Preview zoom scales with window size, listed view scale doesn't change.

Panning doesn't seem to be happinging in screen space so when zoomed it doesn't track intuitively with mouse cursor.

Being able to zoom out below 100% then zoom at mouse cursor would be handy for navigating large images.

Mousewheel zoom with MMB pan would be nice.

Here's the relevant code from one of my projects for mouse-view-transform-as-I-like-it, feel free to steal (QTransform is just a 3X3 transform matrix):

void ImageEditor::rotateScaleAtPoint(QTransform &transform, const qreal rotation, const qreal scaling, const QPointF point)
{
const QPointF pointBefore = (transform.inverted()).map(point);
transform *= QTransform().scale(scaling, scaling) * QTransform().rotate(rotation);
const QPointF pointAfter = (transform.inverted()).map(point);
const QPointF offset = pointAfter - pointBefore;
transform = QTransform().translate(offset.x(), offset.y()) * transform;
}

bool ImageEditor::handleMouseEvent(const Qt::KeyboardModifiers modifiers, const Qt::MouseButton button, const QPoint pos)
{
const QPointF lastMouse = mouseTransform.map(lastMousePos);
const QPointF mousePos = mouseTransform.map(pos);
const QPointF pixelCoordF = viewTransform.inverted().map(QPointF(mousePos));
const QPoint pixelCoord(static_cast(floor(pixelCoordF.x())), static_cast(floor(pixelCoordF.y())));

const QSet states = mouseState.machine.configuration();
if (states.contains(&mouseState.leftToolState)) {
setDocumentModified();
}
else if (states.contains(&mouseState.leftPickState)) {
}
else if (states.contains(&mouseState.rightToolState)) {
}
else if (states.contains(&mouseState.rightPickState)) {
}
else if (states.contains(&mouseState.panState)) {
QPointF translation = QPointF();
translation += mousePos - lastMouse;
viewTransform *= QTransform().translate(translation.x(), translation.y());
update();
}
else if (states.contains(&mouseState.rotozoomState)) {
qreal scaling = QVector2D(mousePos).length() / QVector2D(lastMouse).length();
qreal rotation = qRadiansToDegrees(atan2(mousePos.y(), mousePos.x()) - atan2(lastMouse.y(), lastMouse.x()));
rotateScaleAtPoint(viewTransform, rotation, scaling, QPointF(0., 0.));
update();
}

lastMousePos = pos;
lastPixelCoord = pixelCoord;

return true;
}

void ImageEditor::wheelEvent(QWheelEvent *event)
{
const qreal delta = event->angleDelta().y() / (15.0 * 8.0);
const qreal scaling = pow(2, delta);
const qreal rotation = -15.0 * delta;

if (event->modifiers() == Qt::NoModifier) {
rotateScaleAtPoint(viewTransform, 0.0, scaling, mouseTransform.map(event->posF()));
update();
}
else if (event->modifiers() == Qt::ShiftModifier) {
rotateScaleAtPoint(viewTransform, rotation, 1.0, mouseTransform.map(event->posF()));
update();
}
event->accept();
}