QImage: Add conversion from image::RgbaImage

Because the image crate changes versions somewhat frequently, the
features in CXX-Qt are added with explicit image crate versions.

CHANGELOG.md

@@ -21,6 +21,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `QDateTime::from_string` to parse `QDateTime` from a `QString`.
 - Support for further types: `QUuid`
+- Allow creating a `QImage` from an `image::RgbaImage`.
 
 ### Fixed
 

crates/cxx-qt-lib/Cargo.toml

@@ -31,13 +31,19 @@ time = { version = "0.3.20", optional = true }
 url = { version = "2.3", optional = true }
 uuid = { version = "1.1.0", optional = true }
 serde = { version = "1", features=["derive"], optional = true }
+# Note: The image crate is not yet at 1.0 and a new version is released regularly.
+# To avoid a breaking change at each update, we don't specify a default version, and make the versions explicit.
+# Once 1.0 is released, we can add a dependency on `image`, which would then be `image = "1"`
+# Also, disable the default features, we don't need any, so they would be included unnecessarily and raise the MSRV unnecessarily.
+imagev24 = { version = "0.24", optional=true, package="image", default-features=false }
+imagev25 = { version = "0.25", optional=true, package="image", default-features=false }
 
 [build-dependencies]
 cxx-qt-build.workspace = true
 qt-build-utils.workspace = true
 
 [features]
-full = ["qt_full", "serde", "url", "uuid", "time", "rgb", "http", "chrono", "bytes"]
+full = ["qt_full", "serde", "url", "uuid", "time", "rgb", "http", "chrono", "bytes", "imagev24", "imagev25"]
 default = []
 
 qt_full = ["qt_gui", "qt_qml", "qt_quickcontrols"]
@@ -53,6 +59,8 @@ time = ["dep:time"]
 url = ["dep:url"]
 serde = ["dep:serde"]
 uuid = ["dep:uuid"]
+imagev24 = ["dep:imagev24"]
+imagev25 = ["dep:imagev25"]
 link_qt_object_files = ["cxx-qt-build/link_qt_object_files"]
 
 [lints]

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

@@ -36,6 +36,8 @@ assert_alignment_and_size(QImage, {
 });
 #endif
 
+static_assert(std::is_same_v<QImageCleanupFunction, void (*)(void*)>);
+
 namespace rust {
 namespace cxxqtlib1 {
 

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

@@ -83,6 +83,8 @@ mod ffi {
         include!("cxx-qt-lib/qsizef.h");
         #[allow(dead_code)]
         type QSizeF = crate::QSizeF;
+        type QImageCleanupFunction = super::QImageCleanupFunction;
+        type uchar;
 
         /// Returns true if all the colors in the image are shades of gray
         #[rust_name = "all_gray"]
@@ -236,6 +238,7 @@ mod ffi {
         include!("cxx-qt-lib/common.h");
         type QImageFormat;
         type QImageInvertMode;
+        type c_void = crate::c_void;
 
         #[doc(hidden)]
         #[rust_name = "qimage_init_default"]
@@ -261,6 +264,31 @@ mod ffi {
         #[rust_name = "qimage_eq"]
         fn operatorEq(a: &QImage, b: &QImage) -> bool;
     }
+
+    #[namespace = "rust::cxxqtlib1"]
+    extern "C++" {
+        #[doc(hidden)]
+        #[rust_name = "qimage_init_from_raw_parts_mut"]
+        unsafe fn construct(
+            data: *mut uchar,
+            width: i32,
+            height: i32,
+            format: QImageFormat,
+            image_cleanup_function: QImageCleanupFunction,
+            image_cleanup_data: *mut c_void,
+        ) -> QImage;
+
+        #[doc(hidden)]
+        #[rust_name = "qimage_init_from_raw_parts"]
+        unsafe fn construct(
+            data: *const uchar,
+            width: i32,
+            height: i32,
+            format: QImageFormat,
+            image_cleanup_function: QImageCleanupFunction,
+            image_cleanup_data: *mut c_void,
+        ) -> QImage;
+    }
 }
 
 pub use ffi::{QImageFormat, QImageInvertMode};
@@ -316,6 +344,17 @@ impl Drop for QImage {
     }
 }
 
+// Static assertions on the C++ side assert that this type is equal to:
+// void(*)(void*)
+#[repr(transparent)]
+struct QImageCleanupFunction(extern "C" fn(*mut ffi::c_void));
+
+unsafe impl ExternType for QImageCleanupFunction {
+    type Id = type_id!("QImageCleanupFunction");
+
+    type Kind = cxx::kind::Trivial;
+}
+
 impl QImage {
     /// Convert raw image data to a [`QImage`].
     ///
@@ -332,6 +371,73 @@ impl QImage {
             None
         }
     }
+
+    /// Constructs a QImage from an existing memory buffer.
+    ///
+    /// # Safety
+    /// For details on safety see the [Qt documentation](https://doc.qt.io/qt-6/qimage.html#QImage-7)
+    pub unsafe fn from_raw_parts(
+        data: *const ffi::uchar,
+        width: i32,
+        height: i32,
+        format: QImageFormat,
+        image_cleanup_function: extern "C" fn(x: *mut ffi::c_void),
+        image_cleanup_data: *mut ffi::c_void,
+    ) -> Self {
+        ffi::qimage_init_from_raw_parts(
+            data,
+            width,
+            height,
+            format,
+            QImageCleanupFunction(image_cleanup_function),
+            image_cleanup_data,
+        )
+    }
+
+    /// Constructs a QImage from an existing mutable memory buffer.
+    ///
+    /// # Safety
+    /// For details on safety see the [Qt documentation](https://doc.qt.io/qt-6/qimage.html#QImage-8)
+    pub unsafe fn from_raw_parts_mut(
+        data: *mut ffi::uchar,
+        width: i32,
+        height: i32,
+        format: QImageFormat,
+        image_cleanup_function: extern "C" fn(x: *mut ffi::c_void),
+        image_cleanup_data: *mut ffi::c_void,
+    ) -> Self {
+        ffi::qimage_init_from_raw_parts_mut(
+            data,
+            width,
+            height,
+            format,
+            QImageCleanupFunction(image_cleanup_function),
+            image_cleanup_data,
+        )
+    }
+
+    /// Constructs a QImage from the raw data inside a `Vec<u8>`.
+    ///
+    /// # Safety
+    /// This function is unsafe because it requires that the data matches the given QImageFormat,
+    /// width and height.
+    ///
+    /// It is a convenience function around [Self::from_raw_parts_mut].
+    pub unsafe fn from_raw_bytes(
+        data: Vec<u8>,
+        width: i32,
+        height: i32,
+        format: QImageFormat,
+    ) -> Self {
+        extern "C" fn delete_boxed_vec(boxed_vec: *mut ffi::c_void) {
+            drop(Box::new(boxed_vec as *mut Vec<u8>));
+        }
+        let data = Box::new(data);
+        let bytes = data.as_ptr() as *mut ffi::uchar;
+        let raw_box = Box::into_raw(data) as *mut ffi::c_void;
+        QImage::from_raw_parts_mut(bytes, width, height, format, delete_boxed_vec, raw_box)
+    }
+
     /// Returns a number that identifies the contents of this QImage object.
     pub fn cache_key(&self) -> i64 {
         ffi::qimage_cache_key(self)
@@ -347,6 +453,35 @@ impl QImage {
     }
 }
 
+#[cfg(any(feature = "imagev24", feature = "imagev25"))]
+macro_rules! from_image {
+    ($crt:ident) => {
+        impl From<$crt::RgbaImage> for QImage {
+            fn from(image: $crt::RgbaImage) -> QImage {
+                let width = image.width() as i32;
+                let height = image.height() as i32;
+                // SAFETY: The RgbaImage has the same format as RGBA8888 and the number of
+                // pixels is correct for the images width and height, which is guaranteed by
+                // RgbaImage.
+                unsafe {
+                    QImage::from_raw_bytes(
+                        image.into_raw(),
+                        width,
+                        height,
+                        QImageFormat::Format_RGBA8888,
+                    )
+                }
+            }
+        }
+    };
+}
+
+#[cfg(feature = "imagev24")]
+from_image!(imagev24);
+
+#[cfg(feature = "imagev25")]
+from_image!(imagev25);
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -378,4 +513,25 @@ mod tests {
         assert_eq!(qimage.height(), qimage2.height());
         assert_eq!(qimage.format(), qimage2.format());
     }
+
+    #[test]
+    fn test_from_raw_bytes() {
+        use crate::QColor;
+        let bytes: Vec<u8> = vec![
+            0x01, 0x02, 0x03, 0x04, // Pixel 1
+            0x05, 0x06, 0x07, 0x08, // Pixel 2
+        ];
+
+        let qimage = unsafe { QImage::from_raw_bytes(bytes, 2, 1, QImageFormat::Format_RGBA8888) };
+        assert_eq!(qimage.width(), 2);
+        assert_eq!(qimage.height(), 1);
+        assert_eq!(
+            qimage.pixel_color(0, 0),
+            QColor::from_rgba(0x01, 0x02, 0x03, 0x04),
+        );
+        assert_eq!(
+            qimage.pixel_color(1, 0),
+            QColor::from_rgba(0x05, 0x06, 0x07, 0x08),
+        );
+    }
 }