[Button] Fix icon textStart/End alignment with multiline text

When calculating text width to decide the icon position with textStart/End alignment, we missed accounting for multiline text. Fixes this by calculating each line's width separately and take the widest one to decide the icon position.

Resolves #2007

PiperOrigin-RevId: 440982189

Author: drchen

lib/java/com/google/android/material/button/MaterialButton.java

@@ -568,7 +568,7 @@ private void updateIconPosition(int buttonWidth, int buttonHeight) {
 
       int localIconSize = iconSize == 0 ? icon.getIntrinsicWidth() : iconSize;
       int availableWidth = buttonWidth
-          - getTextWidth()
+          - getTextLayoutWidth()
           - ViewCompat.getPaddingEnd(this)
           - localIconSize
           - iconPadding
@@ -612,9 +612,18 @@ private void updateIconPosition(int buttonWidth, int buttonHeight) {
     }
   }
 
-  private int getTextWidth() {
+  private int getTextLayoutWidth() {
+    int maxWidth = 0;
+    int lineCount = getLineCount();
+    for (int line = 0; line < lineCount; line++) {
+      maxWidth = max(maxWidth, getTextWidth(getTextInLine(line)));
+    }
+    return maxWidth;
+  }
+
+  private int getTextWidth(CharSequence text) {
     Paint textPaint = getPaint();
-    String buttonText = getText().toString();
+    String buttonText = text.toString();
     if (getTransformationMethod() != null) {
       // if text is transformed, add that transformation to to ensure correct calculation
       // of icon padding.
@@ -643,6 +652,12 @@ private int getTextHeight() {
     return min(bounds.height(), getLayout().getHeight());
   }
 
+  private CharSequence getTextInLine(int line) {
+    int start = getLayout().getLineStart(line);
+    int end = getLayout().getLineEnd(line);
+    return getText().subSequence(start, end);
+  }
+
   private boolean isLayoutRTL() {
     return ViewCompat.getLayoutDirection(this) == ViewCompat.LAYOUT_DIRECTION_RTL;
   }