objective-c - 以编程方式获取 TextEdit 中所选文本的字体名称

Question

经过两个月的尝试，我找到了如何从 TextEdit(或任何 NSTextView)的任何文本范围中获取 AttributedString。我的代码如下:

AXUIElementRef systemWideElement = AXUIElementCreateSystemWide();
AXUIElementRef focussedElement = NULL;
AXError error = AXUIElementCopyAttributeValue(systemWideElement,
    kAXFocusedUIElementAttribute, (CFTypeRef*)&focussedElement);
if (error != kAXErrorSuccess) {
    println("Could not get focussed element");
}
else {
    AXValueRef selectedRangeValue = NULL;
    AXError getSelectedRangeError =
        AXUIElementCopyAttributeValue(focussedElement,
        kAXSelectedTextRangeAttribute, (CFTypeRef*)&selectedRangeValue);
    if (getSelectedRangeError == kAXErrorSuccess) {
        CFRange selectedRange;
        AXValueGetValue(selectedRangeValue, kAXValueCFRangeType,
            &selectedRange);
        AXValueRef attributedString = NULL;
        AXError getAttrStrError =
            AXUIElementCopyParameterizedAttributeValue(focussedElement,
            kAXAttributedStringForRangeParameterizedAttribute, selectedRangeValue,
            (CFTypeRef*)&attributedString);
        CFRelease(selectedRangeValue);

        if (getAttrStrError == kAXErrorSuccess)
        {
            CFAttributedStringRef attrStr = (CFAttributedStringRef)attributedString;

            CFTypeRef value = CFAttributedStringGetAttribute(
                attrStr, 0, kAXFontTextAttribute, NULL);

            println("value: %X", value); // value is not NULL, but I can't obtain font name from it.

            CFRelease(attributedString);
        }
        else
        {
            println("Could not get attributed string for selected range");
        }
    }
    else {
        println("Could not get selected range");
    }
}
if (focussedElement != NULL)
    CFRelease(focussedElement);
CFRelease(systemWideElement);

我正确获取了CFAttributedStringRef(我可以从中获取长度或纯文本)，但无法获取字体名称。

注意:

下面代码返回的值不为NULL:

CFTypeRef value = CFAttributedStringGetAttribute(
                attrStr, 0, kAXFontTextAttribute, NULL);

该值不能假定为 CTFontRef 或 CGFontRef、ATSFontRef...(导致异常)。

我还尝试用 kCTFontAttributeName 代替 kAXFontTextAttribute，但返回 NULL。

非常感谢。

Answer 1

与键kAXFontTextAttribute关联的值似乎是一个CFDictionaryRef。请参阅AXTextAttributedString documentation .