Adobe Illustrator Script - Resize selected items

resize-selection.jsx

/**
 * Usage : resizeSelectedItems(getUserInput())
 * 
 * ========= 
 * CAUTION : This script will scale all selected items. It cannot determine if an object is simple or compound. 
 * ========= It is best to group compound objects made up of multiple PageItems.
 * 
 * `getUserInput` is separated so you can easily use the main function, `resizeSelectedItems`, 
 * in your code. Make sure the input to `resizeSelectedItems` is a string indicating the 
 * new size. The options are:
 * 
 * Percentage : Scale to a percentage of the current size entered as integer + '%' (150%, 75%, etc).
 * Max Dimension : Entered as an integer indicating the maximum size of width or height depending on orientation (landscape or portrait).
 * Fixed-width : Sets the width of all selected items to the same size. Entered as an integer followed by a `w` -  `1024w`, '2048w`, etc. 
 * Fixed-height : Sets the height of all selected items to the same size. Entered as an integer followed by a `h` -  `1024h`, '2048h`, etc. 
 */ 

function getUserInput() {
    var doc = activeDocument;
    var sel = doc.selection;

    if (sel.length === 0) {
        alert('No items selected');
        return;
    }

    var input = prompt(
        'Enter scale as percentage or ' + 
        'Max dimension (single integer, in pixels)',
        '100%'
    );

    return input;
}

function resizeSelectedItems(input) {
    var doc = activeDocument;
    var sel = doc.selection;
    
    var percent, 
        targetdim, 
        decimal, 
        maxwidth, 
        maxheight,
        width,
        height;
    
    // Scale to percentage
    if (input.indexOf('%') > 0) {
        percent = parseInt(input) / 100;
    }
    // Scale all to exact width
    else if (input.toLowerCase().indexOf('w') >= 0) {
        targetwidth = parseInt(input);
        targetheight = 0;
        targetdim = 0;
    }
    // Scale all to exact height
    else if (input.toLowerCase().indexOf('h') >= 0) {
        targetheight = parseInt(input);
        targetwidth = 0;
        targetdim = 0;
    }
    // Scale to max targert dimension (width or height)
    else if (! isNaN(input)) {
        targetdim = input;
        targetwidth = 0;
        targetheight = 0;
    }
    
    try {
        var oldUnits = String(activeDocument.rulerUnits).split('.').pop();
        activeDocument.rulerUnits = RulerUnits.Pixels;

        function scaleToTargetWidth(item, targetwidth) {
            item.height = item.height * (targetwidth / item.width);
            item.width  = targetwidth;
        }

        function scaleToTargetHeight(item, targetheight) {
            item.width  = item.width * (targetheight / item.height);
            item.height = targetheight;
        }

        function scaleToTargetDim(item, targetdim) {
            // Get the scale ratio
            var maxdim = Math.max(item.width, item.height);
            var ratio  = targetdim / maxdim;

            // Square
            if (item.width === item.height) {
                item.width  = targetdim;
                item.height = targetdim;
            }
            // Landscape
            else if (item.width > item.height) {
                item.width  = targetdim;
                item.height = item.height * ratio;
            }
            // Portrait
            else {
                item.height = targetdim;
                item.width  = item.width * ratio;
            }
        }
        
        for (var i = 0; i < sel.length; i++) {
            var item = sel[i];
            if (! isNaN(percent)) {
                item.width  = item.width * percent;
                item.height = item.height * percent;
            }
            else if (targetwidth > 0) {
                scaleToTargetWidth(item, targetwidth);
            }
            else if (targetheight > 0) {   
                scaleToTargetHeight(item, targetheight);
            }
            else if (targetdim > 0) {
                scaleToTargetDim(item, targetdim);
            }
        }
        
        activeDocument.rulerUnits = RulerUnits[oldUnits];
    }
    catch(e) {
        alert(e);
    }
}