F3.2 Android: agregar pad manuscrito PNG para firmas

android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/SignaturePad.kt

@@ -0,0 +1,138 @@
+package com.korexlabs.dhinspeccion.ui
+
+import android.graphics.Bitmap
+import android.graphics.Canvas as AndroidCanvas
+import android.graphics.Color as AndroidColor
+import android.graphics.Paint
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.background
+import androidx.compose.foundation.gestures.detectDragGestures
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Button
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateListOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.StrokeCap
+import androidx.compose.ui.input.pointer.consume
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.layout.onSizeChanged
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.dp
+import java.io.File
+import java.io.FileOutputStream
+
+@Composable
+fun SignaturePad(
+    label: String,
+    enabled: Boolean = true,
+    onCaptured: (File) -> Unit,
+) {
+    val context = LocalContext.current
+    val strokes = remember { mutableStateListOf<List<Offset>>() }
+    var currentStroke by remember { mutableStateOf<List<Offset>>(emptyList()) }
+    var canvasSize by remember { mutableStateOf(IntSize.Zero) }
+
+    Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+        Text(label, fontWeight = androidx.compose.ui.text.font.FontWeight.SemiBold)
+        Text(
+            "Firmá dentro del recuadro. La imagen se guarda como PNG y se incorpora al hash del Acta.",
+            style = MaterialTheme.typography.bodySmall,
+        )
+        Canvas(
+            modifier = Modifier
+                .fillMaxWidth()
+                .height(190.dp)
+                .background(Color.White)
+                .onSizeChanged { canvasSize = it }
+                .pointerInput(enabled) {
+                    if (!enabled) return@pointerInput
+                    detectDragGestures(
+                        onDragStart = { position -> currentStroke = listOf(position) },
+                        onDrag = { change, _ ->
+                            change.consume()
+                            currentStroke = currentStroke + change.position
+                        },
+                        onDragEnd = {
+                            if (currentStroke.size > 1) strokes.add(currentStroke)
+                            currentStroke = emptyList()
+                        },
+                        onDragCancel = { currentStroke = emptyList() },
+                    )
+                },
+        ) {
+            val all = strokes + listOf(currentStroke)
+            all.forEach { stroke ->
+                stroke.zipWithNext().forEach { (start, end) ->
+                    drawLine(
+                        color = Color.Black,
+                        start = start,
+                        end = end,
+                        strokeWidth = 4.dp.toPx(),
+                        cap = StrokeCap.Round,
+                    )
+                }
+            }
+        }
+        Row(Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+            OutlinedButton(
+                onClick = { strokes.clear(); currentStroke = emptyList() },
+                enabled = enabled && (strokes.isNotEmpty() || currentStroke.isNotEmpty()),
+                modifier = Modifier.weight(1f),
+            ) { Text("Limpiar") }
+            Button(
+                onClick = {
+                    val width = canvasSize.width.coerceAtLeast(1)
+                    val height = canvasSize.height.coerceAtLeast(1)
+                    val targetWidth = 1000
+                    val targetHeight = 400
+                    val scaleX = targetWidth.toFloat() / width.toFloat()
+                    val scaleY = targetHeight.toFloat() / height.toFloat()
+                    val bitmap = Bitmap.createBitmap(targetWidth, targetHeight, Bitmap.Config.ARGB_8888)
+                    val native = AndroidCanvas(bitmap)
+                    native.drawColor(AndroidColor.WHITE)
+                    val paint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+                        color = AndroidColor.BLACK
+                        strokeWidth = 7f
+                        strokeCap = Paint.Cap.ROUND
+                        strokeJoin = Paint.Join.ROUND
+                        style = Paint.Style.STROKE
+                    }
+                    strokes.forEach { stroke ->
+                        stroke.zipWithNext().forEach { (start, end) ->
+                            native.drawLine(
+                                start.x * scaleX,
+                                start.y * scaleY,
+                                end.x * scaleX,
+                                end.y * scaleY,
+                                paint,
+                            )
+                        }
+                    }
+                    val file = File.createTempFile("DH_FIRMA_", ".png", context.cacheDir)
+                    FileOutputStream(file).use { stream ->
+                        check(bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream))
+                    }
+                    bitmap.recycle()
+                    onCaptured(file)
+                },
+                enabled = enabled && strokes.isNotEmpty(),
+                modifier = Modifier.weight(1f),
+            ) { Text("Usar firma") }
+        }
+    }
+}