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This means I now added a ",{"type":17,"tag":39,"props":1601,"children":1603},{"className":1602},[],[1604],{"type":23,"value":1605},"?? 0",{"type":23,"value":1607}," after each call.",{"type":17,"tag":26,"props":1609,"children":1610},{},[1611,1613,1619],{"type":23,"value":1612},"I'm much happier with this than the first few passes, the code doesn't ",{"type":17,"tag":1614,"props":1615,"children":1616},"em",{},[1617],{"type":23,"value":1618},"work",{"type":23,"value":1620}," yet, but all of the bits that I've tested outside of the core image black box for the filters are behaving properly",{"type":17,"tag":1622,"props":1623,"children":1624},"style",{},[1625],{"type":23,"value":1626},"html .default .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}html.dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}",{"title":7,"searchDepth":74,"depth":74,"links":1628},[1629],{"id":20,"depth":74,"text":24},"markdown","content:archive:2016:2016-01-01-mx65i5h8wp8qdwlte5ecl25sznvtuh.md","content","archive/2016/2016-01-01-mx65i5h8wp8qdwlte5ecl25sznvtuh.md","archive/2016/2016-01-01-mx65i5h8wp8qdwlte5ecl25sznvtuh","md","\u003Ch2 id=\"because-unsolved-problems-bother-me\">Because Unsolved Problems Bother Me\u003C/h2>\u003Cp>I'm working on some code to intelligently remove arbitrary border colors from an image for reasons vaguely related to a project at work. I'm close to a solution, but there's some strangenesses I'm hitting in the core image filter stack that eludes me, so I don't have a full code dump to share, but I'm particularly proud of how I structured the edge insets code to make it more functional.\u003C/p>\u003Cpre class=\"language-swift shiki shiki-themes solarized-dark solarized-light\" code=\"private extension UIImage {\n\n    static func cropEdgeInsets(filterInfo: FilterInfo, startingSize: CGSize) -> UIEdgeInsets {\n        let inputHeight = Int(startingSize.height)\n        let inputWidth = Int(startingSize.width)\n\n        let topInset = filterInfo.calculateInset(1...inputHeight) { row in\n            return CGRect(x: 0, y: 0, width: inputWidth, height: row)\n            } ?? 0\n\n        let bottomRange = ((topInset + 1)...(inputHeight - 1)).reverse()\n        let bottomInset = filterInfo.calculateInset(bottomRange) { row in\n            return CGRect(x: 0, y: row, width: inputWidth, height: inputHeight - row)\n            } ?? 0\n\n        let leftInset = filterInfo.calculateInset(1...inputWidth) { col in\n            return CGRect(x: 0, y: 0, width: col, height: inputHeight)\n            } ?? 0\n\n        let rightRange = ((leftInset + 1)...(inputWidth - 1)).reverse()\n        let rightInset =  filterInfo.calculateInset(rightRange) { col in\n            return CGRect(x: col, y: 0, width: inputWidth - col, height: inputHeight)\n            } ?? 0\n\n        return UIEdgeInsets(top: CGFloat(topInset), left: CGFloat(leftInset), bottom: CGFloat(bottomInset), right: CGFloat(rightInset))\n    }\n\n    struct FilterInfo {\n        let maxFilter :CIFilter\n        let minFilter: CIFilter\n        let context: CIContext\n        let maximumDelta: UInt\n\n        func calculateInset\u003CU: CollectionType>(range: U, rectGenerator: (step: U.Generator.Element) -> CGRect) -> U.Generator.Element? {\n            var inset: U.Generator.Element?\n            for step in range {\n                let rect = rectGenerator(step: step)\n                self.maxFilter.updateFilterExtentsWithRect(rect)\n                self.minFilter.updateFilterExtentsWithRect(rect)\n                guard let rowDiff = self.minFilter.differenceFromFilter(self.maxFilter, context: self.context)\n                    where rowDiff \u003C= self.maximumDelta else {\n                        break\n                }\n                inset = step\n            }\n            return inset\n        }\n    }\n\n}\n\" language=\"swift\" meta=\"\" style=\"\">\u003Ccode __ignoreMap=\"\">\u003Cspan class=\"line\" line=\"1\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">private\u003C/span>\u003Cspan style=\"--shiki-default:#93A1A1;--shiki-dark:#586E75;--shiki-default-font-weight:bold;--shiki-dark-font-weight:bold\"> extension\u003C/span>\u003Cspan style=\"--shiki-default:#CB4B16;--shiki-dark:#CB4B16\"> UIImage\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> {\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"2\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"3\">\u003Cspan style=\"--shiki-default:#93A1A1;--shiki-dark:#586E75;--shiki-default-font-weight:bold;--shiki-dark-font-weight:bold\">    static\u003C/span>\u003Cspan style=\"--shiki-default:#93A1A1;--shiki-dark:#586E75;--shiki-default-font-weight:bold;--shiki-dark-font-weight:bold\"> func\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> cropEdgeInsets\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">filterInfo\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: FilterInfo, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">startingSize\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: CGSize) \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">->\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> UIEdgeInsets {\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"4\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> inputHeight \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\"> Int\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(startingSize.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">height\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"5\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> inputWidth \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\"> Int\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(startingSize.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">width\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"6\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"7\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> topInset \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> filterInfo.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">calculateInset\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\">1\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">...\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">inputHeight\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">) { row \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">in\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"8\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">            return\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> CGRect\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">x\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\">0\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">y\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\">0\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">width\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: inputWidth, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">height\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: row)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"9\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">            } \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">??\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\"> 0\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"10\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"11\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> bottomRange \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> ((topInset \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">+\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\"> 1\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">)\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">...\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(inputHeight \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">-\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\"> 1\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">)).\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">reverse\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">()\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"12\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> bottomInset \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> filterInfo.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">calculateInset\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(bottomRange) { row \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">in\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"13\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">            return\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> CGRect\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">x\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\">0\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">y\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: row, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">width\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: inputWidth, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">height\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: inputHeight \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">-\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> row)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"14\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">            } \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">??\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\"> 0\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"15\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"16\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> leftInset \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> filterInfo.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">calculateInset\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\">1\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">...\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">inputWidth\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">) { col \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">in\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"17\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">            return\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> CGRect\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">x\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\">0\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">y\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\">0\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">width\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: col, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">height\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: inputHeight)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"18\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">            } \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">??\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\"> 0\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"19\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"20\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> rightRange \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> ((leftInset \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">+\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\"> 1\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">)\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">...\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(inputWidth \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">-\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\"> 1\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">)).\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">reverse\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">()\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"21\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> rightInset \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">  filterInfo.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">calculateInset\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(rightRange) { col \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">in\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"22\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">            return\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> CGRect\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">x\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: col, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">y\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\">0\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">width\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: inputWidth \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">-\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> col, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">height\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: inputHeight)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"23\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">            } \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">??\u003C/span>\u003Cspan style=\"--shiki-default:#D33682;--shiki-dark:#D33682\"> 0\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"24\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"25\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        return\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> UIEdgeInsets\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">top\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">CGFloat\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(topInset), \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">left\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">CGFloat\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(leftInset), \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">bottom\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">CGFloat\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(bottomInset), \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">right\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">CGFloat\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(rightInset))\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"26\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">    }\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"27\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"28\">\u003Cspan style=\"--shiki-default:#93A1A1;--shiki-dark:#586E75;--shiki-default-font-weight:bold;--shiki-dark-font-weight:bold\">    struct\u003C/span>\u003Cspan style=\"--shiki-default:#CB4B16;--shiki-dark:#CB4B16\"> FilterInfo\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> {\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"29\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> maxFilter :CIFilter\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"30\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> minFilter: CIFilter\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"31\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> context: CIContext\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"32\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">        let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> maximumDelta: \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">UInt\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"33\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"34\">\u003Cspan style=\"--shiki-default:#93A1A1;--shiki-dark:#586E75;--shiki-default-font-weight:bold;--shiki-dark-font-weight:bold\">        func\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> calculateInset\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"><\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">U\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">CollectionType\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">>(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">range\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: U, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">rectGenerator\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: (step: U.\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">Generator\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">Element\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">) \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">->\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> CGRect) \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">->\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> U.\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">Generator\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">Element?\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> {\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"35\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">            var\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> inset: U.\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">Generator\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">Element?\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"36\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">            for\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> step \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">in\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> range {\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"37\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">                let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> rect \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> rectGenerator\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">step\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: step)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"38\">\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">                self\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">maxFilter\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">updateFilterExtentsWithRect\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(rect)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"39\">\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">                self\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">minFilter\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">updateFilterExtentsWithRect\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(rect)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"40\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">                guard\u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\"> let\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> rowDiff \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> self\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.minFilter.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">differenceFromFilter\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">(\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">self\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">maxFilter\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">, \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">context\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">: \u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">self\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\">context\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">)\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"41\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">                    where\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> rowDiff \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\"><=\u003C/span>\u003Cspan style=\"--shiki-default:#268BD2;--shiki-dark:#268BD2\"> self\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">.maximumDelta \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">else\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> {\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"42\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">                        break\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"43\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">                }\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"44\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">                inset \u003C/span>\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">=\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> step\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"45\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">            }\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"46\">\u003Cspan style=\"--shiki-default:#859900;--shiki-dark:#859900\">            return\u003C/span>\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\"> inset\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"47\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">        }\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"48\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">    }\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"49\">\u003Cspan emptyLinePlaceholder>\n\u003C/span>\u003C/span>\u003Cspan class=\"line\" line=\"50\">\u003Cspan style=\"--shiki-default:#839496;--shiki-dark:#657B83\">}\n\u003C/span>\u003C/span>\u003C/code>\u003C/pre>\u003Cp>The first few passes at the code, I didn't have a great idea to reduce the amount of duplication in iterating in from each of the sides, which I thought may hurt later as I'm assuming there's room for optimizing the search for edges, probably involving subdividing and testing regions rather than a linear walk of the space.\u003C/p>\u003Cp>I then realized that the only major change in each region was generating the rectangle and the range being worked on. Using a closure for the rectangle generation helped, but making a struct to shove all of the important values into and making the \u003Ccode class=\"\">calculateInset\u003C/code> code a function on that struct also helped me keep the function signatures sane.\u003C/p>\u003Cp>Finally, when I made the \u003Ccode class=\"\">calculateInset\u003C/code> function properly generic, I also had to make the return type an optional value because I couldn't set the initial value to \u003Ccode class=\"\">0\u003C/code> in the function body. This means I now added a \u003Ccode class=\"\">?? 0\u003C/code> after each call.\u003C/p>\u003Cp>I'm much happier with this than the first few passes, the code doesn't \u003Cem>work\u003C/em> yet, but all of the bits that I've tested outside of the core image black box for the filters are behaving properly\u003C/p>\u003Cstyle>html .default .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}html.dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}\u003C/style>",2016,1722847701334]