Add support for minEms, minWidth, maxEms, maxWidth in TextLayoutBuilder

Summary: Some attributes from `TextView` are still missing in `TextSpec`, specifically `maxEms` attribute was requested from engineers who are doing NewsFeed conversions to Components. `TextSpec` uses `TextLayoutBuilder` to do its layout and this diff adds support for `ems` and related attributes to `TextLayoutBuilder`, specifically `minEms`, `maxEms`, `minWidth`, `maxWidth`.

Reviewed By: sriramramani

Differential Revision: D4544590

fbshipit-source-id: 5f402d844811c5612af447150dc686c164e16f62

library/src/main/java/com/facebook/fbui/textlayoutbuilder/TextLayoutBuilder.java

@@ -58,6 +58,14 @@ public class TextLayoutBuilder {
   // Default maxLines.
   public static final int DEFAULT_MAX_LINES = Integer.MAX_VALUE;
 
+  private static final int EMS = 1;
+  private static final int PIXELS = 2;
+
+  private int mMinWidth = 0;
+  private int mMinWidthMode = PIXELS;
+  private int mMaxWidth = Integer.MAX_VALUE;
+  private int mMaxWidthMode = PIXELS;
+
   // Cache for text layouts.
   @VisibleForTesting
   static final LruCache<Integer, Layout> sCache = new LruCache<>(100);
@@ -101,6 +109,10 @@ void createNewPaintIfNeeded() {
       }
     }
 
+    int getLineHeight() {
+      return Math.round(paint.getFontMetricsInt(null) * spacingMult + spacingAdd);
+    }
+
     @Override
     public int hashCode() {
       int hashCode = 1;
@@ -618,6 +630,88 @@ public TextLayoutBuilder setGlyphWarmer(GlyphWarmer glyphWarmer) {
     return this;
   }
 
+  /**
+   * Sets the min width expressed in ems (equivalent to setMinEms() in TextView)
+   *
+   * @param minEms min width expressed in ems
+   */
+  public TextLayoutBuilder setMinEms(int minEms) {
+    mMinWidth = minEms;
+    mMinWidthMode = EMS;
+    return this;
+  }
+
+  /**
+   * @return the min width expressed in ems (equivalent to getMinEms() in TextView) or -1
+   * if min width is set in pixels instead by using {@link #setMinWidth(int)}
+   *
+   * @see #setMinEms(int)
+   */
+  public int getMinEms() {
+    return mMinWidthMode == EMS ? mMinWidth : -1;
+  }
+
+  /**
+   * Sets the min width expressed in pixels
+   * @param minWidth
+   */
+  public TextLayoutBuilder setMinWidth(@Px int minWidth) {
+    mMinWidth = minWidth;
+    mMinWidthMode = PIXELS;
+    return this;
+  }
+
+  /**
+   * @return the min width expressed in pixels or -1 if the min width was set in ems instead
+   *
+   * @see #setMinWidth(int)
+   */
+  @Px
+  public int getMinWidth() {
+    return mMinWidthMode == PIXELS ? mMinWidth : -1;
+  }
+
+  /**
+   * Sets the max width expressed in ems (equivalent to setMaxEms() in TextView)
+   *
+   * @param maxEms max width expressed in ems
+   */
+  public TextLayoutBuilder setMaxEms(int maxEms) {
+    mMaxWidth = maxEms;
+    mMaxWidthMode = EMS;
+    return this;
+  }
+
+  /**
+   * @return the max width expressed in ems (equivalent to getMaxEms() in TextView) or -1
+   * if max width is set in pixels instead by using {@link #setMaxWidth(int)}
+   *
+   * @see #setMaxEms(int)
+   */
+  public int getMaxEms() {
+    return mMaxWidthMode == EMS ? mMaxWidth : -1;
+  }
+
+  /**
+   * Sets the max width expressed in pixels
+   * @param maxWidth
+   */
+  public TextLayoutBuilder setMaxWidth(@Px int maxWidth) {
+    mMaxWidth = maxWidth;
+    mMaxWidthMode = PIXELS;
+    return this;
+  }
+
+  /**
+   * @return the max width expressed in pixels or -1 if the max width was set in ems instead
+   *
+   * @see #setMaxWidth(int)
+   */
+  @Px
+  public int getMaxWidth() {
+    return mMaxWidthMode == PIXELS ? mMaxWidth : -1;
+  }
+
   /**
    * Builds and returns a {@link Layout}.
    *
@@ -685,6 +779,19 @@ public Layout build() {
         throw new IllegalStateException("Unexpected measure mode " + mParams.measureMode);
     }
 
+    final int lineHeight = mParams.getLineHeight();
+    if (mMaxWidthMode == EMS) {
+      width = Math.min(width, mMaxWidth * lineHeight);
+    } else {
+      width = Math.min(width, mMaxWidth);
+    }
+
+    if (mMinWidthMode == EMS) {
+      width = Math.max(width, mMinWidth * lineHeight);
+    } else {
+      width = Math.max(width, mMinWidth);
+    }
+
     Layout layout;
     if (metrics != null) {
       layout = BoringLayout.make(

library/src/test/java/com/facebook/fbui/textlayoutbuilder/TextLayoutBuilderTest.java

@@ -199,6 +199,46 @@ public void testMaxLines() {
     assertEquals(mLayout.getLineCount(), 2);
   }
 
+  @Test
+  public void testMinEms() {
+    mBuilder
+        .setText(LONG_TEXT)
+        .setMinEms(10)
+        .build();
+    assertEquals(mBuilder.getMinEms(), 10);
+    assertEquals(mBuilder.getMinWidth(), -1);
+  }
+
+  @Test
+  public void testMaxEms() {
+    mBuilder
+        .setText(LONG_TEXT)
+        .setMaxEms(10)
+        .build();
+    assertEquals(mBuilder.getMaxEms(), 10);
+    assertEquals(mBuilder.getMaxWidth(), -1);
+  }
+
+  @Test
+  public void testMinWidth() {
+    mBuilder
+        .setText(LONG_TEXT)
+        .setMinWidth(100)
+        .build();
+    assertEquals(mBuilder.getMinWidth(), 100);
+    assertEquals(mBuilder.getMinEms(), -1);
+  }
+
+  @Test
+  public void testMaxWidth() {
+    mBuilder
+        .setText(LONG_TEXT)
+        .setMaxWidth(100)
+        .build();
+    assertEquals(mBuilder.getMaxWidth(), 100);
+    assertEquals(mBuilder.getMaxEms(), -1);
+  }
+
   @Test
   public void testDrawableState() {
     int[] drawableState = {0, 1};