rui_orig/background.go

270 lines
8.1 KiB
Go

package rui
import (
"fmt"
"strings"
)
// Constants related to view's background description
const (
// NoRepeat is value of the Repeat property of an background image:
// The image is not repeated (and hence the background image painting area
// will not necessarily be entirely covered). The position of the non-repeated
// background image is defined by the background-position CSS property.
NoRepeat = 0
// RepeatXY is value of the Repeat property of an background image:
// The image is repeated as much as needed to cover the whole background
// image painting area. The last image will be clipped if it doesn't fit.
RepeatXY = 1
// RepeatX is value of the Repeat property of an background image:
// The image is repeated horizontally as much as needed to cover
// the whole width background image painting area. The image is not repeated vertically.
// The last image will be clipped if it doesn't fit.
RepeatX = 2
// RepeatY is value of the Repeat property of an background image:
// The image is repeated vertically as much as needed to cover
// the whole height background image painting area. The image is not repeated horizontally.
// The last image will be clipped if it doesn't fit.
RepeatY = 3
// RepeatRound is value of the Repeat property of an background image:
// As the allowed space increases in size, the repeated images will stretch (leaving no gaps)
// until there is room (space left >= half of the image width) for another one to be added.
// When the next image is added, all of the current ones compress to allow room.
RepeatRound = 4
// RepeatSpace is value of the Repeat property of an background image:
// The image is repeated as much as possible without clipping. The first and last images
// are pinned to either side of the element, and whitespace is distributed evenly between the images.
RepeatSpace = 5
// ScrollAttachment is value of the Attachment property of an background image:
// The background is fixed relative to the element itself and does not scroll with its contents.
// (It is effectively attached to the element's border.)
ScrollAttachment = 0
// FixedAttachment is value of the Attachment property of an background image:
// The background is fixed relative to the viewport. Even if an element has
// a scrolling mechanism, the background doesn't move with the element.
FixedAttachment = 1
// LocalAttachment is value of the Attachment property of an background image:
// The background is fixed relative to the element's contents. If the element has a scrolling mechanism,
// the background scrolls with the element's contents, and the background painting area
// and background positioning area are relative to the scrollable area of the element
// rather than to the border framing them.
LocalAttachment = 2
// BorderBoxClip is value of the BackgroundClip property:
// The background extends to the outside edge of the border (but underneath the border in z-ordering).
BorderBoxClip = 0
// PaddingBoxClip is value of the BackgroundClip property:
// The background extends to the outside edge of the padding. No background is drawn beneath the border.
PaddingBoxClip = 1
// ContentBoxClip is value of the BackgroundClip property:
// The background is painted within (clipped to) the content box.
ContentBoxClip = 2
)
// BackgroundElement describes the background element
type BackgroundElement interface {
Properties
fmt.Stringer
stringWriter
cssStyle(session Session) string
// Tag returns type of the background element.
// Possible values are: "image", "conic-gradient", "linear-gradient" and "radial-gradient"
Tag() string
// Clone creates a new copy of BackgroundElement
Clone() BackgroundElement
}
type backgroundElement struct {
propertyList
}
type backgroundImage struct {
backgroundElement
}
// NewBackgroundImage creates the new background image
func createBackground(obj DataObject) BackgroundElement {
var result BackgroundElement = nil
switch obj.Tag() {
case "image":
image := new(backgroundImage)
image.properties = map[string]any{}
result = image
case "linear-gradient":
gradient := new(backgroundLinearGradient)
gradient.properties = map[string]any{}
result = gradient
case "radial-gradient":
gradient := new(backgroundRadialGradient)
gradient.properties = map[string]any{}
result = gradient
case "conic-gradient":
gradient := new(backgroundConicGradient)
gradient.properties = map[string]any{}
result = gradient
default:
return nil
}
count := obj.PropertyCount()
for i := 0; i < count; i++ {
if node := obj.Property(i); node.Type() == TextNode {
if value := node.Text(); value != "" {
result.Set(node.Tag(), value)
}
}
}
return result
}
// NewBackgroundImage creates the new background image
func NewBackgroundImage(params Params) BackgroundElement {
result := new(backgroundImage)
result.properties = map[string]any{}
for tag, value := range params {
result.Set(tag, value)
}
return result
}
func (image *backgroundImage) Tag() string {
return "image"
}
func (image *backgroundImage) Clone() BackgroundElement {
result := NewBackgroundImage(nil)
for tag, value := range image.properties {
result.setRaw(tag, value)
}
return result
}
func (image *backgroundImage) normalizeTag(tag string) string {
tag = strings.ToLower(tag)
switch tag {
case "source":
tag = Source
case Fit:
tag = backgroundFit
case HorizontalAlign:
tag = ImageHorizontalAlign
case VerticalAlign:
tag = ImageVerticalAlign
}
return tag
}
func (image *backgroundImage) Set(tag string, value any) bool {
tag = image.normalizeTag(tag)
switch tag {
case Attachment, Width, Height, Repeat, ImageHorizontalAlign, ImageVerticalAlign,
backgroundFit, Source:
return image.backgroundElement.Set(tag, value)
}
return false
}
func (image *backgroundImage) Get(tag string) any {
return image.backgroundElement.Get(image.normalizeTag(tag))
}
func (image *backgroundImage) cssStyle(session Session) string {
if src, ok := imageProperty(image, Source, session); ok && src != "" {
buffer := allocStringBuilder()
defer freeStringBuilder(buffer)
buffer.WriteString(`url(`)
buffer.WriteString(src)
buffer.WriteRune(')')
attachment, _ := enumProperty(image, Attachment, session, NoRepeat)
values := enumProperties[Attachment].values
if attachment > 0 && attachment < len(values) {
buffer.WriteRune(' ')
buffer.WriteString(values[attachment])
}
align, _ := enumProperty(image, ImageHorizontalAlign, session, LeftAlign)
values = enumProperties[ImageHorizontalAlign].values
if align >= 0 && align < len(values) {
buffer.WriteRune(' ')
buffer.WriteString(values[align])
} else {
buffer.WriteString(` left`)
}
align, _ = enumProperty(image, ImageVerticalAlign, session, TopAlign)
values = enumProperties[ImageVerticalAlign].values
if align >= 0 && align < len(values) {
buffer.WriteRune(' ')
buffer.WriteString(values[align])
} else {
buffer.WriteString(` top`)
}
fit, _ := enumProperty(image, backgroundFit, session, NoneFit)
values = enumProperties[backgroundFit].values
if fit > 0 && fit < len(values) {
buffer.WriteString(` / `)
buffer.WriteString(values[fit])
} else {
width, _ := sizeProperty(image, Width, session)
height, _ := sizeProperty(image, Height, session)
if width.Type != Auto || height.Type != Auto {
buffer.WriteString(` / `)
buffer.WriteString(width.cssString("auto", session))
buffer.WriteRune(' ')
buffer.WriteString(height.cssString("auto", session))
}
}
repeat, _ := enumProperty(image, Repeat, session, NoRepeat)
values = enumProperties[Repeat].values
if repeat >= 0 && repeat < len(values) {
buffer.WriteRune(' ')
buffer.WriteString(values[repeat])
} else {
buffer.WriteString(` no-repeat`)
}
return buffer.String()
}
return ""
}
func (image *backgroundImage) writeString(buffer *strings.Builder, indent string) {
image.writeToBuffer(buffer, indent, image.Tag(), []string{
Source,
Width,
Height,
ImageHorizontalAlign,
ImageVerticalAlign,
backgroundFit,
Repeat,
Attachment,
})
}
func (image *backgroundImage) String() string {
return runStringWriter(image)
}