OmaPhoto 1.0.0: the Linux port of Compositor

A layered image editor for Linux and Omarchy, ported from Compositor
(github.com/robbietilton/Compositor), whose Swift source is its
specification. It reads and writes Compositor's .comp projects.

Packages for Ubuntu, Fedora and Arch come from the release workflow;
scripts/install/ holds one install script per distribution family,
and flake.nix serves NixOS.

Co-Authored-By: Claude <noreply@anthropic.com>

tests/CanvasThumbnailTests.cpp

@@ -0,0 +1,83 @@
+#include "UI/CanvasThumbnail.h"
+#include "Document/LayerMask.h"
+#include "RenderFixtures.h"
+#include <QtTest>
+
+// Thumbnails take the canvas's shape; pixels sit where they are.
+namespace {
+// One pixel's RGBA bytes of a thumbnail, top row first.
+QList<int> read(const QPixmap &thumbnail, int x, int y)
+{
+    const QImage image = thumbnail.toImage().convertToFormat(QImage::Format_RGBA8888);
+    const uchar *pixel = image.constScanLine(y) + x * 4;
+    return {pixel[0], pixel[1], pixel[2], pixel[3]};
+}
+}
+
+class CanvasThumbnailTests : public QObject {
+    Q_OBJECT
+private slots:
+    void thumbnailsTakeTheCanvasShape();
+    void layerPixelsSitWhereTheyAreOnTheCanvas();
+    void masksFillTheCanvasWithTheirEdgeTone();
+};
+
+void CanvasThumbnailTests::thumbnailsTakeTheCanvasShape()
+{
+    QCOMPARE(CanvasThumbnail::fittedSize(QSizeF(400, 200), 36), QSize(36, 18));
+    QCOMPARE(CanvasThumbnail::fittedSize(QSizeF(300, 600), 36), QSize(18, 36));
+    QCOMPARE(CanvasThumbnail::fittedSize(QSizeF(0, 0), 30), QSize(30, 30));
+    QCOMPARE(CanvasThumbnail::fittedSize(QSizeF(3000, 7), 36), QSize(36, 1));
+    // Rounded, as Swift rounds: 22.5 is 23, not 22.
+    QCOMPARE(CanvasThumbnail::fittedSize(QSizeF(400, 250), 36), QSize(36, 23));
+    QCOMPARE(CanvasThumbnail::fittedSize(QSizeF(std::nan(""), 7), 36), QSize(36, 36));
+}
+
+void CanvasThumbnailTests::layerPixelsSitWhereTheyAreOnTheCanvas()
+{
+    const QImage red = solid(100, 100, qRgba(255, 0, 0, 255));
+    const QPixmap thumbnail = CanvasThumbnail::layer(red, LayerTransform{.origin = {0, 0}, .size = {100, 100}}, QSizeF(400, 200), 36);
+    QCOMPARE(thumbnail.deviceIndependentSize(), QSizeF(36, 18));
+    QCOMPARE(thumbnail.width(), 72);
+    QCOMPARE(read(thumbnail, 4, 4), (QList<int>{255, 0, 0, 255}));
+    QCOMPARE(read(thumbnail, 12, 12)[0], 255);
+    // The rest shows the checkerboard; nothing is flipped.
+    QVERIFY(read(thumbnail, 60, 30)[0] < 200);
+    QVERIFY(read(thumbnail, 4, 30)[0] < 200);
+    const QPixmap blank = CanvasThumbnail::layer(QImage(), LayerTransform{.origin = {0, 0}, .size = {400, 200}}, QSizeF(400, 200), 36);
+    QCOMPARE(read(blank, 4, 4)[3], 255);
+    // Two tones of gray, six points a tile.
+    QCOMPARE(read(blank, 4, 4)[0], 82);
+    QCOMPARE(read(blank, 16, 4)[0], 56);
+    QCOMPARE(read(blank, 16, 16)[0], 82);
+}
+
+void CanvasThumbnailTests::masksFillTheCanvasWithTheirEdgeTone()
+{
+    const LayerTransform transform{.origin = {100, 50}, .size = {100, 100}};
+    const QSizeF canvas(400, 200);
+    const QImage hideAll = LayerMask::solid(false).asset.thumbnail;
+    const QPixmap hidden = CanvasThumbnail::mask(hideAll, transform, canvas, 30);
+    QVERIFY(read(hidden, 1, 1)[0] < 10);
+    QVERIFY(read(hidden, 55, 25)[0] < 10);
+    // White edges round a black middle: white around, black within.
+    QImage framed(20, 20, QImage::Format_Grayscale8);
+    framed.fill(255);
+    for (int y = 5; y < 15; ++y) {
+        for (int x = 5; x < 15; ++x)
+            framed.setPixel(x, y, qRgb(0, 0, 0));
+    }
+    QCOMPARE(CanvasThumbnail::edgeTone(framed), 1.0);
+    const QPixmap shown = CanvasThumbnail::mask(framed, transform, canvas, 30);
+    QCOMPARE(shown.deviceIndependentSize(), QSizeF(30, 15));
+    QVERIFY(read(shown, 2, 2)[0] > 245);
+    QVERIFY(read(shown, 22, 15)[0] < 10);
+    // A mid-gray frame reads as its mean.
+    QImage half(4, 3, QImage::Format_Grayscale8);
+    half.fill(128);
+    half.setPixel(1, 1, qRgb(0, 0, 0));
+    QCOMPARE(CanvasThumbnail::edgeTone(half), 128.0 / 255);
+}
+
+QTEST_MAIN(CanvasThumbnailTests)
+#include "CanvasThumbnailTests.moc"