I assumed from reading the documentation that the third line was apparently needed because the second line merely sets a property and doesn't fire off any notification and hence I saw no way that the webview would be refreshed with the new preferences. Unfortunately my assumption was wrong since looking at the WebKit source shows that if the new preferences pointer is identical to the old one, it does nothing.

Based on that, my next approach was this:

    if (![NSApp enableMinimumFontSize])
        [myWebView setPreferences:defaultWebPrefs];
    else
    {
        WebPreferences * webPrefs = [[WebPreferences alloc] init];
        [webPrefs setMinimumFontSize:[NSApp minimumFontSize]];
        [myWebView setPreferences:webPrefs];
        [webPrefs release];
    }

to toggle setting the minimum font size on or off. This worked fine - except that the webview text font increased to 16pt from the original 12pt and wouldn't budge thenafter. After some thought, I realised that the HTML being rendered didn't include any explicit font size in the stylesheet and thus it was picking up the default from the newly allocated WebPreference. However the default font size in webPrefs was different from that in defaultWebPrefs. I've no idea why but adding the following lines:

        [webPrefs setDefaultFontSize:[defaultWebPrefs defaultFontSize]];
        [webPrefs setDefaultFixedFontSize:[defaultWebPrefs defaultFixedFontSize]];

after the alloc solved the problem. A better approach would appear to copy the entire contents of defaultWebPrefs into webPrefs after the alloc and before setting the minimum font size as that would ensure fidelity between the preferences.

Thanks for the pointer, John!

- Steve



On Aug 22, 2005, at 8:52am, John Sullivan wrote:

On Aug 21, 2005, at 3:55 PM, Steve Palmer wrote:

I asked this on the cocoa-dev alias but got no response. Hopefully this is a more appropriate list?

I'm trying to get my head around web preferences. Based on my reading of the API documentation, this should work to change the minimum font size used by a webview that already has text:

        WebPreferences * webPrefs = [myWebView preferences];
        [webPrefs setMinimumFontSize:12];
        [myWebView setPreferences:webPrefs];

However the existing webview text isn't changed. Any suggestions what I'm missing?

- Steve

The third line above isn't necessary; there's no need to set the preferences back to the same WebPreferences* object.

The other two lines seem correct. It's not clear why this wouldn't be working in your case. You should be able to debug this if you build WebKit from the open-source repository (see webkit.opendarwin.org). Here's what should happen:

Setting the minimum font size runs this code:

- (void)setMinimumFontSize:(int)size
{
    [self _setIntegerValue: size forKey: WebKitMinimumFontSizePreferenceKey];
}


_setIntegerValue should store the new value, and call [self _postPreferencesChangesNotification]. Note that _setIntegerValue will do nothing if the new value matches the old (but that shouldn't be your case, since the initial value of minimumFontSize should be 0, which represents no minimum.

_postPreferencesChangedNotification should send a WebPreferencesChangedNotification

WebView should observe the _postPreferencesChangedNotification and call [self _updateWebCoreSettingsFromPreferences: preferences].

_updateWebCoreSettingsFromPreferences then calls [_private->settings setMinimumFontSize:[preferences minimumFontSize]] to make the new value known to WebCore.

-[WebCoreSettings setMinimumFontSize:] then stores the value and calls [self _updateAllViews], which schedules a redraw that should use the new settings.

So one of these steps must be failing in your case for some reason. You should be able to figure out which one with a little debugging.

I hope this helps,

John

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