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Fix value-axis jumps when enabling drag modifiers #34

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Merged
imakris merged 1 commit into from
Nov 11, 2026
Merged

Fix value-axis jumps when enabling drag modifiers #34

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4 changes: 2 additions & 2 deletions src/qt/plot_interaction_item.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -294,9 +294,9 @@ void Plot_interaction_item::mouseMoveEvent(QMouseEvent* event)
const bool ctrl_held = mods & Qt::ControlModifier;
const bool alt_held = mods & Qt::AltModifier;

const qreal dy = y - m_drag_last_y;
m_drag_last_y = y;
if (ctrl_held || alt_held) {
const qreal dy = y - m_drag_last_y;
m_drag_last_y = y;
m_plot_widget->adjust_v_from_mouse_diff(usable_height(), dy);
}

Expand Down
124 changes: 124 additions & 0 deletions tests/test_plot_interaction_item.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,8 @@ class test_interaction_item_t : public plot::Plot_interaction_item
public:
using plot::Plot_interaction_item::wheelEvent;
using plot::Plot_interaction_item::mousePressEvent;
using plot::Plot_interaction_item::mouseMoveEvent;
using plot::Plot_interaction_item::mouseReleaseEvent;
using plot::Plot_interaction_item::mouseDoubleClickEvent;
};

Expand Down Expand Up @@ -444,6 +446,125 @@ bool test_wheel_zoom_handles_near_zero_value_range()
return true;
}

bool check_drag_modifier_consumes_only_new_vertical_movement(Qt::KeyboardModifier modifier)
{
for (const bool shared_time_axis : {false, true}) {
plot::Plot_time_axis time_axis;
plot::Plot_widget widget;
if (shared_time_axis) {
widget.set_time_axis(&time_axis);
}
configure_view(widget, 1000, 2000, 0.0f, 100.0f);
widget.set_available_t_range(0, 3000);
widget.set_v_auto(true);

test_interaction_item_t item;
item.set_plot_widget(&widget);
item.setSize(QSizeF(1000.0 + widget.vbar_width_qml(), 500.0 + widget.reserved_height()));
int clicks = 0;
QObject::connect(&item, &plot::Plot_interaction_item::mouse_clicked,
[&clicks](qreal, qreal) { ++clicks; });

QMouseEvent press(QEvent::MouseButtonPress, QPointF(100.0, 100.0), QPointF(100.0, 100.0),
Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
item.mousePressEvent(&press);
TEST_ASSERT(press.isAccepted(), "main plot press should begin the gesture");

struct move_t { qreal x; qreal y; bool modified; double applied_y; };
const move_t moves[] = {
{150.0, 200.0, false, 0.0},
{151.0, 201.0, true, 1.0}, // Enable after 100 unmodified vertical pixels.
{170.0, 280.0, false, 1.0},
{170.0, 280.0, true, 1.0}, // Re-enable without movement.
{171.0, 281.0, true, 2.0},
{150.0, 100.0, false, 2.0}, // Cross the original y while remaining outside click slop.
{150.0, 100.0, true, 2.0},
{151.0, 99.0, true, 1.0},
};
qreal previous_x = 100.0;
qint64 expected_time_min = 1000;
for (const auto& move : moves) {
const Qt::KeyboardModifiers modifiers = move.modified ? modifier : Qt::NoModifier;
QMouseEvent event(QEvent::MouseMove, QPointF(move.x, move.y), QPointF(move.x, move.y),
Qt::NoButton, Qt::LeftButton, modifiers);
item.mouseMoveEvent(&event);
const double expected_min = move.applied_y / 5.0;
if (!nearly_equal(widget.v_min(), expected_min, 1e-5)) {
std::cerr << "modifier=" << static_cast<int>(modifier) << " y=" << move.y
<< " v_min=" << widget.v_min() << " expected=" << expected_min << '\n';
}
TEST_ASSERT(nearly_equal(widget.v_min(), expected_min, 1e-5) &&
nearly_equal(widget.v_max(), 100.0 + expected_min, 1e-5),
"enabling a drag modifier must consume only new vertical movement");
TEST_ASSERT(widget.v_auto() == (move.applied_y == 0.0),
"only value-axis movement should leave automatic scaling");

if (!move.modified || modifier != Qt::AltModifier) {
expected_time_min -= static_cast<qint64>(move.x - previous_x);
}
previous_x = move.x;
TEST_ASSERT(widget.t_min() == expected_time_min && widget.t_max() == expected_time_min + 1000,
"Ctrl pans both axes while Alt keeps time unchanged, without replay on release");
}
QMouseEvent release(QEvent::MouseButtonRelease, QPointF(151.0, 99.0), QPointF(151.0, 99.0),
Qt::LeftButton, Qt::NoButton, modifier);
item.mouseReleaseEvent(&release);
TEST_ASSERT(clicks == 0, "changing modifiers must not turn an engaged drag into a click");
}
return true;
}

bool test_ctrl_drag_consumes_only_new_vertical_movement()
{
return check_drag_modifier_consumes_only_new_vertical_movement(Qt::ControlModifier);
}

bool test_alt_drag_consumes_only_new_vertical_movement()
{
return check_drag_modifier_consumes_only_new_vertical_movement(Qt::AltModifier);
}

bool test_drag_modifier_preserves_initial_click_tolerance()
{
for (const auto modifier : {Qt::ControlModifier, Qt::AltModifier}) {
plot::Plot_widget widget;
configure_view(widget, 1000, 2000, 0.0f, 100.0f);
test_interaction_item_t item;
item.set_plot_widget(&widget);
item.setSize(QSizeF(1000.0 + widget.vbar_width_qml(), 500.0 + widget.reserved_height()));
int clicks = 0;
QObject::connect(&item, &plot::Plot_interaction_item::mouse_clicked,
[&clicks](qreal, qreal) { ++clicks; });

QMouseEvent press(QEvent::MouseButtonPress, QPointF(100.0, 100.0), QPointF(100.0, 100.0),
Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
item.mousePressEvent(&press);
for (const auto modifiers : {Qt::NoModifier, modifier}) {
QMouseEvent move(QEvent::MouseMove, QPointF(100.0, 102.0), QPointF(100.0, 102.0),
Qt::NoButton, Qt::LeftButton, modifiers);
item.mouseMoveEvent(&move);
}
TEST_ASSERT(widget.v_min() == 0.0f && widget.v_max() == 100.0f &&
widget.t_min() == 1000 && widget.t_max() == 2000,
"modifier changes inside initial click tolerance must not pan either axis");
QMouseEvent release(QEvent::MouseButtonRelease, QPointF(100.0, 102.0), QPointF(100.0, 102.0),
Qt::LeftButton, Qt::NoButton, modifier);
item.mouseReleaseEvent(&release);
TEST_ASSERT(clicks == 1, "movement within initial tolerance must remain a click");

item.mousePressEvent(&press);
QMouseEvent slop(QEvent::MouseMove, QPointF(100.0, 102.0), QPointF(100.0, 102.0),
Qt::NoButton, Qt::LeftButton, Qt::NoModifier);
item.mouseMoveEvent(&slop);
QMouseEvent drag(QEvent::MouseMove, QPointF(100.0, 105.0), QPointF(100.0, 105.0),
Qt::NoButton, Qt::LeftButton, modifier);
item.mouseMoveEvent(&drag);
TEST_ASSERT(widget.v_min() == 1.0f && widget.v_max() == 101.0f,
"the first engaged move must preserve the full displacement from the press");
}
return true;
}

bool test_vertical_interaction_minimum_preserves_ranges()
{
plot::Plot_widget widget;
Expand Down Expand Up @@ -1548,6 +1669,9 @@ int main(int argc, char** argv)
RUN_TEST(test_zoom_math_handles_zero_velocity);
RUN_TEST(test_wheel_event_uses_platform_pixel_policy);
RUN_TEST(test_wheel_zoom_handles_near_zero_value_range);
RUN_TEST(test_ctrl_drag_consumes_only_new_vertical_movement);
RUN_TEST(test_alt_drag_consumes_only_new_vertical_movement);
RUN_TEST(test_drag_modifier_preserves_initial_click_tolerance);
RUN_TEST(test_vertical_interaction_minimum_preserves_ranges);
RUN_TEST(test_restoring_autoscale_cancels_vertical_zoom_inertia);
RUN_TEST(test_time_wheel_preserves_vertical_scaling_mode);
Expand Down
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