JScrollPane没有滚动超过设定的大小

我正在使用滚动窗格，里面有一个JPanel，它绘制一个方格网格，这些方格是来自[] []数组的对象。

如果数组是[83] [81]大小为18 ^ 2的矩形，它看起来像： http ： //i.imgur.com/fwJ9LV6.png （注意网格边缘的白色边框）

但是，[84] [82]的相同矩形： http ： //i.imgur.com/PZ2rNY3.png （最后一行被切片）。

现在，我：

• 将滚动窗格和Jpanel的首选大小和最大大小增加到远高于所需的大小。
• 检查JPanel是可滚动对象的视口。

它没有改变任何东西。

我的Jpanel课程是：

package BlastRadius; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import javax.swing.JPanel; /** * Canvas Class Stuart Bradley 25-1-2013 Contains the paint component */ public class BlastRadiusCanvas extends JPanel { GridOfNodes grid = new GridOfNodes(); @Override public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; RenderingHints rh = g2d.getRenderingHints(); rh.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.setRenderingHints(rh); //Draw space int pixelsAcross = 32; int pixelsDown = 0; int size = 18; for (int i = 0; i < grid.getRows(); i++) { for (int j = 0; j < grid.getColumns(); j++) { g2d.setColor(grid.getNodeGrid()[i][j].getColour()); g2d.fillRect(pixelsAcross, pixelsDown, size, size); g2d.setColor(new Color(0, 0, 0)); g2d.drawRect(pixelsAcross, pixelsDown, size, size); //Better Ovals maybe needed, try Ellipise2D class if (grid.getNodeGrid()[i][j].getHasOval() == true) { g2d.setColor(new Color(255, 255, 255)); g2d.fillOval((pixelsAcross + (size / 2) - 1), (pixelsDown + (size / 2) - 1), size / 4, size / 4); } pixelsAcross += 18; } pixelsDown += 18; pixelsAcross = 32; //Draws gene string for first object in each row g2d.setColor(new Color(0, 0, 0)); g2d.drawString(grid.getNodeGrid()[i][0].getGeneString(), 5, pixelsDown - 5); } } } 

滚动窗格和相关，可以根据需要发布整个GUI类：

 jScrollPane1 = new javax.swing.JScrollPane(); jScrollPane1.setPreferredSize(new java.awt.Dimension(10000, 10000)); jScrollPane1.setViewportView(drawingJPanel); //Grouping javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addContainerGap() .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 254, Short.MAX_VALUE) .addContainerGap()) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 0, Short.MAX_VALUE) ); 

虽然我之前已经完成了GUI，但是通过RAD环境和手动，可滚动界面对我来说有点新鲜！

Answer 1

BlastRadiusCanvas需要向滚动窗格提供有关它想要的大小的信息。

根据我对您尝试执行的操作的解释，尝试将以下内容添加到BlastRadiusCanvas

 @Override public Dimension getPreferredSize() { return new Dimension((grid.getColumns() * 18) + 64, (grid.getRows() * 18) + 1); } 

现在真的，你不应该依赖“魔术”数字，最好使用类似……

 protected static final int GRID_SIZE = 18; protected static final int H_GAP = 32; @Override public Dimension getPreferredSize() { return new Dimension((grid.getColumns() * GRID_SIZE) + (H_GAP * 2), (grid.getRows() * GRID_SIZE) + 1); } 

这会使你的paintComponent方法看起来更像……

 @Override public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; RenderingHints rh = g2d.getRenderingHints(); rh.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.setRenderingHints(rh); //Draw space int pixelsAcross = H_GAP; int pixelsDown = 0; int size = GRID_SIZE; for (int i = 0; i < grid.getRows(); i++) { for (int j = 0; j < grid.getColumns(); j++) { g2d.setColor(grid.getNodeGrid()[i][j].getColour()); g2d.fillRect(pixelsAcross, pixelsDown, size, size); g2d.setColor(new Color(0, 0, 0)); g2d.drawRect(pixelsAcross, pixelsDown, size, size); //Better Ovals maybe needed, try Ellipise2D class if (grid.getNodeGrid()[i][j].getHasOval() == true) { g2d.setColor(new Color(255, 255, 255)); g2d.fillOval((pixelsAcross + (size / 2) - 1), (pixelsDown + (size / 2) - 1), size / 4, size / 4); } pixelsAcross += size; } pixelsDown += size; pixelsAcross = H_GAP; //Draws gene string for first object in each row g2d.setColor(new Color(0, 0, 0)); g2d.drawString(grid.getNodeGrid()[i][0].getGeneString(), 5, pixelsDown - 5); } } 

Answer 2

由于BlastRadiusCanvas包含自己的组件，因此可以覆盖getPreferredSize()以返回显示网格的最佳大小。 有关详细信息，请参阅此相关答案 。 还要考虑实现Scrollable接口以从getPreferredScrollableViewportSize()返回合适的Dimension 。 图像看起来具有自然的单位和块大小。

Answer 3

任何其他人都有同样的问题 – 因为谷歌搜索的时间没有为我解决。

检查您的JFrame首选大小 。 如果它太低，它会最大化网格数量 – 或任何绘图空间 – 你有。