Read Scripting Parameters within a Filter

Question

Hello,
I'd like to have a Plug In which can read Scripting Parameters and run accordignly.
One of the code samples in the SDK is called "PoorMansTypeTool".
In its documentation it is said to be able to "Read scripting parameters".
I look into its code yet I couldn't figure how it does it.
Let's say I have a script with a variable 'a'.
The script launches a filter from the filter lists and want to pass the valu of the parameter 'a' to the filter.
How could that be done?
Are there any constraints on the parameter type, size, etc?
Has anyone tried it before?
If someone could guide me through the plug in code I'd be happy.
Thank You.

Answer 1

// make this a function so we can hide these from harness script
main();
function main() {
// Save the current preferences
var startRulerUnits = preferences.rulerUnits;
var startTypeUnits = preferences.typeUnits;
var startDisplayDialogs = displayDialogs;
// Set Photoshop to use pixels and display no dialogs
preferences.rulerUnits = Units.PIXELS;
preferences.typeUnits = TypeUnits.PIXELS;
displayDialogs = DialogModes.NO;
// make this stuff controlled by the harness
var maxTime = 1 * 60;
var iterations = 5;
var percIncrease = 20;
var timeIt = new Timer();
var tests = 0;
var errors = 0;
var eArray = new Array();
var dissolveLog = new File( "~/Desktop/Dissolve.log" );
dissolveLog.open( "w", "TEXT", "????" );
dissolveLog.writeln( "width,\theight,\tdepth,\tpercent,\tdoc create time,\tdissolve time" );
var maxWidth = 30000;
var minWidth = 256;
var incWidth = parseInt( (maxWidth - minWidth) / iterations );
if ( incWidth == 0 )
          incWidth = 1;
var maxHeight = 30000;
var minHeight = 256;
var incHeight = parseInt( (maxHeight - minHeight) / iterations );
if ( incHeight == 0 )
          incHeight = 1;
// start clean
while (documents.length) {
    activeDocument.close(SaveOptions.DONOTSAVECHANGES);
var d = BitsPerChannelType.EIGHT;
for ( var w = minWidth; w < maxWidth; w += incWidth ) {
          for ( var h = minHeight; h < maxHeight; h += incHeight ) {
                    try {
                              var timeImport = new Timer();
                              if ( d == BitsPerChannelType.EIGHT )
                                        d = BitsPerChannelType.SIXTEEN;
                              else
                                        d = BitsPerChannelType.EIGHT;
                              app.documents.add(UnitValue(w, "px"), UnitValue(h,"px"), undefined, "Dissolve Test", undefined, undefined, undefined, d);
             timeImport.stop();
                              if ( activeDocument.width != w )
                error++; // alert( activeDocument.width + ", " + w );
                              if ( activeDocument.height != h )
                error++; // alert( activeDocument.height + ", " + h );
                              if ( d == 16 && activeDocument.bitsPerChannel != BitsPerChannelType.SIXTEEN )
                error++; // alert( activeDocument.bitsPerChannel + ", " + d );
                              if ( d == 8 && activeDocument.bitsPerChannel != BitsPerChannelType.EIGHT )
                error++; // alert( activeDocument.bitsPerChannel + ", " + d );
                              if ( activeDocument.bitsPerChannel == BitsPerChannelType.ONE )
                error++; // alert( activeDocument.bitsPerChannel + ", " + d );
             FitOnScreen(); // this makes everything really slow
                              var historyState = activeDocument.activeHistoryState;
                              for ( var dPerc = 0; dPerc <= 100; dPerc += percIncrease ) {
                                        tests++;
                                        var timeDissolve = new Timer();
                                        Dissolve(dPerc);
                                        timeDissolve.stop();
                                        // WaitForRedraw(); // guess what this does to our slowness ness er
                                        dissolveLog.write(w + ",\t" + h + ",\t" + d + ", " + dPerc );
                                        dissolveLog.writeln(",\t" + timeImport.getTime() + ", " + timeDissolve.getTime() );
                 WaitForRedraw();
                                        activeDocument.activeHistoryState = historyState;
                if ( timeIt.getElapsed() > maxTime ) {
                    w = maxWidth + 1;
                    h = maxHeight + 1;
                    dPerc = 101;
                    catch(e) {
                        alert(e + ":" + e.line);
                              if ( e.message.search(/cancel/i) != -1 ) {
                                        w = maxWidth + 1;
                                        h = maxHeight + 1;
                              eArray[eArray.length] = e;
                              errors++;
                              // debugger;
                    } // end catch
          } // end for height
} // end for width
dissolveLog.writeln( errors + " errors. " + tests + " tests in " + timeIt.getElapsed() + " seconds. " + tests/timeIt.getElapsed() + " tests/sec.");
dissolveLog.close();
dissolveLog.execute();
// end clean
while (documents.length) {
    activeDocument.close(SaveOptions.DONOTSAVECHANGES);
// Reset the application preferences
preferences.rulerUnits = startRulerUnits;
preferences.typeUnits = startTypeUnits;
displayDialogs = startDisplayDialogs;
//     1) " FAIL" for failures
//     2) " PASS" for test results OK
//     3) "  BUG" for known bugs, have the file name give the bug number
//     4) "ERROR" this comes from the harness if the script barfed/exception,
return errors == 0 ? ' PASS' : ' FAIL';
} // end function main
  Function WaitForRedraw
  Usage: Use it to force Photoshop to redraw the screen before continuing
  Example:
       WaitForRedraw();
function WaitForRedraw() {
          var keyID = charIDToTypeID( "Stte" );
          var desc = new ActionDescriptor();
          desc.putEnumerated( keyID, keyID, charIDToTypeID( "RdCm" ) );
          executeAction( charIDToTypeID( "Wait" ), desc, DialogModes.NO );
// WaitNSeconds, slow the script down so you can watch and figure out issues
function WaitNSeconds(seconds) {
   startDate = new Date();
   endDate = new Date();
   while ((endDate.getTime() - startDate.getTime()) < (1000 * seconds))
                    endDate = new Date();
// FitOnScreen, fits the document and redraws the screen
function FitOnScreen() {
          var id45 = charIDToTypeID( "slct" );
    var desc7 = new ActionDescriptor();
    var id46 = charIDToTypeID( "null" );
          var ref1 = new ActionReference();
          var id47 = charIDToTypeID( "Mn  " );
          var id48 = charIDToTypeID( "MnIt" );
          var id49 = charIDToTypeID( "FtOn" );
          ref1.putEnumerated( id47, id48, id49 );
          desc7.putReference( id46, ref1 );
          executeAction( id45, desc7, DialogModes.NO );
// Dissolve, given a percentage
function Dissolve( dPercent ) {
          var id18 = stringIDToTypeID( "d9543b0c-3c91-11d4-97bc-00b0d0204936" );
    var desc3 = new ActionDescriptor();
    var id19 = charIDToTypeID( "Amnt" );
    var id20 = charIDToTypeID( "#Prc" );
    desc3.putUnitDouble( id19, id20, dPercent );
    var id21 = charIDToTypeID( "disP" );
    var id22 = charIDToTypeID( "mooD" );
    var id23 = charIDToTypeID( "moD1" );
    desc3.putEnumerated( id21, id22, id23 );
          executeAction( id18, desc3, DialogModes.NO );
// DissolveOld, our old scripting params was this
// an interesting test would be to see the old plug-in vs the current one
function DissolveOld( dPercent ) {
    var id12 = charIDToTypeID( "disS" );
    var desc3 = new ActionDescriptor();
    var id13 = charIDToTypeID( "Amnt" );
    var id14 = charIDToTypeID( "#Prc" );
    desc3.putUnitDouble( id13, id14, dPercent );
    var id15 = charIDToTypeID( "disP" );
    var id16 = charIDToTypeID( "mooD" );
    var id17 = charIDToTypeID( "moD1" );
    desc3.putEnumerated( id15, id16, id17 );
    executeAction( id12, desc3, DialogModes.NO );
// Library for timing things in JavaScript
function Timer() {
          // member variables
          this.startTime = new Date();
          this.endTime = new Date();
          // member functions
          // reset the start time to now
          this.start = function () { this.startTime = new Date(); }
          // reset the end time to now
          this.stop = function () { this.endTime = new Date(); }
          // get the difference in milliseconds between start and stop
          this.getTime = function () { return (this.endTime.getTime() - this.startTime.getTime()) / 1000; }
          // get the current elapsed time from start to now, this sets the endTime
          this.getElapsed = function () { this.endTime = new Date(); return this.getTime(); }
// end Dissolve.jsx