IOS gradient logic

Common gradient logic

        var beginR : CGFloat = 0.endR : CGFloat = 0.beginG : CGFloat = 0.endG : CGFloat = 0.beginB : CGFloat = 0.endB : CGFloat = 0
        / / for RGB
        beginColor.getRed(&beginR, green: &beginG, blue: &beginB, alpha: nil)
        endColor.getRed(&endR, green: &endG, blue: &endB, alpha: nil)
        
        func byRow(direction: DrawDirection){
            var arrayRows : [Int] = []
            for row inminY.. <maxY { arrayRows.append(row) }if direction == .up{
                arrayRows = arrayRows.reversed()
            }
            let deltaR = (endR - beginR) / CGFloat(maxY - minY)
            let deltaG = (endG - beginG) / CGFloat(maxY - minY)
            let deltaB = (endB - beginB) / CGFloat(maxY - minY)
            var offset:CGFloat = 0
            for row in arrayRows{
                let color = UIColor.init(red: beginR+deltaR*offset, green: beginG+deltaG*offset, blue: beginB+deltaB*offset, alpha: 1)
                
// context? .setFillColor(color.cgColor)
// context? .fill(CGRect(x: minX, y: row, width: maxX-minX, height: 1))context? .setStrokeColor(color.cgColor) context? .move(to: CGPoint(x: CGFloat(minX),y: CGFloat(row) + 0.5))   // Add 0.5 so that the line is drawn right on the rowcontext? .addLine(to: CGPoint(x: CGFloat(maxX),y: CGFloat(row) + 0.5) ) context? .strokePath() offset +=1}}Copy the code

2. Gradient logic based on hue

        var beginHue: CGFloat = 0.endHue: CGFloat = 0.beginBrightness:CGFloat=0.endBrightness:CGFloat = 0
        var beginSaturation:CGFloat=0.endSaturation: CGFloat = 0
                // Get chroma and brightness
        beginColor.getHue(&beginHue, saturation: &beginSaturation, brightness: &beginBrightness, alpha: nil)
        endColor.getHue(&endHue, saturation: &endSaturation, brightness: &endBrightness, alpha: nil)
        func byCol(direction: DrawDirection){
            var arrayCols : [Int] = []
            for col inminX.. <maxX { arrayCols.append(col) }if direction == .left{
                arrayCols = arrayCols.reversed()
            }
            let deltaHue = (endHue - beginHue) / CGFloat(maxX - minX)
            var offset:CGFloat = 0
            for col in arrayCols{
                let color = UIColor.init(hue: beginHue+deltaHue*offset, saturation: beginSaturation+deltaHue*offset, brightness: beginBrightness+deltaHue*offset, alpha: 1)
                
// context? .setFillColor(color.cgColor)
// context? .fill(CGRect(x: minX, y: row, width: maxX-minX, height: 1))context? .setStrokeColor(color.cgColor) context? .move(to: CGPoint(x: CGFloat(col) +0.5.y: CGFloat(minY)))  // Add 0.5 so that the line is drawn right on the rowcontext? .addLine(to: CGPoint(x:CGFloat(col) +0.5.y: CGFloat(maxY))) context? .strokePath() offset +=1}}Copy the code