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added support for loading fonts and rendering text (highly unoptimized so far)

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This commit is contained in:
Thomas Friedel 2018-01-25 15:08:03 +01:00
parent 67142c3c8d
commit 85667e8f57
4 changed files with 140 additions and 2 deletions
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7
canvas.go
View file

@ -1,6 +1,7 @@
package canvas
import (
"image"
"unsafe"
"github.com/tfriedel6/lm"
@ -20,6 +21,12 @@ type Canvas struct {
lineWidth float32
}
path []pathPoint
text struct {
font *Font
size float32
target *image.RGBA
tex uint32
}
}
type pathPoint struct {

33
color.go
View file

@ -7,7 +7,7 @@ import (
"strings"
)
func colorToGL(color color.Color) (r, g, b, a float32) {
func colorGoToGL(color color.Color) (r, g, b, a float32) {
ir, ig, ib, ia := color.RGBA()
r = float32(ir) / 65535
g = float32(ig) / 65535
@ -16,6 +16,35 @@ func colorToGL(color color.Color) (r, g, b, a float32) {
return
}
func colorGLToGo(r, g, b, a float32) color.Color {
if r < 0 {
r = 0
} else if r > 1 {
r = 1
}
if g < 0 {
g = 0
} else if g > 1 {
g = 1
}
if b < 0 {
b = 0
} else if b > 1 {
b = 1
}
if a < 0 {
a = 0
} else if a > 1 {
a = 1
}
return color.RGBA{
R: uint8(r * 255),
G: uint8(g * 255),
B: uint8(b * 255),
A: uint8(a * 255),
}
}
func parseHexRune(rn rune) (int, bool) {
switch {
case rn >= '0' && rn <= '9':
@ -93,7 +122,7 @@ func parseColor(value ...interface{}) (r, g, b, a float32, ok bool) {
if len(value) == 1 {
switch v := value[0].(type) {
case color.Color:
r, g, b, a = colorToGL(v)
r, g, b, a = colorGoToGL(v)
ok = true
return
case [3]float32:

3
images.go
View file

@ -43,6 +43,7 @@ func LoadImage(src interface{}) (*Image, error) {
func loadImageRGBA(src *image.RGBA) (*Image, error) {
img := &Image{w: src.Bounds().Dx(), h: src.Bounds().Dy()}
gli.GenTextures(1, &img.tex)
gli.ActiveTexture(gl_TEXTURE0)
gli.BindTexture(gl_TEXTURE_2D, img.tex)
gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MIN_FILTER, gl_LINEAR_MIPMAP_LINEAR)
gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MAG_FILTER, gl_LINEAR)
@ -75,6 +76,7 @@ func loadImageRGBA(src *image.RGBA) (*Image, error) {
func loadImageGray(src *image.Gray) (*Image, error) {
img := &Image{w: src.Bounds().Dx(), h: src.Bounds().Dy()}
gli.GenTextures(1, &img.tex)
gli.ActiveTexture(gl_TEXTURE0)
gli.BindTexture(gl_TEXTURE_2D, img.tex)
gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MIN_FILTER, gl_LINEAR_MIPMAP_LINEAR)
gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MAG_FILTER, gl_LINEAR)
@ -107,6 +109,7 @@ func loadImageGray(src *image.Gray) (*Image, error) {
func loadImageConverted(src image.Image) (*Image, error) {
img := &Image{w: src.Bounds().Dx(), h: src.Bounds().Dy()}
gli.GenTextures(1, &img.tex)
gli.ActiveTexture(gl_TEXTURE0)
gli.BindTexture(gl_TEXTURE_2D, img.tex)
gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MIN_FILTER, gl_LINEAR_MIPMAP_LINEAR)
gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MAG_FILTER, gl_LINEAR)

99
text.go Normal file
View file

@ -0,0 +1,99 @@
package canvas
import (
"errors"
"image"
"io/ioutil"
"unsafe"
"github.com/golang/freetype"
"github.com/golang/freetype/truetype"
"golang.org/x/image/math/fixed"
)
var fontRenderingContext = freetype.NewContext()
type Font struct {
font *truetype.Font
}
func LoadFont(src interface{}) (*Font, error) {
switch v := src.(type) {
case *truetype.Font:
return &Font{font: v}, nil
case string:
data, err := ioutil.ReadFile(v)
if err != nil {
return nil, err
}
font, err := freetype.ParseFont(data)
if err != nil {
return nil, err
}
return &Font{font: font}, nil
case []byte:
font, err := freetype.ParseFont(v)
if err != nil {
return nil, err
}
return &Font{font: font}, nil
}
return nil, errors.New("Unsupported source type")
}
func (cv *Canvas) SetFont(font *Font, size float32) {
cv.text.font = font
cv.text.size = size
}
func (cv *Canvas) FillText(str string, x, y float32) {
cv.activate()
if cv.text.target == nil || cv.text.target.Bounds().Dx() != cv.w || cv.text.target.Bounds().Dy() != cv.h {
if cv.text.tex != 0 {
gli.DeleteTextures(1, &cv.text.tex)
}
cv.text.target = image.NewRGBA(image.Rect(0, 0, cv.w, cv.h))
gli.GenTextures(1, &cv.text.tex)
gli.ActiveTexture(gl_TEXTURE0)
gli.BindTexture(gl_TEXTURE_2D, cv.text.tex)
gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MIN_FILTER, gl_NEAREST)
gli.TexParameteri(gl_TEXTURE_2D, gl_TEXTURE_MAG_FILTER, gl_NEAREST)
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)
}
for i := range cv.text.target.Pix {
cv.text.target.Pix[i] = 0
}
fontRenderingContext.SetFont(cv.text.font.font)
fontRenderingContext.SetFontSize(float64(cv.text.size))
fontRenderingContext.SetSrc(image.NewUniform(colorGLToGo(cv.fill.r, cv.fill.g, cv.fill.b, cv.fill.a)))
fontRenderingContext.SetDst(cv.text.target)
fontRenderingContext.SetClip(cv.text.target.Bounds())
fontRenderingContext.DrawString(str, fixed.Point26_6{X: fixed.Int26_6(x*64 + 0.5), Y: fixed.Int26_6(y*64 + 0.5)})
gli.BlendFunc(gl_ONE, gl_ONE_MINUS_SRC_ALPHA)
gli.ActiveTexture(gl_TEXTURE0)
gli.BindTexture(gl_TEXTURE_2D, cv.text.tex)
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]))
gli.UseProgram(tr.id)
gli.Uniform1i(tr.image, 0)
gli.BindBuffer(gl_ARRAY_BUFFER, buf)
data := [16]float32{-1, -1, -1, 1, 1, 1, 1, -1, 0, 1, 0, 0, 1, 0, 1, 1}
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)
gli.BlendFunc(gl_SRC_ALPHA, gl_ONE_MINUS_SRC_ALPHA)
}