String identifiers for colour ids

Feature Requests
1

The transition to JUCE 6 could be a good moment to convert integer based colour ids to an Identifier or other string based solution.

2

That would be quite expensive for the runtime, since the drawing methods do a lot of lookup for those Colour values. It is probably best not to have a string comparison there.

In my WYSWYG PluginEditor editor PluginGuiMagic I use maps to map from a string to the enum value like this:

I use this lookup table only when the user modifies a value or at startup, when the UI is loaded from an XML. But at runtime it is best to have the mapping using those enum values.

Just my thoughts.

3

Comparing Identifiers is just comparing their pointer value so no more expensive than integers. The real benefit i see is when creating custom components and not having to book keep magic numbers scattered around in different classes that you often won’t touch anymore for years.

4 Likes
4

It would be great to have a solution for custom classes!

The cost is moved to creating the Identifier. I don’t know how that will work out in the end, since I read that the underlying StringPool can flush when it is full, which means you cannot rely on it to be only a pointer comparison? To be honest, I don’t know, I found that discussion confusing, but my takeaway was, that Identifiers are not as great than I thought they were.

This is what I got confused:

5

same request here.
Merging to yours

6

There’s some horror stories about converting to identifiers under the hood of it anyway, e.g.

Colour Component::findColour (int colourID, bool inheritFromParent) const
{
    if (auto* v = properties.getVarPointer (ComponentHelpers::getColourPropertyID (colourID)))
        return Colour ((uint32) static_cast<int> (*v));

    if (inheritFromParent && parentComponent != nullptr
         && (lookAndFeel == nullptr || ! lookAndFeel->isColourSpecified (colourID)))
        return parentComponent->findColour (colourID, true);

    return getLookAndFeel().findColour (colourID);
}

Where getColourPropertyID is:

    static Identifier getColourPropertyID (int colourID)
{
    char buffer[32];
    auto* end = buffer + numElementsInArray (buffer) - 1;
    auto* t = end;
    *t = 0;

    for (auto v = (uint32) colourID;;)
    {
        *--t = "0123456789abcdef" [v & 15];
        v >>= 4;

        if (v == 0)
            break;
    }

    for (int i = (int) sizeof (colourPropertyPrefix) - 1; --i >= 0;)
        *--t = colourPropertyPrefix[i];

    return t;
}