feat: have basic scaling amount input working

5 files changed, 131 insertions, 52 deletions

diff --git a/packages/instant/src/components/asset_amount_input.tsx b/packages/instant/src/components/asset_amount_input.tsx
index c03ef1cf3..0b22c889c 100644
--- a/packages/instant/src/components/asset_amount_input.tsx
+++ b/packages/instant/src/components/asset_amount_input.tsx
@@ -7,33 +7,62 @@ import { ERC20Asset } from '../types';
 import { assetUtils } from '../util/asset';
 import { util } from '../util/util';
 
-import { AmountInput, AmountInputProps } from './amount_input';
+import { ScalingAmountInput } from './scaling_amount_input';
 import { Container, Text } from './ui';
 
 // Asset amounts only apply to ERC20 assets
-export interface AssetAmountInputProps extends AmountInputProps {
+export interface AssetAmountInputProps {
     asset?: ERC20Asset;
     onChange: (value?: BigNumber, asset?: ERC20Asset) => void;
+    startingFontSizePx: number;
+    fontColor?: ColorOption;
 }
 
-export class AssetAmountInput extends React.Component<AssetAmountInputProps> {
+export interface AssetAmountInputState {
+    currentFontSizePx: number;
+}
+
+export class AssetAmountInput extends React.Component<AssetAmountInputProps, AssetAmountInputState> {
     public static defaultProps = {
         onChange: util.boundNoop,
     };
+    constructor(props: AssetAmountInputProps) {
+        super(props);
+        this.state = {
+            currentFontSizePx: props.startingFontSizePx,
+        };
+    }
     public render(): React.ReactNode {
         const { asset, onChange, ...rest } = this.props;
         return (
             <Container>
-                <AmountInput {...rest} onChange={this._handleChange} />
+                <Container borderBottom="1px solid rgba(255,255,255,0.3)" display="inline-block">
+                    <ScalingAmountInput
+                        {...rest}
+                        startWidthCh={3.5}
+                        endWidthCh={5}
+                        fontSizePx={this.state.currentFontSizePx}
+                        onChange={this._handleChange}
+                    />
+                </Container>
                 <Container display="inline-block" marginLeft="10px">
-                    <Text fontSize={rest.fontSize} fontColor={ColorOption.white} textTransform="uppercase">
+                    <Text
+                        fontSize={`${this.state.currentFontSizePx}px`}
+                        fontColor={ColorOption.white}
+                        textTransform="uppercase"
+                    >
                         {assetUtils.bestNameForAsset(asset)}
                     </Text>
                 </Container>
             </Container>
         );
     }
-    private readonly _handleChange = (value?: BigNumber): void => {
+    private readonly _handleChange = (value?: BigNumber, fontSize?: number): void => {
         this.props.onChange(value, this.props.asset);
+        if (!_.isUndefined(fontSize)) {
+            this.setState({
+                currentFontSizePx: fontSize,
+            });
+        }
     };
 }
diff --git a/packages/instant/src/components/instant_heading.tsx b/packages/instant/src/components/instant_heading.tsx
index a36d35a93..defe3b8b1 100644
--- a/packages/instant/src/components/instant_heading.tsx
+++ b/packages/instant/src/components/instant_heading.tsx
@@ -69,7 +69,7 @@ export const InstantHeading: React.StatelessComponent<InstantHeadingProps> = pro
             </Text>
         </Container>
         <Flex direction="row" justify="space-between">
-            <SelectedAssetAmountInput fontSize="45px" />
+            <SelectedAssetAmountInput startingFontSizePx={45} />
             <Flex direction="column" justify="space-between">
                 <Container marginBottom="5px">
                     <Text fontSize="16px" fontColor={ColorOption.white} fontWeight={500}>
diff --git a/packages/instant/src/components/amount_input.tsx b/packages/instant/src/components/scaling_amount_input.tsx
index f6f562be8..a0b7b74af 100644
--- a/packages/instant/src/components/amount_input.tsx
+++ b/packages/instant/src/components/scaling_amount_input.tsx
@@ -8,34 +8,35 @@ import { util } from '../util/util';
 import { ScalingInput } from './scaling_input';
 import { Container, Text } from './ui';
 
-export interface AmountInputProps {
+export interface ScalingAmountInputProps {
+    fontSizePx: number;
+    startWidthCh: number;
+    endWidthCh: number;
     fontColor?: ColorOption;
-    fontSize?: string;
     value?: BigNumber;
-    onChange: (value?: BigNumber) => void;
+    onChange: (value?: BigNumber, fontSize?: number) => void;
 }
 
-export class AmountInput extends React.Component<AmountInputProps> {
+export class ScalingAmountInput extends React.Component<ScalingAmountInputProps> {
     public static defaultProps = {
         onChange: util.boundNoop,
+        onFontSizeChange: util.boundNoop,
     };
     public render(): React.ReactNode {
-        const { fontColor, fontSize, value } = this.props;
+        const { startWidthCh, endWidthCh, fontColor, fontSizePx, value } = this.props;
         return (
-            <Container borderBottom="1px solid rgba(255,255,255,0.3)" display="inline-block">
-                <ScalingInput
-                    startWidthCh={3.5}
-                    endWidthCh={6}
-                    startFontSizePx={45}
-                    fontColor={fontColor}
-                    onChange={this._handleChange}
-                    value={!_.isUndefined(value) ? value.toString() : ''}
-                    placeholder="0.00"
-                />
-            </Container>
+            <ScalingInput
+                startWidthCh={startWidthCh}
+                endWidthCh={endWidthCh}
+                fontSizePx={fontSizePx}
+                fontColor={fontColor}
+                onChange={this._handleChange}
+                value={!_.isUndefined(value) ? value.toString() : ''}
+                placeholder="0.00"
+            />
         );
     }
-    private readonly _handleChange = (event: React.ChangeEvent<HTMLInputElement>): void => {
+    private readonly _handleChange = (event: React.ChangeEvent<HTMLInputElement>, fontSize?: number): void => {
         const value = event.target.value;
         let bigNumberValue;
         if (!_.isEmpty(value)) {
@@ -46,6 +47,6 @@ export class AmountInput extends React.Component<AmountInputProps> {
                 return;
             }
         }
-        this.props.onChange(bigNumberValue);
+        this.props.onChange(bigNumberValue, fontSize);
     };
 }
diff --git a/packages/instant/src/components/scaling_input.tsx b/packages/instant/src/components/scaling_input.tsx
index ea0a925d2..a2c4ba342 100644
--- a/packages/instant/src/components/scaling_input.tsx
+++ b/packages/instant/src/components/scaling_input.tsx
@@ -17,47 +17,79 @@ export enum ScalingInputPhase {
 export interface ScalingInputProps {
     startWidthCh: number;
     endWidthCh: number;
-    startFontSizePx: number;
+    fontSizePx: number;
     value?: string;
-    onChange?: (event: React.ChangeEvent<HTMLInputElement>) => void;
+    onChange: (event: React.ChangeEvent<HTMLInputElement>, fontSize: number) => void;
     fontColor?: ColorOption;
     placeholder?: string;
 }
-// Magic value obtained via trial-and-error
-const scalingRateToMaintainSameWidth = 0.1;
+
+export interface ScalingInputProps {
+    fixedWidthInPxIfExists?: number;
+}
+
 export class ScalingInput extends React.Component<ScalingInputProps> {
     public static defaultProps = {
         onChange: util.boundNoop,
+        onFontSizeChange: util.boundNoop,
     };
+    public state = {
+        fixedWidthInPxIfExists: undefined,
+    };
+    private _inputRef = React.createRef();
+    public static getPhase(startWidthCh: number, endWidthCh: number, value?: string): ScalingInputPhase {
+        if (_.isUndefined(value) || value.length <= startWidthCh) {
+            return ScalingInputPhase.Start;
+        }
+        if (value.length > startWidthCh && value.length <= endWidthCh) {
+            return ScalingInputPhase.Scaling;
+        }
+        return ScalingInputPhase.End;
+    }
+    public static getPhaseFromProps(props: ScalingInputProps): ScalingInputPhase {
+        const { value, startWidthCh, endWidthCh } = props;
+        return ScalingInput.getPhase(startWidthCh, endWidthCh, value);
+    }
+    public componentDidUpdate(prevProps: ScalingInputProps): void {
+        const prevPhase = ScalingInput.getPhaseFromProps(prevProps);
+        const curPhase = ScalingInput.getPhaseFromProps(this.props);
+        // if we went from anything else to end, fix to the current width as it shouldn't change as we grow
+        if (prevPhase !== ScalingInputPhase.End && curPhase === ScalingInputPhase.End) {
+            this.setState({
+                fixedWidthInPxIfExists: this._getInputWidthInPx(),
+            });
+        }
+        // if we end from end to to anything else, un-fix the width
+        if (prevPhase === ScalingInputPhase.End && curPhase !== ScalingInputPhase.End) {
+            this.setState({
+                fixedWidthInPxIfExists: undefined,
+            });
+        }
+    }
     public render(): React.ReactNode {
         const { fontColor, onChange, placeholder, value } = this.props;
-        const phase = this._getPhase();
+        const phase = ScalingInput.getPhaseFromProps(this.props);
         return (
             <Input
+                ref={this._inputRef as any}
                 fontColor={fontColor}
-                onChange={onChange}
+                onChange={this._handleChange}
                 value={value}
                 placeholder={placeholder}
-                fontSize={this._calculateFontSize(phase)}
-                width={this._calculateWidth(phase)}
+                fontSize={`${this.props.fontSizePx}px`}
+                width={this._calculateWidth()}
             />
         );
     }
-    private readonly _calculateFontSize = (phase: ScalingInputPhase): string => {
-        const { value, endWidthCh, startFontSizePx } = this.props;
-        if (_.isUndefined(value) || phase !== ScalingInputPhase.End) {
-            return `${startFontSizePx}px`;
-        }
-        const charactersOverMax = value.length - endWidthCh;
-        const pixelsToReduceFontSizeBy = charactersOverMax * 2;
-        const newFontSizePx = startFontSizePx - pixelsToReduceFontSizeBy;
-        return `${newFontSizePx}px`;
-    };
-    private readonly _calculateWidth = (phase: ScalingInputPhase): string => {
+    private readonly _calculateWidth = (): string => {
+        const phase = ScalingInput.getPhaseFromProps(this.props);
         const { value, startWidthCh, endWidthCh } = this.props;
         if (_.isUndefined(value)) {
             return `${startWidthCh}ch`;
         }
+        if (!_.isUndefined(this.state.fixedWidthInPxIfExists)) {
+            return `${this.state.fixedWidthInPxIfExists}px`;
+        }
         switch (phase) {
             case ScalingInputPhase.Start:
                 return `${startWidthCh}ch`;
@@ -69,14 +101,31 @@ export class ScalingInput extends React.Component<ScalingInputProps> {
                 return `${startWidthCh}ch`;
         }
     };
-    private readonly _getPhase = (): ScalingInputPhase => {
-        const { value, startWidthCh, endWidthCh } = this.props;
-        if (_.isUndefined(value) || value.length <= this.props.startWidthCh) {
-            return ScalingInputPhase.Start;
+    private readonly _getInputWidthInPx = (): number => {
+        const ref = this._inputRef.current;
+        if (!ref) {
+            return 0;
         }
-        if (value.length > startWidthCh && value.length <= endWidthCh) {
-            return ScalingInputPhase.Scaling;
+        return (ref as any).getBoundingClientRect().width;
+    };
+    private readonly _calculateNextFontSize = (
+        currentFontSizePx: number,
+        value: string,
+        startWidthCh: number,
+        endWidthCh: number,
+    ): number => {
+        const phase = ScalingInput.getPhase(startWidthCh, endWidthCh, value);
+        if (_.isUndefined(value) || phase !== ScalingInputPhase.End) {
+            return currentFontSizePx;
         }
-        return ScalingInputPhase.End;
+        const charactersOverMax = value.length - endWidthCh;
+        const pixelsToReduceFontSizeBy = charactersOverMax * 5;
+        const fontSize = currentFontSizePx - pixelsToReduceFontSizeBy;
+        return fontSize;
+    };
+    private readonly _handleChange = (event: React.ChangeEvent<HTMLInputElement>) => {
+        const value = event.target.value;
+        const { fontSizePx, startWidthCh, endWidthCh } = this.props;
+        this.props.onChange(event, this._calculateNextFontSize(fontSizePx, value, startWidthCh, endWidthCh));
     };
 }
diff --git a/packages/instant/src/containers/selected_asset_amount_input.ts b/packages/instant/src/containers/selected_asset_amount_input.ts
index 6cd39b855..1b5f3cd22 100644
--- a/packages/instant/src/containers/selected_asset_amount_input.ts
+++ b/packages/instant/src/containers/selected_asset_amount_input.ts
@@ -17,7 +17,7 @@ import { AssetAmountInput } from '../components/asset_amount_input';
 
 export interface SelectedAssetAmountInputProps {
     fontColor?: ColorOption;
-    fontSize?: string;
+    startingFontSizePx: number;
 }
 
 interface ConnectedState {