# Qt-fortran questions

**URL:** <https://fortran-lang.discourse.group/t/qt-fortran-questions/11300>\
**Category:** Help\
**Created:** [November 12, 2026, 10:35pm UTC](https://fortran-lang.discourse.group/t/qt-fortran-questions/11300 "2026-11-12T22:35:55Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Cean](https://avatars.discourse-cdn.com/v4/letter/c/bc8723/32.png) [@Cean](https://fortran-lang.discourse.group/u/Cean)\
**Post date:** [November 12, 2026, 10:35pm UTC](https://fortran-lang.discourse.group/t/qt-fortran-questions/11300/1 "2026-11-12T22:35:55Z")

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> **[GitHub - jacobwilliams/qt-fortran: Modern Fortran interface to Qt or something?](https://github.com/jacobwilliams/qt-fortran)**
>
> Modern Fortran interface to Qt or something?

**`QVector4D`** `,`QVector3D, QPoint are not exposed in **`qt-fortran.`**

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<div class="post-metadata">

**Author:** ![jacobwilliams](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/jacobwilliams/32/10_2.png) [@jacobwilliams](https://fortran-lang.discourse.group/u/jacobwilliams)\
**Post date:** [November 13, 2026, 1:11am UTC](https://fortran-lang.discourse.group/t/qt-fortran-questions/11300/2 "2026-11-13T01:11:46Z")

</div>

I just had Claude add it:

Run `pixi run example geometry` to see an example:

 ![image](https://global.discourse-cdn.com/free1/uploads/fortran_lang/original/2X/7/7f54244965ab150dc350db60bbcdad468f29be7f.jpeg)

# New API from the geometry updates

Overloads are listed by the name you call: for example, `painter%drawLine(p1, p2)`.

## New value types (pure Fortran, `use qt`)

All have public components, structure constructors and Qt’s methods.

### Integer and floating-point 2D (`qt_geometry`)

| Type | Components | Extra constructors | Methods |
| --- | --- | --- | --- |
| `QPoint` | `x, y` | | `isNull`, `manhattanLength`, `transposed`, `toPointF` |
| `QPointF` | `x, y` | `QPointF(QPoint)` | `isNull`, `manhattanLength`, `transposed`, `toPoint` |
| `QSize` | `width, height` | | `isNull`, `isEmpty`, `isValid`, `transposed`, `expandedTo`, `boundedTo`, `scaled(size [, mode])`, `grownBy`, `shrunkBy`, `toSizeF` |
| `QSizeF` | `width, height` | `QSizeF(QSize)` | `isNull`, `isEmpty`, `isValid`, `transposed`, `expandedTo`, `boundedTo`, `scaled`, `toSize` |
| `QMargins` | `left, top, right, bottom` | | `isNull` |
| `QRect` | `x, y, width, height` | `QRect(topLeft, size)`, `QRect(topLeft, bottomRight)` | `left`, `top`, `right`, `bottom`, `topLeft`, `topRight`, `bottomLeft`, `bottomRight`, `center`, `size`, `isNull`, `isEmpty`, `isValid`, `normalized`, `contains(point or rect [, proper])`, `intersects`, `intersected`, `united`, `translated(dx, dy or point)`, `adjusted`, `marginsAdded`, `marginsRemoved`, `moveTo`, `moveCenter`, `toRectF` |
| `QRectF` | `x, y, width, height` | `QRectF(topLeft, size)`, `QRectF(topLeft, bottomRight)`, `QRectF(QRect)` | same as `QRect` without the margins methods, plus `toRect` and `toAlignedRect` |
| `QLineF` | `x1, y1, x2, y2` | `QLineF(p1, p2)` | `p1`, `p2`, `dx`, `dy`, `isNull`, `length`, `setLength`, `angle`, `setAngle`, `angleTo`, `center`, `pointAt`, `unitVector`, `normalVector`, `intersects(line [, point])`, `translated` |

- **Free functions:** `QPointF_dotProduct`, `QLineF_fromPolar`
- **Constants:** `QLineF_NoIntersection`, `QLineF_BoundedIntersection`, `QLineF_UnboundedIntersection`, `Qt_IgnoreAspectRatio`, `Qt_KeepAspectRatio`, `Qt_KeepAspectRatioByExpanding`
- **Operators:**
  - `+` and `-` (including unary minus) for points, sizes and margins; `rect + margins` and `rect - margins`
  - `*` and `/` by a number; for the integer types `*` also takes an integer, and results are rounded as Qt does
  - `==` and `/=`

### Vectors and quaternions (`qt_vectors`)

| Type | Components | Extra constructors | Methods |
| --- | --- | --- | --- |
| `QVector2D` | `x, y` | `QVector2D(array)`, `QVector2D(QPoint)`, `QVector2D(QPointF)` | `isNull`, `length`, `lengthSquared`, `normalized`, `normalize`, `distanceToPoint`, `distanceToLine`, `toVector3D([z])`, `toVector4D`, `toPoint`, `toPointF`, `toArray` |
| `QVector3D` | `x, y, z` | `QVector3D(array)`, `QVector3D(vector2d [, z])` | same as `QVector2D`, plus `distanceToPlane(point, normal)` or `distanceToPlane(p1, p2, p3)`, `toVector2D`, `toVector4D([w])` |
| `QVector4D` | `x, y, z, w` | `QVector4D(array)`, `QVector4D(vector3d [, w])`, `QVector4D(vector2d [, z, w])` | `isNull`, `length`, `lengthSquared`, `normalized`, `normalize`, `toVector2D`, `toVector2DAffine`, `toVector3D`, `toVector3DAffine`, `toPoint`, `toPointF`, `toArray` |
| `QQuaternion` | `scalar, x, y, z` (identity by default) | `QQuaternion(scalar, vector3d)`, `QQuaternion(vector4d)` | `isNull`, `isIdentity`, `vector`, `length`, `lengthSquared`, `normalized`, `normalize`, `conjugated`, `inverted`, `rotatedVector`, `getAxisAndAngle`, `toEulerAngles`, `toRotationMatrix`, `toVector4D` |

- **Free functions:**
  - `QVector2D_dotProduct`, `QVector3D_dotProduct`, `QVector3D_crossProduct`, `QVector3D_normal(v1, v2)` or `QVector3D_normal(v1, v2, v3)`, `QVector4D_dotProduct`
  - `QQuaternion_dotProduct`, `QQuaternion_fromAxisAndAngle(axis, angle)` or `(x, y, z, angle)`, `QQuaternion_fromEulerAngles(pitch, yaw, roll)` or `(vector3d)`
  - `QQuaternion_fromRotationMatrix`, `QQuaternion_fromAxes`, `QQuaternion_fromDirection`, `QQuaternion_rotationTo`, `QQuaternion_slerp`, `QQuaternion_nlerp`

- **Operators:**
  - `+` and `-`
  - `*` and `/` by a number, or component-wise with another vector
  - quaternion `*` quaternion (composes rotations), and quaternion `*` `QVector3D` (rotates the vector)
  - `==` and `/=` (to within a relative 1e-12)

## `QMatrix4x4` additions

- New overloads: `translate(QVector3D)`, `scale(QVector3D)`, `rotate(angle, QVector3D)`, `rotate(QQuaternion)`, `lookAt(eye, center, up)` with `QVector3D`s
- `map(QVector3D)` and `map(QVector4D)`
- `mapVector(v(3) or QVector3D)` is new: it applies the 3x3 part only, with no translation
- Operators: `matrix * QVector4D`, `matrix * QVector3D`
- Free functions: `QVector3D_project(obj, modelView, projection, viewport)` and `QVector3D_unproject(win, modelView, projection, viewport)`

## New methods on existing classes

**`QWidget`** , inherited by every widget:

- Getters:
  - `pos() → QPoint`, `size() → QSize`
  - `geometry()`, `frameGeometry()`, `rect()`, `contentsRect() → QRect`
  - `sizeHint()`, `minimumSize()`, `maximumSize() → QSize`
  - `contentsMargins() → QMargins`

- New setter: `setGeometry(QRect)`
- New overloads of existing setters: `move(QPoint)`, `resize(QSize)`, `setMinimumSize(QSize)`, `setMaximumSize(QSize)`, `setFixedSize(QSize)`, `setContentsMargins(QMargins)`
- Mapping: `mapToGlobal`, `mapFromGlobal`, `mapToParent`, `mapFromParent` (all `QPoint → QPoint`); `mapTo(ancestor, QPoint)`, `mapFrom(ancestor, QPoint)`
- `childAt(QPoint) → QWidget`

**`QLayout`:** `contentsMargins() → QMargins`, `setContentsMargins(QMargins)`

**`QMenu`:** `popup(QPoint)`, `exec(QPoint) → QAction`

**`QtfPaintCell`:** `rect() → QRect`

**`QPainter`:**

- `drawPoint(QPointF)`
- `drawLine(p1, p2)` and `drawLine(QLineF)`
- `drawRect(QRectF)`
- `drawEllipse(QRectF)` and `drawEllipse(center, rx, ry)`
- `drawText(QPointF, text)` and `drawText(QRectF, flags, text)`
- `fillRect(QRectF, color)`, `setClipRect(QRectF)`

**`QPainterPath`:**

- `moveTo(QPointF)`, `lineTo(QPointF)`, `addRect(QRectF)`, `addEllipse(QRectF)`, `containsPoint(QPointF)`
- `currentPosition() → QPointF`, `pointAtPercent(t) → QPointF`, `boundingRect() → QRectF`

**`QTransform`:** `map(QPointF) → QPointF`, `mapRect(QRectF) → QRectF`

**`QFontMetrics`:** `boundingRect(text) → QRect`, `size(flags, text) → QSize`

**`QImage`, `QPixmap`:** `size() → QSize`

**`QWindow`:**

- `size() → QSize`, `resize(QSize)`
- `position() → QPoint`, `setPosition(QPoint)`
- `geometry() → QRect`, `setGeometry(QRect)`
- `mapToGlobal(QPoint)`, `mapFromGlobal(QPoint)`

**`QScreen`:** `geometry()`, `availableGeometry() → QRect`; `size() → QSize`; `physicalSize() → QSizeF`

**`QDrag`:** `setHotSpot(QPoint)`

**Events:**

- `QMouseEvent`: `position()`, `globalPosition() → QPointF`
- `QWheelEvent`: `position() → QPointF`, `angleDelta()`, `pixelDelta() → QPoint`
- `QResizeEvent`: `size()`, `oldSize() → QSize`
- `QContextMenuEvent`: `pos()`, `globalPos() → QPoint`
- `QDropEvent`: `position() → QPointF`

**`QOpenGLShaderProgram`:** `setUniformValue(name, x, y)` (vec2), and `setUniformValue(name, QVector2D, QVector3D or QVector4D)`

**Free function:** `QCursor_pos() → QPoint`

All the existing scalar versions (`move(x, y)`, `drawLine(x1, y1, x2, y2)`, `mapX`/`mapY`, and so on) are unchanged.