diff --git a/draw2d/draw2d.go b/draw2d/draw2d.go index 79225cb..d1eed46 100644 --- a/draw2d/draw2d.go +++ b/draw2d/draw2d.go @@ -6,6 +6,7 @@ import ( "exp/draw" "image" "log" + "math" "freetype-go.googlecode.com/hg/freetype" "freetype-go.googlecode.com/hg/freetype/raster" ) @@ -198,33 +199,103 @@ func (gc *ImageGraphicContext) Restore() { oldContext.previous = nil } } +//see http://pippin.gimp.org/image_processing/chap_resampling.html +func getColorLinear(img image.Image, x, y float64) image.Color { + return img.At(int(x), int(y)) +} -func (gc *ImageGraphicContext) DrawImage(image image.Image) { - width := raster.Fix32(gc.img.Bounds().Dx() * 256) - height := raster.Fix32(gc.img.Bounds().Dy() * 256) +func getColorBilinear(img image.Image, x, y float64) image.Color { + x0 := math.Floor(x) + y0 := math.Floor(y) + dx := x - x0 + dy := y - y0 - p0 := raster.Point{0, 0} - p1 := raster.Point{0, 0} - p2 := raster.Point{0, 0} - p3 := raster.Point{0, 0} - var i raster.Fix32 = 0 - for ; i < width; i += 256 { - var j raster.Fix32 = 0 - for ; j < height; j += 256 { - p0.X, p0.Y = i, j - p1.X, p1.Y = p0.X+256, p0.Y - p2.X, p2.Y = p1.X, p0.Y+256 - p3.X, p3.Y = p0.X, p2.Y + color0 := img.At(int(x0), int(y0)) + color1 := img.At(int(x0+1), int(y0)) + color2 := img.At(int(x0+1), int(y0+1)) + color3 := img.At(int(x0), int(y0+1)) - gc.current.tr.TransformRasterPoint(&p0, &p1, &p2, &p3) - gc.fillRasterizer.Start(p0) - gc.fillRasterizer.Add1(p1) - gc.fillRasterizer.Add1(p2) - gc.fillRasterizer.Add1(p3) - gc.fillRasterizer.Add1(p0) - gc.painter.SetColor(image.At(int(i>>8), int(j>>8))) - gc.fillRasterizer.Rasterize(gc.painter) - gc.fillRasterizer.Clear() + return lerp(lerp(color0, color1, dx), lerp(color3, color2, dx), dy) +} +/** +-- LERP +-- /lerp/, vi.,n. +-- +-- Quasi-acronym for Linear Interpolation, used as a verb or noun for +-- the operation. "Bresenham's algorithm lerps incrementally between the +-- two endpoints of the line." (From Jargon File (4.4.4, 14 Aug 2003) +*/ +func lerp(c1, c2 image.Color, ratio float64) image.Color { + r1, g1, b1, a1 := c1.RGBA() + r2, g2, b2, a2 := c2.RGBA() + r := int(float64(r1)*(1-ratio) + float64(r2)*ratio) + g := int(float64(g1)*(1-ratio) + float64(g2)*ratio) + b := int(float64(b1)*(1-ratio) + float64(b2)*ratio) + a := int(float64(a1)*(1-ratio) + float64(a2)*ratio) + return image.RGBAColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), uint8(a >> 8)} +} + + +func getColorCubicRow(img image.Image, x, y, offset float64) image.Color { + c0 := img.At(int(x), int(y)) + c1 := img.At(int(x+1), int(y)) + c2 := img.At(int(x+2), int(y)) + c3 := img.At(int(x+3), int(y)) + r0, g0, b0, a0 := c0.RGBA() + r1, g1, b1, a1 := c1.RGBA() + r2, g2, b2, a2 := c2.RGBA() + r3, g3, b3, a3 := c3.RGBA() + r, g, b, a := cubic(offset,float64(r0),float64(r1),float64(r2),float64(r3)), cubic(offset,float64(g0),float64(g1),float64(g2),float64(g3)), cubic(offset,float64(b0),float64(b1),float64(b2),float64(b3)), cubic(offset,float64(a0),float64(a1),float64(a2),float64(a3)) + return image.RGBAColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), uint8(a >> 8)} +} + +func getColorBicubic(img image.Image, x, y float64) image.Color { + x0 := math.Floor(x) + y0 := math.Floor(y) + dx := x - x0 + dy := y - y0 + + c0 := getColorCubicRow(img, x0-1, y0-1, dx) + c1 := getColorCubicRow(img, x0-1, y0, dx) + c2 := getColorCubicRow(img, x0-1, y0+1, dx) + c3 := getColorCubicRow(img, x0-1, y0+2, dx) + r0, g0, b0, a0 := c0.RGBA() + r1, g1, b1, a1 := c1.RGBA() + r2, g2, b2, a2 := c2.RGBA() + r3, g3, b3, a3 := c3.RGBA() + r, g, b, a := cubic(dy,float64(r0),float64(r1),float64(r2),float64(r3)), cubic(dy,float64(g0),float64(g1),float64(g2),float64(g3)), cubic(dy,float64(b0),float64(b1),float64(b2),float64(b3)), cubic(dy,float64(a0),float64(a1),float64(a2),float64(a3)) + return image.RGBAColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), uint8(a >> 8)} +} + +func cubic(offset,v0,v1,v2,v3 float64) uint32{ + // offset is the offset of the sampled value between v1 and v2 + return uint32((((( -7 * v0 + 21 * v1 - 21 * v2 + 7 * v3 ) * offset + + ( 15 * v0 - 36 * v1 + 27 * v2 - 6 * v3 ) ) * offset + + ( -9 * v0 + 9 * v2 ) ) * offset + (v0 + 16 * v1 + v2) ) / 18.0); +} + +func compose(c1, c2 image.Color) image.Color { + r1, g1, b1, a1 := c1.RGBA() + r2, g2, b2, a2 := c2.RGBA() + ia := M - a2 + r := ((r1 * ia) / M) + r2 + g := ((g1 * ia) / M) + g2 + b := ((b1 * ia) / M) + b2 + a := ((a1 * ia) / M) + a2 + return image.RGBAColor{uint8(r >> 8), uint8(g >> 8), uint8(b >> 8), uint8(a >> 8)} +} + +func (gc *ImageGraphicContext) DrawImage(img image.Image) { + width := float64(gc.img.Bounds().Dx()) + height := float64(gc.img.Bounds().Dy()) + gc.current.tr.Transform(&width, &height) + var x, y, u, v float64 + for x = 0; x < width; x++ { + for y = 0; y < height; y++ { + u = x + v = y + gc.current.tr.InverseTransform(&u, &v) + gc.img.Set(int(x), int(y), compose(gc.img.At(int(x), int(y)), getColorLinear(img, u, v))) } } } diff --git a/resource/result/TestDrawImage.png b/resource/result/TestDrawImage.png index 3100ab7..f3a686c 100644 Binary files a/resource/result/TestDrawImage.png and b/resource/result/TestDrawImage.png differ