194 lines
7.4 KiB
JavaScript
194 lines
7.4 KiB
JavaScript
/*
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* This React component is a long way from perfect, but it's a start for
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* handling custom layouts.
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*
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* There are two reasons that (at least in my opinion) implementing this is non-trivial:
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*
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* 1) React re-render vs DOM updates
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*
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* For performance reasons, we can't re-render with React when the user drags a
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* pattern part (or rotates it). It would kill performance.
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* So, we don't re-render with React upon dragging/rotating, but instead manipulate
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* the DOM directly.
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*
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* So far so good, but of course we don't want a pattern that's only correctly laid
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* out in the DOM. We want to updat the pattern gist so that the new layout is stored.
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* For this, we re-render with React on the end of the drag (or rotate).
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*
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* Handling this balance between DOM updates and React re-renders is a first contributing
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* factor to why this component is non-trivial
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*
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* 2) SVG vs DOM coordinates
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*
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* When we drag or rotate with the mouse, all the events are giving us coordinates of
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* where the mouse is in the DOM.
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*
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* The layout uses coordinates from the embedded SVG which are completely different.
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* So we need to make this translation and that adds complexity.
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*
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* 3) Part-level transforms
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*
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* It's not just that the DOM coordinates and SVG coordinate system is different, each
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* part also has it's own transforms applied and because of this behaves as if they have
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* their own coordinate system.
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*
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* In other words, a point (0,0) in the part is not the top-left corner of the page.
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* In the best-case scenario, it's the top-left corner of the part. But even this is
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* often not the case as parts will have transforms applied to them.
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*
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* 4) Flip along X or Y axis
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*
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* Parts can be flipped along the X or Y axis to facilitate a custom layout.
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* This is handled in a transform, so the part's coordinate's don't actually change. They
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* are flipped late into the rendering process (by the browser displaying the SVG).
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*
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* Handling this adds yet more mental overhead
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*
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* 5) Bounding box
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*
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* While moving and rotating parts around is one thing. Recalculating the bounding box
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* (think auto-cropping the pattern) gets kinda complicated because of the reasons
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* outlined above.
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*
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* We are currently handling a lot in the frontend code. It might be more elegant to move
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* some of this to core. For example, core expects the custom layout to set the widht and height
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* rather than figuring it out on its own as it does for auto-generated layouts.
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*
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*
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*
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* Known issues
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*
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* - Rotating gets a little weird sometimes as the part rotates around it's center in the
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* SVG coordinate system, but the mouse uses it's own coordinates as the center point that's
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* used to calculate the angle of the rotation
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*
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* - Moving parts into the negative space (minus X or Y coordinated) does not extend the bounding box.
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*
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* - Rotation gets weird when a part is mirrored
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*
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* - The bounding box update when a part is rotated is not entirely accurate
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*
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*
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* I've sort of left it at this because I'm starting to wonder if we should perhaps re-think
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* how custom layouts are supported in the core. And I would like to discuss this with the core team.
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*/
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import { useEffect, useRef, useState } from 'react'
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import Svg from '../../draft/svg'
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import Defs from '../../draft/defs'
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import { angle } from '../../draft/utils'
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import Part from './part'
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const Draft = props => {
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if (!props.gistReady) {return null}
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const { patternProps, gist, updateGist ,app, bgProps={} } = props
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const { layout=false } = gist
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useEffect(() => {
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if (!layout) {
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// On the initial draft, core does the layout, so we set the layout to the auto-layout
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// After this, core won't handle layout anymore. It's up to the user from this point onwards
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// FIXME: Allow use the option to clear the layout again
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updateGist(['layout'], {
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...patternProps.autoLayout,
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width: patternProps.width,
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height: patternProps.height
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})
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}
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}, [layout])
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if (!patternProps || !layout) return null
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// Helper method to update part layout and re-calculate width * height
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const updateLayout = (name, config) => {
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// Start creating new layout
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const newLayout = {...layout}
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newLayout.parts[name] = config
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newLayout.width = layout.width
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newLayout.height = layout.height
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// Pattern topLeft and bottomRight
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let topLeft = { x: 0, y: 0 }
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let bottomRight = { x: 0, y: 0 }
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for (const [pname, part] of Object.entries(patternProps.parts)) {
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// Pages part does not have its topLeft and bottomRight set by core since it's added post-draft
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if (part.topLeft) {
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// Find topLeft (tl) and bottomRight (br) of this part
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const tl = {
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x: part.topLeft.x + newLayout.parts[pname].move.x,
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y: part.topLeft.y + newLayout.parts[pname].move.y
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}
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const br = {
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x: part.bottomRight.x + newLayout.parts[pname].move.x,
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y: part.bottomRight.y + newLayout.parts[pname].move.y
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}
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// Handle rotate
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if (newLayout.parts[pname].rotate) {
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// Angle to the corners
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const center = {
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x: part.topLeft.x + part.width/2,
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y: part.topLeft.x + part.height/2,
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}
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const corners = {
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tl: part.topLeft,
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br: part.bottomRight,
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}
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const angles = {}
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for (const corner in corners) angles[corner] = angle(center, corners[corner])
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const delta = {}
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const rotation = newLayout.parts[pname].rotate
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for (const corner in corners) {
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delta[corner] = {
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x: part.width/2 * (Math.cos(angles[corner]) - Math.cos(angles[corner] + rotation)),
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y: part.height/2 * (Math.sin(angles[corner]) - Math.sin(angles[corner] + rotation))
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}
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}
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if (delta.br.x > 0) br.x += delta.br.x
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if (delta.br.y > 0) br.y += delta.br.y
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if (delta.tl.x < 0) tl.x -= delta.tl.x
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if (delta.tl.y < 0) tl.y -= delta.tl.y
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}
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if (tl.x < topLeft.x) topLeft.x = tl.x
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if (tl.y < topLeft.y) topLeft.y = tl.y
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if (br.x > bottomRight.x) bottomRight.x = br.x
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if (br.y > bottomRight.y) bottomRight.y = br.y
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}
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}
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newLayout.width = bottomRight.x - topLeft.x
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newLayout.height = bottomRight.y - topLeft.y
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updateGist(['layout'], newLayout)
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}
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// We need to make sure the `pages` part is at the bottom of the pile
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// so we can drag-drop all parts on top of it.
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// Bottom in SVG means we need to draw it first
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const partList = Object.keys(patternProps.parts)
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return (
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<div className="my-8 w-11/12 m-auto border-2 border-dotted border-base-content shadow">
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<Svg {...patternProps} embed={gist.embed}>
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<Defs {...patternProps} />
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<style>{`:root { --pattern-scale: ${gist.scale || 1}}`}</style>
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<g>
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<rect x="0" y="0" width={patternProps.width} height={patternProps.height} {...bgProps} />
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{[
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partList.filter(name => name === 'pages'),
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partList.filter(name => name !== 'pages'),
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].map(list => list.map(name => (
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<Part {...{
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key:name,
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name,
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part: patternProps.parts[name],
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layout,
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app,
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gist,
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updateLayout,
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}}/>
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)))}
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</g>
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</Svg>
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</div>
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)
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}
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export default Draft
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