[core:text/edit] Issue with input_rune proc

[tienery]

Hi all. I have been scratching my head over the text/edit package for some time in an attempt to implement a simple text field. I have it working, but I seem to have stumbled across an issue in which every key I press seems to refresh the string builder data buffer. I cannot see where this may be happening with looking at the source code, both in my own code and in the text edit package. I have stepped through my code and it is clear that new data does not get appended, but rather replaced.

Before Change:

After Change:

Here is the code I am testing with:

TextInput :: struct {
    State : edit.State,
    Text : string,
    Changed : bool,
    Builder : strings.Builder,
    Dimensions : rl.Rectangle,
}

TextInput_Init :: proc(length : int) -> TextInput {
    result := TextInput{}
    result.Text = ""
    strings.builder_init_len(&result.Builder, length)
    // use context.allocator for testing purposes. Change later if needed
    edit.init(&result.State, context.allocator, context.allocator)
    return result
}

TextInput_Update :: proc(input : ^TextInput) {
    edit.begin(&input.State, 0, &input.Builder)

    if rl.IsKeyPressed(.LEFT) {
        edit.perform_command(&input.State, .Left)
    }
    if rl.IsKeyPressed(.RIGHT) {
        edit.perform_command(&input.State, .Right)
    }

    if rl.GetKeyPressed() != rl.KeyboardKey.KEY_NULL {
        for char := rl.GetCharPressed(); char >= rune(32); char = rl.GetCharPressed() {
            edit.input_rune(&input.State, char)
        }
    }

    edit.end(&input.State)
}

TextInput_Render :: proc(input : ^TextInput) {
    characters := string(input.Builder.buf[:])
    rl.DrawRectangleLines(i32(input.Dimensions.x), i32(input.Dimensions.y), i32(input.Dimensions.width), i32(input.Dimensions.height), rl.WHITE)

    textBounds := rl.Rectangle{ input.Dimensions.x + 4, input.Dimensions.y + 2, input.Dimensions.width - 8, input.Dimensions.height - 4 }

    rl.BeginScissorMode(i32(textBounds.x), i32(textBounds.y), i32(textBounds.width), i32(textBounds.height))

    cstr := strings.clone_to_cstring(characters)
    defer delete(cstr)
    rl.DrawText(cstr, i32(textBounds.x), i32(textBounds.y), 24, rl.WHITE)

    if !edit.has_selection(&input.State) {
        selectionText := characters[:input.State.selection[0]]
        selectionCText := strings.clone_to_cstring(selectionText)
        defer delete(selectionCText)
        caretX := rl.MeasureText(selectionCText, 24)
        rl.DrawRectangle(caretX + i32(textBounds.x), i32(textBounds.y), i32(2), i32(textBounds.height), rl.WHITE)
    } else {

    }

    rl.EndScissorMode()
}

Anyone have any idea what is happening?

[tienery]

After some more investigation, I've noticed that insert_rune is checking if there is a selection, and removing it if there is some. This is what it says in the comment, so didn't want to mess around with that code. However, because begin suggests calling the proc every frame (which is what I do), the begin proc sets the end (or second integer) value to 0 every frame, causing insert_rune to always remove a selection, even though there shouldn't be one.

A quick fix to this problem for me was to do the following change in the begin proc:

if len(builder.buf) == cap(builder.buf) && builder.buf[0] == 0 {
    s.selection = {len(builder.buf), 0}
}

This may not be the best solution, and probably only works when using strings.builder_init_* procedures in the strings package to specify a capacity. A better solution is probably to check if there is valid data in builder.buf before resetting selection. I somewhat do this, but probably not in the best manner.