DocumentPanel.java

package edu.stanford.hci.r3.tools.design.gui;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

import edu.stanford.hci.r3.paper.Sheet;
import edu.stanford.hci.r3.units.Pixels;
import edu.stanford.hci.r3.util.MathUtils;
import edu.stanford.hci.r3.util.graphics.GraphicsUtils;

public class DocumentPanel extends JPanel {

        private static final Color BG_BEGIN_COLOR = new Color(114, 121, 139);

        private static final Color BG_END_COLOR = new Color(167, 177, 202);

        public static final int DROP_SHADOW_DISTANCE = 4;

        private static final int MIN_PADDING_HORIZ = 20;

        private static final int MIN_PADDING_VERT = 25;

        public static final Color SHADOW_COLOR = new Color(0, 0, 0, 99);

        private int paddingHorizontal = MIN_PADDING_HORIZ;

        private int paddingVertical = MIN_PADDING_VERT;

        private JFrame parentFrame;

        private JScrollPane parentScrollPane;

        final Pixels pixelsReferenceUnit = new Pixels();

        private Sheet sheet = new Sheet(8.5, 11);

        public DocumentPanel() {
                setBackground(Color.WHITE);
                setLayout(new BorderLayout());
        }

        private void drawGradientBackground(Graphics2D g2d) {
                final GradientPaint gradient = new GradientPaint(0, 0, BG_BEGIN_COLOR, 0, getHeight(),
                                BG_END_COLOR, false);
                g2d.setPaint(gradient);
                g2d.fillRect(0, 0, getWidth(), getHeight());
        }

        public int getDefaultHorizontalScreenPadding() {
                return 2 * paddingHorizontal;
        }

        public int getDefaultVerticalScreenPadding() {
                return 2 * paddingVertical;
        }

        private int getDisplayedDocumentHeight() {
                return MathUtils.rint(sheet.getHeight().getValueIn(pixelsReferenceUnit));
        }

        private int getDisplayedDocumentWidth() {
                return MathUtils.rint(sheet.getWidth().getValueIn(pixelsReferenceUnit));
        }

        public Dimension getPreferredSize() {
                return new Dimension(getDisplayedDocumentWidth() + getDefaultHorizontalScreenPadding()
                                - parentScrollPane.getVerticalScrollBar().getWidth(), getDisplayedDocumentHeight()
                                + getDefaultVerticalScreenPadding()
                                - parentScrollPane.getHorizontalScrollBar().getHeight());
        }

        protected void paintComponent(Graphics g) {
                // do whatever JPanel/JComponent likes to do...
                super.paintComponent(g);

                final Graphics2D g2d = (Graphics2D) g;
                g2d.setRenderingHints(GraphicsUtils.getBestRenderingHints());

                // smooth gradient
                drawGradientBackground(g2d);

                // convert this to pixels
                int widthPixels = getDisplayedDocumentWidth();
                int heightPixels = getDisplayedDocumentHeight();
                // System.out.println("Sheet size is: " + sheet.getWidth() + ", " + sheet.getHeight());
                // System.out.println("Sheet size is: " + widthPixels + ", " + heightPixels);

                int panelWidth = parentFrame.getWidth();
                int panelHeight = parentScrollPane.getHeight();

                paddingHorizontal = Math.max(MathUtils.rint((panelWidth - widthPixels) / 2.0),
                                MIN_PADDING_HORIZ);
                paddingVertical = Math.max(MathUtils.rint((panelHeight - heightPixels) / 2.0),
                                MIN_PADDING_VERT);

                // draw the jpeg image of the sheet...

                // the dark drop shadow
                g2d.setColor(SHADOW_COLOR);
                final Rectangle docBounds = new Rectangle(paddingHorizontal, paddingVertical, widthPixels,
                                heightPixels);
                g2d.fillRect((int) docBounds.getX() + DROP_SHADOW_DISTANCE, (int) docBounds.getY()
                                + DROP_SHADOW_DISTANCE, docBounds.width, docBounds.height);

        }

        public void setParentFrame(JFrame mainFrame) {
                parentFrame = mainFrame;
        }

        public void setParentScrollPane(JScrollPane scrollPane) {
                parentScrollPane = scrollPane;
        }
}

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