table: unable to display table with more than 64 columns

[gucio321]

Hi there,
in refer to OpenDiablo2/HellSpawner#335 (comment) I'd like to show the situation, we can notice the behavior:
when I create a large table, e.g.:

        rowItems := make([]giu.Widget, numCols)
        for i := range rowItems {
                rowItems[i] = giu.Label(strconv.Itoa(i))
        }
        row := giu.TableRow(rowItems...)

full code

package main

import (
	"strconv"

	"github.com/AllenDang/giu"
)

func loop() {
	const numCols = 65

	rowItems := make([]giu.Widget, numCols)
	for i := range rowItems {
		rowItems[i] = giu.Label(strconv.Itoa(i))
	}
	row := giu.TableRow(rowItems...)

	giu.SingleWindow().Layout(
		giu.Table().Rows(row),
	)
}

func main() {
	wnd := giu.NewMasterWindow("table", 640, 480, 0)
	wnd.Run(loop)
}

i'm getting the following panic:

table: imgui_tables.cpp:323: bool ImGui::BeginTableEx(const char*, ImGuiID, int, ImGuiTableFlags, const ImVec2&, float): Assertion `columns_count > 0 && columns_count <= 64 && "Only 1..64 columns allowed!"' failed.
SIGABRT: abort
PC=0x7f7e2133d9e5 m=0 sigcode=18446744073709551610
signal arrived during cgo execution

[r00tc0d3]

This is due to a limitation of imgui not of giu.

From imgui_tables.cpp

// Sanity checks
IM_ASSERT(columns_count > 0 && columns_count <= IMGUI_TABLE_MAX_COLUMNS && "Only 1..64 columns allowed!");

So imgui asserts and you get a SIGABRT: abort

[gucio321]

you're right. I see an issue in imgui repo: ocornut/imgui#3572
maybe the suggested workaround, would work?

[gucio321]

from https://github.com/ocornut/imgui imgui_demog.cpp:

        if (ImGui::BeginTable("table_scrolly", 3, flags, outer_size))
        {
            ImGui::TableSetupScrollFreeze(0, 1); // Make top row always visible
            ImGui::TableSetupColumn("One", ImGuiTableColumnFlags_None);
            ImGui::TableSetupColumn("Two", ImGuiTableColumnFlags_None);
            ImGui::TableSetupColumn("Three", ImGuiTableColumnFlags_None);
            ImGui::TableHeadersRow();

            // Demonstrate using clipper for large vertical lists
            ImGuiListClipper clipper;
            clipper.Begin(1000);
            while (clipper.Step())
            {
                for (int row = clipper.DisplayStart; row < clipper.DisplayEnd; row++)
                {
                    ImGui::TableNextRow();
                    for (int column = 0; column < 3; column++)
                    {
                        ImGui::TableSetColumnIndex(column);
                        ImGui::Text("Hello %d,%d", column, row);
                    }
                }
            }
            ImGui::EndTable();

[gucio321]

ImGuiListClipper work on the vertical axis which is were the count can grow the most.
Both TableSetColumnIndex() and TableNextColumn() return a bool reporting the column visibility so you can skip rendering your contents.

[gucio321]

as an alternative, we can update the internal imgui tables mechanism like suggested in ocornut/imgui#3572 (comment)

so, to sum up:
there are 2 possible workarounds

1. externally affect imgui table to display only the visible rows and bypass 64 columns limit
2. modify the tables mechanism to remove columns limit

@AllenDang should we focus on working around this issue or just wait until the upstream issue gets solved?

[AllenDang]

@gucio321 IMO, let's wait upstream issue gets solved. I've been suffered much to apply custom patches, for now the power-saving patch. I have to do line-by-line diff and merge each time upgrading imgui.

[gucio321]

@AllenDang upstream issue is solved now
IMO, we should wait for cimgui-go migration with that anyway.

[gucio321]

@AllenDang upstream issue has been closed. I think it may be fixed after cimgui migration

[AllenDang]

@gucio321 Yes, after migration this should be fixed.

[fnicastri]

I still get the error with more than 64 columns, using @latest 0.7.0 and master is not compiling

@gucio321

[gucio321]

This works on matter, if it doesn't compile it a separated issue

[fnicastri]

good to know!

can you point me at a working commit?

[gucio321]

this issue was related to old imgui. master uses cimgui-go so relatively new imgui where 64 column tables works. THats why I said master works. (but may not compile, however it does for me)

[fnicastri]

Thank you