Make NumberInput more tolerant to errors

src/components/fields/PropertyGroup.jsx

@@ -40,7 +40,7 @@ export default class PropertyGroup extends React.Component {
 
       const paint = this.props.layer.paint || {}
       const layout = this.props.layer.layout || {}
-      const fieldValue = paint[fieldName] || layout[fieldName]
+      const fieldValue = fieldName in paint ? paint[fieldName] : layout[fieldName]
 
       return <ZoomSpecField
         onChange={this.onPropertyChange.bind(this)}

src/components/inputs/NumberInput.jsx

@@ -11,38 +11,71 @@ class NumberInput extends React.Component {
     onChange: React.PropTypes.func,
   }
 
-  onChange(e) {
-    const value = parseFloat(e.target.value)
-    /*TODO: we can do range validation already here?
-    if(this.props.min && value < this.props.min) return
-    if(this.props.max && value > this.props.max) return
-    */
+  constructor(props) {
+    super(props)
+    this.state = {
+      value: props.value
+    }
+  }
 
-    if(isNaN(value)) {
-      this.props.onChange(this.props.default)
-    } else {
+  componentWillReceiveProps(nextProps) {
+    this.setState({ value: nextProps.value })
+  }
+
+  changeValue(newValue) {
+    const value = parseFloat(newValue)
+
+    const hasChanged = this.state.value !== value
+    if(this.isValid(value) && hasChanged) {
       this.props.onChange(value)
+    } else {
+      this.setState({ value: newValue })
+    }
+  }
+
+  isValid(v) {
+    const value = parseFloat(v)
+    if(isNaN(value)) {
+      return false
+    }
+
+    if(!isNaN(this.props.min) && value < this.props.min) {
+      return false
+    }
+
+    if(!isNaN(this.props.max) && value > this.props.max) {
+      return false
+    }
+
+    return true
+  }
+
+  resetValue() {
+    // Reset explicitly to default value if value has been cleared
+    if(this.state.value === "") {
+      return this.changeValue(this.props.default)
+    }
+
+    // If set value is invalid fall back to the last valid value from props or at last resort the default value
+    if(!this.isValid(this.state.value)) {
+      if(this.isValid(this.props.value)) {
+        this.changeValue(this.props.value)
+      } else {
+        this.changeValue(this.props.default)
+      }
     }
   }
 
   render() {
-    let stepSize = null
-    if(this.props.max && this.props.min) {
-      stepSize = (this.props.max - this.props.min) / 10
-    }
-
     return <input
       style={{
         ...input.input,
         ...this.props.style
       }}
-      type={"number"}
-      min={this.props.min}
-      max={this.props.max}
-      step={stepSize}
       placeholder={this.props.default}
-      value={this.props.value}
-      onChange={this.onChange.bind(this)}
+      value={this.state.value}
+      onChange={e => this.changeValue(e.target.value)}
+      onBlur={this.resetValue.bind(this)}
     />
   }
 }