1 Correct answer
Hi Robert,
Not using transform and matrices explicitly does not mean that coordinate spaces are not involved behind the scenes. In fact, they always are, since InDesign works that way. The critical part of your code is the transformReferencePoint assignment, which explicitly refers to the origin of the pasteboard coordinate space. And this determines the center point of the rotation. Maybe a picture will make it clear:
Code:
var doc = app.properties.activeDocument;
doc.layoutWindows[0].transfor
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Replies
Hi Robert,
Not using transform and matrices explicitly does not mean that coordinate spaces are not involved behind the scenes. In fact, they always are, since InDesign works that way. The critical part of your code is the transformReferencePoint assignment, which explicitly refers to the origin of the pasteboard coordinate space. And this determines the center point of the rotation. Maybe a picture will make it clear:
Code:
var doc = app.properties.activeDocument;
doc.layoutWindows[0].transformReferencePoint = [0,0];
var sel = app.selection[0];
for( i=-1 ; ++i < 40 ; sel.rotationAngle += 2, $.sleep(200) );
Best,
Marc
Yep! And things get even more complicated when spreads are transformed:
The pasteboard space is the one that embraces all these phenomena, incl. gap between spreads, rotated views, etc. This is an absolute coordinate system. Powerful but tricky 😉
Best,
Marc
Hi Robert,
If your goal (?) is to perform a rotation on any set of page items (e.g. the selection) as InDesign would do in the GUI, you only have to follow two rules:
1) work in the pasteboard space for determining individual bounds (that's what ID does),
2) compute the center point as the midpoint of minmax bounds (not the barycenter).
Here is a detailed implementation—in ExtendScript—that should work anywhere and whatever the original transform state of the items:
var myItems = app.selection; // Any array of page items
var myAngleDeg = 20; // Your rotation angle (in degree)
// Absolute transform space (used by InDesign when you transform the selection).
const SPACE = +CoordinateSpaces.pasteboardCoordinates;
var xy = (function(/*PageItem[]*/a,/*CS*/sp, bx,TL,BR,t,l,b,r,i,xy,v)
//----------------------------------
// Center point of `myItems` in SPACE coordinates (considering in-SPACE boxes.)
// This is how InDesign works when you manually perform a transformation on
// the selection: the default transform origin is not the 'barycenter' of the
// different box centers, it is the center of the overall bounding box, hence
// the min-max algo.
// => [num,num]
{
bx = +BoundingBoxLimits.outerStrokeBounds;
TL = [[0,0],bx,sp];
BR = [[1,1],bx,sp];
for( t=l=1/0, b=r=-1/0, i=a.length ; i-- ; )
{
xy = a[i].resolve(TL,sp)[0];
(v=xy[0]) < l && (l=v);
(v=xy[1]) < t && (t=v);
xy = a[i].resolve(BR,sp)[0];
(v=xy[0]) > r && (r=v);
(v=xy[1]) > b && (b=v);
}
return [(l+r)/2, (t+b)/2];
})( myItems, SPACE );
var rot = (function(/*angleRad*/a, c,s)
//----------------------------------
// Get the rotation matrix.
// => [num,num,num,num,0,0]
{
c = Math.cos(a);
s = Math.sin(a);
return [c,-s,s,c,0,0];
})( myAngleDeg*Math.PI/180 );
// Perform the desired rotation around x,y (SPACE coords).
// ---
var orig = [xy,SPACE];
for( var i=myItems.length ; i-- ; myItems[i].transform(SPACE,orig,rot) );
Note that myItems can be set to any array of PageItem objects, not necessarily the active selection, and not even necessarily sharing the same spread!
Best,
Marc
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