97 lines
4.1 KiB
Java
97 lines
4.1 KiB
Java
/*
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* Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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import java.awt.image.BufferedImage;
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import java.awt.image.RenderedImage;
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/**
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* @test
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* @author Martin Desruisseaux
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*/
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public final class GetTileGridOffset {
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public static void main(final String[] args) {
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final BufferedImage image = new BufferedImage(
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20, 20, BufferedImage.TYPE_BYTE_GRAY);
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validate(image);
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final BufferedImage subImage = image.getSubimage(5, 5, 10, 10);
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verifyConsistency(subImage);
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validate(subImage);
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}
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/**
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* Verifies that the tile grid offsets of given image are consistent with
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* other properties (minimum pixel coordinates, minimum tile indices and
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* tile size). This method verifies the general contract, ignoring
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* simplifications brought by the {@link BufferedImage} specialization.
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* The purpose of this method is to demonstrate why tile grid offsets
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* need to be zero in the {@link BufferedImage} case.
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*/
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private static void verifyConsistency(final RenderedImage image) {
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/*
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* This test will convert the coordinates of an arbitrary pixel in
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* the first tile to the indices of that tile. The expected result
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* is (minTileX, minTileY). We take the pixel in lower-right corner
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* of the first tile (the upper-left corner does not demonstrate
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* bug 8166038).
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*/
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final int tileWidth = image.getTileWidth();
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final int tileHeight = image.getTileHeight();
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final int x = image.getMinX() + tileWidth - 1;
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final int y = image.getMinY() + tileHeight - 1;
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/*
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* From javax.media.jai.PlanarImage.XToTileX(int)
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* (omitting rounding toward negative infinity):
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*
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* tileX = (x - tileGridXOffset) / tileWidth
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*/
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int tileX = Math.floorDiv(x - image.getTileGridXOffset(), tileWidth);
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int tileY = Math.floorDiv(y - image.getTileGridYOffset(), tileHeight);
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int minTileX = image.getMinTileX(); // Expected value
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int minTileY = image.getMinTileY();
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if (tileX != minTileX || tileY != minTileY) {
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throw new RuntimeException("Tile indices of upper-left tile"
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+ " shall be (" + minTileX + ", " + minTileY + ")."
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+ " But using the provided tileGridOffsets we got"
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+ " (" + tileX + ", " + tileY + ").");
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}
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}
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/**
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* Verifies that tile grid offsets are zero as required by
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* {@link BufferedImage} specification.
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*/
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private static void validate(final BufferedImage image) {
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final int tileGridXOffset = image.getTileGridXOffset();
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final int tileGridYOffset = image.getTileGridYOffset();
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if (tileGridXOffset != 0) {
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throw new RuntimeException("BufferedImage.getTileGridXOffset()"
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+ " shall be zero. Got " + tileGridXOffset);
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}
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if (tileGridYOffset != 0) {
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throw new RuntimeException("BufferedImage.getTileGridTOffset()"
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+ " shall be zero. Got " + tileGridYOffset);
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}
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}
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}
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