place the selection panel beside what it describes

src/test/CMakeLists.txt

@@ -14,6 +14,7 @@ add_files(
     TunnelCompletionTest.cpp
     WorldCoordinatesTest.cpp
     WorldCameraTest.cpp
+    FloatingPanelPlacementTest.cpp
     SelectionControllerTest.cpp
     BuildModeControllerTest.cpp
     ControlActionTest.cpp

src/test/FloatingPanelPlacementTest.cpp

@@ -0,0 +1,156 @@
+#include "catch.hpp"
+
+#include <vector>
+
+#include <QRect>
+
+#include "FloatingPanelPlacement.h"
+
+// The band every case below places into: 1000x600, so a bottom edge of 599.
+static QRect makeBand()
+{
+    return QRect(0, 0, 1000, 600);
+}
+
+static const int kMarginPx = 8;
+
+TEST_CASE("With nothing in the way a widget may use the whole band", "[layout]")
+{
+    // REQ-UI-SELECTION-PANEL: the band's own bottom is the limit when no other floating
+    // widget has been placed yet.
+    REQUIRE(getAvailableBottomPx(makeBand(), {}, 0, 999, kMarginPx) == 599);
+}
+
+TEST_CASE("A widget in the same column pushes the bottom above it", "[layout]")
+{
+    // The build button bar sitting at the bottom center leaves the space above it, less
+    // the margin kept between the two (REQ-UI-BUILD-BAR).
+    const std::vector<QRect> occupied = { QRect(400, 520, 200, 72) };
+    REQUIRE(getAvailableBottomPx(makeBand(), occupied, 350, 650, kMarginPx) == 511);
+}
+
+TEST_CASE("A widget beside the column does not shorten it", "[layout]")
+{
+    // The controls panel in the bottom-left corner is not in the way of a panel standing
+    // at the right edge, however tall it is (REQ-UI-CONTROLS-PANEL).
+    const std::vector<QRect> occupied = { QRect(0, 100, 200, 499) };
+    REQUIRE(getAvailableBottomPx(makeBand(), occupied, 700, 999, kMarginPx) == 599);
+
+    // Touching columns do count as meeting: the panel starts exactly where the widget
+    // ends, which is an overlap of one pixel.
+    REQUIRE(getAvailableBottomPx(makeBand(), occupied, 199, 999, kMarginPx) == 91);
+}
+
+TEST_CASE("The topmost widget in the column decides", "[layout]")
+{
+    // Several widgets meet the column: the one that reaches highest is the binding one,
+    // whatever order they are given in.
+    const std::vector<QRect> occupied = { QRect(400, 520, 200, 72),
+                                          QRect(0, 300, 500, 299),
+                                          QRect(900, 560, 100, 40) };
+    REQUIRE(getAvailableBottomPx(makeBand(), occupied, 450, 550, kMarginPx) == 291);
+}
+
+TEST_CASE("An empty rectangle occupies nothing", "[layout]")
+{
+    // A floating widget that is hidden contributes a null rect rather than being left
+    // out of the pass.
+    const std::vector<QRect> occupied = { QRect(), QRect(400, 520, 200, 0) };
+    REQUIRE(getAvailableBottomPx(makeBand(), occupied, 0, 999, kMarginPx) == 599);
+}
+
+TEST_CASE("A widget filling the column leaves nothing", "[layout]")
+{
+    // The caller is expected to notice that the space left is not positive rather than
+    // being handed a floor of its own.
+    const std::vector<QRect> occupied = { QRect(0, 0, 1000, 600) };
+    REQUIRE(getAvailableBottomPx(makeBand(), occupied, 0, 999, kMarginPx) == -9);
+}
+
+// ---------------------------------------------------------------------------
+// Which side of the selection the panel takes
+// ---------------------------------------------------------------------------
+
+TEST_CASE("The panel stands to the right of the selection where it fits", "[layout]")
+{
+    // REQ-UI-SELECTION-PANEL: right of the anchor is the first choice.
+    REQUIRE(chooseSide(makeBand(), QRect(100, 100, 60, 60), 300, kMarginPx)
+            == PanelSide::Right);
+}
+
+TEST_CASE("The panel goes left when the right cannot hold it", "[layout]")
+{
+    // A selection near the right edge leaves 100 px there, not enough for a 300 px
+    // panel, and the left is wide open.
+    REQUIRE(chooseSide(makeBand(), QRect(880, 100, 20, 60), 300, kMarginPx)
+            == PanelSide::Left);
+}
+
+TEST_CASE("Fitting on neither side, the panel takes the roomier one", "[layout]")
+{
+    // A bounding box spanning most of the view: 192 px free on the left, 92 on the
+    // right, and a 300 px panel fits in neither. It covers as little as it can.
+    REQUIRE(chooseSide(makeBand(), QRect(200, 100, 700, 200), 300, kMarginPx)
+            == PanelSide::Left);
+    REQUIRE(chooseSide(makeBand(), QRect(100, 100, 700, 200), 300, kMarginPx)
+            == PanelSide::Right);
+}
+
+// ---------------------------------------------------------------------------
+// Where it then stands
+// ---------------------------------------------------------------------------
+
+TEST_CASE("The panel sits beside the anchor with its top edges aligned", "[layout]")
+{
+    // REQ-UI-SELECTION-PANEL: separated by the margin, growing away from the selection,
+    // top edge on the anchor's top edge.
+    const QRect placed = placeBesideAnchor(makeBand(), QRect(100, 120, 60, 60),
+                                           PanelSide::Right, QSize(300, 200), {},
+                                           kMarginPx);
+    REQUIRE(placed == QRect(168, 120, 300, 200));
+
+    const QRect placedLeft = placeBesideAnchor(makeBand(), QRect(500, 120, 60, 60),
+                                               PanelSide::Left, QSize(300, 200), {},
+                                               kMarginPx);
+    REQUIRE(placedLeft == QRect(192, 120, 300, 200));
+}
+
+TEST_CASE("A panel that would hang below the view is lifted", "[layout]")
+{
+    // Top-aligning with a selection low in the view would put the panel's bottom past
+    // the band, so it rises until it fits rather than overrunning it.
+    const QRect placed = placeBesideAnchor(makeBand(), QRect(100, 500, 60, 60),
+                                           PanelSide::Right, QSize(300, 200), {},
+                                           kMarginPx);
+    REQUIRE(placed == QRect(168, 400, 300, 200));
+}
+
+TEST_CASE("A panel standing over another widget rises above it", "[layout]")
+{
+    // The controls panel in the bottom-left is in the way of a panel placed to the left
+    // of a selection: it clears the top of it by the margin (REQ-UI-CONTROLS-PANEL).
+    const std::vector<QRect> occupied = { QRect(0, 300, 260, 300) };
+    const QRect placed = placeBesideAnchor(makeBand(), QRect(500, 250, 60, 60),
+                                           PanelSide::Left, QSize(300, 200), occupied,
+                                           kMarginPx);
+    REQUIRE(placed == QRect(192, 92, 300, 200));
+}
+
+TEST_CASE("A panel taller than the space left is capped", "[layout]")
+{
+    // Capping is the caller's cue to scroll: it asked for 700 and got what there was.
+    const QRect placed = placeBesideAnchor(makeBand(), QRect(100, 100, 60, 60),
+                                           PanelSide::Right, QSize(300, 700), {},
+                                           kMarginPx);
+    REQUIRE(placed == QRect(168, 0, 300, 600));
+}
+
+TEST_CASE("A panel that fits on neither side is pushed inside the view", "[layout]")
+{
+    // The one case where it covers part of the selection (REQ-UI-SELECTION-PANEL): it
+    // stands as far from the anchor as the band allows, not off the edge of it.
+    const QRect placed = placeBesideAnchor(makeBand(), QRect(100, 100, 700, 200),
+                                           PanelSide::Right, QSize(300, 200), {},
+                                           kMarginPx);
+    REQUIRE(placed == QRect(700, 100, 300, 200));
+}