Apply stretch renderer

/* Copyright 2025 Esri
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package com.esri.arcgismaps.sample.applystretchrenderer

import android.content.Intent
import android.os.Bundle
import com.esri.arcgismaps.sample.sampleslib.DownloaderActivity

class DownloadActivity : DownloaderActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        downloadAndStartSample(
            Intent(this, MainActivity::class.java),
            getString(R.string.apply_stretch_renderer_app_name),
            listOf(
                "https://www.arcgis.com/home/item.html?id=7c4c679ab06a4df19dc497f577f111bd"
            )
        )
    }
}

/* Copyright 2025 Esri
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.esri.arcgismaps.sample.applystretchrenderer

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.runtime.Composable
import com.arcgismaps.ApiKey
import com.arcgismaps.ArcGISEnvironment
import com.esri.arcgismaps.sample.sampleslib.theme.SampleAppTheme
import com.esri.arcgismaps.sample.applystretchrenderer.screens.ApplyStretchRendererScreen

class MainActivity : ComponentActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // authentication with an API key or named user is
        // required to access basemaps and other location services
        ArcGISEnvironment.apiKey = ApiKey.create(BuildConfig.ACCESS_TOKEN)

        setContent {
            SampleAppTheme {
                ApplyStretchRendererApp()
            }
        }
    }

    @Composable
    private fun ApplyStretchRendererApp() {
        Surface(color = MaterialTheme.colorScheme.background) {
            ApplyStretchRendererScreen(
                sampleName = getString(R.string.apply_stretch_renderer_app_name)
            )
        }
    }
}

/* Copyright 2025 Esri
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.esri.arcgismaps.sample.applystretchrenderer.components

import android.app.Application
import androidx.lifecycle.AndroidViewModel
import androidx.lifecycle.viewModelScope
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.layers.RasterLayer
import com.arcgismaps.mapping.symbology.raster.MinMaxStretchParameters
import com.arcgismaps.mapping.symbology.raster.PercentClipStretchParameters
import com.arcgismaps.mapping.symbology.raster.StandardDeviationStretchParameters
import com.arcgismaps.mapping.symbology.raster.StretchParameters
import com.arcgismaps.mapping.symbology.raster.StretchRenderer
import com.arcgismaps.raster.Raster
import com.arcgismaps.toolkit.geoviewcompose.MapViewProxy
import com.esri.arcgismaps.sample.applystretchrenderer.R
import com.esri.arcgismaps.sample.sampleslib.components.MessageDialogViewModel
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.launch
import java.io.File

private const val DEFAULT_MIN = 10.0
private const val DEFAULT_MAX = 150.0
private const val DEFAULT_PERCENT_MIN = 0.0
private const val DEFAULT_PERCENT_MAX = 50.0
private const val DEFAULT_STD_DEVIATION_FACTOR = 0.5

/**
 * ViewModel for the "Apply stretch renderer" sample.
 */
class ApplyStretchRendererViewModel(private val app: Application) : AndroidViewModel(app) {

    // The map with imagery basemap style
    val arcGISMap: ArcGISMap = ArcGISMap(BasemapStyle.ArcGISImageryStandard)

    // MapViewProxy used to set viewpoint after layer loads
    val mapViewProxy = MapViewProxy()

    // Message dialog view model for error handling
    val messageDialogVM = MessageDialogViewModel()

    // Provision path for local offline resources
    private val provisionPath by lazy {
        app.getExternalFilesDir(null)?.path.toString() + File.separator +
                app.getString(R.string.apply_stretch_renderer_app_name)
    }

    // The raster data (raster-file/Shasta.tif) should be downloaded to external storage on launch
    private val raster by lazy {
        val rasterFile = File(provisionPath, "raster-file${File.separator}Shasta.tif")
        Raster.createWithPath(rasterFile.path)
    }

    // The raster layer to which the stretch renderer will be applied
    private val rasterLayer = RasterLayer(raster)

    // Stretch type options for UI
    val stretchTypeOptions = listOf("MinMax", "Percent Clip", "Std Deviation")

    // Current selected stretch type
    private val _selectedStretchType = MutableStateFlow(StretchType.MinMax)
    val selectedStretchType = _selectedStretchType.asStateFlow()

    // Min-Max parameters (values represent pixel value range)
    private val _minValue = MutableStateFlow(DEFAULT_MIN)
    val minValue = _minValue.asStateFlow()

    private val _maxValue = MutableStateFlow(DEFAULT_MAX)
    val maxValue = _maxValue.asStateFlow()

    // Percent clip parameters (values represent percent 0..100)
    private val _percentMin = MutableStateFlow(DEFAULT_PERCENT_MIN)
    val percentMin = _percentMin.asStateFlow()

    private val _percentMax = MutableStateFlow(DEFAULT_PERCENT_MAX)
    val percentMax = _percentMax.asStateFlow()

    // Standard deviation factor (typical range 0.25..4.0)
    private val _stdDeviationFactor = MutableStateFlow(DEFAULT_STD_DEVIATION_FACTOR)
    val stdDeviationFactor = _stdDeviationFactor.asStateFlow()

    init {
        viewModelScope.launch {
            rasterLayer.load().onSuccess {
                arcGISMap.operationalLayers.add(rasterLayer)
            }.onFailure {
                return@launch messageDialogVM.showMessageDialog(it)
            }

            arcGISMap.load().onFailure {
                return@launch messageDialogVM.showMessageDialog(it)
            }

            rasterLayer.fullExtent?.center?.let { center ->
                mapViewProxy.setViewpoint(Viewpoint(center = center, scale = 80_000.0))
            }
            updateRenderer()
        }
    }

    /** Update the current stretch type by index from [stretchTypeOptions]. */
    fun updateStretchTypeByIndex(index: Int) {
        val safeIndex = index.coerceIn(0, stretchTypeOptions.lastIndex)
        _selectedStretchType.value = when (safeIndex) {
            0 -> StretchType.MinMax
            1 -> StretchType.PercentClip
            else -> StretchType.StandardDeviation
        }
        updateRenderer()
    }

    /** Update MinMax minimum value (clamped to 0..(max-1)). */
    fun updateMinValue(value: Double) {
        val max = _maxValue.value
        _minValue.value = value.coerceIn(DEFAULT_MIN, max - 1.0)
        updateRenderer()
    }

    /** Update MinMax maximum value (clamped to (min+1)..255). */
    fun updateMaxValue(value: Double) {
        val min = _minValue.value
        _maxValue.value = value.coerceIn(min + 1.0, 255.0)
        updateRenderer()
    }

    /** Update Percent Clip minimum percent (clamped to 0..percentMax). */
    fun updatePercentMin(value: Double) {
        val max = _percentMax.value
        _percentMin.value = value.coerceIn(DEFAULT_MIN, max)
        updateRenderer()
    }

    /** Update Percent Clip maximum percent (clamped to percentMin..100). */
    fun updatePercentMax(value: Double) {
        val min = _percentMin.value
        _percentMax.value = value.coerceIn(min, 100.0)
        updateRenderer()
    }

    /** Update Standard Deviation factor (clamped to 0.25..4.0). */
    fun updateStdDeviationFactor(value: Double) {
        _stdDeviationFactor.value = value.coerceIn(0.25, 4.0)
        updateRenderer()
    }

    /** Construct and apply a StretchRenderer to the raster layer using current UI parameters. */
    private fun updateRenderer() {
        val parameters: StretchParameters = when (_selectedStretchType.value) {
            StretchType.MinMax -> {
                // apply the values to the renderer
                MinMaxStretchParameters(
                    minValues = listOf(_minValue.value),
                    maxValues = listOf(_maxValue.value)
                )
            }

            StretchType.PercentClip -> {
                // apply the values to the renderer
                PercentClipStretchParameters(
                    min = _percentMin.value,
                    max = _percentMax.value
                )
            }

            StretchType.StandardDeviation -> {
                // apply the value to the renderer
                StandardDeviationStretchParameters(
                    factor = _stdDeviationFactor.value
                )
            }
        }
        rasterLayer.renderer = StretchRenderer(
            parameters = parameters,
            gammas = emptyList(),
            estimateStatistics = true,
            colorRamp = null
        )
    }

    /** Reset all parameters to their initial default values. */
    fun resetAllChanges() {
        _selectedStretchType.value = StretchType.MinMax
        _minValue.value = DEFAULT_MIN
        _maxValue.value = DEFAULT_MAX
        _percentMin.value = DEFAULT_PERCENT_MIN
        _percentMax.value = DEFAULT_PERCENT_MAX
        _stdDeviationFactor.value = DEFAULT_STD_DEVIATION_FACTOR
        updateRenderer()
    }
}

/** Enum representing available stretch parameter types. */
enum class StretchType { MinMax, PercentClip, StandardDeviation }

/* Copyright 2025 Esri
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.esri.arcgismaps.sample.applystretchrenderer.screens

import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Settings
import androidx.compose.material3.Button
import androidx.compose.material3.FloatingActionButton
import androidx.compose.material3.Icon
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.RangeSlider
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Slider
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
import androidx.lifecycle.compose.collectAsStateWithLifecycle
import androidx.lifecycle.viewmodel.compose.viewModel
import com.arcgismaps.toolkit.geoviewcompose.MapView
import com.esri.arcgismaps.sample.applystretchrenderer.components.ApplyStretchRendererViewModel
import com.esri.arcgismaps.sample.applystretchrenderer.components.StretchType
import com.esri.arcgismaps.sample.sampleslib.components.BottomSheet
import com.esri.arcgismaps.sample.sampleslib.components.DropDownMenuBox
import com.esri.arcgismaps.sample.sampleslib.components.MessageDialog
import com.esri.arcgismaps.sample.sampleslib.components.SampleTopAppBar

/**
 * Main screen layout for the sample app.
 */
@Composable
fun ApplyStretchRendererScreen(sampleName: String) {
    val mapViewModel: ApplyStretchRendererViewModel = viewModel()

    // UI state
    val selectedStretchType by mapViewModel.selectedStretchType.collectAsStateWithLifecycle()
    val minValue by mapViewModel.minValue.collectAsStateWithLifecycle()
    val maxValue by mapViewModel.maxValue.collectAsStateWithLifecycle()
    val percentMin by mapViewModel.percentMin.collectAsStateWithLifecycle()
    val percentMax by mapViewModel.percentMax.collectAsStateWithLifecycle()
    val stdDevFactor by mapViewModel.stdDeviationFactor.collectAsStateWithLifecycle()

    var isBottomSheetVisible by remember { mutableStateOf(false) }

    Scaffold(
        topBar = { SampleTopAppBar(title = sampleName) },
        content = { padding ->
            MapView(
                modifier = Modifier
                    .fillMaxSize()
                    .padding(padding),
                arcGISMap = mapViewModel.arcGISMap,
                mapViewProxy = mapViewModel.mapViewProxy,
                onDown = {
                    isBottomSheetVisible = false
                },
            )

            BottomSheet(
                isVisible = isBottomSheetVisible,
                sheetTitle = "Stretch Renderer Settings",
                onDismissRequest = {
                    isBottomSheetVisible = false
                }
            ) {
                Column(
                    modifier = Modifier
                        .fillMaxWidth()
                        .padding(horizontal = 12.dp),
                    verticalArrangement = Arrangement.spacedBy(12.dp),
                    horizontalAlignment = Alignment.CenterHorizontally
                ) {
                    Text(
                        text = "Choose stretch type and configure parameters.",
                        style = MaterialTheme.typography.labelLarge
                    )

                    // Stretch type dropdown
                    DropDownMenuBox(
                        textFieldValue = when (selectedStretchType) {
                            StretchType.MinMax -> mapViewModel.stretchTypeOptions[0]
                            StretchType.PercentClip -> mapViewModel.stretchTypeOptions[1]
                            StretchType.StandardDeviation -> mapViewModel.stretchTypeOptions[2]
                        },
                        textFieldLabel = "Stretch Type",
                        dropDownItemList = mapViewModel.stretchTypeOptions,
                        onIndexSelected = mapViewModel::updateStretchTypeByIndex
                    )

                    when (selectedStretchType) {
                        StretchType.MinMax -> {
                            MinMaxSettings(
                                minValue = minValue,
                                maxValue = maxValue,
                                onMinValueChange = mapViewModel::updateMinValue,
                                onMaxValueChange = mapViewModel::updateMaxValue
                            )
                        }

                        StretchType.PercentClip -> {
                            PercentClipSettings(
                                percentMin = percentMin,
                                percentMax = percentMax,
                                onPercentMinChange = mapViewModel::updatePercentMin,
                                onPercentMaxChange = mapViewModel::updatePercentMax
                            )
                        }

                        StretchType.StandardDeviation -> {
                            StdDevSettings(
                                stdDevFactor = stdDevFactor,
                                onStdDevFactorChange = mapViewModel::updateStdDeviationFactor
                            )
                        }
                    }
                    Button(
                        onClick = {
                            mapViewModel.resetAllChanges()
                            isBottomSheetVisible = false
                        }
                    ) {
                        Text("Reset all changes")
                    }
                }
            }

            // Error dialog
            mapViewModel.messageDialogVM.apply {
                if (dialogStatus) {
                    MessageDialog(
                        title = messageTitle,
                        description = messageDescription,
                        onDismissRequest = ::dismissDialog
                    )
                }
            }
        },
        floatingActionButton = {
            if (!isBottomSheetVisible) {
                FloatingActionButton(
                    modifier = Modifier.padding(bottom = 36.dp, end = 12.dp),
                    onClick = { isBottomSheetVisible = true }
                ) {
                    Icon(
                        Icons.Filled.Settings,
                        contentDescription = "Show Renderer Settings"
                    )
                }
            }
        }
    )
}

// UI for Min-Max stretch parameters
@Composable
fun MinMaxSettings(
    minValue: Double,
    maxValue: Double,
    onMinValueChange: (Double) -> Unit,
    onMaxValueChange: (Double) -> Unit,
    valueRange: ClosedFloatingPointRange<Float> = 0f..255f
) {
    var range by remember { mutableStateOf(minValue.toFloat()..maxValue.toFloat()) }

    Column(horizontalAlignment = Alignment.CenterHorizontally) {
        Text("Min-Max Parameters", style = MaterialTheme.typography.titleMedium)

        Text(text = "Min Value: ${range.start.toInt()}  Max Value: ${range.endInclusive.toInt()}")

        RangeSlider(
            value = range,
            onValueChange = { newRange ->
                if (newRange.start < newRange.endInclusive) {
                    range = newRange
                    onMinValueChange(newRange.start.toDouble())
                    onMaxValueChange(newRange.endInclusive.toDouble())
                }

            },
            valueRange = valueRange,
            steps = 254 // steps between 0 and 255
        )

        Row(
            modifier = Modifier.fillMaxWidth(),
            horizontalArrangement = Arrangement.SpaceBetween
        ) {
            Text(text = "${valueRange.start.toInt()}")
            Text(text = "${valueRange.endInclusive.toInt()}")
        }
    }
}

// UI for Percent Clip stretch parameters
@Composable
fun PercentClipSettings(
    percentMin: Double,
    percentMax: Double,
    onPercentMinChange: (Double) -> Unit,
    onPercentMaxChange: (Double) -> Unit,
    valueRange: ClosedFloatingPointRange<Float> = 0f..100f
) {
    var range by remember { mutableStateOf(percentMin.toFloat()..percentMax.toFloat()) }
    Column(horizontalAlignment = Alignment.CenterHorizontally) {
        Text("Percent Clip Parameters", style = MaterialTheme.typography.titleMedium)

        // Percent min slider (0 .. percentMax)
        Text(text = " Min %: ${range.start.toInt()}  Max %: ${range.endInclusive.toInt()}")
        RangeSlider(
            value = range,
            onValueChange = { newRange ->
                // Ensure min is always less than max
                if (newRange.start < newRange.endInclusive) {
                    range = newRange
                    onPercentMinChange(newRange.start.toDouble())
                    onPercentMaxChange(newRange.endInclusive.toDouble())
                }
            },
            valueRange = valueRange,
            steps = 99 // steps between 0 and 100
        )
        Row(
            modifier = Modifier.fillMaxWidth(),
            horizontalArrangement = Arrangement.SpaceBetween
        ) {
            Text(text = "${valueRange.start.toInt()}")
            Text(text = "${valueRange.endInclusive.toInt()}")
        }
    }
}

// UI for Standard Deviation stretch parameters
@Composable
fun StdDevSettings(
    stdDevFactor: Double,
    onStdDevFactorChange: (Double) -> Unit
) {
    Column(horizontalAlignment = Alignment.CenterHorizontally) {
        Text("Standard Deviation Parameters", style = MaterialTheme.typography.titleMedium)

        // Factor slider (0.25 .. 4.0)
        Text(text = "Factor: %.2f".format(stdDevFactor))
        Slider(
            value = stdDevFactor.toFloat(),
            onValueChange = { value -> onStdDevFactorChange(value.toDouble()) },
            valueRange = 0.25f..4.0f
        )
    }
}