fix: do not add opacity for transparent background color (#162)

Fixes:
#161

Author: exploIF

android/src/main/java/com/swmansion/enriched/styles/HtmlStyle.kt

@@ -154,6 +154,8 @@ class HtmlStyle {
   }
 
   private fun withOpacity(color: Int, alpha: Int): Int {
+    // Do not apply opacity to transparent color
+    if (Color.alpha(color) == 0) return color
     val a = alpha.coerceIn(0, 255)
     return (color and 0x00FFFFFF) or (a shl 24)
   }

ios/styles/InlineCodeStyle.mm

@@ -3,6 +3,7 @@
 #import "FontExtension.h"
 #import "OccurenceUtils.h"
 #import "ParagraphsUtils.h"
+#import "ColorExtension.h"
 
 @implementation InlineCodeStyle {
   EnrichedTextInputView *_input;
@@ -33,7 +34,7 @@ - (void)addAttributes:(NSRange)range {
     NSRange currentRange = [value rangeValue];
     [_input->textView.textStorage beginEditing];
 
-    [_input->textView.textStorage addAttribute:NSBackgroundColorAttributeName value:[[_input->config inlineCodeBgColor] colorWithAlphaComponent:0.4] range:currentRange];
+    [_input->textView.textStorage addAttribute:NSBackgroundColorAttributeName value:[[_input->config inlineCodeBgColor] colorWithAlphaIfNotTransparent:0.4] range:currentRange];
     [_input->textView.textStorage addAttribute:NSForegroundColorAttributeName value:[_input->config inlineCodeFgColor] range:currentRange];
     [_input->textView.textStorage addAttribute:NSUnderlineColorAttributeName value:[_input->config inlineCodeFgColor] range:currentRange];
     [_input->textView.textStorage addAttribute:NSStrikethroughColorAttributeName value:[_input->config inlineCodeFgColor] range:currentRange];
@@ -53,7 +54,7 @@ - (void)addAttributes:(NSRange)range {
 
 - (void)addTypingAttributes {
   NSMutableDictionary *newTypingAttrs = [_input->textView.typingAttributes mutableCopy];
-  newTypingAttrs[NSBackgroundColorAttributeName] = [[_input->config inlineCodeBgColor] colorWithAlphaComponent:0.4];
+  newTypingAttrs[NSBackgroundColorAttributeName] = [[_input->config inlineCodeBgColor] colorWithAlphaIfNotTransparent:0.4];
   newTypingAttrs[NSForegroundColorAttributeName] = [_input->config inlineCodeFgColor];
   newTypingAttrs[NSUnderlineColorAttributeName] = [_input->config inlineCodeFgColor];
   newTypingAttrs[NSStrikethroughColorAttributeName] = [_input->config inlineCodeFgColor];

ios/styles/MentionStyle.mm

@@ -4,6 +4,7 @@
 #import "TextInsertionUtils.h"
 #import "WordsUtils.h"
 #import "UIView+React.h"
+#import "ColorExtension.h"
 
 // custom NSAttributedStringKey to differentiate from links
 static NSString *const MentionAttributeName = @"MentionAttributeName";
@@ -154,7 +155,7 @@ - (void)addMention:(NSString *)indicator text:(NSString *)text attributes:(NSStr
     NSForegroundColorAttributeName: styleProps.color,
     NSUnderlineColorAttributeName: styleProps.color,
     NSStrikethroughColorAttributeName: styleProps.color,
-    NSBackgroundColorAttributeName: [styleProps.backgroundColor colorWithAlphaComponent:0.4],
+    NSBackgroundColorAttributeName: [styleProps.backgroundColor colorWithAlphaIfNotTransparent:0.4],
   } mutableCopy];
 
   if(styleProps.decorationLine == DecorationUnderline) {
@@ -186,7 +187,7 @@ - (void)addMentionAtRange:(NSRange)range params:(MentionParams *)params {
     NSForegroundColorAttributeName: styleProps.color,
     NSUnderlineColorAttributeName: styleProps.color,
     NSStrikethroughColorAttributeName: styleProps.color,
-    NSBackgroundColorAttributeName: [styleProps.backgroundColor colorWithAlphaComponent:0.4],
+    NSBackgroundColorAttributeName: [styleProps.backgroundColor colorWithAlphaIfNotTransparent:0.4],
   } mutableCopy];
 
   if(styleProps.decorationLine == DecorationUnderline) {

ios/utils/ColorExtension.h

@@ -3,4 +3,5 @@
 
 @interface UIColor (ColorExtension)
 - (BOOL)isEqualToColor:(UIColor *)otherColor;
+- (UIColor *)colorWithAlphaIfNotTransparent:(CGFloat)newAlpha;
 @end

ios/utils/ColorExtension.mm

@@ -24,4 +24,13 @@ - (BOOL)isEqualToColor:(UIColor *)otherColor {
 
   return [selfColor isEqual:otherColor];
 }
+
+- (UIColor *)colorWithAlphaIfNotTransparent:(CGFloat)newAlpha {
+  CGFloat alpha = 0.0;
+  [self getRed:nil green:nil blue:nil alpha:&alpha];
+  if (alpha > 0.0) {
+      return [self colorWithAlphaComponent:newAlpha];
+  }
+  return self;
+}
 @end