New function flatHeights (Android)

Author: aMarCruz

CHANGELOG.md

@@ -4,7 +4,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ## [Unreleased]
 
+## [2.0.0-beta.5] - 2018-08-21
+
 ### Added
+- New function `flatHeights` to calculate the height of multiple strings at once, much faster than` measure`.
 - Revised REAME. Now it's clearer, part of its content  moved to the Wiki.
 - Docummented the iOS only properties `capHeight` and `xHeight` from the `fontFromSpecs` result.
 - New flag `usePreciseWidth` (default `false`) request the most accurate calculation of the width (Android) and the value of `lastWidth` (both), but its is a bit slower.

README.md

@@ -72,6 +72,10 @@ This function measures the text like RN does when the text does not have embedde
 
 If you provide the `width`, the measurement will apply the restriction and take into account the automatic line breaks, in addition to the explicit ones.
 
+**NOTE:**
+
+Although this function is accurate and provides complete information, it can be heavy if the text is a lot, like the one that can be displayed in a FlatList. For these cases, it is better to use `flatHeights` which is much faster.
+
 <a name="tsmeasureparams"></a>**TSMeasureParams**
 
 JS object with the text to measure, the maximum width, and properties like ones in the react-native [`<Text>`](https://facebook.github.io/react-native/docs/text) component.
@@ -166,6 +170,46 @@ class Test extends Component<Props, State> {
 
 ---
 
+## `flatHeights`
+
+```ts
+flatHeights(options: TSHeightsParams): Promise<number[]>
+```
+
+Calculate the height of each of the strings in an array.
+
+This is an alternative to `measure` designed for cases in which you have to calculate the height of numerous text blocks with common characteristics (width, font, etc), a Typical case in the `<FlatList>`.
+
+The measurement uses the same algorithm as `measure`, but it returns only the height of each block and, by avoiding multiple steps through the bridge, it is much faster (in my tests, with 3500 random blocks of text, it took 778 ms, while mesure took 33,218).
+
+In the future I will prepare an example of its use with FlatList and multiple styles on the same card.
+
+**TSHeightsParams**
+
+This is an object similar to the one received by measure, with the difference that the text property is an array of strings, and the usePreciseWidth property is ignored.
+
+The result is an array with the height of each block, in the same order was given.
+
+This is an object similar to the one received by `measure`, but the `text` property is an array of strings and the `usePreciseWidth` property is ignored.
+
+Property   | Type   | Default
+---------- | ------ | --------
+text       | string | (none)
+width      | number | Infinity
+fontFamily | string | OS dependent
+fontWeight | string | 'normal'
+fontSize   | number | 14
+fontStyle  | string | 'normal'
+fontVariant         | array   | (none)
+allowFontScaling    | boolean | true
+letterSpacing       | number  | (none)
+includeFontPadding  | boolean | true
+textBreakStrategy   | string  | 'highQuality'
+
+The result is a Promise that resolves to an array with the height of each block (_SP_), in the same order in which they were received.
+
+---
+
 ## `specsForTextStyles`
 
 ```ts

android/build.gradle

@@ -69,3 +69,9 @@ task customClean(type: Delete) {
     delete rootProject.buildDir
 }
 clean.dependsOn customClean
+
+//gradle.projectsEvaluated {
+//    tasks.withType(JavaCompile) {
+//        options.compilerArgs << "-Xlint:unchecked" << "-Xlint:deprecation"
+//    }
+//}

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

@@ -1,14 +1,19 @@
 package com.github.amarcruz.rntextsize;
 
-import android.annotation.TargetApi;
 import android.graphics.Typeface;
+import android.os.Build;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.text.Layout;
+import android.util.Log;
 
 import com.facebook.react.bridge.JSApplicationIllegalArgumentException;
+import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.bridge.ReadableArray;
 import com.facebook.react.bridge.ReadableMap;
-import com.facebook.react.modules.systeminfo.ReactNativeVersion;
+import com.facebook.react.bridge.ReadableType;
+import com.facebook.react.uimanager.PixelUtil;
+import com.facebook.react.views.text.ReactFontManager;
 
 import java.util.Map;
 
@@ -19,13 +24,32 @@ final class RNTextSizeConf {
     static {
         int version = 0;
         try {
-            Map<String, Object> rnv = ReactNativeVersion.VERSION;
+            Class.forName("com.facebook.react.modules.systeminfo.ReactNativeVersion");
+            Map<String, Object> rnv = com.facebook.react.modules.systeminfo.ReactNativeVersion.VERSION;
             version = ((int) rnv.get("major") << 16) | (int) rnv.get("minor");
-        } catch (Exception ignore) {
+        } catch (Exception ex) {
+            Log.v("RNTextSize", "Cannot get RN version.", ex);
         }
         reactNativeVersion = version;
     }
 
+
+    /**
+     * Make a Typeface from the supplied font family and style.
+     */
+    @NonNull
+    static Typeface getFont(
+            @NonNull final ReactApplicationContext context,
+            @Nullable String family,
+            final int style
+    ) {
+        final Typeface typeface = family != null
+                ? ReactFontManager.getInstance().getTypeface(family, style, context.getAssets())
+                : null;
+
+        return typeface != null ? typeface : Typeface.defaultFromStyle(style);
+    }
+
     // letterSpacing is supported in RN 0.55+
     static boolean supportLetterSpacing() {
         return reactNativeVersion >= 55;
@@ -36,11 +60,11 @@ static float getDefaultFontSize() {
     }
 
     private final ReadableMap mOpts;
+    private final boolean allowFontScaling;
 
     final String fontFamily;
     final float fontSize;
     final int fontStyle;
-    final boolean allowFontScaling;
     final boolean includeFontPadding;
     final float letterSpacing;
 
@@ -68,8 +92,8 @@ boolean has(@NonNull final String name) {
         return mOpts.hasKey(name);
     }
 
-    float getFloatOrNaN(@NonNull final String name) {
-        return mOpts.hasKey(name) ? (float) mOpts.getDouble(name) : Float.NaN;
+    boolean getBooleanOrTrue(@NonNull final String name) {
+        return !mOpts.hasKey(name) || mOpts.getBoolean(name);
     }
 
     @Nullable
@@ -78,8 +102,33 @@ String getString(@NonNull final String name) {
                 ? mOpts.getString(name) : null;
     }
 
-    @TargetApi(23)
+    @SuppressWarnings("SameParameterValue")
+    @Nullable
+    ReadableArray getArray(@NonNull final String name) {
+        return mOpts.hasKey(name) && mOpts.getType(name) == ReadableType.Array
+                ? mOpts.getArray(name) : null;
+    }
+
+    float scale(final float measure) {
+        return allowFontScaling
+                ? PixelUtil.toPixelFromSP(measure)
+                : PixelUtil.toPixelFromDIP(measure);
+    }
+
+    float getWidth(final float density) {
+        float width = getFloatOrNaN("width");
+        if (!Float.isNaN(width) && width > 0) {
+            return width * density;                // always DIP
+        } else {
+            return Float.MAX_VALUE;
+        }
+    }
+
     int getTextBreakStrategy() {
+        if (Build.VERSION.SDK_INT < 23) {
+            return 0;
+        }
+
         final String textBreakStrategy = getString("textBreakStrategy");
 
         if (textBreakStrategy != null) {
@@ -98,6 +147,10 @@ int getTextBreakStrategy() {
         return Layout.BREAK_STRATEGY_HIGH_QUALITY;
     }
 
+    private float getFloatOrNaN(@NonNull final String name) {
+        return mOpts.hasKey(name) ? (float) mOpts.getDouble(name) : Float.NaN;
+    }
+
     private float getFontSizeOrDefault() {
         if (mOpts.hasKey("fontSize")) {
             final float num = (float) mOpts.getDouble("fontSize");
@@ -127,8 +180,4 @@ private int getFontStyle() {
         }
         return style;
     }
-
-    boolean getBooleanOrTrue(@NonNull final String name) {
-        return !mOpts.hasKey(name) || mOpts.getBoolean(name);
-    }
 }