Class ImageTool<SS>
Type parameters
-
SS
Hierarchy
-
Component<BaseToolProps, ImageToolModel>
- ImageTool
Implements
- ISignTool
Index
Constructors
Properties
Methods
Constructors
constructor
-
Parameters
-
props: BaseToolProps
-
Optional context: any
Returns ImageTool
-
Properties
context
If using the new style context, re-declare this in your class to be the
React.ContextType of your static contextType.
Should be used with type annotation or static contextType.
static contextType = MyContext
// For TS pre-3.7:
context!: React.ContextType<typeof MyContext>
// For TS 3.7 and above:
declare context: React.ContextType<typeof MyContext>refs
Type declaration
-
[key: string]: ReactInstance
Static Optional contextType
If set, this.context will be set at runtime to the current value of the given Context.
Usage:
type MyContext = number
const Ctx = React.createContext<MyContext>(0)
class Foo extends React.Component {
static contextType = Ctx
context!: React.ContextType<typeof Ctx>
render () {
return <>My context's value: {this.context}</>;
}
}Methods
Optional UNSAFE_componentWillMount
-
Called immediately before mounting occurs, and before
Component#render. Avoid introducing any side-effects or subscriptions in this method.This method will not stop working in React 17.
Note: the presence of getSnapshotBeforeUpdate or getDerivedStateFromProps prevents this from being invoked.
Returns void
Optional UNSAFE_componentWillReceiveProps
-
Called when the component may be receiving new props. React may call this even if props have not changed, so be sure to compare new and existing props if you only want to handle changes.
Calling
Component#setStategenerally does not trigger this method.This method will not stop working in React 17.
Note: the presence of getSnapshotBeforeUpdate or getDerivedStateFromProps prevents this from being invoked.
Parameters
-
nextProps: Readonly<BaseToolProps>
-
nextContext: any
Returns void
-
Optional UNSAFE_componentWillUpdate
-
Called immediately before rendering when new props or state is received. Not called for the initial render.
Note: You cannot call
Component#setStatehere.This method will not stop working in React 17.
Note: the presence of getSnapshotBeforeUpdate or getDerivedStateFromProps prevents this from being invoked.
Parameters
-
nextProps: Readonly<BaseToolProps>
-
nextState: Readonly<ImageToolModel>
-
nextContext: any
Returns void
-
Optional componentDidCatch
-
Catches exceptions generated in descendant components. Unhandled exceptions will cause the entire component tree to unmount.
Parameters
-
error: Error
-
errorInfo: ErrorInfo
Returns void
-
Optional componentDidMount
-
Called immediately after a component is mounted. Setting state here will trigger re-rendering.
Returns void
Optional componentDidUpdate
-
Called immediately after updating occurs. Not called for the initial render.
The snapshot is only present if getSnapshotBeforeUpdate is present and returns non-null.
Parameters
-
prevProps: Readonly<BaseToolProps>
-
prevState: Readonly<ImageToolModel>
-
Optional snapshot: SS
Returns void
-
Optional componentWillMount
-
Called immediately before mounting occurs, and before
Component#render. Avoid introducing any side-effects or subscriptions in this method.Note: the presence of getSnapshotBeforeUpdate or getDerivedStateFromProps prevents this from being invoked.
Returns void
Optional componentWillReceiveProps
-
Called when the component may be receiving new props. React may call this even if props have not changed, so be sure to compare new and existing props if you only want to handle changes.
Calling
Component#setStategenerally does not trigger this method.Note: the presence of getSnapshotBeforeUpdate or getDerivedStateFromProps prevents this from being invoked.
Parameters
-
nextProps: Readonly<BaseToolProps>
-
nextContext: any
Returns void
-
Optional componentWillUnmount
-
Called immediately before a component is destroyed. Perform any necessary cleanup in this method, such as cancelled network requests, or cleaning up any DOM elements created in
componentDidMount.Returns void
Optional componentWillUpdate
-
Called immediately before rendering when new props or state is received. Not called for the initial render.
Note: You cannot call
Component#setStatehere.Note: the presence of getSnapshotBeforeUpdate or getDerivedStateFromProps prevents this from being invoked.
Parameters
-
nextProps: Readonly<BaseToolProps>
-
nextState: Readonly<ImageToolModel>
-
nextContext: any
Returns void
-
Optional getSnapshotBeforeUpdate
-
Runs before React applies the result of
renderto the document, and returns an object to be given to componentDidUpdate. Useful for saving things such as scroll position beforerendercauses changes to it.Note: the presence of getSnapshotBeforeUpdate prevents any of the deprecated lifecycle events from running.
Parameters
-
prevProps: Readonly<BaseToolProps>
-
prevState: Readonly<ImageToolModel>
Returns SS | null
-
Optional shouldComponentUpdate
-
Called to determine whether the change in props and state should trigger a re-render.
Componentalways returns true.PureComponentimplements a shallow comparison on props and state and returns true if any props or states have changed.If false is returned,
Component#render,componentWillUpdateandcomponentDidUpdatewill not be called.Parameters
-
nextProps: Readonly<BaseToolProps>
-
nextState: Readonly<ImageToolModel>
-
nextContext: any
Returns boolean
-
toDataURL
-
Returns result image as data url.
Returns string
toImageData
-
Returns result image blob data.
Returns Promise<Uint8Array | null>
Signature tool component.