9patch.lua

-- [[
-- # Free-to-use License

-- Copyright (c) 2024 Salem Raddaoui
-- Creation Date: December 10, 2024, 9:21 AM

-- Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

-- 1. The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

-- 2. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

-- End of License
--]]

local NinePatch = {}
NinePatch.__index = NinePatch

function NinePatch.new(filename)
    local self = setmetatable({}, NinePatch)
    
    -- Load the image and its data
    self.image = love.graphics.newImage(filename)
    self.imageData = love.image.newImageData(filename)
    
    -- Store original dimensions
    self.width = self.image:getWidth()
    self.height = self.image:getHeight()
    
    -- Parse 9-patch markers
    self:parseMarkers()
    
    -- Create the quads for each region
    self:createQuads()
    
    return self
end

function NinePatch:parseMarkers()
    -- Find horizontal stretchable region from top strip
    self.stretchX = {start = 0, ending = 0}
    local foundStart = false
    
    for x = 1, self.width - 1 do
        local r, g, b, a = self.imageData:getPixel(x, 0)
        
        if not foundStart and r == 0 and g == 0 and b == 0 and a == 1 then
            self.stretchX.start = x
            foundStart = true
        elseif foundStart and (r ~= 0 or g ~= 0 or b ~= 0 or a ~= 1) then
            self.stretchX.ending = x - 1
            break
        end
    end
    
    -- Find vertical stretchable region from left strip
    self.stretchY = {start = 0, ending = 0}
    foundStart = false
    
    for y = 1, self.height - 1 do
        local r, g, b, a = self.imageData:getPixel(0, y)
        
        if not foundStart and r == 0 and g == 0 and b == 0 and a == 1 then
            self.stretchY.start = y
            foundStart = true
        elseif foundStart and (r ~= 0 or g ~= 0 or b ~= 0 or a ~= 1) then
            self.stretchY.ending = y - 1
            break
        end
    end
    
    -- Calculate content regions (excluding the 1px borders)
    self.regions = {
        topLeft = {x = 1, y = 1, w = self.stretchX.start - 1, h = self.stretchY.start - 1},
        topCenter = {x = self.stretchX.start, y = 1, w = self.stretchX.ending - self.stretchX.start, h = self.stretchY.start - 1},
        topRight = {x = self.stretchX.ending, y = 1, w = self.width - self.stretchX.ending - 1, h = self.stretchY.start - 1},
        middleLeft = {x = 1, y = self.stretchY.start, w = self.stretchX.start - 1, h = self.stretchY.ending - self.stretchY.start},
        middleCenter = {x = self.stretchX.start, y = self.stretchY.start, w = self.stretchX.ending - self.stretchX.start, h = self.stretchY.ending - self.stretchY.start},
        middleRight = {x = self.stretchX.ending, y = self.stretchY.start, w = self.width - self.stretchX.ending - 1, h = self.stretchY.ending - self.stretchY.start},
        bottomLeft = {x = 1, y = self.stretchY.ending, w = self.stretchX.start - 1, h = self.height - self.stretchY.ending - 1},
        bottomCenter = {x = self.stretchX.start, y = self.stretchY.ending, w = self.stretchX.ending - self.stretchX.start, h = self.height - self.stretchY.ending - 1},
        bottomRight = {x = self.stretchX.ending, y = self.stretchY.ending, w = self.width - self.stretchX.ending - 1, h = self.height - self.stretchY.ending - 1}
    }
end

function NinePatch:createQuads()
    self.quads = {}
    for name, region in pairs(self.regions) do
        self.quads[name] = love.graphics.newQuad(
            region.x, region.y, region.w, region.h,
            self.width, self.height
        )
    end
end

function NinePatch:draw(x, y, width, height)
    -- Calculate scale factors
    local scaleX = (width - self.regions.topLeft.w - self.regions.topRight.w) / self.regions.topCenter.w
    local scaleY = (height - self.regions.topLeft.h - self.regions.bottomLeft.h) / self.regions.middleLeft.h
    
    -- Pre-calculate some common positions
    local centerX = x + self.regions.topLeft.w
    local rightX = x + width - self.regions.topRight.w
    local middleY = y + self.regions.topLeft.h
    local bottomY = y + height - self.regions.bottomLeft.h
    
    -- Use a single draw call for each region using the pre-created quads
    love.graphics.draw(self.image, self.quads.topLeft, x, y)
    love.graphics.draw(self.image, self.quads.topCenter, centerX, y, 0, scaleX, 1)
    love.graphics.draw(self.image, self.quads.topRight, rightX, y)
    
    love.graphics.draw(self.image, self.quads.middleLeft, x, middleY, 0, 1, scaleY)
    love.graphics.draw(self.image, self.quads.middleCenter, centerX, middleY, 0, scaleX, scaleY)
    love.graphics.draw(self.image, self.quads.middleRight, rightX, middleY, 0, 1, scaleY)
    
    love.graphics.draw(self.image, self.quads.bottomLeft, x, bottomY)
    love.graphics.draw(self.image, self.quads.bottomCenter, centerX, bottomY, 0, scaleX, 1)
    love.graphics.draw(self.image, self.quads.bottomRight, rightX, bottomY)
end

return NinePatch