Close #7352: Always set scaleFactor on TabThumbnailView

components/browser/tabstray/src/main/java/mozilla/components/browser/tabstray/thumbnail/TabThumbnailView.kt

@@ -17,13 +17,17 @@ class TabThumbnailView(context: Context, attrs: AttributeSet) : AppCompatImageVi
 
     @VisibleForTesting
     public override fun setFrame(l: Int, t: Int, r: Int, b: Int): Boolean {
-        val changed = super.setFrame(l, t, r, b)
-        if (changed) {
-            val matrix = imageMatrix
-            val scaleFactor = width / drawable.intrinsicWidth.toFloat()
-            matrix.setScale(scaleFactor, scaleFactor, 0f, 0f)
-            imageMatrix = matrix
+        val result = super.setFrame(l, t, r, b)
+
+        val matrix = imageMatrix
+        val scaleFactor = if (drawable != null) {
+            width / drawable.intrinsicWidth.toFloat()
+        } else {
+            1F
         }
-        return changed
+        matrix.setScale(scaleFactor, scaleFactor, 0f, 0f)
+        imageMatrix = matrix
+
+        return result
     }
 }

components/browser/tabstray/src/test/java/mozilla/components/browser/tabstray/thumbnail/TabThumbnailViewTest.kt

@@ -4,6 +4,7 @@
 
 package mozilla.components.browser.tabstray.thumbnail
 
+import android.graphics.Matrix
 import android.graphics.drawable.Drawable
 import android.widget.ImageView
 import androidx.test.ext.junit.runners.AndroidJUnit4
@@ -14,6 +15,8 @@ import org.junit.Assert.assertNotEquals
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mockito.Mockito.`when`
+import org.mockito.Mockito.spy
+import org.mockito.Mockito.verify
 import org.robolectric.Robolectric.buildAttributeSet
 
 @RunWith(AndroidJUnit4::class)
@@ -61,6 +64,18 @@ class TabThumbnailViewTest {
 
         assertEquals(matrix, matrix2)
     }
+
+    @Test
+    fun `view scaleFactor does not change if there is no drawable`() {
+        val view = spy(TabThumbnailView(testContext, emptyAttributeSet()))
+        val matrix: Matrix = spy(Matrix())
+
+        `when`(view.imageMatrix).thenReturn(matrix)
+
+        view.setFrame(5, 5, 5, 5)
+
+        verify(matrix).setScale(1f, 1f, 0f, 0f)
+    }
 }
 
 private fun emptyAttributeSet() = buildAttributeSet().build()