Nav: DragBehavior: Adjust minimum step to displayed precision when us…

…ing navigation (#323, #180)

imgui.cpp

@@ -7662,6 +7662,8 @@ bool ImGui::DragBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v_s
 
             if (v_speed == 0.0f && (v_max - v_min) != 0.0f && (v_max - v_min) < FLT_MAX)
                 v_speed = (v_max - v_min) * g.DragSpeedDefaultRatio;
+            if (g.ActiveIdSource == ImGuiInputSource_Nav)
+                v_speed = ImMax(v_speed, GetMinimumStepAtDecimalPrecision(decimal_precision));
 
             float v_cur = g.DragCurrentValue;
             const ImVec2 mouse_drag_delta = GetMouseDragDelta(0, 1.0f);

imgui.h

@@ -282,6 +282,7 @@ namespace ImGui
 
     // Widgets: Drags (tip: ctrl+click on a drag box to input with keyboard. manually input values aren't clamped, can go off-bounds)
     // For all the Float2/Float3/Float4/Int2/Int3/Int4 versions of every functions, remember than a 'float v[3]' function argument is the same as 'float* v'. You can pass address of your first element out of a contiguous set, e.g. &myvector.x
+    // Speed are per-pixel of mouse movement (v_speed=0.2f: mouse needs to move by 5 pixels to increase value by 1). For gamepad/keyboard navigation, minimum speed is Max(v_speed, minimum_step_at_given_precision).
     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_min >= v_max we have no bound
     IMGUI_API bool          DragFloat2(const char* label, float v[2], float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f", float power = 1.0f);
     IMGUI_API bool          DragFloat3(const char* label, float v[3], float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f", float power = 1.0f);