SegFault while loading Japanese Fonts

[JohnPiwinski]

When trying to display a kanji character via the FYNE_FONT environment variable, my program reaches a segmentation fault and exits. The root of the error appears to reside in the goki truetype font loading system. Removing the environment variable allows my program to execute normally; however, blank rectangles are displayed instead of kanji as mentioned in issue #63. I pulled the ttf files from https://github.com/minoryorg/Noto-Sans-CJK-JP.

To Reproduce:
FYNE_FONT=NotoSansCJKjp-Regular.ttf ./my_fyne_executable

Device:

• OS: Ubuntu
• Version: Eoan 19.10
• Go version: go1.14.6
• Fyne version: Latest

Verbatim Output:

Fyne error: font load error

Cause: freetype: invalid TrueType format: bad TTF version
At: /go/src/fyne.io/fyne/internal/painter/font.go:20
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x1d4 pc=0x7676a1]

goroutine 1 [running, locked to thread]:
fyne.io/fyne/vendor/github.com/goki/freetype/truetype.(*Font).Bounds(0x0, 0xc0000003cb, 0x200, 0xc000644000)
/go/src/fyne.io/fyne/vendor/github.com/goki/freetype/truetype/truetype.go:386 +0x11
fyne.io/fyne/vendor/github.com/goki/freetype/truetype.NewFace(0x0, 0xc00063ba88, 0xc00063ba88, 0x10bbca0)
/go/src/fyne.io/fyne/vendor/github.com/goki/freetype/truetype/face.go:205 +0x2d7
fyne.io/fyne/internal/painter.CachedFontFace(0xc000000000, 0xc00063ba88, 0x0, 0x0)
/go/src/fyne.io/fyne/internal/painter/font.go:164 +0x177
fyne.io/fyne/internal/painter.RenderedTextSize(0x97b0e2, 0x1, 0xe, 0x0, 0x10bae60, 0x9a7bc0)
/go/src/fyne.io/fyne/internal/painter/font.go:32 +0xa6
fyne.io/fyne/internal/driver/glfw.(*gLDriver).RenderedTextSize(0xc0000b80f0, 0x97b0e2, 0x1, 0xe, 0x0, 0xc0000c26c0, 0xe)
/go/src/fyne.io/fyne/internal/driver/glfw/driver.go:33 +0x5a
fyne.io/fyne.MeasureText(0x97b0e2, 0x1, 0xe, 0x0, 0xc0000c26c0, 0xc000609ba8)
/go/src/fyne.io/fyne/text.go:40 +0x86
fyne.io/fyne/widget.(*textProvider).charMinSize(0xc00051e090, 0xc000609c18, 0x7e43e4)
/go/src/fyne.io/fyne/widget/text.go:217 +0xbb
fyne.io/fyne/widget.(*textRenderer).Layout(0xc000034040, 0x0, 0x0)
/go/src/fyne.io/fyne/widget/text.go:284 +0x8d
fyne.io/fyne/widget.(*textRenderer).Refresh(0xc000034040)
/go/src/fyne.io/fyne/widget/text.go:354 +0x569
fyne.io/fyne/widget.(*textProvider).CreateRenderer(0xc00051e090, 0xc00051e090, 0x5)
/go/src/fyne.io/fyne/widget/text.go:69 +0xda
fyne.io/fyne/widget.(*Label).CreateRenderer(0xc000122080, 0x9611c0, 0xc000122080)
/go/src/fyne.io/fyne/widget/label.go:104 +0x10c
fyne.io/fyne/internal/cache.Renderer(0xa343c0, 0xc000122080, 0xc000122080, 0x9a7bc8)
/go/src/fyne.io/fyne/internal/cache/widget.go:29 +0x112
fyne.io/fyne/widget.(*BaseWidget).MinSize(0xc000122080, 0xa343c0, 0xc000122080)
/go/src/fyne.io/fyne/widget/widget.go:84 +0x43
fyne.io/fyne/widget.(*Label).MinSize(0xc000122080, 0xa33920, 0xc000122080)
/go/src/fyne.io/fyne/widget/label.go:110 +0x4c
fyne.io/fyne/layout.(*boxLayout).MinSize(0xc0000e1f5a, 0xc00000e080, 0x2, 0x2, 0x8b8da0, 0xc0000c2801)
/go/src/fyne.io/fyne/layout/boxlayout.go:128 +0x1d0
fyne.io/fyne.NewContainerWithLayout(0xa2ad80, 0xc0000e1f5a, 0xc00000e080, 0x2, 0x2, 0x0)
/go/src/fyne.io/fyne/container.go:130 +0x9b
main.generate_text_question_form(0x97c5db, 0x5, 0x18b62)
/Desktop/tmk/final.go:66 +0x13f
main.main()
/Desktop/tmk/final.go:82 +0xfa

[andydotxyz]

I can't replicate here unfortunately, but the bug needs fixed.
Can you please try adding the following lines at internal/painter/font.go line 158 (immediately above the &fontCacheItem line:

		if f1 == nil {
			f1 = f2
		}

Let me know if that helps, if so we can apply it to next release...

[andydotxyz]

Should be fixed on develop now, commit 5db0633 - will try to get it in 1.3.3 as well