Eliminate rounding errors for GridLayout expand ratios (#19797)

Change-Id: Idf05dde5d6526fafee618fd3e2eb1afa63fab7bc

2 files changed, 97 insertions, 0 deletions

diff --git a/uitest/src/main/java/com/vaadin/tests/components/gridlayout/GridLayoutExpandWithManyRows.java b/uitest/src/main/java/com/vaadin/tests/components/gridlayout/GridLayoutExpandWithManyRows.java
new file mode 100644
index 0000000000..a901093e31
--- /dev/null
+++ b/uitest/src/main/java/com/vaadin/tests/components/gridlayout/GridLayoutExpandWithManyRows.java
@@ -0,0 +1,57 @@
+package com.vaadin.tests.components.gridlayout;
+
+import com.vaadin.annotations.Theme;
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.ui.Component;
+import com.vaadin.ui.GridLayout;
+import com.vaadin.ui.Label;
+import com.vaadin.ui.Panel;
+import com.vaadin.ui.UI;
+
+@Theme("tests-valo")
+public class GridLayoutExpandWithManyRows extends UI {
+
+    static final int POPULATED_ROWS = 20;
+    static int ROW_COUNT = 58;
+
+    public static class ColoredLabel extends Label {
+        private static int colorNumber = 0;
+
+        public ColoredLabel() {
+            super();
+            addStyleName("color-label");
+            addStyleName("color-" + (colorNumber++) % 10);
+        }
+    }
+
+    @Override
+    protected void init(VaadinRequest request) {
+        for (int i = 0; i < 10; i++) {
+            getPage().getStyles().add(".color-" + i + " {" //
+                    + "background-color: hsl(" + (i * 90) + ", 60%, 70%);" //
+                    + "}");
+        }
+
+        GridLayout gridLayout = new GridLayout(6, ROW_COUNT);
+        for (int i = 0; i < ROW_COUNT; i++) {
+            gridLayout.setRowExpandRatio(i, 1);
+        }
+        gridLayout.setSizeFull();
+        for (int i = 0; i < POPULATED_ROWS; i++) {
+            int upperLeftRow = i * 2;
+            int upperLeftCol = 0;
+            int lowerRightCol = 5;
+            int lowerRightRow = upperLeftRow + 1;
+            ColoredLabel coloredLabel = new ColoredLabel();
+            coloredLabel.setSizeFull();
+            gridLayout.addComponent(coloredLabel, upperLeftCol, upperLeftRow,
+                    lowerRightCol, lowerRightRow);
+        }
+
+        gridLayout.setHeight("500%");
+        Component root = new Panel(gridLayout);
+        root.setSizeFull();
+        setContent(root);
+
+    }
+}
diff --git a/uitest/src/test/java/com/vaadin/tests/components/gridlayout/GridLayoutExpandWithManyRowsTest.java b/uitest/src/test/java/com/vaadin/tests/components/gridlayout/GridLayoutExpandWithManyRowsTest.java
new file mode 100644
index 0000000000..693fdc73db
--- /dev/null
+++ b/uitest/src/test/java/com/vaadin/tests/components/gridlayout/GridLayoutExpandWithManyRowsTest.java
@@ -0,0 +1,40 @@
+package com.vaadin.tests.components.gridlayout;
+
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.openqa.selenium.By;
+import org.openqa.selenium.WebElement;
+
+import com.vaadin.testbench.elements.GridLayoutElement;
+import com.vaadin.tests.tb3.SingleBrowserTest;
+
+public class GridLayoutExpandWithManyRowsTest extends SingleBrowserTest {
+
+    @Test
+    public void equalRowHeights() {
+        openTestURL();
+        GridLayoutElement gridlayout = $(GridLayoutElement.class).first();
+
+        // Rows are expanded using integer pixels and leftover pixels are added
+        // to the first N rows.
+        // The tests uses rowspan=2 so one row in the DOM should be max 2 pixels
+        // lower than the first row
+        List<WebElement> slots = gridlayout.findElements(By
+                .className("v-gridlayout-slot"));
+        Assert.assertEquals(GridLayoutExpandWithManyRows.POPULATED_ROWS,
+                slots.size());
+
+        int firstRowHeight = slots.get(0).getSize().height;
+        int lastRowHeight = firstRowHeight;
+        for (int i = 1; i < GridLayoutExpandWithManyRows.POPULATED_ROWS; i++) {
+            int rowHeight = slots.get(i).getSize().height;
+            Assert.assertTrue(rowHeight <= firstRowHeight);
+            Assert.assertTrue(rowHeight >= firstRowHeight - 2);
+            Assert.assertTrue(rowHeight <= lastRowHeight);
+
+            lastRowHeight = rowHeight;
+        }
+    }
+}