Add numberOfLines parameter to limit number of lines

Author: hsource

README.md

@@ -28,6 +28,7 @@ In both functions, the text to be measured is required, but the rest of the para
 - `textBreakStrategy` (Android)
 - `letterSpacing`
 - `allowFontScaling`
+- `numberOfLines`
 - `width`: Constraint for automatic line-break based on text-break strategy.
 
 In addition, the library includes functions to obtain information about the fonts visible to the App.
@@ -100,6 +101,7 @@ allowFontScaling   | boolean | true     | To respect the user' setting of large
 letterSpacing      | number  | (none)   | Additional spacing between characters (aka `tracking`).<br>**Note:** In iOS a zero cancels automatic kerning.<br>_All iOS, Android with API 21+_
 includeFontPadding | boolean | true     | Include additional top and bottom padding, to avoid clipping certain characters.<br>_Android only_
 textBreakStrategy  | string  | 'highQuality' | One of 'simple', 'balanced', or 'highQuality'.<br>_Android only, with API 23+_
+numberOfLines      | number  | (none)   | Limit the number of lines the text can render on
 width              | number  | MAX_INT  | Restrict the width. The resulting height will vary depending on the automatic flow of the text.
 usePreciseWidth    | boolean | false    | If `true`, the result will include an exact `width` and the `lastLineWidth` property.<br>You can see the effect of this flag in the [sample App][sample-app].
 lineInfoForLine    | number  | (none)   | If `>=0`, the result will include a [lineInfo](#lineinfo) property with information for the required line number.
@@ -228,6 +230,7 @@ allowFontScaling    | boolean  | true
 letterSpacing       | number   | (none)
 includeFontPadding  | boolean  | true
 textBreakStrategy   | string   | 'highQuality'
+numberOfLines       | number   | (none)
 
 The result is a Promise that resolves to an array with the height of each block (in _SP_), in the same order in which the blocks were received.
 

android/src/main/java/com/github/amarcruz/rntextsize/RNTextSizeConf.java

@@ -69,6 +69,7 @@ static boolean supportUpperCaseTransform() {
     final int fontStyle;
     final boolean includeFontPadding;
     final float letterSpacing;
+    final @Nullable Integer numberOfLines;
 
     /**
      * Proccess the user specs. Set both `allowFontScaling` & `includeFontPadding` to the user
@@ -88,6 +89,10 @@ static boolean supportUpperCaseTransform() {
 
         // letterSpacing is supported in RN 0.55+
         letterSpacing = supportLetterSpacing() ? getFloatOrNaN("letterSpacing") : Float.NaN;
+
+        Integer rawNumberOfLines = getIntOrNull("numberOfLines");
+        if (rawNumberOfLines != null && rawNumberOfLines < 0) rawNumberOfLines = null;
+        numberOfLines = rawNumberOfLines;
     }
 
     boolean has(@Nonnull final String name) {

android/src/main/java/com/github/amarcruz/rntextsize/RNTextSizeModule.java

@@ -10,6 +10,7 @@
 import android.text.SpannableStringBuilder;
 import android.text.StaticLayout;
 import android.text.TextPaint;
+import android.text.TextUtils;
 
 import com.facebook.react.bridge.Arguments;
 import com.facebook.react.bridge.Promise;
@@ -118,13 +119,17 @@ public void measure(@Nullable final ReadableMap specs, final Promise promise) {
 
             if (layout == null) {
                 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-                    layout = StaticLayout.Builder.obtain(text, 0, text.length(), textPaint, hintWidth)
+                    StaticLayout.Builder builder = StaticLayout.Builder.obtain(text, 0, text.length(), textPaint, hintWidth)
                             .setAlignment(Layout.Alignment.ALIGN_NORMAL)
                             .setBreakStrategy(conf.getTextBreakStrategy())
                             .setHyphenationFrequency(Layout.HYPHENATION_FREQUENCY_NORMAL)
                             .setIncludePad(includeFontPadding)
-                            .setLineSpacing(SPACING_ADDITION, SPACING_MULTIPLIER)
-                            .build();
+                            .setLineSpacing(SPACING_ADDITION, SPACING_MULTIPLIER);
+                    if (conf.numberOfLines != null) {
+                        builder = builder.setMaxLines(conf.numberOfLines)
+                                .setEllipsize(TextUtils.TruncateAt.END);
+                    }
+                    layout = builder.build();
                 } else {
                     layout = new StaticLayout(
                             text,
@@ -228,13 +233,17 @@ public void flatHeights(@Nullable final ReadableMap specs, final Promise promise
                 sb.replace(0, sb.length(), text);
 
                 if (Build.VERSION.SDK_INT >= 23) {
-                    layout = StaticLayout.Builder.obtain(sb, 0, sb.length(), textPaint, (int) width)
+                    StaticLayout.Builder builder = StaticLayout.Builder.obtain(sb, 0, sb.length(), textPaint, (int) width)
                             .setAlignment(Layout.Alignment.ALIGN_NORMAL)
                             .setBreakStrategy(textBreakStrategy)
                             .setHyphenationFrequency(Layout.HYPHENATION_FREQUENCY_NORMAL)
                             .setIncludePad(includeFontPadding)
-                            .setLineSpacing(SPACING_ADDITION, SPACING_MULTIPLIER)
-                            .build();
+                            .setLineSpacing(SPACING_ADDITION, SPACING_MULTIPLIER);
+                    if (conf.numberOfLines != null) {
+                        builder = builder.setMaxLines(conf.numberOfLines)
+                                .setEllipsize(TextUtils.TruncateAt.END);
+                    }
+                    layout = builder.build();
                 } else {
                     layout = new StaticLayout(
                             sb,

index.d.ts

@@ -72,6 +72,8 @@ declare module "react-native-text-size" {
     includeFontPadding?: boolean;
     /** @platform android (SDK 23+) */
     textBreakStrategy?: TSTextBreakStrategy;
+    /** Number of lines to limit the text to */
+    numberOfLines?: number;
   }
 
   export type TSFontForStyle = {

index.js.flow

@@ -72,6 +72,8 @@ export type TSFontSpecs = {
   includeFontPadding?: boolean,
   /** @platform android (SDK 23+) */
   textBreakStrategy?: TSTextBreakStrategy,
+  /** Number of lines to limit the text to */
+  numberOfLines?: number,
 }
 
 export type TSFontForStyle = {

ios/RNTextSize.m

@@ -6,8 +6,8 @@
 #import <React/RCTUtils.h>
 #else
 #import "React/RCTConvert.h"   // Required when used as a Pod in a Swift project
-#import "React/RCTFont.h"
-#import "React/RCTUtils.h"
+#import <React/RCTFont.h>
+#import <React/RCTUtils.h>
 #endif
 
 #import <CoreText/CoreText.h>
@@ -99,7 +99,12 @@ - (dispatch_queue_t)methodQueue {
 
   NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:maxSize];
   textContainer.lineFragmentPadding = 0.0;
-  textContainer.lineBreakMode = NSLineBreakByClipping; // no maxlines support
+  textContainer.lineBreakMode = NSLineBreakByClipping;
+
+  const NSInteger numberOfLines = [RCTConvert NSInteger:options[@"numberOfLines"]];
+  if (numberOfLines > 0) {
+    textContainer.maximumNumberOfLines = numberOfLines;
+  }
 
   NSLayoutManager *layoutManager = [NSLayoutManager new];
   [layoutManager addTextContainer:textContainer];
@@ -178,7 +183,12 @@ - (dispatch_queue_t)methodQueue {
 
   NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:maxSize];
   textContainer.lineFragmentPadding = 0.0;
-  textContainer.lineBreakMode = NSLineBreakByClipping; // no maxlines support
+  textContainer.lineBreakMode = NSLineBreakByClipping;
+
+  const NSInteger numberOfLines = [RCTConvert NSInteger:options[@"numberOfLines"]];
+  if (numberOfLines > 0) {
+    textContainer.maximumNumberOfLines = numberOfLines;
+  }
 
   NSLayoutManager *layoutManager = [NSLayoutManager new];
   [layoutManager addTextContainer:textContainer];