map_controls

Overview

The floating buttons both map surfaces overlay on their maps: a shared button base, four glyphs, and the corner-stacking helper. It is a sibling of map_render rather than part of it because these are QWidgets and map_render deliberately holds none; it sits after map_render in libs/CMakeLists.txt for reading order only, and links only Qt. The dashboard’s map widget and scope’s map panel both link it, and neither may reach into the other’s tree for a button again.

Everything here is chrome. The zoom, the recentre, the orientation cycle and the view-mode toggle belong to the host; the buttons emit clicks, and the compass emits a bearing while dragged.

Public headers

Header	Declares
`map_controls/map_button.h`	`MapButton`, the `QAbstractButton` base with `kSize`, `kMargin`, `kSpacing`, the `paintGlyph()` hook and `setEmphasis()`; `layOutStack()`.
`map_controls/recentre_button.h`	`RecentreButton`, shown only once the user has dragged the camera away.
`map_controls/compass_button.h`	`CompassButton` with `setBearing()` and the `bearingDragged(double)` signal.
`map_controls/view_mode_button.h`	`ViewModeButton` with `setPerspective()`.
`map_controls/zoom_button.h`	`ZoomButton` with `Direction::In` / `Direction::Out`; auto-repeats while held.

Using it

Link the map_controls target. Construct each button as a child of the embedder with the style’s label colours, connect clicked, and lay them out again whenever the host resizes or a button shows or hides. This is libs/dashboard_widgets/widgets/map/map_widget.cpp; apps/scope/panels/map does the same with a different stacking order.

const QColor glyph = qt_helpers::toQColor(mConfig.style.label_text);
const QColor disc = qt_helpers::toQColor(mConfig.style.label_halo);
mRecentre = new map_controls::RecentreButton(glyph, disc, this);
mCompass = new map_controls::CompassButton(glyph, disc, this);
mZoomIn = new map_controls::ZoomButton(map_controls::ZoomButton::Direction::In, glyph, disc, this);
connect(mRecentre, &QAbstractButton::clicked, this, &MapWidget::recentreCamera);
connect(mCompass, &map_controls::CompassButton::bearingDragged, this, &MapWidget::setManualBearing);

// on resize, and whenever a button shows or hides
map_controls::layOutStack({ mRecentre, mZoomOut, mZoomIn, mViewMode, mCompass },
                          QSize(width(), height()), Qt::BottomRightCorner);

Behaviour worth knowing

These are real QAbstractButtons rather than rectangles painted into the host’s paintEvent, for three reasons that are each small and together decisive: hover and press states come for free, the editor already makes child widgets mouse-transparent in edit mode so a button cannot swallow a selection drag, and each one appears in ui_snapshot as an addressable widget rather than a coordinate the agent interface has to be told about. They paint themselves because there is no icon pipeline in this tree.

The button takes the style’s label text and halo colours rather than colours of its own; that pair was already chosen to stay readable over water and motorway alike. kSize is 34 logical pixels, sized for a finger on a dashboard.

layOutStack() stacks nearest the corner first, kSpacing apart, and hidden buttons take no slot, so a transient button leaves no hole; pass every button and call again when one shows or hides. Both current users stack vertically; horizontal is not implemented.

The compass needle draws at minus the camera bearing, which is where north is on screen. Dragging it spins the map, with bearingDragged emitted per move and nothing on release; confining rotation to the button is what keeps it from fighting the pan gesture. When the map is effectively north-up the button de-emphasises to kDeEmphasized rather than hiding, because it is the only door into heading-up. The view-mode glyph shows the view a press would give, not the current one; showing the current state reads as a broken toggle.

The buttons must be children of the embedder, not of the map_surface widget. The surface is transparent for mouse events and Qt’s hit test does not descend into it, so a button parented there draws and is never clickable. The headers are listed as sources in CMakeLists.txt for AUTOMOC; leave one out and findChild<>() on that type fails to link.

Tests

There is no test target in libs/map_controls. The buttons are exercised through the gui-labelled tests of their two hosts, map_test_widget in libs/dashboard_widgets/widgets/map and the map panel tests under apps/scope/tests.