improve loading state management in theme service

frontend/src/app/components/block-overview-graph/block-overview-graph.component.ts

@@ -64,7 +64,8 @@ export class BlockOverviewGraphComponent implements AfterViewInit, OnDestroy, On
 
   @ViewChild('blockCanvas')
   canvas: ElementRef<HTMLCanvasElement>;
-  themeChangedSubscription: Subscription;
+  themeStateSubscription: Subscription;
+  loadedTheme = 'default';
 
   gl: WebGLRenderingContext;
   animationFrameRequest: number;
@@ -129,7 +130,11 @@ export class BlockOverviewGraphComponent implements AfterViewInit, OnDestroy, On
       if (this.gl) {
         this.initCanvas();
         this.resizeCanvas();
-        this.themeChangedSubscription = this.themeService.themeChanged$.subscribe(() => {
+        this.themeStateSubscription = this.themeService.themeState$.subscribe((state) => {
+          if (state.loading) {
+            return;
+          }
+          this.loadedTheme = state.theme;
           this.scene.setColorFunction(this.getColorFunction());
         });
       }
@@ -184,7 +189,7 @@ export class BlockOverviewGraphComponent implements AfterViewInit, OnDestroy, On
     }
     this.vertexArray.destroy();
     this.vertexArray = null;
-    this.themeChangedSubscription?.unsubscribe();
+    this.themeStateSubscription?.unsubscribe();
     this.searchSubscription?.unsubscribe();
   }
 
@@ -670,13 +675,13 @@ export class BlockOverviewGraphComponent implements AfterViewInit, OnDestroy, On
           break;
       }
       if (matches) {
-        if (this.themeService.theme !== 'contrast' && this.themeService.theme !== 'bukele') {
+        if (this.loadedTheme !== 'contrast' && this.loadedTheme !== 'bukele') {
           return (gradient === 'age') ? ageColorFunction(tx, defaultColors.fee, defaultAuditColors, this.relativeTime || (Date.now() / 1000)) : defaultColorFunction(tx, defaultColors.fee, defaultAuditColors, this.relativeTime || (Date.now() / 1000));
         } else {
           return (gradient === 'age') ? ageColorFunction(tx, contrastColors.fee, contrastAuditColors, this.relativeTime || (Date.now() / 1000)) : contrastColorFunction(tx, contrastColors.fee, contrastAuditColors, this.relativeTime || (Date.now() / 1000));
         }
       } else {
-        if (this.themeService.theme !== 'contrast' && this.themeService.theme !== 'bukele') {
+        if (this.loadedTheme !== 'contrast' && this.loadedTheme !== 'bukele') {
           return (gradient === 'age') ? { r: 1, g: 1, b: 1, a: 0.05 } : defaultColorFunction(
             tx,
             defaultColors.unmatchedfee,

frontend/src/app/components/fees-box/fees-box.component.ts

@@ -16,7 +16,7 @@ import { ThemeService } from '@app/services/theme.service';
 export class FeesBoxComponent implements OnInit, OnDestroy {
   isLoading$: Observable<boolean>;
   recommendedFees$: Observable<Recommendedfees>;
-  themeSubscription: Subscription;
+  themeStateSubscription: Subscription;
   gradient = 'linear-gradient(to right, var(--skeleton-bg), var(--skeleton-bg))';
   noPriority = 'var(--skeleton-bg)';
   fees: Recommendedfees;
@@ -42,8 +42,10 @@ export class FeesBoxComponent implements OnInit, OnDestroy {
         }
       )
     );
-    this.themeSubscription = this.themeService.themeChanged$.subscribe(() => {
-      this.setFeeGradient();
+    this.themeStateSubscription = this.themeService.themeState$.subscribe((state) => {
+      if (!state.loading) {
+        this.setFeeGradient();
+      }
     });
   }
 
@@ -66,6 +68,6 @@ export class FeesBoxComponent implements OnInit, OnDestroy {
   }
 
   ngOnDestroy(): void {
-    this.themeSubscription.unsubscribe();
+    this.themeStateSubscription.unsubscribe();
   }
 }

frontend/src/app/components/mempool-blocks/mempool-blocks.component.ts

@@ -50,6 +50,7 @@ export class MempoolBlocksComponent implements OnInit, OnChanges, OnDestroy {
   blockDisplayMode: 'size' | 'fees';
   blockTransformation = {};
   blocksSubscription: Subscription;
+  themeStateSubscription: Subscription;
 
   mempoolBlocksFull: MempoolBlock[] = [];
   mempoolBlockStyles = [];
@@ -146,6 +147,12 @@ export class MempoolBlocksComponent implements OnInit, OnChanges, OnDestroy {
     this.reduceEmptyBlocksToFitScreen(this.mempoolEmptyBlocks);
 
     this.isTabHiddenSubscription = this.stateService.isTabHidden$.subscribe((tabHidden) => this.tabHidden = tabHidden);
+    this.themeStateSubscription = this.themeService.themeState$.subscribe((state) => {
+      if (!state.loading) {
+        this.updateMempoolBlockStyles();
+        this.cd.markForCheck();
+      }
+    });
     this.loadingBlocks$ = combineLatest([
       this.stateService.isLoadingWebSocket$,
       this.stateService.isLoadingMempool$
@@ -300,6 +307,7 @@ export class MempoolBlocksComponent implements OnInit, OnChanges, OnDestroy {
     this.networkSubscription.unsubscribe();
     this.blockDisplayModeSubscription.unsubscribe();
     this.timeLtrSubscription.unsubscribe();
+    this.themeStateSubscription.unsubscribe();
     this.chainTipSubscription.unsubscribe();
     this.keySubscription.unsubscribe();
     this.isTabHiddenSubscription.unsubscribe();

frontend/src/app/components/theme-selector/theme-selector.component.scss

@@ -1,3 +1,7 @@
 .custom-select {
   width: 100px;
 }
+
+.custom-select:disabled {
+  opacity: 0.6;
+}

frontend/src/app/components/theme-selector/theme-selector.component.ts

@@ -13,7 +13,7 @@ import { Subscription } from 'rxjs';
 export class ThemeSelectorComponent implements OnInit {
   themeForm: UntypedFormGroup;
   themes = ['default', 'contrast', 'softsimon', 'bukele'];
-  themeSubscription: Subscription;
+  themeStateSubscription: Subscription;
 
   constructor(
     private formBuilder: UntypedFormBuilder,
@@ -24,11 +24,13 @@ export class ThemeSelectorComponent implements OnInit {
     this.themeForm = this.formBuilder.group({
       theme: ['default']
     });
-    this.themeForm.get('theme')?.setValue(this.themeService.theme);
-    // Subscribe to theme changes because two instances of this component exist
-    this.themeSubscription = this.themeService.themeChanged$.subscribe(() => {
-      if (this.themeForm.get('theme')?.value !== this.themeService.theme){
-        this.themeForm.get('theme')?.setValue(this.themeService.theme);
+    this.themeStateSubscription = this.themeService.themeState$.subscribe(({ theme, loading }) => {
+      console.log('Theme state changed:', theme, loading);
+      this.themeForm.get('theme')?.setValue(theme, { emitEvent: false });
+      if (loading) {
+        this.themeForm.get('theme')?.disable({ emitEvent: false });
+      } else {
+        this.themeForm.get('theme')?.enable({ emitEvent: false });
       }
     });
   }
@@ -39,6 +41,6 @@ export class ThemeSelectorComponent implements OnInit {
   }
 
   ngOnDestroy() {
-    this.themeSubscription.unsubscribe();
+    this.themeStateSubscription.unsubscribe();
   }
 }

frontend/src/app/services/theme.service.ts

@@ -1,5 +1,5 @@
 import { Injectable } from '@angular/core';
-import { Subject } from 'rxjs';
+import { BehaviorSubject } from 'rxjs';
 import { defaultMempoolFeeColors, contrastMempoolFeeColors } from '@app/app.constants';
 import { StorageService } from '@app/services/storage.service';
 import { StateService } from '@app/services/state.service';
@@ -10,7 +10,7 @@ import { StateService } from '@app/services/state.service';
 export class ThemeService {
   style: HTMLLinkElement | null = null;
   theme: string = 'default';
-  themeChanged$: Subject<string> = new Subject();
+  themeState$: BehaviorSubject<{ theme: string; loading: boolean; }>;
   mempoolFeeColors: string[] = defaultMempoolFeeColors;
 
   constructor(
@@ -23,6 +23,7 @@ export class ThemeService {
       theme = 'default';
       this.storageService.setValue('theme-preference', 'default');
     }
+    this.themeState$ = new BehaviorSubject({ theme, loading: false });
     this.apply(theme);
   }
 
@@ -32,33 +33,41 @@ export class ThemeService {
     }
 
     this.theme = theme;
-    if (theme !== 'default') {
-      this.mempoolFeeColors = (theme === 'contrast'  || theme === 'bukele') ? contrastMempoolFeeColors : defaultMempoolFeeColors;
-      try {
-        if (!this.style) {
-          this.style = document.createElement('link');
-          this.style.rel = 'stylesheet';
-          this.style.href = `${theme}.css`;
-          this.style.onerror = (): void => { // something went wrong (eg the css resource does not exist, revert to default)
-            this.apply('default');
-          };
-          document.head.appendChild(this.style); // load the css now
-        } else {
-          this.style.href = `${theme}.css`;
-        }
-      } catch (err) {
-        console.log('failed to apply theme stylesheet: ', err);
-      }
-    } else {
-      this.mempoolFeeColors = defaultMempoolFeeColors;
+    if (theme === 'default') {
       if (this.style) {
         this.style.remove();
         this.style = null;
       }
+      if (!this.stateService.env.customize?.theme) {
+        this.storageService.setValue('theme-preference', theme);
+      }
+      this.mempoolFeeColors = defaultMempoolFeeColors;
+      this.themeState$.next({ theme, loading: false });
+      return;
     }
-    if (!this.stateService.env.customize?.theme) {
-      this.storageService.setValue('theme-preference', theme);
+
+    // Load theme stylesheet
+    this.themeState$.next({ theme, loading: true });
+    try {
+      if (!this.style) {
+        this.style = document.createElement('link');
+        this.style.rel = 'stylesheet';
+        document.head.appendChild(this.style); // load the css now
+      }
+
+      this.style.onload = () => {
+        this.mempoolFeeColors = theme === 'contrast' || theme === 'bukele' ? contrastMempoolFeeColors : defaultMempoolFeeColors;
+        this.themeState$.next({ theme, loading: false });
+      };
+      this.style.onerror = () => this.apply('default');
+      this.style.href = `${theme}.css`;
+
+      if (!this.stateService.env.customize?.theme) {
+        this.storageService.setValue('theme-preference', theme);
+      }
+    } catch (err) {
+      console.log('failed to apply theme stylesheet: ', err);
+      this.apply('default');
     }
-    this.themeChanged$.next(this.theme);
   }
 }