//  Controller.m

//  TextLinks

//  Copyright (c) 2003 Apple Computer, Inc. All rights reserved.

//  See legal notice at end of file.

//  This application demonstrates how to programmatically create links in text,

//  and optionally handle clicks in those links. See README.rtf for more information.

//  MSM

//  version 0.2 July 2003 -- fixes logic for mouse tracking

//  version 0.1 February 2003

#import "Controller.h"

//  Tags in createLinkType NSMatrix

typedef enum

{   linkToURLFromSelectionTag = 0,      // create a link which shows the URL

    linkToOtherURLTag = 1,              // create a link which doesn't show the URL

    linkToAlertTag = 2                  // create a link to something other than a URL

} linkTag;

typedef enum

{   linkShowLinkInfo = 0,               // show the NSLink part of the attributes

    linkShowAttributes = 1              // show all attributes

} showTag;

@implementation Controller

#pragma mark PRIVATE INSTANCE METHODS

//  Return any text selected in the main text-view, cleaned up a little bit.

- (NSString *) selectedText

{

    NSString    *result;

    result = [[[textView textStorage] string] substringWithRange: [textView selectedRange]];

    //  Remove trailing newlines and other junk, which will mess up the radio button we fill in.

    //  (Really should remove newlines in the middle, too.)

    return [result stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]];

}

- (NSObject *) urlFromString: (NSString *) aString; // RETURN: nil means user's been alerted to the error

{

    NSURL   *url;

    url = [NSURL URLWithString: aString];

    if (url == nil)

        NSRunAlertPanel (@"Create Link",

            @"Ò%@Ó isnÕt a valid URL",

            nil, nil, nil,

            aString);                   // argument for %@ in the string above

    return url;

}

//  Create and return the object which we'll link to. This can be an NSURL for a traditional link,

//  or anything else.

//  This method gets invoked only from -createLink:, and is broken out to simplify that method.

- (NSObject *) linkObject;              // RETURN: nil means user's been alerted to the error

{

    NSString    *alertText;

    switch ((linkTag) [createLinkTypeMatrix selectedTag])

    {

        //  If the user selects Òhttp://www.apple.comÓ, create a link to that address.

        case linkToURLFromSelectionTag:

            return [self urlFromString: [self selectedText]];

        //  No matter what the user selected, create a link to the address in the field.

        case linkToOtherURLTag:

            if ([createLinkURLField stringValue] == 0)

            {

                [createLinkURLField selectText: nil]; // make it easy for them to correct

                NSRunAlertPanel (@"Create Link", @"Please enter a URL.", nil, nil, nil);

                return nil;

            }

            return [self urlFromString: [createLinkURLField stringValue]];

        //  No matter what the user selected, create a link to an NSString instance.

        case linkToAlertTag:

            alertText = [createLinkAlertField stringValue];

            if ([alertText length] == nil)

            {

                [createLinkAlertField selectText: nil]; // make it easy for them to correct

                NSRunAlertPanel (@"Create Link", @"Please enter the text to alert.", nil, nil, nil);

                return nil;

            }

            return alertText;

            break;

        default:                        // don't expect this

            return nil;

    }

}

//  Find the attributes of the text the mouse is pointing to in the NSTextView and display them.

- (void) showAttributesUnderMouse

{

    NSPoint         mouseLoc, mouseLocInContentView;

    NSView          *contentView;

    int             glyphIndex, charIndex;

    NSDictionary    *attributes;

    //  Limit the work we do if the app isnÕt active

    //  (Would be even better to stop the timer entirely...)

    if (! [[NSApplication sharedApplication] isActive])

    {

        [feedbackField setStringValue: @"(the application is not active)"];

        [feedbackField setTextColor: [NSColor darkGrayColor]];

        return;

    }

    //  Get mouse location in window coordinates

    mouseLoc = [[textView window] mouseLocationOutsideOfEventStream];

    //  Convert to view coordinates

    mouseLoc = [textView convertPoint: mouseLoc  fromView: nil];

    //  Note that using [[textView textContainer] containsPoint: mouseLoc] won't work,

    //  because the container for a flexible-height text-view is ÒbottomlessÓ -- it

    //  will consider the mouse to be inside the text even when the mouse is below it.

    //  And... using [textView mouse: mouseLoc  inRect: [textView bounds]] won't work,

    //  because the text view itself can grow below the bottom of the scroll-view. So use

    //  the scroll-view's content view.

    contentView = [[textView enclosingScrollView] contentView];

    mouseLocInContentView = [contentView convertPoint: mouseLoc  fromView: textView];

    if ([contentView mouse: mouseLocInContentView  inRect: [contentView bounds]])

    {

        //  Map the mouse location to the glyph index.

        glyphIndex = [[textView layoutManager] glyphIndexForPoint: mouseLoc  inTextContainer: [textView textContainer]];

        //  Glyphs aren't always the same as characters in a string, so now find the character index in the string.

        charIndex = [[textView layoutManager] characterIndexForGlyphAtIndex: glyphIndex];

    }

    else

    {

        //  Flag that we're not in view

        charIndex = -1;

    }

    //  It's tempting to cache ÒcharIndexÓ here, then compare to the cache to avoid

    //  updating the field. But if the user (for example) bolds the font with the

    //  keyboard, the attributes could change without the character index changing...

    if (charIndex != -1)

    {

        //  They're pointing at some text; get its attributes and show them.

        attributes = [[textView textStorage] attributesAtIndex: charIndex  effectiveRange: NULL];

        if ([feedbackTypeMatrix selectedTag] == linkShowLinkInfo)

        {

            NSObject    *link;

            link = [attributes objectForKey: @"NSLink"];

            if (link == nil)

            {

                [feedbackField setStringValue: @"(the mouse is not over a link)"];

            }

            else

            {

                [feedbackField setStringValue:

                    [NSString stringWithFormat: @"link class = %@\nlink value = %@",

                        [link class], link]];

            }

        }

        else

            [feedbackField setStringValue: [attributes description]];

        [feedbackField setTextColor: [NSColor blackColor]];

    }

    else

    {

        //  Hint that they should move the mouse into the text-view to see something in this field

        [feedbackField setStringValue: @"(point at some text to see its link)"];

        [feedbackField setTextColor: [NSColor redColor]];

    }

}

#pragma mark PUBLIC INSTANCE METHODS -- NSNibAwaking PROTOCOL

- (void) awakeFromNib

{

    //  On startup, begin redisplaying the attributes every 1/10th of a second.

    //  (It'd be smarter to do this only when the mouse enters, moves, or exits,

    //   but this is just an example app.)

    [[NSTimer scheduledTimerWithTimeInterval: 0.1

        target: self

        selector: @selector(showAttributesUnderMouse)

        userInfo: nil

        repeats: YES] retain];

    //  Fake a selection change so the matrix reflects the starting situation.

    [self textViewDidChangeSelection: nil];

}

#pragma mark PUBLIC INSTANCE METHODS -- NSTextField DELEGATE METHODS

//  If they type into a field, select the relevant radio button for them.

- (void) controlTextDidChange: (NSNotification *) notification

{

    if ([notification object] == createLinkURLField)

        [createLinkTypeMatrix selectCellWithTag: linkToOtherURLTag];

    if ([notification object] == createLinkAlertField)

        [createLinkTypeMatrix selectCellWithTag: linkToAlertTag];

}

#pragma mark PUBLIC INSTANCE METHODS -- NSTextView DELEGATE METHODS

//  Handle a click in a link.

- (BOOL) textView: (NSTextView *) textView

    clickedOnLink: (id) link

    atIndex: (unsigned) charIndex

{

    if ([link isKindOfClass: [NSString class]])

    {

        NSRunAlertPanel (@"Whee!",

                    [NSString stringWithFormat: @"You clicked a link containing the text Ò%@Ó", link],

                    nil, nil, nil);

        return YES;

    }

    //  We don't need to check for a link belonging to the NSURL class;

    //  NSTextView automatically does that.

    //  If we don't recognize the link object, say so.

    return NO;

}

//  When the selection changes in the big text-view,

//  update the title of the relevant radio button.

- (void) textViewDidChangeSelection: (NSNotification *) aNotification

{

    NSString    *selected, *title;

    BOOL        enable;

    NSCell      *matrixCell;

    //  Assume 'aNotification' is for our NSTextView -- it's the only one in the app

    selected = [self selectedText];

    //  Truncate a really long selection, to avoid messing up the matrix display.

    if ([selected length] > 30)

        selected = [[selected substringToIndex: 30] stringByAppendingString: @"É"];

    if ([selected length] == 0)

    {

        title = @"Éto (selected text)";

        enable = NO;

    }

    else

    {

        title = [NSString stringWithFormat: @"Éto \"%@\"", selected];

        enable = YES;

    }

    matrixCell = [createLinkTypeMatrix cellWithTag: linkToURLFromSelectionTag];

    [matrixCell setTitle: title];

    [matrixCell setEnabled: enable];

    //  If we've just disabled the selected cell, we should really push the selection to another cell...

}

//  Optionally return the cursor for a given type of link.

//  This isn't really an NSTextView delegate method, but our NSTextView subclass sends it to the delegate.

- (NSCursor *) cursorForLink: (NSObject *) linkObject

    atIndex: (unsigned) charIndex

    ofTextView: (NSTextView *) aTextView

{

    //  Return something distinctive for alert strings.

    if ([linkObject isKindOfClass: [NSString class]])

        return [NSCursor arrowCursor];

    //  Ignore everything else; the text-view subclass will default.

    return nil;

}

#pragma mark PUBLIC INSTANCE METHODS -- INTERFACE BUILDER ACTIONS

//  Turn the selection in the text-view into a link, optionally blue-and-underlined.

- (IBAction) createLink: (id) sender

{

    NSRange                 selection;

    NSObject                *linkObject;

    NSMutableDictionary     *linkAttributes;

    selection = [textView selectedRange];

    if (selection.length == 0)

    {

        NSRunAlertPanel (@"Create Link", @"Please select some text before creating a link.", nil, nil, nil);

        return;

    }

    //  Get the object which will go into the link. If it comes back nil, the user's been alerted.

    linkObject = [self linkObject];

    if (linkObject == nil)

        return;

    //  Start to build attributes

    //      NSLinkAttributeName => the object

    linkAttributes = [NSMutableDictionary dictionaryWithObject: linkObject

        forKey: NSLinkAttributeName];

    //  If the user wants it to look like a traditional link, add these attributes

    //      NSForegroundColorAttributeName => blue

    //      NSUnderlineStyleAttributeName => YES

    if ([blueUnderlineCheckbox state] == NSOnState)

    {

        [linkAttributes setObject: [NSColor blueColor]  forKey: NSForegroundColorAttributeName];

        [linkAttributes setObject: [NSNumber numberWithBool: YES]  forKey: NSUnderlineStyleAttributeName];

    }

    //  Add the attributes. This adds the link (and perhaps color and underline) attributes to the selected range.

    //  (Don't "set" the attributes, which would lose unrelated attributes like the ruler.)

    //  Note that we don't need to follow this with -edited:range:changeInLength:;

    //  that's only for folks who subclass NSTextStorage.

    [[textView textStorage] addAttributes: linkAttributes  range: selection];

    //  Tickle the AppKit into calling our -resetCursorRects implementation.

    //  One would expect [[textView window] invalidateCursorRectsForView: textView]

    //  to work, but it doesn't for us, so just go the direct route...

    [[textView window] resetCursorRects];

}

//  When they click a radio button, select the relevant field (if any) for them.

//  (Would be even better to select only if the field doesn't already have a selection.)

- (IBAction) linkTypeSelected: (id) sender

{

    switch ((linkTag) [createLinkTypeMatrix selectedTag])

    {

        case linkToURLFromSelectionTag:

            break;

        case linkToOtherURLTag:

            [createLinkURLField selectText: nil];

            break;

        case linkToAlertTag:

            [createLinkAlertField selectText: nil];

            break;

        default:                        // don't expect this

            break;

    }

}

@end

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