107 lines
3.3 KiB
Go
107 lines
3.3 KiB
Go
package canvas
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import (
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"errors"
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"image"
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"io/ioutil"
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"unsafe"
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"github.com/golang/freetype"
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"github.com/golang/freetype/truetype"
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"golang.org/x/image/math/fixed"
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)
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var fontRenderingContext = newFRContext()
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type Font struct {
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font *truetype.Font
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}
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func LoadFont(src interface{}) (*Font, error) {
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switch v := src.(type) {
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case *truetype.Font:
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return &Font{font: v}, nil
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case string:
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data, err := ioutil.ReadFile(v)
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if err != nil {
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return nil, err
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}
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font, err := freetype.ParseFont(data)
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if err != nil {
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return nil, err
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}
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return &Font{font: font}, nil
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case []byte:
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font, err := freetype.ParseFont(v)
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if err != nil {
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return nil, err
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}
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return &Font{font: font}, nil
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}
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return nil, errors.New("Unsupported source type")
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}
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func (cv *Canvas) FillText(str string, x, y float32) {
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cv.activate()
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if cv.text.target == nil || cv.text.target.Bounds().Dx() != cv.w || cv.text.target.Bounds().Dy() != cv.h {
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if cv.text.tex != 0 {
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gli.DeleteTextures(1, &cv.text.tex)
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}
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cv.text.target = image.NewRGBA(image.Rect(0, 0, cv.w, cv.h))
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gli.GenTextures(1, &cv.text.tex)
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gli.ActiveTexture(gl_TEXTURE0)
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gli.BindTexture(gl_TEXTURE_2D, cv.text.tex)
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gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MIN_FILTER, gl_NEAREST)
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gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MAG_FILTER, gl_NEAREST)
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gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_WRAP_S, gl_CLAMP_TO_EDGE)
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gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_WRAP_T, gl_CLAMP_TO_EDGE)
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gli.TexImage2D(gl_TEXTURE_2D, 0, gl_RGBA, int32(cv.w), int32(cv.h), 0, gl_RGBA, gl_UNSIGNED_BYTE, nil)
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}
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fontRenderingContext.setFont(cv.state.font.font)
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fontRenderingContext.setFontSize(float64(cv.state.fontSize))
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f := cv.state.fill
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fontRenderingContext.setSrc(image.NewUniform(colorGLToGo(f.r, f.g, f.b, f.a)))
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fontRenderingContext.setDst(cv.text.target)
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fontRenderingContext.setClip(cv.text.target.Bounds())
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_, bounds, _ := fontRenderingContext.drawString(str, fixed.Point26_6{X: fixed.Int26_6(x*64 + 0.5), Y: fixed.Int26_6(y*64 + 0.5)})
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subImg := cv.text.target.SubImage(bounds).(*image.RGBA)
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gli.BlendFunc(gl_ONE, gl_ONE_MINUS_SRC_ALPHA)
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gli.ActiveTexture(gl_TEXTURE0)
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gli.BindTexture(gl_TEXTURE_2D, cv.text.tex)
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for y, w, h := 0, bounds.Dx(), bounds.Dy(); y < h; y++ {
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off := y * subImg.Stride
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pix := subImg.Pix
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gli.TexSubImage2D(gl_TEXTURE_2D, 0, 0, int32(cv.h-1-y), int32(w), 1, gl_RGBA, gl_UNSIGNED_BYTE, gli.Ptr(&pix[off]))
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for b := w * 4; b > 0; b-- {
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pix[off] = 0
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off++
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}
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}
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gli.UseProgram(tr.id)
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gli.Uniform1i(tr.image, 0)
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gli.BindBuffer(gl_ARRAY_BUFFER, buf)
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x0 := float32(bounds.Min.X) / cv.fw
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y0 := float32(bounds.Min.Y) / cv.fh
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x1 := float32(bounds.Max.X) / cv.fw
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y1 := float32(bounds.Max.Y) / cv.fh
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data := [16]float32{x0*2 - 1, -y0*2 + 1, x0*2 - 1, -y1*2 + 1, x1*2 - 1, -y1*2 + 1, x1*2 - 1, -y0*2 + 1,
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0, 1, 0, 1 - (y1 - y0), x1 - x0, 1 - (y1 - y0), x1 - x0, 1}
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gli.BufferData(gl_ARRAY_BUFFER, len(data)*4, unsafe.Pointer(&data[0]), gl_STREAM_DRAW)
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gli.VertexAttribPointer(tr.vertex, 2, gl_FLOAT, false, 0, nil)
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gli.VertexAttribPointer(tr.texCoord, 2, gl_FLOAT, false, 0, gli.PtrOffset(8*4))
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gli.EnableVertexAttribArray(tr.vertex)
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gli.EnableVertexAttribArray(tr.texCoord)
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gli.DrawArrays(gl_TRIANGLE_FAN, 0, 4)
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gli.DisableVertexAttribArray(tr.vertex)
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gli.DisableVertexAttribArray(tr.texCoord)
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gli.BlendFunc(gl_SRC_ALPHA, gl_ONE_MINUS_SRC_ALPHA)
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}
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