Fixes #752 - Use non-beveled borders for collapsed table cells...

with solid style borders only.

This should stop them being anti-aliased and problematic.

Unfortunately some tests had to be re-proofed for this change.

Additional test kindly provided by @gandboy91

openhtmltopdf-core/src/main/java/com/openhtmltopdf/render/BorderPainter.java

@@ -27,6 +27,7 @@
 import java.awt.geom.Arc2D;
 import java.awt.geom.Area;
 import java.awt.geom.Path2D;
+import java.awt.geom.Rectangle2D;
 
 import com.openhtmltopdf.css.constants.IdentValue;
 import com.openhtmltopdf.css.parser.FSRGBColor;
@@ -81,7 +82,37 @@ public static Path2D generateBorderShape(Rectangle bounds, int side, BorderPrope
     public static Path2D generateBorderShape(Rectangle bounds, int side, BorderPropertySet border, boolean drawInterior, float scaledOffset) {
         return generateBorderShape(bounds, side, border, drawInterior, scaledOffset, 1);
     }
-
+
+    /**
+     * Generate a simple rectangle without beveling for a solid border side.
+     * Turning off beveling should disable anti-aliasing and work better with
+     * table cell borders.
+     * See https://github.com/danfickle/openhtmltopdf/issues/752
+     */
+    private static Shape generateSimpleBorderShape(Rectangle bounds, int currentSide, BorderPropertySet border) {
+        if (currentSide == TOP || currentSide == BOTTOM) {
+            double x = bounds.getX();
+            double y = currentSide == TOP ?
+                    bounds.getY() :
+                    bounds.getY() + bounds.getHeight() - border.bottom();
+            double w = bounds.getWidth();
+            double h = currentSide == TOP ?
+                    border.top() : border.bottom();
+
+            return new Rectangle2D.Double(x, y, w, h);
+        } else {
+            double x = currentSide == LEFT ?
+                    bounds.getX() :
+                    bounds.getX() + bounds.getWidth() - border.right();
+            double y = bounds.getY();
+            double w = currentSide == LEFT ?
+                    border.left() : border.right();
+            double h = bounds.getHeight();
+
+            return new Rectangle2D.Double(x, y, w, h);
+        }
+    }
+
     /**
      * Generates one side of a border
      * @param bounds bounds of the container
@@ -328,23 +359,30 @@ private static void paintBorderSide(OutputDevice outputDevice,
                     0, 1, sides, currentSide, bevel);
         } else if (borderSideStyle == IdentValue.SOLID) {
             outputDevice.setStroke(new BasicStroke(1f));
-            if(currentSide == TOP) {
+
+            switch (currentSide) {
+            case TOP:
                 outputDevice.setColor(border.topColor());
-                outputDevice.fill(generateBorderShape(bounds, TOP, border, true, 0, 1));
-            }
-            if(currentSide == RIGHT) {
+                break;
+            case RIGHT:
                 outputDevice.setColor(border.rightColor());
-                outputDevice.fill(generateBorderShape(bounds, RIGHT, border, true, 0, 1));
-            }
-            if(currentSide == BOTTOM) {
+                break;
+            case BOTTOM:
                 outputDevice.setColor(border.bottomColor());
-                outputDevice.fill(generateBorderShape(bounds, BOTTOM, border, true, 0, 1));
-            }
-            if(currentSide == LEFT) {
+                break;
+            case LEFT:
                 outputDevice.setColor(border.leftColor());
-                outputDevice.fill(generateBorderShape(bounds, LEFT, border, true, 0, 1));
+                break;
+            default:
+                return;
             }
-
+
+            Shape s = bevel || border.hasBorderRadius() ?
+                    generateBorderShape(bounds, currentSide, border, true, 0, 1) :
+                    generateSimpleBorderShape(bounds, currentSide, border);
+
+            outputDevice.fill(s);
+
         } else if (borderSideStyle == IdentValue.DOUBLE) {
             paintDoubleBorder(outputDevice, border, bounds, sides, currentSide, bevel);
         } else {

openhtmltopdf-examples/src/main/resources/visualtest/html/issue-752-table-border-strange.html

@@ -0,0 +1,38 @@
+<html>
+<head>
+<style>
+table {
+  border-collapse: collapse;
+  border: 1px solid black;
+}
+table td {
+  border: 1px solid black;
+  width: 100px;
+}
+table td.no-border-right {
+  border-right: none;
+}
+table td.no-border-left {
+  border-left: none;
+}
+</style>
+</head>
+<body>
+
+<table>
+  <tr>
+    <td>1</td>
+    <td class="no-border-right">2</td>
+    <td class="no-border-left no-border-right">3</td>
+    <td class="no-border-left">4</td>
+  </tr>
+  <tr>
+    <td>5</td>
+    <td>6</td>
+    <td>7</td>
+    <td>8</td>
+  </tr>
+</table>
+
+</body>
+</html>

openhtmltopdf-examples/src/test/java/com/openhtmltopdf/visualregressiontests/VisualRegressionTest.java

@@ -1450,6 +1450,17 @@ public void testIssue551PageBreakInsideAvoidDeep() throws IOException {
         assertTrue(vt.runTest("issue-551-page-break-inside-avoid-deep"));
     }
 
+    /**
+     * Test weirdness in table borders when PDF is zoomed.
+     * Apparently was caused by anti-aliasing selectively applied
+     * to beveled borders.
+     */
+    @Test
+    public void testIssue752TableBorderInconcistency() throws IOException {
+        assertTrue(vt.runTest("issue-752-table-border-strange"));
+    }
+
+
     // TODO:
     // + Elements that appear just on generated overflow pages.
     // + content property (page counters, etc)