1 files changed, 123 insertions, 0 deletions
diff --git a/vendor/golang.org/x/exp/shiny/driver/x11driver/buffer_fallback.go b/vendor/golang.org/x/exp/shiny/driver/x11driver/buffer_fallback.go
new file mode 100644
index 0000000..bfdd9c7
--- /dev/null
+++ b/vendor/golang.org/x/exp/shiny/driver/x11driver/buffer_fallback.go
@@ -0,0 +1,123 @@
+// Copyright 2020 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"
+	"sync"
+
+	"github.com/BurntSushi/xgb"
+	"github.com/BurntSushi/xgb/xproto"
+	"golang.org/x/exp/shiny/driver/internal/swizzle"
+)
+
+const (
+	xPutImageReqSizeMax   = (1 << 16) * 4
+	xPutImageReqSizeFixed = 28
+	xPutImageReqDataSize  = xPutImageReqSizeMax - xPutImageReqSizeFixed
+)
+
+type bufferFallbackImpl struct {
+	xc *xgb.Conn
+
+	buf  []byte
+	rgba image.RGBA
+	size image.Point
+
+	mu       sync.Mutex
+	nUpload  uint32
+	released bool
+}
+
+func (b *bufferFallbackImpl) Size() image.Point       { return b.size }
+func (b *bufferFallbackImpl) Bounds() image.Rectangle { return image.Rectangle{Max: b.size} }
+func (b *bufferFallbackImpl) RGBA() *image.RGBA       { return &b.rgba }
+
+func (b *bufferFallbackImpl) preUpload() {
+	// Check that the program hasn't tried to modify the rgba field via the
+	// pointer returned by the bufferFallbackImpl.RGBA method. This check doesn't catch
+	// 100% of all cases; it simply tries to detect some invalid uses of a
+	// screen.Buffer such as:
+	//	*buffer.RGBA() = anotherImageRGBA
+	if len(b.buf) != 0 && len(b.rgba.Pix) != 0 && &b.buf[0] != &b.rgba.Pix[0] {
+		panic("x11driver: invalid Buffer.RGBA modification")
+	}
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.released {
+		panic("x11driver: Buffer.Upload called after Buffer.Release")
+	}
+	if b.nUpload == 0 {
+		swizzle.BGRA(b.buf)
+	}
+	b.nUpload++
+}
+
+func (b *bufferFallbackImpl) postUpload() {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	b.nUpload--
+	if b.nUpload != 0 {
+		return
+	}
+
+	if !b.released {
+		swizzle.BGRA(b.buf)
+	}
+}
+
+func (b *bufferFallbackImpl) Release() {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	b.released = true
+}
+
+func (b *bufferFallbackImpl) upload(xd xproto.Drawable, xg xproto.Gcontext, depth uint8, dp image.Point, sr image.Rectangle) {
+	originalSRMin := sr.Min
+	sr = sr.Intersect(b.Bounds())
+	if sr.Empty() {
+		return
+	}
+	dp = dp.Add(sr.Min.Sub(originalSRMin))
+	b.preUpload()
+
+	b.putImage(xd, xg, depth, dp, sr)
+
+	b.postUpload()
+}
+
+// putImage issues xproto.PutImage requests in batches.
+func (b *bufferFallbackImpl) putImage(xd xproto.Drawable, xg xproto.Gcontext, depth uint8, dp image.Point, sr image.Rectangle) {
+	widthPerReq := b.size.X
+	rowPerReq := xPutImageReqDataSize / (widthPerReq * 4)
+	dataPerReq := rowPerReq * widthPerReq * 4
+	dstX := dp.X
+	dstY := dp.Y
+	start := 0
+	end := 0
+
+	for end < len(b.buf) {
+		end = start + dataPerReq
+		if end > len(b.buf) {
+			end = len(b.buf)
+		}
+
+		data := b.buf[start:end]
+		heightPerReq := len(data) / (widthPerReq * 4)
+
+		xproto.PutImage(
+			b.xc, xproto.ImageFormatZPixmap, xd, xg,
+			uint16(widthPerReq), uint16(heightPerReq),
+			int16(dstX), int16(dstY),
+			0, depth, data)
+
+		start = end
+		dstY += rowPerReq
+	}
+}