Welcome to the Java Programming Forums


The professional, friendly Java community. 21,500 members and growing!


The Java Programming Forums are a community of Java programmers from all around the World. Our members have a wide range of skills and they all have one thing in common: A passion to learn and code Java. We invite beginner Java programmers right through to Java professionals to post here and share your knowledge. Become a part of the community, help others, expand your knowledge of Java and enjoy talking with like minded people. Registration is quick and best of all free. We look forward to meeting you.


>> REGISTER NOW TO START POSTING


Members have full access to the forums. Advertisements are removed for registered users.

Results 1 to 8 of 8

Thread: Scroll position from the past (SSCCE)

  1. #1
    Junior Member
    Join Date
    Jan 2013
    Posts
    13
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default Scroll position from the past (SSCCE)

    Hello! [Please go to second post in this thread first]

    First of all, in attachments is SSCCE program which shows main problem.

    You should complie it with (after going to folder javatest_SSCCE):

    javac -d \javatest *.java

    and run it from the same folder with:

    java javatest.JavaTest

    Instruction: You should now have a window with nice picture. Program is set to scroll always to 50% of width of the image.
    When you press zoom in or zoom out it looks ok. But if you use slider and slide it about 100% you will see it is not in the center.
    The best is to do this after starting the application.
    It is happeining because all parameters of scrollBar are taken from previous state of application window and not from the current one:

    [class ScrolledPictureViewer]
        /*
         * Gets vertical scroll position in percentage
         */
        public final int getVerticalScrollPosition()
        {
            //This is calculated from the previous state
            int maxPositionV = this.getVerticalScrollBar().getMaximum () - this.getVerticalScrollBar().getVisibleAmount();
            int scrollPos = this.getVerticalScrollBar().getValue();
     
            int percentage = 0;
     
            if(maxPositionV > 0)
            {
                //percentage = java.lang.Math.round(((float)scrollPos / (float)maxPositionV)*100);
                percentage = (int)(((float)scrollPos / (float)maxPositionV)*100);
            }
     
            return percentage;
        }


    Here is code which directly makes zoom:

        public void setZoom(float zoom)
        {
            this.picViewer1.setZoom(zoom);
     
            //Resizing picture and setting its new parameters
            this.picViewer1.refreshImage();
     
            this.setScrollPosition(50,50);
        }

    For me it's ok. First I'm resizing picture, so scrollbars should have correct sizes... but repaint is happening in other thread. How can i synchronize everything.

    Target is to set always the same focus on picture during zooming, if I set scroll to 20% it should be always in position of 20% of the picture, but it's not.

    I think answer on this simple question will solve most of my problems now.

    PS. I don't want to post here all the code not to make mess. Everything should me in attachment.
    Attached Files Attached Files


  2. #2
    Junior Member
    Join Date
    Jan 2013
    Posts
    13
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default Re: Scroll position from the past (SSCCE)

    OK. I simplify the problem.

    Please compile program below and tell me why program is setting correct position of JPanel and JScrollPanel scrollbars after 3 clicks of button. It should take one click.

    import java.awt.*;
    import java.awt.event.ActionEvent;
    import javax.swing.*;
    import javax.swing.border.Border;
     
    /**
     *
     * @author blazejp
     */
    class JPanelCircle extends JPanel
    {
        public JPanelCircle()
        {
            super();
     
            this.setLayout(new FlowLayout());
            this.setBackground(Color.red);
            this.setBounds(50, 50, 500, 300);
            this.setPreferredSize(new Dimension(500, 300));
        }
     
        @Override
        protected void paintComponent(Graphics g) 
        { 
            int h = getHeight();
            int w = getWidth();
            super.paintComponent(g); 
            g.setColor(Color.CYAN);
            g.fillOval(w/2, h/2, w, h); 
        } 
    }
     
    class Scroll2 extends JPanel 
    {
        private JPanelCircle panel;
        private JScrollPane sPane;
     
        public Scroll2()
        {
            super(new BorderLayout());
     
            panel = new JPanelCircle();
     
            panel.repaint();
     
            sPane = new JScrollPane(panel);
            sPane.getViewport().setBackground(Color.black);
            sPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
            sPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
            sPane.setBorder(BorderFactory.createBevelBorder(0, Color.lightGray, Color.yellow));
     
            javax.swing.GroupLayout layout = new javax.swing.GroupLayout(sPane.getViewport());
            sPane.getViewport().setLayout(layout);
            layout.setHorizontalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGap(0, 594, Short.MAX_VALUE)
            );
            layout.setVerticalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGap(0, 508, Short.MAX_VALUE)
            );
     
            this.add(sPane, BorderLayout.NORTH);
     
            JButton scroll = new JButton("scroll");
     
            scroll.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    scrollActionPerformed(evt);
                } 
            });
     
            JButton resizeScroll = new JButton("resize&scroll");
     
            resizeScroll.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    resizeScrollActionPerformed(evt);
                } 
            });
     
            this.add(scroll);
            this.add(resizeScroll);
        }
     
        private void scrollActionPerformed(ActionEvent evt)
        {
            this.setScrollPosition(50, 50);
        }
     
        private void resizeScrollActionPerformed(ActionEvent evt)
        {
            this.panel.setPreferredSize(new Dimension(1000, 300));
            this.panel.setBounds(50, 50, 1000, 300);
            this.panel.repaint();
     
            this.setScrollPosition(50, 50);
            this.sPane.repaint();
        }
     
        private static void createAndShowGUI() {
            //Create and set up the window.
            JFrame frame = new JFrame("Scroll");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     
            //Create and set up the content pane.
            Scroll2 newContentPane = new Scroll2();
            newContentPane.setOpaque(true); //content panes must be opaque
            frame.setContentPane(newContentPane);
     
            //Display the window.
            frame.pack();
            frame.setVisible(true);
        }
     
        public final int getHorizontalScrollPosition()
        {
            int maxPositionH = sPane.getHorizontalScrollBar().getMaximum () - sPane.getHorizontalScrollBar().getVisibleAmount();
            int scrollPos = sPane.getHorizontalScrollBar().getValue();
     
            int percentage = 0;
     
            if(maxPositionH > 0)
            {
                percentage = (int)(((float)scrollPos / (float)maxPositionH)*100);
            }
     
            return percentage;
        }
     
        public final void setHorizontalScrollPosition(int posPercentage)
        {
            int maxPositionH = sPane.getHorizontalScrollBar().getMaximum () - sPane.getHorizontalScrollBar().getVisibleAmount();
            int scrollPos = maxPositionH;//this.getHorizontalScrollBar().getValue();
     
     
            if(maxPositionH > 0 && posPercentage >= 0 && posPercentage <= 100)
            {
                //scrollPos = java.lang.Math.round(((float)maxPositionH * (float)posPercentage)/100);
                scrollPos = (int)(((float)maxPositionH * (float)posPercentage)/100);
            }
            else if(posPercentage > 100)
            {
                scrollPos = maxPositionH;
            }  
     
            sPane.getHorizontalScrollBar().setValue(scrollPos);
        }
     
        /*
         * Gets vertical scroll position in percentage
         */
        public final int getVerticalScrollPosition()
        {
            int maxPositionV = sPane.getVerticalScrollBar().getMaximum () - sPane.getVerticalScrollBar().getVisibleAmount();
            int scrollPos = sPane.getVerticalScrollBar().getValue();
     
            int percentage = 0;
     
            if(maxPositionV > 0)
            {
                percentage = (int)(((float)scrollPos / (float)maxPositionV)*100);
            }
     
            return percentage;
        }
     
        public final void setVerticalScrollPosition(int posPercentage)
        {
            int maxPositionV = sPane.getVerticalScrollBar().getMaximum () - sPane.getVerticalScrollBar().getVisibleAmount();
            int scrollPos = maxPositionV;//this.getVerticalScrollBar().getValue();
     
            if(maxPositionV > 0 && posPercentage >= 0 && posPercentage <= 100)
            {
                scrollPos = (int)(((float)maxPositionV * (float)posPercentage)/100);
            }
            else if(posPercentage > 100)
            {
                scrollPos = maxPositionV;
            }
     
            sPane.getVerticalScrollBar().setValue(scrollPos);
        }
     
        public final void setScrollPosition(int hPercentage, int vPercentage)
        {
            this.setHorizontalScrollPosition(hPercentage);
            this.setVerticalScrollPosition(vPercentage);
        }
     
        public static void main(String[] args) {
            // TODO code application logic here
            java.awt.EventQueue.invokeLater(new Runnable() {
     
                @Override
                public void run() 
                {
                    createAndShowGUI();
                }
            });
        }
    }

  3. #3
    Super Moderator Norm's Avatar
    Join Date
    May 2010
    Location
    Eastern Florida
    Posts
    25,042
    Thanks
    63
    Thanked 2,708 Times in 2,658 Posts

    Default Re: Scroll position from the past (SSCCE)

    Can you explain what you see and what position is the correct position?
    When I click the button once the display changes. What is wrong with the change that I see?
    If you don't understand my answer, don't ignore it, ask a question.

  4. #4
    Junior Member
    Join Date
    Jan 2013
    Posts
    13
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default Re: Scroll position from the past (SSCCE)

    Quote Originally Posted by Norm View Post
    Can you explain what you see and what position is the correct position?
    When I click the button once the display changes. What is wrong with the change that I see?
    First click:

    Red JPanel i moving down by 50 and resizes to (1000, 300)

    Second click:

    Horizontal scrollbar moves to 50% of scrollbar length

    Third click:

    Red JPanel i moving down by 50 to the right

    This is what i see on m screen

    And I want it happen in one button click.

  5. #5
    Super Moderator Norm's Avatar
    Join Date
    May 2010
    Location
    Eastern Florida
    Posts
    25,042
    Thanks
    63
    Thanked 2,708 Times in 2,658 Posts

    Default Re: Scroll position from the past (SSCCE)

    How do I change the height (make shorter) of the window?
    If you don't understand my answer, don't ignore it, ask a question.

  6. #6
    Junior Member
    Join Date
    Jan 2013
    Posts
    13
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default Re: Scroll position from the past (SSCCE)

    Quote Originally Posted by Norm View Post
    How do I change the height (make shorter) of the window?
    I don't understand what You want to do...?

    The goal is to make all three steps in one button click - somehow force to repaint once or wait when full repaint is finished.

  7. #7
    Super Moderator Norm's Avatar
    Join Date
    May 2010
    Location
    Eastern Florida
    Posts
    25,042
    Thanks
    63
    Thanked 2,708 Times in 2,658 Posts

    Default Re: Scroll position from the past (SSCCE)

    The window is too tall and covers up what I want to see behind it. How can I make its height be 400 pixels?

    Is the code using a layout manager and also calling setBounds()? Which should control the location? Are they competing to control the locations of the components?
    If you don't understand my answer, don't ignore it, ask a question.

  8. #8
    Junior Member
    Join Date
    Jan 2013
    Posts
    13
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default Re: Scroll position from the past (SSCCE)

    Here is repaired code. Now JScrollPane should be (400,400) - variable mainSize. Also I changed LayoutManager of JScrollPane to SpringLayout which is, I think, most suitable for me.

    Now calling function below, JPanel is moved and resized. Is this resizing algorithm ok? For me this is strange that I have to change parameters by setBounds, setPreferredSize and layout.putConstraints (!?)... 3 operations to make a new position and resize of JPanel? Is there better way to do this?

    And still there is a problem with setting horizontal scrollbar.

     
    private void resizeScrollActionPerformed(ActionEvent evt)
        {
            SpringLayout layout = (SpringLayout)sPane.getViewport().getLayout();
     
            layout.putConstraint(SpringLayout.WEST, panel, 50, SpringLayout.WEST, sPane);
            layout.putConstraint(SpringLayout.NORTH, panel, 50, SpringLayout.NORTH, sPane);
     
            this.panel.setPreferredSize(new Dimension(1000, 100));
            this.panel.setBounds(0, 0, 1000, 100);
     
            this.setScrollPosition(50, 50);
        }


    Full Program:

    import java.awt.*;
    import java.awt.event.ActionEvent;
    import javax.swing.*;
     
    /**
     *
     * @author blazejp
     */
    class JPanelCircle extends JPanel
    {
        public JPanelCircle()
        {
            super();
     
            this.setLayout(new FlowLayout());
            this.setBackground(Color.red);
            this.setBounds(0, 0, 200, 50);
            this.setPreferredSize(new Dimension(200, 50));
        }
     
        @Override
        protected void paintComponent(Graphics g) 
        { 
            int h = getHeight();
            int w = getWidth();
            super.paintComponent(g); 
            g.setColor(Color.CYAN);
            g.fillOval(w/2, h/2, w, h); 
        } 
    }
     
    class Scroll2 extends JPanel 
    {
        private JPanelCircle panel;
        private JScrollPane sPane;
     
        private Dimension mainSize = new Dimension(400, 400);
     
        public Scroll2()
        {
            super(new BorderLayout());
     
            panel = new JPanelCircle();
     
            panel.repaint();
     
            sPane = new JScrollPane(panel);
            sPane.setBounds(0,0,mainSize.width,mainSize.height);
            sPane.setPreferredSize(mainSize);
            sPane.getViewport().setBackground(Color.black);
            sPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
            sPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
     
            sPane.setBorder(BorderFactory.createBevelBorder(0, Color.lightGray, Color.yellow));
     
            sPane.getViewport().setLayout(new SpringLayout());
     
            this.add(sPane, BorderLayout.NORTH);
     
            JButton resizeScroll = new JButton("resize&scroll");
     
            resizeScroll.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    resizeScrollActionPerformed(evt);
                } 
            });
            this.add(resizeScroll);
        }
     
        private void scrollActionPerformed(ActionEvent evt)
        {
            this.setScrollPosition(50, 50);
        }
     
        private void resizeScrollActionPerformed(ActionEvent evt)
        {
            SpringLayout layout = (SpringLayout)sPane.getViewport().getLayout();
     
            layout.putConstraint(SpringLayout.WEST, panel, 50, SpringLayout.WEST, sPane);
            layout.putConstraint(SpringLayout.NORTH, panel, 50, SpringLayout.NORTH, sPane);
     
            this.panel.setPreferredSize(new Dimension(1000, 100));
            this.panel.setBounds(0, 0, 1000, 100);
     
            this.setScrollPosition(50, 50);
        }
     
        private static void createAndShowGUI() {
            //Create and set up the window.
            JFrame frame = new JFrame("Scroll");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     
            //Create and set up the content pane.
            Scroll2 newContentPane = new Scroll2();
            newContentPane.setOpaque(true); //content panes must be opaque
            frame.setContentPane(newContentPane);
     
            //Display the window.
            frame.pack();
            frame.setVisible(true);
        }
     
        public final int getHorizontalScrollPosition()
        {
            int maxPositionH = sPane.getHorizontalScrollBar().getMaximum () - sPane.getHorizontalScrollBar().getVisibleAmount();
            int scrollPos = sPane.getHorizontalScrollBar().getValue();
     
            int percentage = 0;
     
            if(maxPositionH > 0)
            {
                percentage = (int)(((float)scrollPos / (float)maxPositionH)*100);
            }
     
            return percentage;
        }
     
        public final void setHorizontalScrollPosition(int posPercentage)
        {
            int maxPositionH = sPane.getHorizontalScrollBar().getMaximum () - sPane.getHorizontalScrollBar().getVisibleAmount();
            int scrollPos = maxPositionH;
     
     
            if(maxPositionH > 0 && posPercentage >= 0 && posPercentage <= 100)
            {
                scrollPos = (int)(((float)maxPositionH * (float)posPercentage)/100);
            }
            else if(posPercentage > 100)
            {
                scrollPos = maxPositionH;
            }  
     
            sPane.getHorizontalScrollBar().setValue(scrollPos);
        }
     
        /*
         * Gets vertical scroll position in percentage
         */
        public final int getVerticalScrollPosition()
        {
            int maxPositionV = sPane.getVerticalScrollBar().getMaximum () - sPane.getVerticalScrollBar().getVisibleAmount();
            int scrollPos = sPane.getVerticalScrollBar().getValue();
     
            int percentage = 0;
     
            if(maxPositionV > 0)
            {
                percentage = (int)(((float)scrollPos / (float)maxPositionV)*100);
            }
     
            return percentage;
        }
     
        public final void setVerticalScrollPosition(int posPercentage)
        {
            int maxPositionV = sPane.getVerticalScrollBar().getMaximum () - sPane.getVerticalScrollBar().getVisibleAmount();
            int scrollPos = maxPositionV;
     
            if(maxPositionV > 0 && posPercentage >= 0 && posPercentage <= 100)
            {
                scrollPos = (int)(((float)maxPositionV * (float)posPercentage)/100);
            }
            else if(posPercentage > 100)
            {
                scrollPos = maxPositionV;
            }
     
            sPane.getVerticalScrollBar().setValue(scrollPos);
        }
     
        public final void setScrollPosition(int hPercentage, int vPercentage)
        {
            this.setHorizontalScrollPosition(hPercentage);
            this.setVerticalScrollPosition(vPercentage);
        }
     
        public static void main(String[] args) {
            // TODO code application logic here
            java.awt.EventQueue.invokeLater(new Runnable() {
     
                @Override
                public void run() 
                {
                    createAndShowGUI();
                }
            });
        }
    }

Similar Threads

  1. [SOLVED] Edge of screen detection in LWJGL + SSCCE
    By Tjstretch in forum Java Theory & Questions
    Replies: 1
    Last Post: August 14th, 2012, 06:35 PM
  2. [SOLVED] URLConnection inconsistency + SSCCE
    By Tjstretch in forum What's Wrong With My Code?
    Replies: 6
    Last Post: March 15th, 2012, 05:41 PM
  3. [SOLVED] Stuck and can't get past it!
    By Wonderlandslost in forum What's Wrong With My Code?
    Replies: 64
    Last Post: February 13th, 2012, 11:27 PM
  4. Please help not sure how to get past the Syntax error
    By KnightC in forum Other Programming Languages
    Replies: 2
    Last Post: December 23rd, 2011, 10:09 AM
  5. Having Issues Past this
    By baGoGoodies111 in forum What's Wrong With My Code?
    Replies: 1
    Last Post: November 12th, 2009, 08:19 PM