JindongJindong

RepeatWithIndex

DSL function to repeat content N times with index access

RepeatWithIndex

Module: jindong-compose | Package: io.github.compose.jindong.dsl

Repeats the content block N times, providing the iteration index to each repetition.

Signature

@Composable
fun JindongScope.RepeatWithIndex(
    count: Int,
    content: @Composable JindongScope.(index: Int) -> Unit
)

Parameters

ParameterTypeDescription
countIntNumber of times to repeat (must be non-negative)
content@Composable JindongScope.(index: Int) -> UnitPattern with 0-based index

Description

RepeatWithIndex is similar to Repeat but provides the current iteration index (0-based) to the content block. This enables dynamic patterns where each iteration can have different parameters.

Unlike Repeat which creates a single RepeatNode, RepeatWithIndex generates N different child nodes at composition time, allowing each iteration to be unique.

Usage

Basic Usage

Jindong(trigger) {
    RepeatWithIndex(3) { index ->
        // index: 0, 1, 2
        Haptic(50.ms)
        Delay(30.ms)
    }
}

Dynamic Intensity

Jindong(trigger) {
    RepeatWithIndex(5) { index ->
        val intensity = HapticIntensity.Custom(1.0f - (index * 0.2f))
        Haptic(50.ms, intensity)
        Delay(30.ms)
    }
    // Intensities: 1.0, 0.8, 0.6, 0.4, 0.2
}

Dynamic Duration

Jindong(trigger) {
    RepeatWithIndex(4) { index ->
        val duration = (50 + index * 25).ms
        Haptic(duration)
        Delay(30.ms)
    }
    // Durations: 50ms, 75ms, 100ms, 125ms
}

Examples

Fade Out Effect

Jindong(trigger) {
    RepeatWithIndex(5) { index ->
        val fade = HapticIntensity.Custom(1.0f - (index * 0.2f))
        Haptic(50.ms, fade)
        Delay(30.ms)
    }
}

Fade In Effect

Jindong(trigger) {
    RepeatWithIndex(5) { index ->
        val fadeIn = HapticIntensity.Custom(index * 0.25f)
        Haptic(50.ms, fadeIn)
        Delay(30.ms)
    }
}

Accelerating Pattern

Jindong(trigger) {
    RepeatWithIndex(5) { index ->
        Haptic(50.ms)
        // Decreasing delay: 100ms, 75ms, 50ms, 25ms, 0ms
        val delay = (100 - index * 25).ms
        Delay(delay)
    }
}

Wave Pattern

Jindong(trigger) {
    RepeatWithIndex(6) { index ->
        // Intensity goes up then down: 0.2, 0.5, 0.8, 0.8, 0.5, 0.2
        val wave = if (index < 3) {
            0.2f + (index * 0.3f)
        } else {
            0.8f - ((index - 3) * 0.3f)
        }
        Haptic(40.ms, HapticIntensity.Custom(wave))
        Delay(30.ms)
    }
}

Crescendo

Jindong(trigger) {
    RepeatWithIndex(4) { index ->
        // Both duration and intensity increase
        val duration = (30 + index * 20).ms
        val intensity = HapticIntensity.Custom(0.25f + (index * 0.25f))
        Haptic(duration, intensity)
        Delay(40.ms)
    }
}

vs Repeat

FeatureRepeatRepeatWithIndex
Index accessNoYes
Dynamic contentNoYes
ImplementationSingle RepeatNodeN separate nodes
Use caseIdentical iterationsVarying iterations

Choose Repeat for simple repetition:

Repeat(5) { Haptic(50.ms) }

Choose RepeatWithIndex for dynamic patterns:

RepeatWithIndex(5) { i -> Haptic((50 + i * 10).ms) }

Notes

  • Index is 0-based (0 to count-1)
  • Each iteration generates a separate node
  • count must be a positive value.
  • The index can be used in any expression within the content block

See Also

Repeat

DSL function to repeat content N times

Documentation

Guide for contributing to Jindong documentation

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