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DragFloat() added power parameter for logarithmic drag on both side o…
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…f zero #180
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@ocornut
ocornut committed Apr 12, 2015
1 parent f5ad362 commit 6ed06a8
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Showing 2 changed files with 33 additions and 15 deletions.
44 changes: 31 additions & 13 deletions imgui.cpp
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// ImGui library v1.38 WIP
// ImGui library v1.38 WIP
// See ImGui::ShowTestWindow() for sample code.
// Read 'Programmer guide' below for notes on how to setup ImGui in your codebase.
// Get latest version at https://github.com/ocornut/imgui
Expand Down Expand Up @@ -1145,7 +1145,7 @@ struct ImGuiState
ImGuiID ScalarAsInputTextId; // Temporary text input when CTRL+clicking on a slider, etc.
ImGuiStorage ColorEditModeStorage; // for user selection
ImGuiID ActiveComboID;
float DragCurrentValue;
float DragCurrentValue; // current dragged value, always float, not rounded by end-user precision settings
ImVec2 DragLastMouseDelta;
float DragSpeedScaleSlow;
float DragSpeedScaleFast;
Expand Down Expand Up @@ -5478,7 +5478,7 @@ bool ImGui::SliderInt4(const char* label, int v[4], int v_min, int v_max, const
}

// FIXME-WIP: Work in progress. May change API / behavior.
static bool DragScalarBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v_speed, float v_min, float v_max, int decimal_precision)
static bool DragScalarBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v_speed, float v_min, float v_max, int decimal_precision, float power)
{
ImGuiState& g = *GImGui;
ImGuiWindow* window = GetCurrentWindow();
Expand All @@ -5505,22 +5505,40 @@ static bool DragScalarBehavior(const ImRect& frame_bb, ImGuiID id, float* v, flo
const ImVec2 mouse_drag_delta = ImGui::GetMouseDragDelta(0, 1.0f);
if (fabsf(mouse_drag_delta.x - g.DragLastMouseDelta.x) > 0.0f)
{
float step = v_speed;
float speed = v_speed;
if (g.IO.KeyShift && g.DragSpeedScaleFast >= 0.0f)
step = v_speed * g.DragSpeedScaleFast;
speed = v_speed * g.DragSpeedScaleFast;
if (g.IO.KeyAlt && g.DragSpeedScaleSlow >= 0.0f)
step = v_speed * g.DragSpeedScaleSlow;
speed = v_speed * g.DragSpeedScaleSlow;

g.DragCurrentValue += (mouse_drag_delta.x - g.DragLastMouseDelta.x) * step;
float v_cur = g.DragCurrentValue;
float delta = (mouse_drag_delta.x - g.DragLastMouseDelta.x) * speed;
if (fabsf(power - 1.0f) > 0.001f)
{
// Logarithmic curve on both side of 0.0
float v0_abs = v_cur >= 0.0f ? v_cur : -v_cur;
float v0_sign = v_cur >= 0.0f ? 1.0f : -1.0f;
float v1 = powf(v0_abs, 1.0f / power) + (delta * v0_sign);
float v1_abs = v1 >= 0.0f ? v1 : -v1;
float v1_sign = v1 >= 0.0f ? 1.0f : -1.0f; // Crossed sign line
v_cur = powf(v1_abs, power) * v0_sign * v1_sign; // Reapply sign
}
else
{
v_cur += delta;
}
g.DragLastMouseDelta.x = mouse_drag_delta.x;

// Clamp
if (v_min < v_max)
g.DragCurrentValue = ImClamp(g.DragCurrentValue, v_min, v_max);
g.DragCurrentValue = ImClamp(v_cur, v_min, v_max);
g.DragCurrentValue = v_cur;

float new_value = RoundScalar(g.DragCurrentValue, decimal_precision);
if (*v != new_value)
// Round to user desired precision, then apply
v_cur = RoundScalar(v_cur, decimal_precision);
if (*v != v_cur)
{
*v = new_value;
*v = v_cur;
value_changed = true;
}
}
Expand All @@ -5534,7 +5552,7 @@ static bool DragScalarBehavior(const ImRect& frame_bb, ImGuiID id, float* v, flo
return value_changed;
}

bool ImGui::DragFloat(const char* label, float *v, float v_speed, float v_min, float v_max, const char* display_format)
bool ImGui::DragFloat(const char* label, float *v, float v_speed, float v_min, float v_max, const char* display_format, float power)
{
ImGuiState& g = *GImGui;
ImGuiWindow* window = GetCurrentWindow();
Expand Down Expand Up @@ -5586,7 +5604,7 @@ bool ImGui::DragFloat(const char* label, float *v, float v_speed, float v_min, f
ItemSize(total_bb, style.FramePadding.y);

// Actual drag behavior
const bool value_changed = DragScalarBehavior(frame_bb, id, v, v_speed, v_min, v_max, decimal_precision);
const bool value_changed = DragScalarBehavior(frame_bb, id, v, v_speed, v_min, v_max, decimal_precision, power);

// Display value using user-provided display format so user can add prefix/suffix/decorations to the value.
char value_buf[64];
Expand Down
4 changes: 2 additions & 2 deletions imgui.h
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Original file line number Diff line number Diff line change
Expand Up @@ -316,8 +316,8 @@ namespace ImGui

// Widgets: Drags (tip: ctrl+click on a drag box to input text)
// ImGui 1.38+ work-in-progress, may change name or API.
IMGUI_API bool DragFloat(const char* label, float* v, float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f"); // If v_max >= v_max we have no bound
IMGUI_API bool DragInt(const char* label, int* v, float v_speed = 1.0f, int v_min = 0, int v_max = 0, const char* display_format = "%.0f"); // If v_max >= v_max we have no bound
IMGUI_API bool DragFloat(const char* label, float* v, float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f", float power = 1.0f); // If v_max >= v_max we have no bound
IMGUI_API bool DragInt(const char* label, int* v, float v_speed = 1.0f, int v_min = 0, int v_max = 0, const char* display_format = "%.0f"); // If v_max >= v_max we have no bound

// Widgets: Input
IMGUI_API bool InputText(const char* label, char* buf, size_t buf_size, ImGuiInputTextFlags flags = 0, ImGuiTextEditCallback callback = NULL, void* user_data = NULL);
Expand Down

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