Add cross-platform canvas test and fix JS text rendering

uhabits-core/karma.config.d/karma.conf.js

@@ -1,9 +1,33 @@
 const path = require("path");
+const fs = require("fs");
 const migrationsDir = path.resolve(__dirname, "../../../../uhabits-core/assets/main/migrations");
 const testAssetsDir = path.resolve(__dirname, "../../../../uhabits-core/assets/test");
 const fontsDir = path.resolve(__dirname, "../../../../uhabits-core/assets/main/fonts");
 
+function saveFileMiddleware(req, res, next) {
+    if (req.url !== "/save-file" || req.method !== "POST") return next();
+    const filePath = req.headers["x-file-path"];
+    if (!filePath) {
+        res.writeHead(400);
+        res.end("Missing X-File-Path header");
+        return;
+    }
+    const chunks = [];
+    req.on("data", chunk => chunks.push(chunk));
+    req.on("end", () => {
+        const dir = path.dirname(filePath);
+        fs.mkdirSync(dir, { recursive: true });
+        fs.writeFileSync(filePath, Buffer.concat(chunks));
+        res.writeHead(200);
+        res.end("OK");
+    });
+}
+
 config.set({
+    beforeMiddleware: ["saveFile"],
+    plugins: (config.plugins || []).concat([
+        { "middleware:saveFile": ["value", saveFileMiddleware] }
+    ]),
     browserNoActivityTimeout: 120000,
     browserDisconnectTimeout: 30000,
     browserDisconnectTolerance: 3,

uhabits-core/src/commonTest/kotlin/org/isoron/platform/gui/CanvasTest.kt

@@ -0,0 +1,16 @@
+package org.isoron.platform.gui
+
+import kotlinx.coroutines.test.runTest
+import org.isoron.platform.io.createTestCanvas
+import org.isoron.platform.io.ensureFontsLoaded
+import kotlin.test.Test
+
+class CanvasTest {
+    @Test
+    fun testDrawTestImage() = runTest {
+        ensureFontsLoaded()
+        val canvas = createTestCanvas(500, 400)
+        canvas.drawTestImage()
+        assertRenders("views/CanvasTest.png", canvas)
+    }
+}

uhabits-core/src/jsMain/kotlin/org/isoron/platform/gui/JsCanvas.kt

@@ -45,12 +45,15 @@ class JsCanvas(
         val py = toPixel(y)
         val metrics = ctx.measureText(text)
         val textWidth = metrics.width
+        val ascent = metrics.asDynamic().actualBoundingBoxAscent as Double
+        val descent = metrics.asDynamic().actualBoundingBoxDescent as Double
         val xPos = when (textAlign) {
             TextAlign.CENTER -> px - textWidth / 2
             TextAlign.RIGHT -> px - textWidth
             TextAlign.LEFT -> px
         }
-        ctx.fillText(text, xPos, py)
+        val yPos = py + (ascent - descent) / 2
+        ctx.fillText(text, xPos, yPos)
     }
 
     override fun fillRect(x: Double, y: Double, width: Double, height: Double) {
@@ -148,7 +151,6 @@ class JsCanvas(
         }
         val weight = if (font == Font.BOLD) "bold" else "normal"
         ctx.font = "$weight ${sizePx}px $family"
-        ctx.asDynamic().textBaseline = "middle"
     }
 
     companion object {

uhabits-core/src/jsMain/kotlin/org/isoron/platform/gui/JsImage.kt

@@ -1,8 +1,14 @@
 package org.isoron.platform.gui
 
 import kotlinx.browser.document
+import kotlinx.browser.window
 import org.w3c.dom.CanvasRenderingContext2D
 import org.w3c.dom.HTMLCanvasElement
+import org.w3c.fetch.RequestInit
+import kotlin.coroutines.resume
+import kotlin.coroutines.resumeWithException
+import kotlin.coroutines.suspendCoroutine
+import kotlin.js.json
 
 class JsImage(private val canvas: HTMLCanvasElement) : Image {
     private val ctx = canvas.getContext("2d") as CanvasRenderingContext2D
@@ -31,7 +37,20 @@ class JsImage(private val canvas: HTMLCanvasElement) : Image {
     }
 
     override suspend fun export(path: String) {
-        // No-op on JS browser; images can't be exported to filesystem
+        val blob = suspendCoroutine<dynamic> { cont ->
+            canvas.asDynamic().toBlob { b: dynamic -> cont.resume(b) }
+        }
+        val init = RequestInit(
+            method = "POST",
+            body = blob,
+            headers = json("X-File-Path" to path),
+        )
+        suspendCoroutine<Unit> { cont ->
+            window.fetch("/save-file", init).then(
+                { cont.resume(Unit) },
+                { err -> cont.resumeWithException(RuntimeException("$err")) }
+            )
+        }
     }
 
     companion object {

uhabits-core/src/jsTest/kotlin/org/isoron/platform/io/TestPlatformHelper.kt

@@ -6,6 +6,7 @@ import org.isoron.platform.gui.JsCanvas
 import org.isoron.platform.time.JsLocalDateFormatter
 import org.isoron.platform.time.LocalDateFormatter
 import kotlin.coroutines.resume
+import kotlin.coroutines.resumeWithException
 import kotlin.coroutines.suspendCoroutine
 
 val sharedTestStorage = JsFileStorage()
@@ -48,10 +49,14 @@ actual suspend fun ensureFontsLoaded() {
     fontsLoaded = true
 }
 
-private suspend fun loadFontAsync(fontSpec: String) = suspendCoroutine<Unit> { cont ->
-    val promise = document.asDynamic().fonts.load(fontSpec)
-    promise.then(
-        { _: dynamic -> cont.resume(Unit) },
-        { _: dynamic -> cont.resume(Unit) }
-    )
+private suspend fun loadFontAsync(fontSpec: String) {
+    suspendCoroutine<Unit> { cont ->
+        val promise = document.asDynamic().fonts.load(fontSpec)
+        promise.then(
+            { _: dynamic -> cont.resume(Unit) },
+            { err: dynamic -> cont.resumeWithException(RuntimeException("Failed to load font '$fontSpec': $err")) }
+        )
+    }
+    val loaded = document.asDynamic().fonts.check(fontSpec) as Boolean
+    if (!loaded) error("Font not available after loading: '$fontSpec'")
 }

uhabits-core/src/jvmTest/java/org/isoron/platform/gui/JavaCanvasTest.kt

@@ -1,77 +0,0 @@
-/*
- * Copyright (C) 2016-2025 Álinson Santos Xavier <git@axavier.org>
- *
- * This file is part of Loop Habit Tracker.
- *
- * Loop Habit Tracker is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by the
- * Free Software Foundation, either version 3 of the License, or (at your
- * option) any later version.
- *
- * Loop Habit Tracker is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package org.isoron.platform.gui
-
-import kotlinx.coroutines.runBlocking
-import org.isoron.platform.io.JavaFileOpener
-import org.junit.Assert.fail
-import org.junit.Test
-import java.awt.image.BufferedImage
-import java.awt.image.BufferedImage.TYPE_INT_ARGB
-
-class JavaCanvasTest {
-    @Test
-    fun run() = runBlocking {
-        assertRenders("views/CanvasTest.png", createCanvas(500, 400).apply { drawTestImage() })
-    }
-}
-
-private fun createCanvas(w: Int, h: Int) = JavaCanvas(BufferedImage(2 * w, 2 * h, TYPE_INT_ARGB), 2.0)
-
-private suspend fun assertRenders(
-    path: String,
-    canvas: Canvas
-) {
-    val actualImage = canvas.toImage()
-    val failedActualPath = "/tmp/failed/$path"
-    val failedExpectedPath = failedActualPath.replace(
-        ".png",
-        ".expected.png"
-    )
-    val failedDiffPath = failedActualPath.replace(".png", ".diff.png")
-    val fileOpener = JavaFileOpener()
-    val expectedFile = fileOpener.openResourceFile(path)
-    if (expectedFile.exists()) {
-        val expectedImage = expectedFile.toImage()
-        val diffImage = expectedFile.toImage()
-        diffImage.diff(actualImage)
-        val distance = diffImage.averageLuminosity * 100
-        if (distance >= 1.0) {
-            expectedImage.export(failedExpectedPath)
-            actualImage.export(failedActualPath)
-            diffImage.export(failedDiffPath)
-            fail("Images differ (distance=$distance)")
-        }
-    } else {
-        actualImage.export(failedActualPath)
-        fail("Expected image file is missing. Actual image: $failedActualPath")
-    }
-}
-
-private suspend fun assertRenders(
-    width: Int,
-    height: Int,
-    expectedPath: String,
-    view: View
-) {
-    val canvas = createCanvas(width, height)
-    view.draw(canvas)
-    assertRenders(expectedPath, canvas)
-}