suit the existing viewbox

If you choose to avoid manipulating the viewbox—due to valid reasons—you can modify the path to align with the default viewing rectangle using Raphael's utility functions. Here's how I would handle it, assuming you already have variables width and height representing your paper's dimensions:

var bbox = Raphael.pathBBox(statePathString); // Convenient function for obtaining a bounding box without creating a path

// Calculate the larger dimensional quotient between width and height
var scale = Math.max(bbox.width / width, bbox.height / height);

// Transform the path so it starts at 0,0 and scales to fill the SVG appropriately
var transformedPathString = Raphael.transformPath(statePathString,
["T", 0 - bbox.x, 0 - bbox.y, /* Adjust position up and left to align upper-left corner with 0,0 */
"S", 1.0 / scale, 1.0 / scale, 0, 0]);

Now you can further manipulate the transformedPathString as needed—most likely by passing it to paper.path and styling it accordingly.

Answer 2

There are multiple approaches to tackle this issue. Here are a couple of methods you can consider.

Adjusting the viewbox to match the path

Your initial attempt at using this method was incorrect when initially searching for a solution. The viewbox serves as a tool for dynamically scaling the translation of SVG coordinates to screen coordinates. Setting the viewbox to match the dimensions of the SVG in screen units essentially does nothing, as it's the default behavior.

Instead, try aligning the viewbox with the bounding box of the target path:

var statePathString = "..."; // insert your path here
var statePath = paper.path(statePathString).attr({ /* your attributes */ });
var bbox = statePath.getBBox();
paper.setViewBox(bbox.x, bbox.y, bbox.width, bbox.height, true);

This creates the path for the state, calculates its dimensions, and zooms the viewbox to focus solely on that portion of the SVG coordinate system. Additional adjustments may be necessary to maintain aspect ratios and include margins, but this is a straightforward approach.

Adapting the path to suit the existing viewbox

If you choose to avoid manipulating the viewbox—due to valid reasons—you can modify the path to align with the default viewing rectangle using Raphael's utility functions. Here's how I would handle it, assuming you already have variables width and height representing your paper's dimensions:

var bbox = Raphael.pathBBox(statePathString); // Convenient function for obtaining a bounding box without creating a path

// Calculate the larger dimensional quotient between width and height
var scale = Math.max(bbox.width / width, bbox.height / height);

// Transform the path so it starts at 0,0 and scales to fill the SVG appropriately
var transformedPathString = Raphael.transformPath(statePathString,
["T", 0 - bbox.x, 0 - bbox.y, /* Adjust position up and left to align upper-left corner with 0,0 */
"S", 1.0 / scale, 1.0 / scale, 0, 0]);

Now you can further manipulate the transformedPathString as needed—most likely by passing it to paper.path and styling it accordingly.

RaphaelJS: Ensuring Consistent Size of SVG Path Shapes

Update

Answer №1

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