cvat/cvat-canvas/README.md

Module CVAT-CANVAS

Description

The CVAT module presents a canvas to viewing, drawing and editing of annotations.

• It has been written on typescript
• It contains the class Canvas and the enum Rotation

Commands

• Building of the module from sources in the dist directory:

npm run build
npm run build -- --mode=development     # without a minification

• Updating of a module version:

npm version patch   # updated after minor fixes
npm version minor   # updated after major changes which don't affect API compatibility with previous versions
npm version major   # updated after major changes which affect API compatibility with previous versions

Creation

Canvas is created by using constructor:

    const { Canvas } = require('./canvas');
    const canvas = new Canvas(ObjectStateClass);

• Canvas has transparent background

Canvas itself handles:

• Shape context menu (PKM)
• Image moving (mousedrag)
• Image resizing (mousewheel)
• Image fit (dblclick)
• Remove point (PKM)
• Polyshape editing (Shift + LKM)

API

Methods

All methods are sync.

    interface DrawData {
        enabled: boolean;
        shapeType?: string;
        numberOfPoints?: number;
        initialState?: any;
        crosshair?: boolean;
    }

    html(): HTMLDivElement;
    setup(frameData: FrameData, objectStates: ObjectState): void;
    activate(clientID: number, attributeID?: number): void;
    rotate(rotation: Rotation, remember?: boolean): void;
    focus(clientID: number, padding?: number): void;
    fit(): void;
    grid(stepX: number, stepY: number): void;

    draw(drawData: DrawData): void;
    split(enabled?: boolean): void;
    group(enabled?: boolean): void;
    merge(enabled?: boolean): void;

    cancel(): any;

CSS Classes/IDs

• All drawn objects (shapes, tracks) have an id cvat_canvas_object_{objectState.id}
• Drawn shapes and tracks have classes cvat_canvas_shape, cvat_canvas_shape_activated, cvat_canvas_shape_grouping, cvat_canvas_shape_merging, cvat_canvas_shape_drawing
• Drawn texts have the class cvat_canvas_text
• Tags have the class cvat_canvas_tag
• Canvas image has ID cvat_canvas_image
• Grid on the canvas has ID cvat_canvas_grid_pattern
• Crosshair during a draw has class cvat_canvas_crosshair

Events

Standard JS events are used.

    - canvas.setup
    - canvas.activated => ObjectState
    - canvas.deactivated
    - canvas.moved => [ObjectState], x, y
    - canvas.drawn => ObjectState
    - canvas.edited => ObjectState
    - canvas.splitted => ObjectState
    - canvas.groupped => [ObjectState]
    - canvas.merged => [ObjectState]
    - canvas.canceled

States

API Reaction

	IDLE	GROUPING	SPLITTING	DRAWING	MERGING	EDITING
html()	+	+	+	+	+	+
setup()	+	+	+	+	+	-
activate()	+	-	-	-	-	-
rotate()	+	+	+	+	+	+
focus()	+	+	+	+	+	+
fit()	+	+	+	+	+	+
grid()	+	+	+	+	+	+
draw()	+	-	-	-	-	-
split()	+	-	+	-	-	-
group	+	+	-	-	-	-
merge()	+	-	-	-	+	-
cancel()	-	+	+	+	+	+