Minimal implementation of QImage.

crates/cxx-qt-lib-headers/include/gui/qimage.h

@@ -0,0 +1,34 @@
+// clang-format off
+// SPDX-FileCopyrightText: 2023 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
+// clang-format on
+// SPDX-FileContributor: Leon Matthes <leon.matthes@kdab.com>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+#pragma once
+
+#ifdef CXX_QT_GUI_FEATURE
+
+#include <QtGui/QImage>
+
+#include "rust/cxx.h"
+
+#include <cstdint>
+
+namespace rust {
+
+// QImage has a move constructor, however it is basically trivial.
+template<>
+struct IsRelocatable<QImage> : ::std::true_type
+{
+};
+
+namespace cxxqtlib1 {
+using QImageFormat = QImage::Format;
+
+QImage
+qimageInitFromData(const rust::Slice<std::uint8_t const> data,
+                   rust::Str format);
+
+} // namespace cxxqtlib1
+} // namespace rust
+#endif

crates/cxx-qt-lib-headers/src/lib.rs

@@ -71,6 +71,8 @@ pub fn write_headers(directory: impl AsRef<Path>) {
             "qguiapplication.h",
         ),
         #[cfg(feature = "qt_gui")]
+        (include_str!("../include/gui/qimage.h"), "qimage.h"),
+        #[cfg(feature = "qt_gui")]
         (include_str!("../include/gui/qvector2d.h"), "qvector2d.h"),
         #[cfg(feature = "qt_gui")]
         (include_str!("../include/gui/qvector3d.h"), "qvector3d.h"),

crates/cxx-qt-lib/build.rs

@@ -158,6 +158,7 @@ fn main() {
             "core/qvector/qvector_qcolor",
             "gui/qcolor",
             "gui/qguiapplication",
+            "gui/qimage",
             "gui/qvector2d",
             "gui/qvector3d",
             "gui/qvector4d",
@@ -225,6 +226,7 @@ fn main() {
         cpp_files.extend([
             "gui/qcolor",
             "gui/qguiapplication",
+            "gui/qimage",
             "gui/qvector2d",
             "gui/qvector3d",
             "gui/qvector4d",

crates/cxx-qt-lib/src/gui/mod.rs

@@ -17,3 +17,6 @@ pub use qvector3d::QVector3D;
 
 mod qvector4d;
 pub use qvector4d::QVector4D;
+
+mod qimage;
+pub use qimage::QImage;

crates/cxx-qt-lib/src/gui/qimage.cpp

@@ -0,0 +1,51 @@
+// clang-format off
+// SPDX-FileCopyrightText: 2023 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
+// clang-format on
+// SPDX-FileContributor: Leon Matthes <leon.matthes@kdab.com>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+#ifdef CXX_QT_GUI_FEATURE
+
+#include "cxx-qt-lib/qimage.h"
+#include "../assertion_utils.h"
+#include <string>
+
+// A QImage inherits from QPaintDevice.
+
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+// QPaintDevice in Qt5 contains two things:
+// 1. ushort painters; (due to the following field this has padding to make it
+// 64-bit long)
+// 2. QPaintDevicePrivate *reserved;
+// Then QImage adds an additional field:
+// 3. QImageData *d;
+// For a total of 3 pointers in length.
+// Because of the added v-table, it's a total of 4 pointers in size.
+assert_alignment_and_size(QImage,
+                          alignof(::std::size_t),
+                          sizeof(::std::size_t) * 4);
+#else
+// In Qt6 the QPaintDevice doesn't contain the `reserved` pointer, making it 1
+// pointer smaller
+assert_alignment_and_size(QImage,
+                          alignof(::std::size_t),
+                          sizeof(::std::size_t) * 3);
+#endif
+
+namespace rust {
+namespace cxxqtlib1 {
+
+QImage
+qimageInitFromData(const rust::Slice<std::uint8_t const> data, rust::Str format)
+{
+  std::string formatString(format);
+  return QImage::fromData(static_cast<const unsigned char*>(data.data()),
+                          static_cast<int>(data.size()),
+                          formatString.empty() ? nullptr : formatString.data());
+}
+
+}
+}
+
+#endif

crates/cxx-qt-lib/src/gui/qimage.rs

@@ -0,0 +1,82 @@
+// SPDX-FileCopyrightText: 2023 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
+// SPDX-FileContributor: Leon Matthes <leon.matthes@kdab.com>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+use cxx::{type_id, ExternType};
+use std::mem::MaybeUninit;
+
+#[cxx::bridge]
+mod ffi {
+    unsafe extern "C++" {
+        include!("cxx-qt-lib/qimage.h");
+        type QImage = super::QImage;
+
+        /// Whether the QImage is null.
+        ///
+        /// This means that the QImage has all parameters set to zero and no allocated data.
+        #[rust_name = "is_null"]
+        fn isNull(self: &QImage) -> bool;
+    }
+
+    #[namespace = "rust::cxxqtlib1"]
+    unsafe extern "C++" {
+        include!("cxx-qt-lib/common.h");
+
+        #[doc(hidden)]
+        #[rust_name = "qimage_drop"]
+        fn drop(image: &mut QImage);
+
+        #[doc(hidden)]
+        #[rust_name = "qimage_init_from_data"]
+        fn qimageInitFromData(data: &[u8], format: &str) -> QImage;
+    }
+}
+
+/// > ⚠ **Warning**: The QImage API in CXX-Qt-lib is not yet complete and subject to change.
+///
+/// This struct is the Rust representation of the [`QImage`](https://doc.qt.io/qt-6/qimage.html)
+/// class.
+///
+/// It provides a way to store and manipulate images in a hardware-independent manner.
+#[repr(C)]
+pub struct QImage {
+    // Static checks on the C++ side ensure this is true.
+    // See qcolor.cpp
+    #[cfg(qt_version_major = "5")]
+    _data: MaybeUninit<[usize; 4]>,
+    #[cfg(qt_version_major = "6")]
+    _data: MaybeUninit<[usize; 3]>,
+}
+
+// Safety:
+//
+// Static checks on the C++ side to ensure the size & alignment is the same.
+unsafe impl ExternType for QImage {
+    type Id = type_id!("QImage");
+    type Kind = cxx::kind::Trivial;
+}
+
+impl Drop for QImage {
+    fn drop(&mut self) {
+        ffi::qimage_drop(self);
+    }
+}
+
+impl QImage {
+    /// Convert raw image data to a [`QImage`].
+    ///
+    /// The data must be in the given `format`.
+    /// See [`QImageReader::supportedImageFormats()`](https://doc.qt.io/qt-6/qimagereader.html#supportedImageFormats) for the list of supported formats.
+    ///
+    /// If no `format` is provided, the format will be quessed from the image header.
+    pub fn from_data(data: &[u8], format: Option<&str>) -> Option<Self> {
+        let image = ffi::qimage_init_from_data(data, format.unwrap_or(""));
+
+        if !image.is_null() {
+            Some(image)
+        } else {
+            None
+        }
+    }
+}