ui: basic map scroller

2026-03-06 23:29:06 +02:00
parent 29d188969b
commit 1de621c743
68 changed files with 9861 additions and 118 deletions
@@ -0,0 +1,171 @@
+package world
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestWorldDeltaFixedToCanvasPx_RemainderAccumulatesPositive(t *testing.T) {
+	t.Parallel()
+
+	// zoom=1: px = (deltaWorldFp * 1000) / 1e6
+	// For deltaWorldFp=1, each step contributes 0 px with remainder,
+	// and after 1000 steps it must become 1 px total.
+	zoomFp := SCALE
+	var rem int64
+	sum := 0
+
+	for i := 0; i < 1000; i++ {
+		sum += worldDeltaFixedToCanvasPx(1, zoomFp, &rem)
+	}
+
+	require.Equal(t, 1, sum)
+}
+
+func TestWorldDeltaFixedToCanvasPx_RemainderAccumulatesNegative(t *testing.T) {
+	t.Parallel()
+
+	zoomFp := SCALE
+	var rem int64
+	sum := 0
+
+	for i := 0; i < 1000; i++ {
+		sum += worldDeltaFixedToCanvasPx(-1, zoomFp, &rem)
+	}
+
+	require.Equal(t, -1, sum)
+}
+
+func TestComputePanShiftPx_FirstCallRequiresFullRedraw(t *testing.T) {
+	t.Parallel()
+
+	w := NewWorld(10, 10)
+
+	params := RenderParams{
+		ViewportWidthPx:  100,
+		ViewportHeightPx: 80,
+		MarginXPx:        25,
+		MarginYPx:        20,
+		CameraXWorldFp:   5 * SCALE,
+		CameraYWorldFp:   5 * SCALE,
+		CameraZoom:       1.0,
+	}
+
+	_, _, err := w.ComputePanShiftPx(params)
+	require.ErrorIs(t, err, errIncrementalStateNotReady)
+}
+
+func TestComputePanShiftPx_ZoomOrViewportChangeForcesFullRedraw(t *testing.T) {
+	t.Parallel()
+
+	w := NewWorld(10, 10)
+
+	base := RenderParams{
+		ViewportWidthPx:  100,
+		ViewportHeightPx: 80,
+		MarginXPx:        25,
+		MarginYPx:        20,
+		CameraXWorldFp:   5 * SCALE,
+		CameraYWorldFp:   5 * SCALE,
+		CameraZoom:       1.0,
+	}
+	require.NoError(t, w.CommitFullRedrawState(base))
+
+	changed := base
+	changed.CameraZoom = 2.0
+
+	_, _, err := w.ComputePanShiftPx(changed)
+	require.ErrorIs(t, err, errIncrementalZoomMismatch)
+
+	changed2 := base
+	changed2.ViewportWidthPx = 101
+
+	_, _, err = w.ComputePanShiftPx(changed2)
+	require.ErrorIs(t, err, errIncrementalZoomMismatch)
+}
+
+func TestComputePanShiftPx_PanRightShiftsImageLeft(t *testing.T) {
+	t.Parallel()
+
+	w := NewWorld(10, 10)
+
+	params := RenderParams{
+		ViewportWidthPx:  100,
+		ViewportHeightPx: 80,
+		MarginXPx:        25,
+		MarginYPx:        20,
+		CameraXWorldFp:   5 * SCALE,
+		CameraYWorldFp:   5 * SCALE,
+		CameraZoom:       1.0,
+	}
+	require.NoError(t, w.CommitFullRedrawState(params))
+
+	// Move camera right by 1 world unit => world rect minX increases by 1 unit,
+	// so content moves left by 1px at zoom=1 => image shift should be -1.
+	params2 := params
+	params2.CameraXWorldFp += 1 * SCALE
+
+	dx, dy, err := w.ComputePanShiftPx(params2)
+	require.NoError(t, err)
+	require.Equal(t, -1, dx)
+	require.Equal(t, 0, dy)
+}
+
+func TestComputePanShiftPx_PanUpShiftsImageDown(t *testing.T) {
+	t.Parallel()
+
+	w := NewWorld(10, 10)
+
+	params := RenderParams{
+		ViewportWidthPx:  100,
+		ViewportHeightPx: 80,
+		MarginXPx:        25,
+		MarginYPx:        20,
+		CameraXWorldFp:   5 * SCALE,
+		CameraYWorldFp:   5 * SCALE,
+		CameraZoom:       1.0,
+	}
+	require.NoError(t, w.CommitFullRedrawState(params))
+
+	// Move camera up by 1 world unit => world rect minY decreases by 1 unit,
+	// so content moves down by 1px => image shift should be +1 in dy.
+	params2 := params
+	params2.CameraYWorldFp -= 1 * SCALE
+
+	dx, dy, err := w.ComputePanShiftPx(params2)
+	require.NoError(t, err)
+	require.Equal(t, 0, dx)
+	require.Equal(t, 1, dy)
+}
+
+func TestComputePanShiftPx_SubPixelPanAccumulatesToOnePixel(t *testing.T) {
+	t.Parallel()
+
+	w := NewWorld(10, 10)
+
+	params := RenderParams{
+		ViewportWidthPx:  100,
+		ViewportHeightPx: 80,
+		MarginXPx:        25,
+		MarginYPx:        20,
+		CameraXWorldFp:   5 * SCALE,
+		CameraYWorldFp:   5 * SCALE,
+		CameraZoom:       1.0,
+	}
+	require.NoError(t, w.CommitFullRedrawState(params))
+
+	// Pan camera right by 0.001 world units (1 fixed-point) 1000 times.
+	// At zoom=1 this should accumulate to a 1px content shift left, hence image shift -1.
+	totalDx := 0
+	p := params
+	for i := 0; i < 1000; i++ {
+		p.CameraXWorldFp += 1
+		dx, dy, err := w.ComputePanShiftPx(p)
+		require.NoError(t, err)
+		require.Equal(t, 0, dy)
+		totalDx += dx
+	}
+
+	require.Equal(t, -1, totalDx)
+}