use HSB grid for color picker; fixes #762

docs/resources/changelog.md

@@ -20,6 +20,8 @@ _During the beta period, these restrictions may be relaxed in the event of a mis
 - Improved behavior of clearable and password toggle buttons in `<sl-input>` and `<sl-select>` [#745](https://github.com/shoelace-style/shoelace/issues/745)
 - Improved performance of `<sl-select>` by caching menu items instead of traversing for them each time
 - Improved drag utility so initial click/touch events can be accepted [#758](https://github.com/shoelace-style/shoelace/issues/758)
+- Improved `<sl-color-picker>` to use an HSB grid instead of HSL to be more consistent with existing color picker implementations [#762](https://github.com/shoelace-style/shoelace/issues/762)
+- Improved `<sl-color-picker>` so the cursor is hidden and the preview is larger when dragging the grid
 - Refactored `<sl-menu>` to be more performant by caching menu items on slot change
 - Reverted form submit logic [#718](https://github.com/shoelace-style/shoelace/issues/718)
 - Updated the `disabled` attribute so it reflects in `<sl-dropdown>` [#741](https://github.com/shoelace-style/shoelace/discussions/741)

src/components/color-picker/color-picker.styles.ts

@@ -39,14 +39,8 @@ export default css`
   .color-picker__grid {
     position: relative;
     height: var(--grid-height);
-    background-image: linear-gradient(
+    background-image: linear-gradient(to bottom, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 1) 100%),
-        to bottom,
+      linear-gradient(to right, #fff 0%, rgba(255, 255, 255, 0) 100%);
-        hsl(0, 0%, 100%) 0%,
-        hsla(0, 0%, 100%, 0) 50%,
-        hsla(0, 0%, 0%, 0) 50%,
-        hsl(0, 0%, 0%) 100%
-      ),
-      linear-gradient(to right, hsl(0, 0%, 50%) 0%, hsla(0, 0%, 50%, 0) 100%);
     border-top-left-radius: var(--sl-border-radius-medium);
     border-top-right-radius: var(--sl-border-radius-medium);
     cursor: crosshair;
@@ -61,6 +55,12 @@ export default css`
     border: solid 2px white;
     margin-top: calc(var(--grid-handle-size) / -2);
     margin-left: calc(var(--grid-handle-size) / -2);
+    transition: var(--sl-transition-fast) transform;
+  }
+
+  .color-picker__grid-handle--dragging {
+    cursor: none;
+    transform: scale(1.5);
   }
 
   .color-picker__grid-handle${focusVisibleSelector} {
@@ -133,10 +133,10 @@ export default css`
     align-items: center;
     justify-content: center;
     position: relative;
-    width: 3.25rem;
+    width: 2.25rem;
     height: 2.25rem;
     border: none;
-    border-radius: var(--sl-input-border-radius-medium);
+    border-radius: var(--sl-border-radius-circle);
     background: none;
     margin-left: var(--sl-spacing-small);
     cursor: copy;

src/components/color-picker/color-picker.ts

@@ -93,10 +93,12 @@ export default class SlColorPicker extends LitElement {
   private lastValueEmitted: string;
   private readonly localize = new LocalizeController(this);
 
+  @state() private isDraggingGridHandle = false;
   @state() private inputValue = '';
   @state() private hue = 0;
   @state() private saturation = 100;
   @state() private lightness = 100;
+  @state() private brightness = 100;
   @state() private alpha = 100;
 
   /** The current color. */
@@ -211,6 +213,14 @@ export default class SlColorPicker extends LitElement {
     }
   }
 
+  getBrightness(lightness: number) {
+    return clamp(-1 * ((200 * lightness) / (this.saturation - 200)), 0, 100);
+  }
+
+  getLightness(brightness: number) {
+    return clamp(((((200 - this.saturation) * brightness) / 100) * 5) / 10, 0, 100);
+  }
+
   /** Checks for validity and shows the browser's validation message if the control is invalid. */
   reportValidity() {
     // If the input is invalid, show the dropdown so the browser can focus on it
@@ -262,14 +272,13 @@ export default class SlColorPicker extends LitElement {
     handle.focus();
     event.preventDefault();
 
-    drag(
+    drag(container, {
-      container,
+      onMove: x => {
-      x => {
         this.alpha = clamp((x / width) * 100, 0, 100);
         this.syncValues();
       },
-      { initialEvent: event }
+      initialEvent: event
-    );
+    });
   }
 
   handleHueDrag(event: PointerEvent) {
@@ -280,14 +289,13 @@ export default class SlColorPicker extends LitElement {
     handle.focus();
     event.preventDefault();
 
-    drag(
+    drag(container, {
-      container,
+      onMove: x => {
-      x => {
         this.hue = clamp((x / width) * 360, 0, 360);
         this.syncValues();
       },
-      { initialEvent: event }
+      initialEvent: event
-    );
+    });
   }
 
   handleGridDrag(event: PointerEvent) {
@@ -298,17 +306,19 @@ export default class SlColorPicker extends LitElement {
     handle.focus();
     event.preventDefault();
 
-    drag(
+    this.isDraggingGridHandle = true;
-      grid,
+
-      (x, y) => {
+    drag(grid, {
+      onMove: (x, y) => {
         this.saturation = clamp((x / width) * 100, 0, 100);
-        this.lightness = clamp(100 - (y / height) * 100, 0, 100);
+        this.brightness = clamp(100 - (y / height) * 100, 0, 100);
+        this.lightness = this.getLightness(this.brightness);
+
         this.syncValues();
       },
-      {
+      onStop: () => (this.isDraggingGridHandle = false),
-        initialEvent: event
+      initialEvent: event
-      }
+    });
-    );
   }
 
   handleAlphaKeyDown(event: KeyboardEvent) {
@@ -384,13 +394,17 @@ export default class SlColorPicker extends LitElement {
 
     if (event.key === 'ArrowUp') {
       event.preventDefault();
-      this.lightness = clamp(this.lightness + increment, 0, 100);
+      this.brightness = clamp(this.brightness + increment, 0, 100);
+      this.lightness = this.getLightness(this.brightness);
+      console.log(this.lightness, this.brightness);
       this.syncValues();
     }
 
     if (event.key === 'ArrowDown') {
       event.preventDefault();
-      this.lightness = clamp(this.lightness - increment, 0, 100);
+      this.brightness = clamp(this.brightness - increment, 0, 100);
+      this.lightness = this.getLightness(this.brightness);
+      console.log(this.lightness, this.brightness);
       this.syncValues();
     }
   }
@@ -543,6 +557,7 @@ export default class SlColorPicker extends LitElement {
     this.hue = newColor.hsla.h;
     this.saturation = newColor.hsla.s;
     this.lightness = newColor.hsla.l;
+    this.brightness = this.getBrightness(newColor.hsla.l);
     this.alpha = this.opacity ? newColor.hsla.a * 100 : 100;
 
     this.syncValues();
@@ -623,6 +638,7 @@ export default class SlColorPicker extends LitElement {
         this.hue = newColor.hsla.h;
         this.saturation = newColor.hsla.s;
         this.lightness = newColor.hsla.l;
+        this.brightness = this.getBrightness(newColor.hsla.l);
         this.alpha = newColor.hsla.a * 100;
       } else {
         this.inputValue = oldValue;
@@ -636,8 +652,8 @@ export default class SlColorPicker extends LitElement {
   }
 
   render() {
-    const x = this.saturation;
+    const gridHandleX = this.saturation;
-    const y = 100 - this.lightness;
+    const gridHandleY = 100 - this.brightness;
 
     const colorPicker = html`
       <div
@@ -668,10 +684,13 @@ export default class SlColorPicker extends LitElement {
         >
           <span
             part="grid-handle"
-            class="color-picker__grid-handle"
+            class=${classMap({
+              'color-picker__grid-handle': true,
+              'color-picker__grid-handle--dragging': this.isDraggingGridHandle
+            })}
             style=${styleMap({
-              top: `${y}%`,
+              top: `${gridHandleY}%`,
-              left: `${x}%`,
+              left: `${gridHandleX}%`,
               backgroundColor: `hsla(${this.hue}deg, ${this.saturation}%, ${this.lightness}%)`
             })}
             role="application"

src/components/image-comparer/image-comparer.ts

@@ -44,15 +44,12 @@ export default class SlImageComparer extends LitElement {
 
     event.preventDefault();
 
-    drag(
+    drag(this.base, {
-      this.base,
+      onMove: x => {
-      x => {
         this.position = parseFloat(clamp((x / width) * 100, 0, 100).toFixed(2));
       },
-      {
+      initialEvent: event
-        initialEvent: event
+    });
-      }
-    );
   }
 
   handleKeyDown(event: KeyboardEvent) {

src/components/split-panel/split-panel.ts

@@ -108,9 +108,8 @@ export default class SlSplitPanel extends LitElement {
     // Prevent text selection when dragging
     event.preventDefault();
 
-    drag(
+    drag(this, {
-      this,
+      onMove: (x, y) => {
-      (x, y) => {
         let newPositionInPixels = this.vertical ? y : x;
 
         // Flip for end panels
@@ -142,10 +141,8 @@ export default class SlSplitPanel extends LitElement {
 
         this.position = clamp(this.pixelsToPercentage(newPositionInPixels), 0, 100);
       },
-      {
+      initialEvent: event
-        initialEvent: event
+    });
-      }
-    );
   }
 
   handleKeyDown(event: KeyboardEvent) {

src/internal/drag.ts

@@ -1,4 +1,8 @@
 interface DragOptions {
+  /** Callback that runs as dragging occurs. */
+  onMove: (x: number, y: number) => void;
+  /** Callback that runs when dragging stops. */
+  onStop: () => void;
   /**
    * When an initial event is passed, the first drag will be triggered immediately using the coordinates therein. This
    * is useful when the drag is initiated by a mousedown/touchstart event but you want the initial "click" to activate
@@ -7,7 +11,7 @@ interface DragOptions {
   initialEvent: PointerEvent;
 }
 
-export function drag(container: HTMLElement, onMove: (x: number, y: number) => void, options?: Partial<DragOptions>) {
+export function drag(container: HTMLElement, options?: Partial<DragOptions>) {
   function move(pointerEvent: PointerEvent) {
     const dims = container.getBoundingClientRect();
     const defaultView = container.ownerDocument.defaultView!;
@@ -16,12 +20,18 @@ export function drag(container: HTMLElement, onMove: (x: number, y: number) => v
     const x = pointerEvent.pageX - offsetX;
     const y = pointerEvent.pageY - offsetY;
 
-    onMove(x, y);
+    if (options?.onMove) {
+      options.onMove(x, y);
+    }
   }
 
   function stop() {
     document.removeEventListener('pointermove', move);
     document.removeEventListener('pointerup', stop);
+
+    if (options?.onStop) {
+      options.onStop();
+    }
   }
 
   document.addEventListener('pointermove', move, { passive: true });