99 lines
2.9 KiB
Go
99 lines
2.9 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 = freetype.NewContext()
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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) SetFont(font *Font, size float32) {
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cv.text.font = font
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cv.text.size = size
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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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}
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for i := range cv.text.target.Pix {
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cv.text.target.Pix[i] = 0
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}
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fontRenderingContext.SetFont(cv.text.font.font)
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fontRenderingContext.SetFontSize(float64(cv.text.size))
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fontRenderingContext.SetSrc(image.NewUniform(colorGLToGo(cv.fill.r, cv.fill.g, cv.fill.b, cv.fill.a)))
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fontRenderingContext.SetDst(cv.text.target)
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fontRenderingContext.SetClip(cv.text.target.Bounds())
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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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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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gli.TexImage2D(gl_TEXTURE_2D, 0, gl_RGBA, int32(cv.w), int32(cv.h), 0, gl_RGBA, gl_UNSIGNED_BYTE, gli.Ptr(&cv.text.target.Pix[0]))
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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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data := [16]float32{-1, -1, -1, 1, 1, 1, 1, -1, 0, 1, 0, 0, 1, 0, 1, 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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