viewflif window does not draw to its canvas or repaint

[Traneptora]

Attempting to use the command-line flif-viewer "viewflif" will create a window but the canvas will not paint the decoded FLIF or repaint if the window is moved. This is true for any flif file. Testing with fish.png yields a valid flif file that cannot be displayed with viewflif.

Steps to reproduce:

1. Take any flif file, which I will call fish.flif here. (e.g. one generated from flif -e fish.png fish.flif)
2. Run viewflif fish.flif and the frame will open but it won't actually display anything, and won't repaint.
3. To test the integrity of the flif file, you can use dflif fish.flif - | display - and ImageMagick will be able to view the decoded file.

System:

• FLIF version 0.3, from April 28, 2017
• uname -snrmo: Linux gauss 4.10.13-1-ARCH x86_64 GNU/Linux
• X.org X11 server

Screenshots of the problem:

• viewflif starts fullscreen in all white
• Dragging it around causes classic no-repaint afterimages
• Integrity check with dflif and ImageMagick

[lehitoskin]

What graphics card are you using? I've come across this problem myself with my NVidia card and when I asked around the response was that there's a bug or something in SDL. However, in my case the canvas is all black.

[Traneptora]

I have an nVidia GeForce GTX 1070, with the 378.13-6 driver, and SDL2 version 2.0.5-3. However, no other SDL2 application exhibits this behavior, such as ffplay.

[grinapo]

Seems to me my bug I have reported to the Debian package. The problem is that while full decoding works, progressive decoding will not. Unfortunately I cannot debug it through unknown-to-me SDL mechanisms, but glad to compile anything enriched with debug output or else.