Timeline: Use theme getContrastText to calculate value color based on background color (#34072)

* Timeline: Use theme getContrastText to calculate value color based on background color

* Changed back to using the old functions fill, and stroke

packages/grafana-data/src/themes/createColors.ts

@@ -73,7 +73,7 @@ export interface ThemeHoverStrengh {}
 /** @beta */
 export interface ThemeColors extends ThemeColorsBase<ThemeRichColor> {
   /** Returns a text color for the background */
-  getContrastText(background: string): string;
+  getContrastText(background: string, threshold?: number): string;
   /* Brighten or darken a color by specified factor (0-1) */
   emphasize(color: string, amount?: number): string;
 }
@@ -255,11 +255,9 @@ export function createColors(colors: ThemeColorsInput): ThemeColors {
     ...other
   } = colors;
 
-  function getContrastText(background: string) {
+  function getContrastText(background: string, threshold: number = contrastThreshold) {
     const contrastText =
-      getContrastRatio(background, dark.text.maxContrast) >= contrastThreshold
-        ? dark.text.maxContrast
-        : light.text.maxContrast;
+      getContrastRatio(background, dark.text.maxContrast) >= threshold ? dark.text.maxContrast : light.text.maxContrast;
     // todo, need color framework
     return contrastText;
   }

public/app/plugins/panel/timeline/timeline.ts

@@ -3,7 +3,7 @@ import { FIXED_UNIT } from '@grafana/ui/src/components/GraphNG/GraphNG';
 import { Quadtree, Rect, pointWithin } from 'app/plugins/panel/barchart/quadtree';
 import { distribute, SPACE_BETWEEN } from 'app/plugins/panel/barchart/distribute';
 import { TimelineMode } from './types';
-import { TimeRange } from '@grafana/data';
+import { GrafanaTheme2, TimeRange } from '@grafana/data';
 import { BarValueVisibility } from '@grafana/ui';
 
 const { round, min, ceil } = Math;
@@ -12,8 +12,6 @@ const pxRatio = devicePixelRatio;
 
 const laneDistr = SPACE_BETWEEN;
 
-const font = Math.round(10 * pxRatio) + 'px Roboto';
-
 type WalkCb = (idx: number, offPx: number, dimPx: number) => void;
 
 function walk(rowHeight: number, yIdx: number | null, count: number, dim: number, draw: WalkCb) {
@@ -33,12 +31,13 @@ export interface TimelineCoreOptions {
   numSeries: number;
   rowHeight: number;
   colWidth?: number;
+  theme: GrafanaTheme2;
   showValue: BarValueVisibility;
   isDiscrete: (seriesIdx: number) => boolean;
-
+  colorLookup: (seriesIdx: number, value: any) => string;
   label: (seriesIdx: number) => string;
-  fill: (seriesIdx: number, valueIdx: number, value: any) => CanvasRenderingContext2D['fillStyle'];
-  stroke: (seriesIdx: number, valueIdx: number, value: any) => CanvasRenderingContext2D['strokeStyle'];
+  fill: (seriesIdx: number, value: any) => CanvasRenderingContext2D['fillStyle'];
+  stroke: (seriesIdx: number, value: any) => CanvasRenderingContext2D['strokeStyle'];
   getTimeRange: () => TimeRange;
   formatValue?: (seriesIdx: number, value: any) => string;
   onHover?: (seriesIdx: number, valueIdx: number) => void;
@@ -56,11 +55,13 @@ export function getConfig(opts: TimelineCoreOptions) {
     rowHeight = 0,
     colWidth = 0,
     showValue,
+    theme,
     label,
     fill,
     stroke,
     formatValue,
     getTimeRange,
+    colorLookup,
     // onHover,
     // onLeave,
   } = opts;
@@ -73,10 +74,11 @@ export function getConfig(opts: TimelineCoreOptions) {
       let mark = document.createElement('div');
       mark.classList.add('bar-mark');
       mark.style.position = 'absolute';
-      mark.style.background = 'rgba(255,255,255,0.4)';
+      mark.style.background = 'rgba(255,255,255,0.2)';
       return mark;
     });
 
+  const font = `500 ${Math.round(12 * devicePixelRatio)}px ${theme.typography.fontFamily}`;
   const hovered: Array<Rect | null> = Array(numSeries).fill(null);
 
   const size = [colWidth, Infinity];
@@ -117,7 +119,7 @@ export function getConfig(opts: TimelineCoreOptions) {
     discrete: boolean
   ) {
     if (discrete) {
-      let fillStyle = fill(seriesIdx + 1, valueIdx, value);
+      let fillStyle = fill(seriesIdx + 1, value);
       let fillPath = fillPaths.get(fillStyle);
 
       if (fillPath == null) {
@@ -127,7 +129,7 @@ export function getConfig(opts: TimelineCoreOptions) {
       rect(fillPath, lft, top, wid, hgt);
 
       if (strokeWidth) {
-        let strokeStyle = stroke(seriesIdx + 1, valueIdx, value);
+        let strokeStyle = stroke(seriesIdx + 1, value);
         let strokePath = strokePaths.get(strokeStyle);
 
         if (strokePath == null) {
@@ -139,13 +141,13 @@ export function getConfig(opts: TimelineCoreOptions) {
     } else {
       ctx.beginPath();
       rect(ctx, lft, top, wid, hgt);
-      ctx.fillStyle = fill(seriesIdx, valueIdx, value);
+      ctx.fillStyle = fill(seriesIdx, value);
       ctx.fill();
 
       if (strokeWidth) {
         ctx.beginPath();
         rect(ctx, lft + strokeWidth / 2, top + strokeWidth / 2, wid - strokeWidth, hgt - strokeWidth);
-        ctx.strokeStyle = stroke(seriesIdx, valueIdx, value);
+        ctx.strokeStyle = stroke(seriesIdx, value);
         ctx.stroke();
       }
     }
@@ -195,7 +197,7 @@ export function getConfig(opts: TimelineCoreOptions) {
                   yOff,
                   lft,
                   round(yOff + y0),
-                  rgt - lft,
+                  rgt - lft - 2,
                   round(hgt),
                   strokeWidth,
                   iy,
@@ -257,7 +259,6 @@ export function getConfig(opts: TimelineCoreOptions) {
           u.ctx.clip();
 
           u.ctx.font = font;
-          u.ctx.fillStyle = 'black';
           u.ctx.textAlign = mode === TimelineMode.Changes ? 'left' : 'center';
           u.ctx.textBaseline = 'middle';
 
@@ -285,6 +286,15 @@ export function getConfig(opts: TimelineCoreOptions) {
               for (let ix = 0; ix < dataY.length; ix++) {
                 if (dataY[ix] != null) {
                   let x = valToPosX(dataX[ix], scaleX, xDim, xOff);
+
+                  // For the left aligned values shift them 2 pixels of edge
+                  if (mode === TimelineMode.Changes) {
+                    x += 2;
+                  }
+
+                  const valueColor = colorLookup(sidx, dataY[ix]);
+
+                  u.ctx.fillStyle = theme.colors.getContrastText(valueColor, 3);
                   u.ctx.fillText(formatValue(sidx, dataY[ix]), x, y);
                 }
               }

public/app/plugins/panel/timeline/utils.ts

@@ -6,8 +6,8 @@ import {
   formattedValueToString,
   getFieldDisplayName,
   outerJoinDataFrames,
-  classicColors,
   Field,
+  FALLBACK_COLOR,
 } from '@grafana/data';
 import {
   UPlotConfigBuilder,
@@ -72,15 +72,17 @@ export const preparePlotConfigBuilder: UPlotConfigPrepFn<{
     return !(mode && field.display && mode.startsWith('continuous-'));
   };
 
-  const colorLookup = (seriesIdx: number, valueIdx: number, value: any) => {
+  const colorLookup = (seriesIdx: number, value: any) => {
     const field = frame.fields[seriesIdx];
+
     if (field.display) {
       const disp = field.display(value); // will apply color modes
       if (disp.color) {
         return disp.color;
       }
     }
-    return classicColors[Math.floor(value % classicColors.length)];
+
+    return FALLBACK_COLOR;
   };
 
   const yAxisWidth =
@@ -99,9 +101,11 @@ export const preparePlotConfigBuilder: UPlotConfigPrepFn<{
     rowHeight: rowHeight!,
     colWidth: colWidth,
     showValue: showValue!,
+    theme,
     label: (seriesIdx) => getFieldDisplayName(frame.fields[seriesIdx], frame),
     fill: colorLookup,
     stroke: colorLookup,
+    colorLookup,
     getTimeRange,
     // hardcoded formatter for state values
     formatValue: (seriesIdx, value) => formattedValueToString(frame.fields[seriesIdx].display!(value)),