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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package x11driver
import (
"image"
"image/color"
"image/draw"
"math"
"sync"
"github.com/BurntSushi/xgb/render"
"github.com/BurntSushi/xgb/xproto"
"golang.org/x/exp/shiny/screen"
"golang.org/x/image/math/f64"
)
const textureDepth = 32
type textureImpl struct {
s *screenImpl
size image.Point
xm xproto.Pixmap
xp render.Picture
// renderMu is a mutex that enforces the atomicity of methods like
// Window.Draw that are conceptually one operation but are implemented by
// multiple X11/Render calls. X11/Render is a stateful API, so interleaving
// X11/Render calls from separate higher-level operations causes
// inconsistencies.
renderMu sync.Mutex
releasedMu sync.Mutex
released bool
}
func (t *textureImpl) degenerate() bool { return t.size.X == 0 || t.size.Y == 0 }
func (t *textureImpl) Size() image.Point { return t.size }
func (t *textureImpl) Bounds() image.Rectangle { return image.Rectangle{Max: t.size} }
func (t *textureImpl) Release() {
t.releasedMu.Lock()
released := t.released
t.released = true
t.releasedMu.Unlock()
if released || t.degenerate() {
return
}
render.FreePicture(t.s.xc, t.xp)
xproto.FreePixmap(t.s.xc, t.xm)
}
func (t *textureImpl) Upload(dp image.Point, src screen.Buffer, sr image.Rectangle) {
if t.degenerate() {
return
}
src.(*bufferImpl).upload(xproto.Drawable(t.xm), t.s.gcontext32, textureDepth, dp, sr)
}
func (t *textureImpl) Fill(dr image.Rectangle, src color.Color, op draw.Op) {
if t.degenerate() {
return
}
fill(t.s.xc, t.xp, dr, src, op)
}
// f64ToFixed converts from float64 to X11/Render's 16.16 fixed point.
func f64ToFixed(x float64) render.Fixed {
return render.Fixed(x * 65536)
}
func inv(x *f64.Aff3) f64.Aff3 {
invDet := 1 / (x[0]*x[4] - x[1]*x[3])
return f64.Aff3{
+x[4] * invDet,
-x[1] * invDet,
(x[1]*x[5] - x[2]*x[4]) * invDet,
-x[3] * invDet,
+x[0] * invDet,
(x[2]*x[3] - x[0]*x[5]) * invDet,
}
}
func (t *textureImpl) draw(xp render.Picture, src2dst *f64.Aff3, sr image.Rectangle, op draw.Op, opts *screen.DrawOptions) {
sr = sr.Intersect(t.Bounds())
if sr.Empty() {
return
}
t.renderMu.Lock()
defer t.renderMu.Unlock()
// For simple copies and scales, the inverse matrix is trivial to compute,
// and we do not need the "Src becomes OutReverse plus Over" dance (see
// below). Thus, draw can be one render.SetPictureTransform call and then
// one render.Composite call, regardless of whether or not op is Src.
if src2dst[1] == 0 && src2dst[3] == 0 {
dstXMin := float64(sr.Min.X)*src2dst[0] + src2dst[2]
dstXMax := float64(sr.Max.X)*src2dst[0] + src2dst[2]
if dstXMin > dstXMax {
// TODO: check if this (and below) works when src2dst[0] < 0.
dstXMin, dstXMax = dstXMax, dstXMin
}
dXMin := int(math.Floor(dstXMin))
dXMax := int(math.Ceil(dstXMax))
dstYMin := float64(sr.Min.Y)*src2dst[4] + src2dst[5]
dstYMax := float64(sr.Max.Y)*src2dst[4] + src2dst[5]
if dstYMin > dstYMax {
// TODO: check if this (and below) works when src2dst[4] < 0.
dstYMin, dstYMax = dstYMax, dstYMin
}
dYMin := int(math.Floor(dstYMin))
dYMax := int(math.Ceil(dstYMax))
render.SetPictureTransform(t.s.xc, t.xp, render.Transform{
f64ToFixed(1 / src2dst[0]), 0, 0,
0, f64ToFixed(1 / src2dst[4]), 0,
0, 0, 1 << 16,
})
render.Composite(t.s.xc, renderOp(op), t.xp, 0, xp,
int16(sr.Min.X), int16(sr.Min.Y), // SrcX, SrcY,
0, 0, // MaskX, MaskY,
int16(dXMin), int16(dYMin), // DstX, DstY,
uint16(dXMax-dXMin), uint16(dYMax-dYMin), // Width, Height,
)
return
}
// The X11/Render transform matrix maps from destination pixels to source
// pixels, so we invert src2dst.
dst2src := inv(src2dst)
render.SetPictureTransform(t.s.xc, t.xp, render.Transform{
f64ToFixed(dst2src[0]), f64ToFixed(dst2src[1]), render.Fixed(sr.Min.X << 16),
f64ToFixed(dst2src[3]), f64ToFixed(dst2src[4]), render.Fixed(sr.Min.Y << 16),
0, 0, 1 << 16,
})
points := trifanPoints(src2dst, sr)
if op == draw.Src {
// render.TriFan visits every dst-space pixel in the axis-aligned
// bounding box (AABB) containing the transformation of the sr
// rectangle in src-space to a quad in dst-space.
//
// render.TriFan is like render.Composite, except that the AABB is
// defined implicitly by the transformed triangle vertices instead of
// being passed explicitly as arguments. It implies the minimal AABB.
//
// In any case, for arbitrary src2dst affine transformations, which
// include rotations, this means that a naive render.TriFan call will
// affect those pixels inside the AABB but outside the quad. For the
// draw.Src operator, this means that pixels in that AABB can be
// incorrectly set to zero.
//
// Instead, we implement the draw.Src operator as two render.TriFan
// calls. The first one (using the PictOpOutReverse operator and a
// fully opaque source) clears the dst-space quad but leaves pixels
// outside that quad (but inside the AABB) untouched. The second one
// (using the PictOpOver operator and the texture t as source) fills in
// the quad and again does not touch the pixels outside.
//
// What X11/Render calls PictOpOutReverse is also known as dst-out. See
// http://www.w3.org/TR/SVGCompositing/examples/compop-porterduff-examples.png
// for a visualization.
render.TriFan(t.s.xc, render.PictOpOutReverse, t.s.opaqueP, xp, 0, 0, 0, points[:])
}
render.TriFan(t.s.xc, render.PictOpOver, t.xp, xp, 0, 0, 0, points[:])
}
func trifanPoints(src2dst *f64.Aff3, sr image.Rectangle) [4]render.Pointfix {
minX := float64(sr.Min.X)
maxX := float64(sr.Max.X)
minY := float64(sr.Min.Y)
maxY := float64(sr.Max.Y)
return [4]render.Pointfix{{
f64ToFixed(src2dst[0]*minX + src2dst[1]*minY + src2dst[2]),
f64ToFixed(src2dst[3]*minX + src2dst[4]*minY + src2dst[5]),
}, {
f64ToFixed(src2dst[0]*maxX + src2dst[1]*minY + src2dst[2]),
f64ToFixed(src2dst[3]*maxX + src2dst[4]*minY + src2dst[5]),
}, {
f64ToFixed(src2dst[0]*maxX + src2dst[1]*maxY + src2dst[2]),
f64ToFixed(src2dst[3]*maxX + src2dst[4]*maxY + src2dst[5]),
}, {
f64ToFixed(src2dst[0]*minX + src2dst[1]*maxY + src2dst[2]),
f64ToFixed(src2dst[3]*minX + src2dst[4]*maxY + src2dst[5]),
}}
}
func renderOp(op draw.Op) byte {
if op == draw.Src {
return render.PictOpSrc
}
return render.PictOpOver
}
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