问题
I understand that the declaration #targetengine "myEngineName" would be used for InDesign to remember global variables (found information on this here: http://incom.org/post/89818).
However, this was still not enough for it to remember global variables as it still throws an error regarding the global variable
imgs:
Error Number: 30476
Error String: "if(imgs[i].itemLink != null)" could not be completed because the object no longer exists.
...or something like that anyway. It doesn't like that particular line in my code, and seems to be forgetting what the global variable imgs was instantiated as.
So I implemented a try-catch statement, and reinstatiated the variable
imgs and decremented the iterator in the catch... Though this did solve the problem, why doesn't #targetengine "myEngineName" solve the problem like it is supposed to?
Here is my code:
#target "InDesign" // this solves the "Error Number: 29446" problem
#targetengine "session" // this solves the "Error Number: 30476" problem
var imgs; // global variable for the #targetengine "session" to keep track of
var document = app.activeDocument;
var newFolder = createFolder(document); // if subdirectory images DNE, create this folder with the function below
saveAllImages(document, newFolder); // with the function below
alert("The file conversion is complete!\n\nAll black & white images have been copied to:\n" + newFolder +
"\.\n\nAll color images have been replaced with the new black & white images in the current InDesign document.");
//---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
function createFolder(doc)
{
try
{
/*
* type-casting the filePath property (of type object) into a String type;
* must be a String type to concatenate with the subdirectory variable (also of type String)
*/
var docPath = String(doc.filePath);
var subdirectory = "/BLACK AND WHITE IMAGES";
}
catch(e)
{
alert(e.message + "\n - reload the script, and it should work.");
exit();
}
var imagesFolder = docPath + subdirectory; // concatenating the two variables
if(!Folder(imagesFolder).exists)
{
Folder(imagesFolder).create();
}
return imagesFolder; // for instantiation outside of this function
} // end of function createFolder
//---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
function saveAllImages(doc, folder)
{
imgs = document.allGraphics; // this is a global variable, for the #targetengine "session" to keep track of
var fileName = "";
var img = "";
var imgType = "";
for(var i = 0; i < imgs.length; i++)
{
try
{
if(imgs[i].itemLink != null)
{
fileName = imgs[i].itemLink.name;
img = new File(folder + "/" + fileName); // each image instantiated here
imgType = imgs[i].imageTypeName; // image type is determined here (.tif, .jpg, .png, etc..)
//alert("The file \"" + fileName + "\"\n\tis a " + imgType + " file."); // Note: escape characters
/*
* array for image options, instantiated from the function below;
* options[0] is the "MAXIMUM" image quality property, &
* options[1] is the "GRAY" image conversion property;
*/
var options = convertToBlackAndWhite(imgType);
// each image exported to the new folder here, by file type
switch(imgType)
{
case "GIF":
alert("This script cannot convert and export the GIF file:\n\t" + fileName + " !"); // Note: escape characters
break;
case "Adobe PDF":
break;
case "EPS":
break;
case "Windows Bitmap":
break;
case "JPEG":
break;
case "PNG":
break;
case "TIFF":
options[0]; // maximum image quality
options[1]; // black & white conversion
imgs[i].exportFile(ExportFormat.JPG, img, false);
replaceWithNewImage(doc, fileName, img); // with the function below
break;
default:
alert("\tUnlisted image type: " + imgType + "!\nAdd this type to the switch statement.");
break;
} // end of switch statement
} // end of if statement
} // end of try statement
catch(e)
{
/*
* in case the #targetengine is overloaded, this solves the "Error Number: 30476" problem:
* - "The requested action could not be completed because the object no longer exists."
* (the second statement #targetengine "session" is also in place to solve this error)
*/
imgs = document.allGraphics; // global variable reinstantiated in case of error
i--; // retry the same iteration again, in case of error (the variable " i " is the iterator in the for loop)
}
} // end of for loop
} // end of function saveAllImages
//---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
function convertToBlackAndWhite(fileType)
{
// array for image-quality and color-conversion values
var settings = [];
// each image exported to the new folder here, by file type
switch(fileType)
{
case "Windows Bitmap":
break;
case "JPEG":
break;
case "PNG":
break;
case "TIFF":
settings[0] = "app.jpegExportPreferences.jpegQuality = JPEGOptionsQuality.MAXIMUM"; // maximum image quality
settings[1] = "app.jpegExportPreferences.jpegColorSpace = JpegColorSpaceEnum.GRAY"; // black & white conversion
break;
default:
break;
} // end of switch statement
return settings; // for instantiation outside of this function
} // end of function convertToBlackAndWhite
//---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
function replaceWithNewImage(doc, imageName, newImage)
{
var links = doc.links;
var link = "";
for(var i = 0; i < links.length; i++)
{
link = links[i];
if ( (link.status == LinkStatus.NORMAL) && (link.name == imageName) )
{
try
{
link.relink(newImage);
link.update();
}
catch(e)
{
}
} // end of if statement
} // end of for loop
} // end of function replaceWithNewImage
This is the only information out there I could find regarding this error: http://forums.adobe.com/thread/748419
EDIT --
I'm pretty sure the problem has something to do with the function replaceWithNewImage, because this error did not occur without this function, and there was then no need for the try-catch statement...
回答1:
Reading over your code, I see something that may be really problematic. You set the reference to the document to the active document. But this reference remains all over the session. Fact is if you switch to another document or close the document, then the reference is lost. This may explain why imgs can be undefined at some point although I think it should raise an error instead. Do wrap your variables in a function scope and I warranty you everything will be fine ;)
回答2:
First of all, just avoid global variables as much as you can and especially while using session engines.
If the aim of your script is a simple export links/modify links/replace links, why do you want to have persistent variables ?
In my humble opinion, I will get rid of the engine and just do a regular funbction call
//myscript.jsx
mySuperFunction();
function mySuperFunction()
{
var doc;
if ( app.documents.length == 0 ){ return; }
doc = app.activeDocument;
//Do all your stuff
}
It should be all you need ;)
Loic
来源：https://stackoverflow.com/questions/11405987/indesign-cs5-script-why-is-targetengine-not-working-correctly