Wiley-World.of.Warcraft.Programming.A.Guide.and.Reference.for.Creating.WoW.Addons

322 Part III ■ Advanced Addon Techniquesmodifier == “CTRL“ ormodifier == “ALT“ orkey == “UNKNOWN“ thenreturnendWhen OnKeyDown receives a modifier key, it differentiates between keys onthe left and right sides of the keyboard. For example, the left shift key is calledLSHIFT and the right shift key is called RSHIFT. The first line in the precedingsnippet eliminates a bit of redundancy in the if clause by stripping the firstcharacter off the key. You also check for UNKNOWN, which is triggered by keysthat WoW doesn’t recognize (like Scroll Lock and Pause on Windows).You should also add special treatment for the key normally used to takescreenshots. Otherwise there would be no way to take a screenshot of thebinding. Add the following code immediately after the previous snippet:if GetBindingFromClick(key) == “SCREENSHOT“ thenTakeScreenshot()returnendThe function GetBindingFromClick, defined in FrameXML\UIParent.lua,returns the action associated with the current key press, if any. If the actionturns out to be SCREENSHOT, this code takes a screenshot and aborts the function.Once you’ve eliminated the special cases, you can begin building thekey argument. Although you ignored the modifier keys when they directlytriggered OnKeyDown, you need to check their status to apply the appropriateprefixes to the key. Add this code following the screenshot check:if IsShiftKeyDown() thenkey = “SHIFT-“..keyendif IsControlKeyDown() thenkey = “CTRL-“..keyendif IsAltKeyDown() thenkey = “ALT-“..keyendNote that the order of these modifier checks is crucial; SetBinding onlyaccepts modifier prefixes in the order ALT-CTRL-SHIFT-. In this snippet,you’re adding them one at a time, as applicable, to the beginning of thekey. If you pressed A with all the modifier keys held down, the key parameterwould progress as follows:ASHIFT-A