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Replicate border instead of using a constant

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Constant border could lead to wrong values alpha values with certain
configurations.
This commit is contained in:
jst 2012-12-10 19:27:21 +01:00
parent dd1c157427
commit 378e366327
1 changed files with 24 additions and 21 deletions
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45
converter.go
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@ -33,6 +33,23 @@ type genericConverter struct {
src image.Image
}
func replicateBorder1d(x, min, max int) int {
if (x < min) {
x = min
} else if (x >= max) {
x = max-1
}
return x
}
func replicateBorder(x, y int, rect image.Rectangle) (xx, yy int) {
xx = replicateBorder1d(x, rect.Min.X, rect.Max.X)
yy = replicateBorder1d(y, rect.Min.Y, rect.Max.Y)
return
}
func (c *genericConverter) at(x, y int) colorArray {
r, g, b, a := c.src.At(x, y).RGBA()
return colorArray{
@ -48,10 +65,7 @@ type rgbaConverter struct {
}
func (c *rgbaConverter) at(x, y int) colorArray {
if !(image.Point{x, y}.In(c.src.Rect)) {
return colorArray{0, 0, 0, 0}
}
i := c.src.PixOffset(x, y)
i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect))
return colorArray{
float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+0])),
float32(uint16(c.src.Pix[i+1])<<8 | uint16(c.src.Pix[i+1])),
@ -65,10 +79,7 @@ type rgba64Converter struct {
}
func (c *rgba64Converter) at(x, y int) colorArray {
if !(image.Point{x, y}.In(c.src.Rect)) {
return colorArray{0, 0, 0, 0}
}
i := c.src.PixOffset(x, y)
i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect))
return colorArray{
float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+1])),
float32(uint16(c.src.Pix[i+2])<<8 | uint16(c.src.Pix[i+3])),
@ -82,10 +93,7 @@ type grayConverter struct {
}
func (c *grayConverter) at(x, y int) colorArray {
if !(image.Point{x, y}.In(c.src.Rect)) {
return colorArray{0, 0, 0, 0}
}
i := c.src.PixOffset(x, y)
i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect))
g := float32(uint16(c.src.Pix[i])<<8 | uint16(c.src.Pix[i]))
return colorArray{
g,
@ -100,10 +108,7 @@ type gray16Converter struct {
}
func (c *gray16Converter) at(x, y int) colorArray {
if !(image.Point{x, y}.In(c.src.Rect)) {
return colorArray{0, 0, 0, 0}
}
i := c.src.PixOffset(x, y)
i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect))
g := float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+1]))
return colorArray{
g,
@ -118,11 +123,9 @@ type ycbcrConverter struct {
}
func (c *ycbcrConverter) at(x, y int) colorArray {
if !(image.Point{x, y}.In(c.src.Rect)) {
return colorArray{0, 0, 0, 0}
}
yi := c.src.YOffset(x, y)
ci := c.src.COffset(x, y)
xx, yy := replicateBorder(x, y, c.src.Rect)
yi := c.src.YOffset(xx, yy)
ci := c.src.COffset(xx, yy)
r, g, b := color.YCbCrToRGB(c.src.Y[yi], c.src.Cb[ci], c.src.Cr[ci])
return colorArray{
float32(uint16(r) * 0x101),