Fix settings slider knob unclickable at track minimum (#242)

The interact rect started at trackLeft, which is also the min-value knob center, so the left half of the disc missed hit-testing. Expand the hit pad by the 8px knob radius.

Author: justnullname

QuickView/SettingsOverlay.cpp

@@ -3644,9 +3644,10 @@ void SettingsOverlay::Render(ID2D1DeviceContext* pRT, float winW, float winH) {
                   const float valueW = 80.0f * s;
                   const float buttonW = 28.0f * s;
 
-                  // Standard slider rect (Track + Padding)
+                  // Track + right pad + knob radius so a min-value knob is still hittable.
+                  const float knobPad = QuickView::SliderKnobHitRadius();
                   item.interactRect = D2D1::RectF(
-                      controlRect.right - (trackW + padding), item.rect.top,
+                      controlRect.right - (trackW + padding) - knobPad, item.rect.top,
                       controlRect.right, item.rect.bottom);
 
                   if (item.onReset) {
@@ -4411,6 +4412,19 @@ SettingsAction SettingsOverlay::OnMouseMove(float x, float y) {
                     }
                 }
 
+                // Knob at min sits half outside the track; test it even if interactRect is stale.
+                if (item.type == OptionType::Slider && !item.isDisabled) {
+                    const float val = item.pFloatVal ? *item.pFloatVal : item.minVal;
+                    const QuickView::SliderGeom g = QuickView::ComputeSliderGeom(
+                        item.rect.right, item.rect.top, item.rect.bottom,
+                        m_uiScale, val, item.minVal, item.maxVal);
+                    if (QuickView::HitTestSlider(g, x, y, item.rect.top, item.rect.bottom, item.rect.right)) {
+                        m_pHoverItem = &item;
+                        item.isHovered = true;
+                        g_currentCursor = ::LoadCursor(NULL, IDC_HAND);
+                    }
+                }
+
                 bool inR1 = (x >= item.interactRect.left && x <= item.interactRect.right &&
                            y >= item.interactRect.top && y <= item.interactRect.bottom);
                 bool inR2 = (x >= item.interactRect2.left && x <= item.interactRect2.right &&
@@ -4429,7 +4443,7 @@ SettingsAction SettingsOverlay::OnMouseMove(float x, float y) {
                         const QuickView::SliderGeom g = QuickView::ComputeSliderGeom(
                             item.rect.right, item.rect.top, item.rect.bottom,
                             m_uiScale, val, item.minVal, item.maxVal);
-                        if (x >= g.trackLeft && x <= item.rect.right && y >= item.rect.top && y <= item.rect.bottom) {
+                        if (QuickView::HitTestSlider(g, x, y, item.rect.top, item.rect.bottom, item.rect.right)) {
                             g_currentCursor = ::LoadCursor(NULL, IDC_HAND);
                             m_pHoverItem = &item;
                         }

QuickView/SettingsSliderMath.h

@@ -15,6 +15,18 @@ struct SliderGeom {
     float TrackWidth() const { return trackRight - trackLeft; }
 };
 
+// Draw uses an 8px hovered knob. Hit tests must include the full disc,
+// including the half that sits left of trackLeft when value == min.
+inline float SliderKnobHitRadius() { return 8.f; }
+
+inline bool HitTestSlider(const SliderGeom& g, float x, float y,
+                          float itemTop, float itemBottom, float itemRight) {
+    const float r = SliderKnobHitRadius();
+    const float left = (std::min)(g.trackLeft, g.knobX) - r;
+    const float right = (std::max)(itemRight, g.trackRight + r);
+    return x >= left && x <= right && y >= itemTop && y <= itemBottom;
+}
+
 inline float QuantizeSliderValue(float v, float minV, float maxV, float step) {
     if (maxV < minV) std::swap(minV, maxV);
     v = std::clamp(v, minV, maxV);

tests/SettingsSliderMathTests.cpp

@@ -26,6 +26,13 @@ TEST(SettingsSliderMath, IntegerStepHits375) {
     EXPECT_FLOAT_EQ(QuantizeSliderValue(640.f, 190.f, 800.f, 1.f), 640.f);
 }
 
+TEST(SettingsSliderMath, MinKnobIsHittableLeftOfTrack) {
+    const auto g = ComputeSliderGeom(400.f, 10.f, 40.f, 1.f, 190.f, 190.f, 800.f);
+    EXPECT_FLOAT_EQ(g.knobX, g.trackLeft);
+    EXPECT_TRUE(QuickView::HitTestSlider(g, g.knobX - 6.f, 25.f, 10.f, 40.f, 400.f));
+    EXPECT_FALSE(QuickView::HitTestSlider(g, g.knobX - 20.f, 25.f, 10.f, 40.f, 400.f));
+}
+
 TEST(SettingsSliderMath, EffectiveStepMatchesWheelHeuristic) {
     EXPECT_FLOAT_EQ(EffectiveStep(0.f, 10.f, 100.f, L"%.0f %%"), 1.f);
     EXPECT_FLOAT_EQ(EffectiveStep(0.f, 0.f, 1.f, L"%.0f %%"), 0.01f);