PDFBOX-5660: add test, as suggested by Valery Bokov; closes #448

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1934768 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/test/java/org/apache/pdfbox/printing/TestPDFPrintable.java

@@ -0,0 +1,257 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.pdfbox.printing;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.awt.BasicStroke;
+import java.awt.Color;
+import java.awt.Graphics2D;
+import java.awt.Shape;
+import java.awt.Stroke;
+import java.awt.geom.AffineTransform;
+import java.awt.geom.Rectangle2D;
+import java.awt.image.BufferedImage;
+import java.awt.print.PageFormat;
+import java.awt.print.Paper;
+import java.awt.print.Printable;
+
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.pdmodel.PDPage;
+import org.apache.pdfbox.pdmodel.common.PDRectangle;
+
+import org.junit.jupiter.api.Test;
+
+
+/**
+ * Tests for {@link PDFPrintable}.
+ */
+class TestPDFPrintable
+{
+    private final int IMAGE_WIDTH = 100;
+    private final int IMAGE_HEIGHT = 100;
+
+    /**
+     * Tests that the page border is drawn with Color.GRAY when showPageBorder is true.
+     *
+     * Without rasterization, {@code graphics} and {@code graphics2D} are the same object,
+     * so setColor(GRAY) and drawRect() both act on the same Graphics2D. The border is drawn
+     * correctly.
+     */
+    @Test
+    void testShowPageBorderIsGrayWithoutRasterization() throws Exception
+    {
+        testShowPageBorderIsGray(PDFPrintable.RASTERIZE_OFF);
+    }
+
+    /**
+     * Tests that the page border is drawn with Color.GRAY when rasterizing.
+     *
+     * <p>When rasterizing (dpi &gt; 0), the border is drawn on a raster image that is
+     * larger than the page (scaled by dpiScale), then blitted down to the output.
+     * The {@code setClip} in the showPageBorder block must use raster-pixel dimensions
+     * (imageableWidth * scale), not raw point dimensions (imageableWidth). Otherwise
+     * the clip is too small, the border is drawn in only a fraction of the raster image,
+     * and the thin border line gets lost during the scale-down blit to the output.</p>
+     */
+    @Test
+    void testShowPageBorderIsGrayWithRasterization() throws Exception
+    {
+        testShowPageBorderIsGray(150f);
+    }
+
+    /**
+     * {@code print()} would otherwise mutate the caller's Graphics2D in several places:
+     * translate() for imageable area and centering, scale() during rasterization,
+     * setBackground() before the raster blit, and setColor / setStroke / setClip / setTransform
+     * in the showPageBorder block. To isolate the caller, {@code print()} works on a private
+     * copy obtained via {@code graphics.create()} and disposes it in the finally block, so none
+     * of those mutations reach the caller. This test verifies that isolation by setting
+     * distinctive state on the caller's Graphics2D before {@code print()} and asserting it is
+     * unchanged afterwards.
+     */
+    @Test
+    void testPrinterGraphicsStateIsUnchangedAfterPrint() throws Exception
+    {
+        assertPrinterGraphicsStateUnchanged(PDFPrintable.RASTERIZE_OFF);
+    }
+
+    @Test
+    void testPrinterGraphicsStateIsUnchangedAfterPrintWhenRasterizing() throws Exception
+    {
+        assertPrinterGraphicsStateUnchanged(150f);
+    }
+
+    private void assertPrinterGraphicsStateUnchanged(float dpi) throws Exception
+    {
+        try (PDDocument doc = new PDDocument())
+        {
+            doc.addPage(new PDPage(new PDRectangle(IMAGE_WIDTH, IMAGE_HEIGHT)));
+
+            PDFPrintable printable = new PDFPrintable(doc, Scaling.ACTUAL_SIZE, true, dpi);
+
+            BufferedImage output = new BufferedImage(IMAGE_WIDTH, IMAGE_HEIGHT, BufferedImage.TYPE_INT_ARGB);
+            Graphics2D g2d = output.createGraphics();
+
+            // set a distinctive transform so we can detect leaks from internal translate()/scale() calls
+            g2d.translate(7.0, 11.0);
+            g2d.scale(1.3, 1.3);
+
+            Color originalColor = Color.RED;
+            Color originalBackground = Color.BLUE;
+            Stroke originalStroke = new BasicStroke(3.7f);
+            g2d.setColor(originalColor);
+            g2d.setBackground(originalBackground);
+            g2d.setStroke(originalStroke);
+            AffineTransform originalTransform = g2d.getTransform();
+            Rectangle2D originalClipDeviceBounds = deviceClipBounds(g2d);
+
+            PageFormat pf = createPageFormat(IMAGE_WIDTH, IMAGE_HEIGHT);
+            int result = printable.print(g2d, pf, 0);
+
+            assertEquals(Printable.PAGE_EXISTS, result);
+            assertEquals(originalColor, g2d.getColor(),
+                    "color should be unchanged after print()");
+            assertEquals(originalBackground, g2d.getBackground(),
+                    "background should be unchanged after print()");
+            assertEquals(originalStroke, g2d.getStroke(),
+                    "stroke should be unchanged after print()");
+            assertEquals(originalTransform, g2d.getTransform(),
+                    "transform should be unchanged after print() (translate/scale inside print() must not leak)");
+            // device-space comparison — invariant under transform changes on the same Graphics2D
+            assertEquals(originalClipDeviceBounds, deviceClipBounds(g2d),
+                    "clip should be unchanged after print()");
+
+            g2d.dispose();
+        }
+    }
+
+    /**
+     * Returns the bounds of the current clip projected into device space via the current transform.
+     * This is stable across transform changes on the same Graphics2D (unlike getClip().getBounds2D(),
+     * which is in current user space).
+     */
+    private static Rectangle2D deviceClipBounds(Graphics2D g2d)
+    {
+        Shape clip = g2d.getClip();
+        if (clip == null)
+        {
+            return null;
+        }
+        return g2d.getTransform().createTransformedShape(clip).getBounds2D();
+    }
+
+    @Test
+    void testPrintReturnsNoSuchPageForInvalidIndex() throws Exception
+    {
+        try (PDDocument doc = new PDDocument())
+        {
+            doc.addPage(new PDPage());
+
+            PDFPrintable printable = new PDFPrintable(doc);
+
+            BufferedImage output = new BufferedImage(IMAGE_WIDTH, IMAGE_HEIGHT, BufferedImage.TYPE_INT_ARGB);
+            Graphics2D g2d = output.createGraphics();
+            PageFormat pf = createPageFormat(IMAGE_WIDTH, IMAGE_HEIGHT);
+
+            assertEquals(Printable.NO_SUCH_PAGE, printable.print(g2d, pf, -1));
+            assertEquals(Printable.NO_SUCH_PAGE, printable.print(g2d, pf, 1));
+            assertEquals(Printable.PAGE_EXISTS, printable.print(g2d, pf, 0));
+
+            g2d.dispose();
+        }
+    }
+
+    private void testShowPageBorderIsGray(float dpi) throws Exception
+    {
+        try (PDDocument doc = new PDDocument())
+        {
+            PDPage page = new PDPage(new PDRectangle(IMAGE_WIDTH, IMAGE_HEIGHT));
+            doc.addPage(page);
+
+            PDFPrintable printable = new PDFPrintable(doc, Scaling.ACTUAL_SIZE, true, dpi);
+
+            BufferedImage output = new BufferedImage(IMAGE_WIDTH, IMAGE_HEIGHT, BufferedImage.TYPE_INT_ARGB);
+            Graphics2D g2d = output.createGraphics();
+            // fill with white so we can detect gray border pixels
+            g2d.setColor(Color.WHITE);
+            g2d.fillRect(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);
+
+            PageFormat pf = createPageFormat(IMAGE_WIDTH, IMAGE_HEIGHT);
+            int result = printable.print(g2d, pf, 0);
+            g2d.dispose();
+
+            assertEquals(Printable.PAGE_EXISTS, result);
+            assertBorderPixelIsGray(output);
+        }
+    }
+
+    /**
+     * Asserts that at least one pixel along the top edge of the image is gray
+     * (R == G == B, not white and not black), proving the border was drawn with Color.GRAY.
+     */
+    private static void assertBorderPixelIsGray(BufferedImage image)
+    {
+        boolean foundGray = false;
+        int width = image.getWidth();
+        // scan top row and left column where the border rect starts
+        for (int x = 0; x < width; x++)
+        {
+            if (isGray(image.getRGB(x, 0)))
+            {
+                foundGray = true;
+                break;
+            }
+        }
+        if (!foundGray)
+        {
+            int height = image.getHeight();
+            for (int y = 0; y < height; y++)
+            {
+                if (isGray(image.getRGB(0, y)))
+                {
+                    foundGray = true;
+                    break;
+                }
+            }
+        }
+        assertTrue(foundGray,
+                "Expected a gray border pixel in the top-left corner. " +
+                        "If this fails, drawRect may be called on the wrong Graphics object.");
+    }
+
+    private static boolean isGray(int argb)
+    {
+        int a = (argb >> 24) & 0xFF;
+        int r = (argb >> 16) & 0xFF;
+        int g = (argb >> 8) & 0xFF;
+        int b = argb & 0xFF;
+        // Color.GRAY is (128, 128, 128) — allow some tolerance for antialiasing
+        return a > 0 && r == g && g == b && r > 50 && r < 200;
+    }
+
+    private static PageFormat createPageFormat(double width, double height)
+    {
+        Paper paper = new Paper();
+        paper.setSize(width, height);
+        paper.setImageableArea(0, 0, width, height);
+        PageFormat pf = new PageFormat();
+        pf.setPaper(paper);
+        return pf;
+    }
+}