Add some debug composable to measure manually items on Preview.

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/ruler/HorizontalRuler.kt

@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * 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 io.element.android.libraries.designsystem.ruler
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.size
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import io.element.android.libraries.designsystem.preview.ElementPreviewDark
+import io.element.android.libraries.designsystem.preview.ElementPreviewLight
+
+/**
+ * Horizontal ruler is a debug composable that displays a horizontal ruler.
+ * It can be used to display the horizontal ruler in the composable preview.
+ */
+@Composable
+fun HorizontalRuler(
+    modifier: Modifier = Modifier,
+) {
+    val baseColor = Color.Magenta
+    val alphaBaseColor = baseColor.copy(alpha = 0.2f)
+    Row(modifier = modifier.fillMaxWidth()) {
+        repeat(50) {
+            HorizontalRulerItem(1.dp, alphaBaseColor)
+            HorizontalRulerItem(2.dp, baseColor)
+            HorizontalRulerItem(1.dp, alphaBaseColor)
+            HorizontalRulerItem(2.dp, baseColor)
+            HorizontalRulerItem(5.dp, alphaBaseColor)
+            HorizontalRulerItem(2.dp, baseColor)
+            HorizontalRulerItem(1.dp, alphaBaseColor)
+            HorizontalRulerItem(2.dp, baseColor)
+            HorizontalRulerItem(1.dp, alphaBaseColor)
+            HorizontalRulerItem(10.dp, baseColor)
+        }
+    }
+}
+
+@Composable
+private fun HorizontalRulerItem(height: Dp, color: Color) {
+    Spacer(
+        modifier = Modifier
+            .size(height = height, width = 1.dp)
+            .background(color = color)
+    )
+}
+
+@Preview
+@Composable
+internal fun HorizontalRulerLightPreview() =
+    ElementPreviewLight { ContentToPreview() }
+
+@Preview
+@Composable
+internal fun HorizontalRulerDarkPreview() =
+    ElementPreviewDark { ContentToPreview() }
+
+@Composable
+private fun ContentToPreview() {
+    HorizontalRuler()
+}
+

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/ruler/VerticalRuler.kt

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * 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 io.element.android.libraries.designsystem.ruler
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.foundation.layout.size
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import io.element.android.libraries.designsystem.preview.ElementPreviewDark
+import io.element.android.libraries.designsystem.preview.ElementPreviewLight
+
+/**
+ * Vertical ruler is a debug composable that displays a vertical ruler.
+ * It can be used to display the vertical ruler in the composable preview.
+ */
+@Composable
+fun VerticalRuler(
+    modifier: Modifier = Modifier,
+) {
+    val baseColor = Color.Red
+    val alphaBaseColor = baseColor.copy(alpha = 0.2f)
+    Column(modifier = modifier.fillMaxHeight()) {
+        repeat(50) {
+            VerticalRulerItem(1.dp, alphaBaseColor)
+            VerticalRulerItem(2.dp, baseColor)
+            VerticalRulerItem(1.dp, alphaBaseColor)
+            VerticalRulerItem(2.dp, baseColor)
+            VerticalRulerItem(5.dp, alphaBaseColor)
+            VerticalRulerItem(2.dp, baseColor)
+            VerticalRulerItem(1.dp, alphaBaseColor)
+            VerticalRulerItem(2.dp, baseColor)
+            VerticalRulerItem(1.dp, alphaBaseColor)
+            VerticalRulerItem(10.dp, baseColor)
+        }
+    }
+}
+
+@Composable
+private fun VerticalRulerItem(width: Dp, color: Color) {
+    Spacer(
+        modifier = Modifier
+            .size(height = 1.dp, width = width)
+            .background(color = color)
+    )
+}
+
+@Preview
+@Composable
+internal fun VerticalRulerLightPreview() =
+    ElementPreviewLight { ContentToPreview() }
+
+@Preview
+@Composable
+internal fun VerticalRulerDarkPreview() =
+    ElementPreviewDark { ContentToPreview() }
+
+@Composable
+private fun ContentToPreview() {
+    VerticalRuler()
+}

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/ruler/WithRulers.kt

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * 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 io.element.android.libraries.designsystem.ruler
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.layout.Layout
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import io.element.android.libraries.designsystem.preview.ElementPreviewDark
+import io.element.android.libraries.designsystem.preview.ElementPreviewLight
+import io.element.android.libraries.designsystem.theme.components.OutlinedButton
+import io.element.android.libraries.designsystem.theme.components.Text
+
+/**
+ * Debug tool to add a vertical and a horizontal ruler on top of the content.
+ */
+@Composable
+fun WithRulers(
+    xRulersOffset: Dp = 0.dp,
+    yRulersOffset: Dp = 0.dp,
+    content: @Composable () -> Unit
+) {
+    Layout(
+        content = {
+            content()
+            VerticalRuler()
+            HorizontalRuler()
+        },
+        measurePolicy = { measurables, constraints ->
+            val placeables = measurables.map { it.measure(constraints) }
+            // Use layout size of the first item (the content)
+            layout(
+                width = placeables.first().width,
+                height = placeables.first().height
+            ) {
+                placeables.forEachIndexed { index, placeable ->
+                    if (index == 0) {
+                        placeable.place(0, 0)
+                    } else {
+                        placeable.place(xRulersOffset.roundToPx(), yRulersOffset.roundToPx())
+                    }
+                }
+            }
+        }
+    )
+}
+
+@Preview
+@Composable
+internal fun WithRulerLightPreview() =
+    ElementPreviewLight { ContentToPreview() }
+
+@Preview
+@Composable
+internal fun WithRulerDarkPreview() =
+    ElementPreviewDark { ContentToPreview() }
+
+@Composable
+private fun ContentToPreview() {
+    WithRulers(xRulersOffset = 20.dp, yRulersOffset = 15.dp) {
+        OutlinedButton(onClick = {}) {
+            Text(text = "A Button with rulers on it!")
+        }
+    }
+}