44 lines
1.2 KiB
Go
44 lines
1.2 KiB
Go
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package main
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import (
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"image"
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"image/color"
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)
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func HexToRGBA(hexcolor int) color.RGBA {
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return color.RGBA{
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R: uint8(hexcolor >> 0x10 & 0xff),
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G: uint8(hexcolor >> 0x08 & 0xff),
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B: uint8(hexcolor >> 0x00 & 0xff),
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A: 0xff,
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}
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}
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// performs linear gradient fill on target image for the background from top to bottom colors
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func FillGradient(target *image.RGBA, width int, height int, top, bottom color.RGBA) {
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for y := 0; y < height; y++ {
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//the percent of our transition informs our blending
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percentIn := float64(y) / float64(height)
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//compute top and bottom blend values as factor of percentage
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pTopR := float64(top.R) * (1 - percentIn)
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pTopG := float64(top.G) * (1 - percentIn)
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pTopB := float64(top.B) * (1 - percentIn)
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pBottomR := float64(bottom.R) * (percentIn)
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pBottomG := float64(bottom.G) * (percentIn)
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pBottomB := float64(bottom.B) * (percentIn)
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//perform blending on per pixel row basis
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for x := 0; x < width; x++ {
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pixelIndex := 4 * (width*y + x)
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target.Pix[pixelIndex] = uint8(pTopR + pBottomR)
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target.Pix[pixelIndex+1] = uint8(pTopG + pBottomG)
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target.Pix[pixelIndex+2] = uint8(pTopB + pBottomB)
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target.Pix[pixelIndex+3] = 0xff
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}
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}
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}
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