shape() parameters when using getChild()

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start99

shape() parameters when using getChild()

in Programming Questions • 1 year ago

In Inkscape, I have 3 separate rectangles in a page 388w x 297h px.

Each rectangle has id: house, door, window.

Inkscape / svg question

The svg file shows:

<svg
width="388.57144"
height="297.73553"

That agrees with Page size.

But it also includes:

<g
inkscape:label="Layer 1"
inkscape:groupmode="layer"
id="layer1"
transform="translate(-8.5714245,593.94476)">
<rect
style="fill:#00ff00;fill-opacity:1;stroke:none"
id="house"
width="300"
height="200"
x="8.5714245"
y="-584.7807"
ry="8.1554852"
inkscape:label="#rect2985" />
<rect
style="fill:#ff0000;fill-opacity:1;stroke:none"
id="door"
width="60"
height="100"
x="337.14285"
y="-593.94476"
ry="5.6589088"
inkscape:label="#rect2987" />
<rect
style="fill:#00ffff;fill-opacity:1;stroke:none"
id="window"
width="100"
height="70"
x="294.28571"
y="-366.20923"
ry="7.7640224"
inkscape:label="#rect2992" />
</g>

Where does the transform="translate(-8.5714245,593.94476)"> get these values?

I couldn’t find them in Inkscape.

Processing question

In the sketch I have:

main = loadShape("drawing08_3RectsId.svg");
house = main.getChild("house");
door = main.getChild("door");
window = main.getChild("window");

shape(main);

displays the whole file, all three rectangles as they appear in Inkscape.

But to see the children, I need to use

translate(-9, 593);
shape(house,0, 0);
shape(door,0, 0);
shape(window,0, 0);

The objects appear as in main.

In Reference, shape() it indicates that parameters x, y, width, and height refer to location and size of drawn shape.

http://processing.org/reference/shape_.html

The only way I’ve seen this works is if:

There’s one shape per file, and
Page size is made equal to the selected object

Then in Processing, the shape(x, y, width, height) values work as expected.

It's confusing that main appears with no translation but the children don't.

Are there additional steps needed with children so that shape() parameters work?
If not, shouldn't Reference shape() provide some further explanation?

Replies(4)

PhiLho

Re: shape() parameters when using getChild()

1 year ago

window, for example, has x and y coordinates. Drawing the children takes in account these coordinates, you need to make a reverse translate of these values to display them at 0.

start99

Re: shape() parameters when using getChild()

1 year ago

you need to make a reverse translate of these values to display them at 0.

translate(-9, 593); // Isn’t this a reverse translation from what Inkscape does?
shape(house,0, 0);
shape(door,0, 0);
shape(window,0, 0);

All the children shapes appear exactly as they do in the Inkscape page!

The shape() Reference says:

“Displays shapes to the screen…. The sh parameter specifies the shape to display and the x and y parameters define the location of the shape from its upper-left corner.”

The reader assumes that it refers to the location in Processing, not Inkscape!

When there is a solitary shape (as described in first post) the x,y values are absolute.

But with getChild() shapes, the x and y parameters are processed as offset values. The Reference does not mention this complication.

If I enter:

shape(door,-250,110);
shape(window,-120,-160);

The door and window appear in new locations relative to their original locations in the Inkscape page.

Obviously, we're interested in positioning shapes on the Processing page.

PhiLho

Re: shape() parameters when using getChild()

1 year ago

Each (primitive) shape has its own set of x / y coordinates.
And for complex shapes, it is even harder as the offset is coded in the shape definition itself.
Only experiments, or direct study & manipulation (with a text editor!) can help here.
SVG isn't a simple medium!

start99

Re: shape() parameters when using getChild()

1 year ago

In this case, there seems to be a simple workaround.

Change x and y values in the group section of the svg file to 0 (zero).

The single translate and all the child shapes.

The edited file can not be opened in Inkscape, but it enables absolute x,y values in the Processing shape() function.

Append “_zero” to the file name as a reminder.

main = loadShape("drawing08_3RectsId_zero.svg");
house = main.getChild("house");
door = main.getChild("door");
window = main.getChild("window");

svg file:

<g
inkscape:label="Layer 1"
inkscape:groupmode="layer"
id="layer1"
transform="translate(0,0)">
<rect
style="fill:#00ff00;fill-opacity:1;stroke:none"
id="house"
width="300"
height="200"
x="0"
y="0"
ry="8.1554852"
inkscape:label="#rect2985" />
<rect
style="fill:#ff0000;fill-opacity:1;stroke:none"
id="door"
width="60"
height="100"
x="0"
y="0"
ry="5.6589088"
inkscape:label="#rect2987" />
<rect
style="fill:#00ffff;fill-opacity:1;stroke:none"
id="window"
width="100"
height="70"
x="0"
y="0"
ry="7.7640224"
inkscape:label="#rect2992" />
</g>

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