LLKennedy/imagetemplate

// Package rectangle is a simple rectangle component with customisable size, colour and location.
package rectangle

import (
    "fmt"
    "image"
    "image/color"

    "github.com/LLKennedy/imagetemplate/v3/cutils"
    "github.com/LLKennedy/imagetemplate/v3/render"
    "golang.org/x/tools/godoc/vfs"
)

// Component implements the Component interface for rectangles.
type Component struct {
    /*
        NamedPropertiesMap maps user/application variables to properties of the component.
        This field is filled automatically by VerifyAndSetJSONData, then used in
        SetNamedProperties to determine whether a variable being passed in is relevant to this
        component.

        For example, map[string][]string{"squareSize": []string{"width", "height"}} would
        indicate that the user specified variable "squareSize" will fill the Width and Height
        properties.
    */
    NamedPropertiesMap map[string][]string
    /*
        TopLeft is the coordinates of the top-left corner of the rectangle relative to the
        top-left corner of the canvas.
    */
    TopLeft image.Point
    // Width is the width of the rectangle.
    Width int
    // Height is the height of the rectangle.
    Height int
    // Colour is the colour of the rectangle.
    Colour color.NRGBA
}

type rectangleFormat struct {
    TopLeftX string `json:"topLeftX"`
    TopLeftY string `json:"topLeftY"`
    Width    string `json:"width"`
    Height   string `json:"height"`
    Colour   struct {
        Red   string `json:"R"`
        Green string `json:"G"`
        Blue  string `json:"B"`
        Alpha string `json:"A"`
    } `json:"colour"`
}

// Write draws a rectangle on the canvas.
func (component Component) Write(canvas render.Canvas) (render.Canvas, error) {
    if len(component.NamedPropertiesMap) != 0 {
        return canvas, fmt.Errorf("cannot draw rectangle, not all named properties are set: %v", component.NamedPropertiesMap)
    }
    return canvas.Rectangle(component.TopLeft, component.Width, component.Height, component.Colour)
}

// SetNamedProperties processes the named properties and sets them into the rectangle properties.
func (component Component) SetNamedProperties(properties render.NamedProperties) (render.Component, error) {
    c := component
    var err error
    c.NamedPropertiesMap, err = render.StandardSetNamedProperties(properties, component.NamedPropertiesMap, (&c).delegatedSetProperties)
    if err != nil {
        return component, err
    }
    return c, nil
}

// GetJSONFormat returns the JSON structure of a rectangle component.
func (component Component) GetJSONFormat() interface{} {
    return &rectangleFormat{}
}

// VerifyAndSetJSONData processes the data parsed from JSON and uses it to set rectangle properties and fill the named properties map.
func (component Component) VerifyAndSetJSONData(data interface{}) (render.Component, render.NamedProperties, error) {
    c := component
    props := make(render.NamedProperties)
    stringStruct, ok := data.(*rectangleFormat)
    if !ok {
        return component, props, fmt.Errorf("failed to convert returned data to component properties")
    }
    // Get named properties and assign each real property
    var newVal interface{}
    var err error
    c.TopLeft.X, c.NamedPropertiesMap, err = cutils.ExtractInt(stringStruct.TopLeftX, "topLeftX", c.NamedPropertiesMap)
    if err != nil {
        return component, props, err
    }
    c.TopLeft.Y, c.NamedPropertiesMap, err = cutils.ExtractInt(stringStruct.TopLeftY, "topLeftY", c.NamedPropertiesMap)
    if err != nil {
        return component, props, err
    }
    c.Width, c.NamedPropertiesMap, err = cutils.ExtractInt(stringStruct.Width, "width", c.NamedPropertiesMap)
    if err != nil {
        return component, props, err
    }
    c.Height, c.NamedPropertiesMap, err = cutils.ExtractInt(stringStruct.Height, "height", c.NamedPropertiesMap)
    if err != nil {
        return component, props, err
    }
    c.NamedPropertiesMap, newVal, err = render.ExtractSingleProp(stringStruct.Colour.Red, "R", render.Uint8Type, c.NamedPropertiesMap)
    if err != nil {
        return component, props, err
    }
    if newVal != nil {
        c.Colour.R = newVal.(uint8)
    }
    c.NamedPropertiesMap, newVal, err = render.ExtractSingleProp(stringStruct.Colour.Green, "G", render.Uint8Type, c.NamedPropertiesMap)
    if err != nil {
        return component, props, err
    }
    if newVal != nil {
        c.Colour.G = newVal.(uint8)
    }
    c.NamedPropertiesMap, newVal, err = render.ExtractSingleProp(stringStruct.Colour.Blue, "B", render.Uint8Type, c.NamedPropertiesMap)
    if err != nil {
        return component, props, err
    }
    if newVal != nil {
        c.Colour.B = newVal.(uint8)
    }
    c.NamedPropertiesMap, newVal, err = render.ExtractSingleProp(stringStruct.Colour.Alpha, "A", render.Uint8Type, c.NamedPropertiesMap)
    if err != nil {
        return component, props, err
    }
    if newVal != nil {
        c.Colour.A = newVal.(uint8)
    }

    for key := range c.NamedPropertiesMap {
        props[key] = struct {
            Message string
        }{Message: "Please replace me with real data"}
    }
    return c, props, nil
}

func init() {
    for _, name := range []string{"rect", "RECT", "Rect", "rectangle", "Rectangle", "RECTANGLE"} {
        render.RegisterComponent(name, func(vfs.FileSystem) render.Component { return Component{} })
    }
}