Relax checks on character entry in numeric validators

We can't perform the check for the invalid number in IsCharOk() because
it's perfectly normal for the number to be temporarily invalid while
it's being entered and, worse, sometimes this can't be avoided at all
and the existing behaviour prevented the user from entering _anything_
into a control limited to the values between 10 and 20.

Do ensure that the control still has a correct value after losing focus.

See #12968, #23561.

(combined cherry pick of c269932c4e,
dccddcdd59 and
1c16055713 from master)

docs/changes.txt

@@ -260,6 +260,7 @@ All (GUI):
 - Fix return value of wxAuiToolBarItem::GetDisabledBitmap() (taler21, #23666).
 - Fix buffer overflow in wxHTMLDataObject::GetDataHere() (mcorino, #23660).
 - Fix crash when loading some mal-formed GIFs (PB, #23409).
+- Relax checks on character entry in numeric validators (#12968, #23561).
 
 wxGTK:
 

include/wx/valnum.h

@@ -101,8 +101,9 @@ private:
     // this function.
     virtual bool IsCharOk(const wxString& val, int pos, wxChar ch) const = 0;
 
-    // NormalizeString the contents of the string if it's a valid number, return
-    // empty string otherwise.
+    // Return the canonical form of the number corresponding to the contents of
+    // the string: if the input string is invalid, return a string representing
+    // some valid value.
     virtual wxString NormalizeString(const wxString& s) const = 0;
 
 
@@ -239,8 +240,23 @@ protected:
     virtual wxString NormalizeString(const wxString& s) const wxOVERRIDE
     {
         LongestValueType value;
-        return BaseValidator::FromString(s, &value) ? NormalizeValue(value)
-                                                    : wxString();
+        if ( !BaseValidator::FromString(s, &value) )
+        {
+            // We don't have any valid number at all, just arbitrarily decide
+            // to return the minimum value.
+            value = static_cast<LongestValueType>(m_min);
+        }
+        else if ( !this->IsInRange(value) )
+        {
+            // We do have a value, but it's out of range: clamp it to the
+            // closest limit.
+            if ( value > static_cast<LongestValueType>(m_max) )
+                value = static_cast<LongestValueType>(m_max);
+            else
+                value = static_cast<LongestValueType>(m_min);
+        }
+
+        return NormalizeValue(value);
     }
 
     virtual bool CanBeNegative() const wxOVERRIDE { return m_min < 0; }

src/common/valnum.cpp

@@ -264,19 +264,19 @@ wxIntegerValidatorBase::FromString(const wxString& s,
 }
 
 bool
-wxIntegerValidatorBase::IsCharOk(const wxString& val, int pos, wxChar ch) const
+wxIntegerValidatorBase::IsCharOk(const wxString& WXUNUSED(val),
+                                 int WXUNUSED(pos),
+                                 wxChar ch) const
 {
     // We only accept digits here (remember that '-' is taken care of by the
     // base class already).
     if ( ch < '0' || ch > '9' )
         return false;
 
-    // And the value after insertion needs to be in the defined range.
-    LongestValueType value;
-    if ( !FromString(GetValueAfterInsertingChar(val, pos, ch), &value) )
-        return false;
-
-    return IsInRange(value);
+    // Accept anything that looks like a number here, notably do _not_ call
+    // IsInRange() because this would prevent entering any digits in an
+    // initially empty control limited to the values between "10" and "20".
+    return true;
 }
 
 // ============================================================================
@@ -342,7 +342,8 @@ wxFloatingPointValidatorBase::IsCharOk(const wxString& val,
     if ( ch < '0' || ch > '9' )
         return false;
 
-    // Check whether the value we'd obtain if we accepted this key is correct.
+    // Check whether the value we'd obtain if we accepted this key passes some
+    // basic checks.
     const wxString newval(GetValueAfterInsertingChar(val, pos, ch));
 
     LongestValueType value;
@@ -354,8 +355,9 @@ wxFloatingPointValidatorBase::IsCharOk(const wxString& val,
     if ( posSep != wxString::npos && newval.length() - posSep - 1 > m_precision )
         return false;
 
-    // Finally check whether it is in the range.
-    return IsInRange(value);
+    // Note that we do _not_ check if it's in range here, see the comment in
+    // wxIntegerValidatorBase::IsCharOk().
+    return true;
 }
 
 #endif // wxUSE_VALIDATORS && wxUSE_TEXTCTRL

tests/validators/valnum.cpp

@@ -343,9 +343,27 @@ TEST_CASE_METHOD(NumValidatorTestCase, "ValNum::Interactive", "[valnum]")
     wxYield();
     CHECK( text2->GetValue() == "9" );
 
+    // Entering a value which is out of range is allowed.
     sim.Char('9');
     wxYield();
-    CHECK( text2->GetValue() == "9" );
+    CHECK( text2->GetValue() == "99" );
+
+    // But it must be clamped to the valid range on focus loss.
+    m_text->SetFocus();
+    wxYield();
+    CHECK( text2->GetValue() == "10.000" );
+
+    // Repeat the test with a too small invalid value.
+    text2->Clear();
+    text2->SetFocus();
+
+    sim.Text("-22");
+    wxYield();
+    CHECK( text2->GetValue() == "-22" );
+
+    m_text->SetFocus();
+    wxYield();
+    CHECK( text2->GetValue() == "-10.000" );
 }
 
 #endif // wxUSE_UIACTIONSIMULATOR