added image data functions

imagedata.go

@@ -0,0 +1,95 @@
+package canvas
+
+import (
+	"image"
+	"image/color"
+	"unsafe"
+)
+
+var imageBufTex uint32
+var imageBuf []byte
+
+func (cv *Canvas) GetImageData(x, y, w, h int) *image.RGBA {
+	cv.activate()
+
+	if x < 0 {
+		w += x
+		x = 0
+	}
+	if y < 0 {
+		h += y
+		y = 0
+	}
+	if w > cv.w {
+		w = cv.w
+	}
+	if h > cv.h {
+		h = cv.h
+	}
+	if len(imageBuf) < w*h*3 {
+		imageBuf = make([]byte, w*h*3)
+	}
+
+	gli.ReadPixels(int32(x), int32(y), int32(w), int32(h), gl_RGB, gl_UNSIGNED_BYTE, gli.Ptr(&imageBuf[0]))
+	rgba := image.NewRGBA(image.Rect(x, y, x+w, y+h))
+	bp := 0
+	for cy := y; cy < y+h; cy++ {
+		for cx := x; cx < x+w; cx++ {
+			rgba.SetRGBA(cx, y+h-1-cy, color.RGBA{R: imageBuf[bp], G: imageBuf[bp+1], B: imageBuf[bp+2], A: 255})
+			bp += 3
+		}
+	}
+	return rgba
+}
+
+func (cv *Canvas) PutImageData(img *image.RGBA, x, y int) {
+	cv.activate()
+
+	if imageBufTex == 0 {
+		gli.GenTextures(1, &imageBufTex)
+	}
+	gli.ActiveTexture(gl_TEXTURE0)
+	gli.BindTexture(gl_TEXTURE_2D, imageBufTex)
+	gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MIN_FILTER, gl_LINEAR)
+	gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MAG_FILTER, gl_LINEAR)
+	gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_WRAP_S, gl_CLAMP_TO_EDGE)
+	gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_WRAP_T, gl_CLAMP_TO_EDGE)
+
+	w, h := img.Bounds().Dx(), img.Bounds().Dy()
+
+	if img.Stride == img.Bounds().Dx()*4 {
+		gli.TexImage2D(gl_TEXTURE_2D, 0, gl_RGBA, int32(w), int32(h), 0, gl_RGBA, gl_UNSIGNED_BYTE, gli.Ptr(&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]...)
+		}
+		gli.TexImage2D(gl_TEXTURE_2D, 0, gl_RGBA, int32(w), int32(h), 0, gl_RGBA, gl_UNSIGNED_BYTE, gli.Ptr(&data[0]))
+	}
+
+	dx, dy := float32(x), float32(y)
+	dw, dh := float32(w), float32(h)
+
+	dx0, dy0 := dx*2/cv.fw-1, -dy*2/cv.fh+1
+	dx1, dy1 := dx0, -(dy+dh)*2/cv.fh+1
+	dx2, dy2 := (dx+dw)*2/cv.fw-1, dy1
+	dx3, dy3 := dx2, dy0
+
+	gli.UseProgram(tr.id)
+	gli.Uniform1i(tr.image, 0)
+
+	gli.BindBuffer(gl_ARRAY_BUFFER, buf)
+	data := [16]float32{dx0, dy0, dx1, dy1, dx2, dy2, dx3, dy3,
+		0, 0, 0, 1, 1, 1, 1, 0}
+	gli.BufferData(gl_ARRAY_BUFFER, len(data)*4, unsafe.Pointer(&data[0]), gl_STREAM_DRAW)
+
+	gli.VertexAttribPointer(tr.vertex, 2, gl_FLOAT, false, 0, nil)
+	gli.VertexAttribPointer(tr.texCoord, 2, gl_FLOAT, false, 0, gli.PtrOffset(8*4))
+	gli.EnableVertexAttribArray(tr.vertex)
+	gli.EnableVertexAttribArray(tr.texCoord)
+	gli.DrawArrays(gl_TRIANGLE_FAN, 0, 4)
+	gli.DisableVertexAttribArray(tr.vertex)
+	gli.DisableVertexAttribArray(tr.texCoord)
+}