x/exp/shiny: windows: win.Copy coordinates scaled unexpectedly

[as]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.8rc3 windows/amd64

What operating system and processor architecture are you using (go env)?

Microsoft Windows [Version 10.0.14393]
(The "Change the size of apps on the screen" option is set to 100%)

set GOARCH=amd64
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=C:\g
set GOROOT=C:\Go
set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64
set CGO_CFLAGS=-g -O2
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2

What did you do?

Copying a texture to a window doesn't work as expected when a partial copy
of the texture is desired instead of the entire texture. The coordinates of pt
are scaled by a factor of two.

The call to below win.Copy doesn't align pt with r if r != winSize

winSize := image.Pt(1920, 1080)
win, _ := src.NewWindow(&screen.NewWindowOptions{winSize.X, winSize.Y})
tx, _ := src.NewTexture(winSize)
r := image.Rect(10, 10, 20, 20) // only recopy this part to the window
// r := winSize // works if you copy the whole texture
sp := r.Min
// Uncomment the following two statements and it works
// pt.X *= 2
// pt.Y *= 2
win.Copy(pt, tx, r, screen.Src, nil)

What did you expect to see?

Rectangle updated

What did you see instead?

Some other area updated

Full example program (needs exp/shiny)

Draws on mouse click

https://play.golang.org/p/lut2R9xBMW

[alexbrainman]

@as thank you for the issue. But I cannot see what the problem is - I am slow. Is it possible to make your example simpler to make it obvious for me?

Alex

[as]

Sorry, I was in a hurry so didn't have time to make a lucid example. Hopefully this one is easier to understand:

https://play.golang.org/p/wZx8QWcWwJ

The example attempts to paint rectangles at the location (200,200)-(400-400) in a shiny window.

The green rectangle paints at expected location (200,200)-(400-400). It uses a buf (screen.Buffer) and win (screen.Window).

The red rectangle paints at (0,0)-(200,200) instead. It uploads the buf to tx (screen.Texture) before copying to win.

Something I find confusing happens in the call to win.Copy(dp, src, sr). It works when the entire texture is copied to the window and aligned to image.ZP. Otherwise dp needs to be multiplied x 2 to make things align correctly.

[alexbrainman]

@as
Thank you for simple example.
Does this https://go-review.googlesource.com/40891 fixes your problem?

Alex

[gopherbot]

CL https://golang.org/cl/40891 mentions this issue.

[as]

@alexbrainman

Yes, thank you. The cl fixes the issue and the example now works as expected.

The issue can be closed at this time.

[alexbrainman]

The cl fixes the issue and the example now works as expected.

Thank you for checking.

The issue can be closed at this time.

Lets leave it open for the moment. The issue will get closed automatically once CL https://golang.org/cl/40891 is submitted.

Alex