forked from tfriedel6/canvas
/
imagedata.go
executable file
·102 lines (88 loc) · 2.99 KB
/
imagedata.go
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package xmobilebackend
import (
"image"
"image/color"
"unsafe"
"golang.org/x/mobile/gl"
)
// GetImageData returns an RGBA image of the current image
func (b *XMobileBackend) GetImageData(x, y, w, h int) *image.RGBA {
b.activate()
if x < 0 {
w += x
x = 0
}
if y < 0 {
h += y
y = 0
}
if w > b.w {
w = b.w
}
if h > b.h {
h = b.h
}
var vp [4]int32
b.glctx.GetIntegerv(vp[:], gl.VIEWPORT)
size := int(vp[2] * vp[3] * 3)
if len(b.imageBuf) < size {
b.imageBuf = make([]byte, size)
}
b.glctx.ReadPixels(b.imageBuf[0:], int(vp[0]), int(vp[1]), int(vp[2]), int(vp[3]), gl.RGB, gl.UNSIGNED_BYTE)
rgba := image.NewRGBA(image.Rect(x, y, x+w, y+h))
for cy := y; cy < y+h; cy++ {
bp := (int(vp[3])-h+cy)*int(vp[2])*3 + x*3
for cx := x; cx < x+w; cx++ {
rgba.SetRGBA(cx, y+h-1-cy, color.RGBA{R: b.imageBuf[bp], G: b.imageBuf[bp+1], B: b.imageBuf[bp+2], A: 255})
bp += 3
}
}
return rgba
}
// PutImageData puts the given image at the given x/y coordinates
func (b *XMobileBackend) PutImageData(img *image.RGBA, x, y int) {
b.activate()
b.glctx.ActiveTexture(gl.TEXTURE0)
if b.imageBufTex.Value == 0 {
b.imageBufTex = b.glctx.CreateTexture()
b.glctx.BindTexture(gl.TEXTURE_2D, b.imageBufTex)
b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
} else {
b.glctx.BindTexture(gl.TEXTURE_2D, b.imageBufTex)
}
w, h := img.Bounds().Dx(), img.Bounds().Dy()
if img.Stride == img.Bounds().Dx()*4 {
b.glctx.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, w, h, gl.RGBA, gl.UNSIGNED_BYTE, img.Pix[0:])
} else {
data := make([]uint8, 0, w*h*4)
for cy := 0; cy < h; cy++ {
start := cy * img.Stride
end := start + w*4
data = append(data, img.Pix[start:end]...)
}
b.glctx.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, w, h, gl.RGBA, gl.UNSIGNED_BYTE, data[0:])
}
dx, dy := float32(x), float32(y)
dw, dh := float32(w), float32(h)
b.glctx.BindBuffer(gl.ARRAY_BUFFER, b.buf)
data := [16]float32{dx, dy, dx + dw, dy, dx + dw, dy + dh, dx, dy + dh,
0, 0, 1, 0, 1, 1, 0, 1}
b.glctx.BufferData(gl.ARRAY_BUFFER, byteSlice(unsafe.Pointer(&data[0]), len(data)*4), gl.STREAM_DRAW)
b.glctx.UseProgram(b.shd.ID)
b.glctx.Uniform1i(b.shd.Image, 0)
b.glctx.Uniform2f(b.shd.CanvasSize, float32(b.fw), float32(b.fh))
b.glctx.UniformMatrix3fv(b.shd.Matrix, mat3identity[:])
b.glctx.Uniform1f(b.shd.GlobalAlpha, 1)
b.glctx.Uniform1i(b.shd.UseAlphaTex, 0)
b.glctx.Uniform1i(b.shd.Func, shdFuncImage)
b.glctx.VertexAttribPointer(b.shd.Vertex, 2, gl.FLOAT, false, 0, 0)
b.glctx.VertexAttribPointer(b.shd.TexCoord, 2, gl.FLOAT, false, 0, 8*4)
b.glctx.EnableVertexAttribArray(b.shd.Vertex)
b.glctx.EnableVertexAttribArray(b.shd.TexCoord)
b.glctx.DrawArrays(gl.TRIANGLE_FAN, 0, 4)
b.glctx.DisableVertexAttribArray(b.shd.Vertex)
b.glctx.DisableVertexAttribArray(b.shd.TexCoord)
}