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added support for shadows (not yet blurred)

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This commit is contained in:
Thomas Friedel 2018-06-14 11:41:54 +02:00
parent 3b9604efab
commit 6b4af8f29f
6 changed files with 205 additions and 26 deletions
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4
README.md
View file

@ -113,13 +113,15 @@ These features *should* work just like their HTML5 counterparts, but there are l
- getImageData
- putImageData
- clearRect
- shadowColor
- shadowOffset(X/Y)
# Missing features
- globalCompositeOperation
- lineDashOffset
- miterLimit
- shadows
- shadowBlur
- textBaseline
- getLineDash
- isPointInPath

37
canvas.go
View file

@ -45,6 +45,11 @@ type drawState struct {
scissor scissor
clip []pathPoint
shadowColor glColor
shadowOffsetX float64
shadowOffsetY float64
/*
The current transformation matrix.
The current clipping region.
@ -99,6 +104,7 @@ func New(x, y, w, h int) *Canvas {
cv := &Canvas{stateStack: make([]drawState, 0, 20)}
cv.SetBounds(x, y, w, h)
cv.state.lineWidth = 1
cv.state.lineAlpha = 1
cv.state.globalAlpha = 1
cv.state.fill.color = glColor{a: 1}
cv.state.stroke.color = glColor{a: 1}
@ -171,6 +177,7 @@ const alphaTexSize = 2048
var (
gli GL
buf uint32
shadowBuf uint32
alphaTex uint32
sr *solidShader
lgr *linearGradientShader
@ -280,6 +287,12 @@ func LoadGL(glimpl GL) (err error) {
return
}
gli.GenBuffers(1, &shadowBuf)
err = glError()
if err != nil {
return
}
gli.ActiveTexture(gl_TEXTURE0)
gli.GenTextures(1, &alphaTex)
gli.BindTexture(gl_TEXTURE_2D, alphaTex)
@ -610,3 +623,27 @@ func (cv *Canvas) Transform(a, b, c, d, e, f float64) {
func (cv *Canvas) SetTransform(a, b, c, d, e, f float64) {
cv.state.transform = mat{a, b, 0, c, d, 0, e, f, 1}
}
// SetShadowColor sets the color of the shadow. If it is fully transparent (default)
// then no shadow is drawn
func (cv *Canvas) SetShadowColor(color ...interface{}) {
if c, ok := parseColor(color...); ok {
cv.state.shadowColor = c
}
}
// SetShadowOffsetX sets the x offset of the shadow
func (cv *Canvas) SetShadowOffsetX(offset float64) {
cv.state.shadowOffsetX = offset
}
// SetShadowOffsetY sets the y offset of the shadow
func (cv *Canvas) SetShadowOffsetY(offset float64) {
cv.state.shadowOffsetY = offset
}
// SetShadowOffset sets the offset of the shadow
func (cv *Canvas) SetShadowOffset(x, y float64) {
cv.state.shadowOffsetX = x
cv.state.shadowOffsetY = y
}

18
images.go
View file

@ -250,6 +250,24 @@ func (cv *Canvas) DrawImage(image interface{}, coords ...float64) {
p2 := cv.tf(vec{dx + dw, dy + dh})
p3 := cv.tf(vec{dx + dw, dy})
if cv.state.shadowColor.a != 0 {
tris := [24]float32{
0, 0,
float32(cv.fw), 0,
float32(cv.fw), float32(cv.fh),
0, 0,
float32(cv.fw), float32(cv.fh),
0, float32(cv.fh),
float32(p0[0]), float32(p0[1]),
float32(p3[0]), float32(p3[1]),
float32(p2[0]), float32(p2[1]),
float32(p0[0]), float32(p0[1]),
float32(p2[0]), float32(p2[1]),
float32(p1[0]), float32(p1[1]),
}
cv.drawShadow(tris[:])
}
gli.StencilFunc(gl_EQUAL, 0, 0xFF)
gli.BindBuffer(gl_ARRAY_BUFFER, buf)

26
paths.go
View file

@ -360,6 +360,10 @@ func (cv *Canvas) stroke(path []pathPoint) {
gli.BindBuffer(gl_ARRAY_BUFFER, buf)
gli.BufferData(gl_ARRAY_BUFFER, len(tris)*4, unsafe.Pointer(&tris[0]), gl_STREAM_DRAW)
cv.drawShadow(tris)
gli.BindBuffer(gl_ARRAY_BUFFER, buf)
gli.ColorMask(false, false, false, false)
gli.StencilFunc(gl_ALWAYS, 1, 0xFF)
gli.StencilOp(gl_REPLACE, gl_REPLACE, gl_REPLACE)
@ -513,6 +517,10 @@ func (cv *Canvas) Fill() {
gli.BindBuffer(gl_ARRAY_BUFFER, buf)
gli.BufferData(gl_ARRAY_BUFFER, len(tris)*4, unsafe.Pointer(&tris[0]), gl_STREAM_DRAW)
cv.drawShadow(tris)
gli.BindBuffer(gl_ARRAY_BUFFER, buf)
gli.ColorMask(false, false, false, false)
gli.StencilFunc(gl_ALWAYS, 1, 0xFF)
gli.StencilOp(gl_REPLACE, gl_REPLACE, gl_REPLACE)
@ -700,6 +708,24 @@ func (cv *Canvas) FillRect(x, y, w, h float64) {
p2 := cv.tf(vec{x + w, y + h})
p3 := cv.tf(vec{x + w, y})
if cv.state.shadowColor.a != 0 {
tris := [24]float32{
0, 0,
float32(cv.fw), 0,
float32(cv.fw), float32(cv.fh),
0, 0,
float32(cv.fw), float32(cv.fh),
0, float32(cv.fh),
float32(p0[0]), float32(p0[1]),
float32(p3[0]), float32(p3[1]),
float32(p2[0]), float32(p2[1]),
float32(p0[0]), float32(p0[1]),
float32(p2[0]), float32(p2[1]),
float32(p1[0]), float32(p1[1]),
}
cv.drawShadow(tris[:])
}
gli.BindBuffer(gl_ARRAY_BUFFER, buf)
data := [8]float32{float32(p0[0]), float32(p0[1]), float32(p1[0]), float32(p1[1]), float32(p2[0]), float32(p2[1]), float32(p3[0]), float32(p3[1])}
gli.BufferData(gl_ARRAY_BUFFER, len(data)*4, unsafe.Pointer(&data[0]), gl_STREAM_DRAW)

95
shadows.go Normal file
View file

@ -0,0 +1,95 @@
package canvas
import (
"image"
"unsafe"
)
func (cv *Canvas) drawShadow(tris []float32) {
if len(tris) == 0 || cv.state.shadowColor.a == 0 {
return
}
ox, oy := float32(cv.state.shadowOffsetX), float32(cv.state.shadowOffsetY)
count := len(tris)
for i := 12; i < count; i += 2 {
tris[i] += ox
tris[i+1] += oy
}
gli.BindBuffer(gl_ARRAY_BUFFER, shadowBuf)
gli.BufferData(gl_ARRAY_BUFFER, len(tris)*4, unsafe.Pointer(&tris[0]), gl_STREAM_DRAW)
gli.ColorMask(false, false, false, false)
gli.StencilFunc(gl_ALWAYS, 1, 0xFF)
gli.StencilOp(gl_REPLACE, gl_REPLACE, gl_REPLACE)
gli.StencilMask(0x01)
gli.UseProgram(sr.id)
gli.Uniform4f(sr.color, 0, 0, 0, 0)
gli.Uniform2f(sr.canvasSize, float32(cv.fw), float32(cv.fh))
gli.EnableVertexAttribArray(sr.vertex)
gli.VertexAttribPointer(sr.vertex, 2, gl_FLOAT, false, 0, 0)
gli.DrawArrays(gl_TRIANGLES, 6, int32(len(tris)/2-6))
gli.DisableVertexAttribArray(sr.vertex)
gli.ColorMask(true, true, true, true)
gli.StencilFunc(gl_EQUAL, 1, 0xFF)
var style drawStyle
style.color = cv.state.shadowColor
vertex := cv.useShader(&style)
gli.EnableVertexAttribArray(vertex)
gli.VertexAttribPointer(vertex, 2, gl_FLOAT, false, 0, 0)
gli.DrawArrays(gl_TRIANGLES, 0, 6)
gli.DisableVertexAttribArray(vertex)
gli.StencilOp(gl_KEEP, gl_KEEP, gl_KEEP)
gli.StencilFunc(gl_ALWAYS, 0, 0xFF)
gli.Clear(gl_STENCIL_BUFFER_BIT)
gli.StencilMask(0xFF)
}
func (cv *Canvas) drawTextShadow(offset image.Point, strWidth, strHeight int, x, y float64) {
x += cv.state.shadowOffsetX
y += cv.state.shadowOffsetY
gli.StencilFunc(gl_EQUAL, 0, 0xFF)
gli.BindBuffer(gl_ARRAY_BUFFER, buf)
var style drawStyle
style.color = cv.state.shadowColor
vertex, alphaTexCoord := cv.useAlphaShader(&style, 1)
gli.EnableVertexAttribArray(vertex)
gli.EnableVertexAttribArray(alphaTexCoord)
p0 := cv.tf(vec{float64(offset.X) + x, float64(offset.Y) + y})
p1 := cv.tf(vec{float64(offset.X) + x, float64(offset.Y+strHeight) + y})
p2 := cv.tf(vec{float64(offset.X+strWidth) + x, float64(offset.Y+strHeight) + y})
p3 := cv.tf(vec{float64(offset.X+strWidth) + x, float64(offset.Y) + y})
tw := float64(strWidth) / alphaTexSize
th := float64(strHeight) / alphaTexSize
data := [16]float32{float32(p0[0]), float32(p0[1]), float32(p1[0]), float32(p1[1]), float32(p2[0]), float32(p2[1]), float32(p3[0]), float32(p3[1]),
0, 1, 0, float32(1 - th), float32(tw), float32(1 - th), float32(tw), 1}
gli.BufferData(gl_ARRAY_BUFFER, len(data)*4, unsafe.Pointer(&data[0]), gl_STREAM_DRAW)
gli.VertexAttribPointer(vertex, 2, gl_FLOAT, false, 0, 0)
gli.VertexAttribPointer(alphaTexCoord, 2, gl_FLOAT, false, 0, 8*4)
gli.DrawArrays(gl_TRIANGLE_FAN, 0, 4)
gli.DisableVertexAttribArray(vertex)
gli.DisableVertexAttribArray(alphaTexCoord)
gli.ActiveTexture(gl_TEXTURE0)
gli.StencilFunc(gl_ALWAYS, 0, 0xFF)
}

25
text.go
View file

@ -183,23 +183,24 @@ func (cv *Canvas) FillText(str string, x, y float64) {
x -= float64(strWidth)
}
gli.ActiveTexture(gl_TEXTURE1)
gli.BindTexture(gl_TEXTURE_2D, alphaTex)
for y := 0; y < strHeight; y++ {
off := y * textImage.Stride
gli.TexSubImage2D(gl_TEXTURE_2D, 0, 0, int32(alphaTexSize-1-y), int32(strWidth), 1, gl_ALPHA, gl_UNSIGNED_BYTE, gli.Ptr(&textImage.Pix[off]))
}
cv.drawTextShadow(textOffset, strWidth, strHeight, x, y)
gli.StencilFunc(gl_EQUAL, 0, 0xFF)
gli.BindBuffer(gl_ARRAY_BUFFER, buf)
vertex, alphaTexCoord := cv.useAlphaShader(&cv.state.fill, 1)
gli.ActiveTexture(gl_TEXTURE1)
gli.BindTexture(gl_TEXTURE_2D, alphaTex)
gli.EnableVertexAttribArray(vertex)
gli.EnableVertexAttribArray(alphaTexCoord)
for y := 0; y < strHeight; y++ {
off := y * textImage.Stride
gli.TexSubImage2D(gl_TEXTURE_2D, 0, 0, int32(alphaTexSize-1-y), int32(strWidth), 1, gl_ALPHA, gl_UNSIGNED_BYTE, gli.Ptr(&textImage.Pix[off]))
}
p0 := cv.tf(vec{float64(textOffset.X) + x, float64(textOffset.Y) + y})
p1 := cv.tf(vec{float64(textOffset.X) + x, float64(textOffset.Y+strHeight) + y})
p2 := cv.tf(vec{float64(textOffset.X+strWidth) + x, float64(textOffset.Y+strHeight) + y})
@ -215,16 +216,16 @@ func (cv *Canvas) FillText(str string, x, y float64) {
gli.VertexAttribPointer(alphaTexCoord, 2, gl_FLOAT, false, 0, 8*4)
gli.DrawArrays(gl_TRIANGLE_FAN, 0, 4)
for y := 0; y < strHeight; y++ {
gli.TexSubImage2D(gl_TEXTURE_2D, 0, 0, int32(alphaTexSize-1-y), int32(strWidth), 1, gl_ALPHA, gl_UNSIGNED_BYTE, gli.Ptr(&zeroes[0]))
}
gli.DisableVertexAttribArray(vertex)
gli.DisableVertexAttribArray(alphaTexCoord)
gli.ActiveTexture(gl_TEXTURE0)
gli.StencilFunc(gl_ALWAYS, 0, 0xFF)
for y := 0; y < strHeight; y++ {
gli.TexSubImage2D(gl_TEXTURE_2D, 0, 0, int32(alphaTexSize-1-y), int32(strWidth), 1, gl_ALPHA, gl_UNSIGNED_BYTE, gli.Ptr(&zeroes[0]))
}
}
// TextMetrics is the result of a MeasureText call