JComponents 在 Repaint() 之后移动到 Origin
JComponents Moving to Origin After Repaint()
类似于，但对该问题的回答只说明了他没有使用布局管理器这一事实，而我是使用布局管理器（很差），所以它并没有真正帮助，不幸的是。
详情
计划的意图：
要显示 1920x1080 网格的预览（缩小到 640x480 以节省 space），在您更改每个正方形的高度、每个正方形的宽度以及它的列数时进行拉伸和收缩会有的（您首先指定要在网格中的总方块数，因此程序会推断出行数。）
结构：
- 一个顶级 JFrame。
- 包含两个 JPanel：Grid 和侧边栏，使用 BorderLayout 将它们对齐到东边和西边。
- 侧边栏是一个 JPanel，包含 Y 轴对齐的 BoxLayout 中的所有 JComponent。
- Grid 扩展 JComponent，并使用 Graphics.drawLine() 绘制网格。
- 边栏中的每个组件在更改时调用 Grid.repaint() 以更新网格。
Current UI, with the two main JPanels outlined in red.
问题
每当我更改任何组件并因此调用 Grid.repaint():
- 网格不清晰，导致出现多行；
- 所有侧边栏组件都绘制在左上角，同时仍然 showing/functioning 在侧边栏上；
- 出于某种原因，网格将自身调整为比正常情况更宽。
Current UI, but borked.
我尝试过的
- 将 repaint() 区域更改为仅覆盖网格的矩形，
- 检查文档以了解有关此的任何信息，
- Google,
- 问你们
代码
Reprex：（简化为“按下按钮重现”，同时仍然保留潜在问题区域的本质。）
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BuildGridGUI2
{
static final int WIDTH_MIN = 100;
static final int WIDTH_MAX = 2000;
static final int WIDTH_INIT = 520;
static final int HEIGHT_MIN = 100;
static final int HEIGHT_MAX = 2000;
static final int HEIGHT_INIT = 300;
int widthOfFrames = 255;
int heightOfFrames = 255;
int numCols = 3;
int numFrames = 1;
private final JComponent makeUI()
{
JPanel p = new JPanel();
p.setLayout(new BorderLayout());
Grid g = new Grid();
JComponent j = makeSideMenu(g);
g.setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createLineBorder(Color.red),
g.getBorder()));
j.setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createLineBorder(Color.red),
j.getBorder()));
p.add(j, BorderLayout.EAST);
p.add(g, BorderLayout.WEST);
return p;
}
private final JComponent makeSideMenu(Grid grid)
{
JPanel p = new JPanel();
JLabel numColsSelectorLabel = new JLabel("Frames Per Column");
JSpinner numColsSelectorField = new JSpinner();
JLabel widthLabel = new JLabel("Width per Frame (Pixels)");
JSpinner widthSpinner = new JSpinner();
JSlider widthSlider = new JSlider(WIDTH_MIN, WIDTH_MAX, WIDTH_INIT);
JLabel heightLabel = new JLabel("Height per Frame (Pixels)");
JSpinner heightSpinner = new JSpinner();
JSlider heightSlider = new JSlider(BuildGridGUI2.HEIGHT_MIN, BuildGridGUI2.HEIGHT_MAX, BuildGridGUI2.HEIGHT_INIT);
JButton confirmButton = new JButton("Confirm");
numColsSelectorField.setEditor(new JSpinner.NumberEditor(numColsSelectorField));
numColsSelectorField.setMaximumSize(numColsSelectorField.getPreferredSize());
widthSlider.setMajorTickSpacing(300);
widthSlider.setMinorTickSpacing(20);
widthSlider.setPaintTicks(true);
widthSlider.setPaintLabels(true);
widthSpinner.setEditor(new JSpinner.NumberEditor(widthSpinner));
widthSpinner.setPreferredSize(new Dimension(70, 30));
widthSpinner.setMaximumSize(widthSpinner.getPreferredSize());
heightSlider.setMajorTickSpacing(300);
heightSlider.setMinorTickSpacing(20);
heightSlider.setPaintTicks(true);
heightSlider.setPaintLabels(true);
heightSpinner.setEditor(new JSpinner.NumberEditor(heightSpinner));
heightSpinner.setPreferredSize(new Dimension(70, 30));
heightSpinner.setMaximumSize(heightSpinner.getPreferredSize());
confirmButton.addActionListener(new ActionListener() {
@Override public void actionPerformed(ActionEvent e)
{
widthOfFrames = 200;
grid.refresh();
}
});
p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
p.setPreferredSize(new Dimension(300, 480));
p.setSize(new Dimension(300, 480));
numColsSelectorLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
numColsSelectorField.setAlignmentX(Component.CENTER_ALIGNMENT);
widthSlider.setAlignmentX(Component.CENTER_ALIGNMENT);
heightSlider.setAlignmentX(Component.CENTER_ALIGNMENT);
confirmButton.setAlignmentX(Component.CENTER_ALIGNMENT);
widthLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
heightLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
widthSpinner.setAlignmentX(Component.CENTER_ALIGNMENT);
heightSpinner.setAlignmentX(Component.CENTER_ALIGNMENT);
p.add(Box.createRigidArea(new Dimension(300, 30)));
p.add(numColsSelectorLabel);
p.add(Box.createRigidArea(new Dimension(300, 5)));
p.add(numColsSelectorField);
p.add(Box.createRigidArea(new Dimension(300, 25)));
p.add(widthLabel);
p.add(Box.createRigidArea(new Dimension(300, 3)));
p.add(widthSpinner);
p.add(widthSlider);
p.add(Box.createRigidArea(new Dimension(300, 25)));
p.add(heightLabel);
p.add(Box.createRigidArea(new Dimension(300, 3)));
p.add(heightSpinner);
p.add(heightSlider);
p.add(Box.createRigidArea(new Dimension(300, 45)));
p.add(confirmButton);
return p;
}
private static void createAndShowGUI() {
BuildGridGUI2 b = new BuildGridGUI2();
JFrame mainFrame = new JFrame("Grid Builder");
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setSize(940, 480);
mainFrame.getContentPane().add(b.makeUI());
mainFrame.setResizable(false);
mainFrame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable() {
@Override public void run() {
createAndShowGUI();
}
});
}
class Grid extends JComponent
{
static final int CANVAS_WIDTH = 640;
static final int CANVAS_HEIGHT = 480;
private final double conversionRatio = 4.0/9.0; // 1080p scaled down to 480p preview
private int squareHeight, squareWidth, numColumns, numRows;
public Grid()
{
setOpaque(true);
setSize(CANVAS_WIDTH, CANVAS_HEIGHT); // trying to get the size to work properly.
setPreferredSize(new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT));
}
@Override
public Dimension getPreferredSize()
{
return new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT);
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
updateVars();
int k;
for (k = 0; k < numColumns; k++)
{
// @param: (x1, y1), (x2, y2)
g.drawLine(k * squareWidth, 0, k * squareWidth, CANVAS_HEIGHT);
}
for (k = 0; k < numRows; k++)
{
g.drawLine(0, k * squareHeight, CANVAS_WIDTH, k * squareHeight);
}
}
public void refresh()
{
// Attempting to set the repaint area to only the grid region
// because CTRL+F is free and parameters are not
repaint(0, 0, CANVAS_WIDTH, CANVAS_HEIGHT);
}
public void updateVars()
{
this.squareWidth = (int)(
(double)BuildGridGUI2.this.widthOfFrames
*
conversionRatio);
this.squareHeight = (int)(
(double)BuildGridGUI2.this.heightOfFrames
*
conversionRatio);
this.numColumns = BuildGridGUI2.this.numCols;
this.numRows = (int)(
(
(double)BuildGridGUI2.this.numFrames
/
numColumns
)
+ 0.5);
}
}
}
Actual Source Code (Not strictly relevant, but if you're in the mood for code review 那么我很想学习更好的编码约定。）
谢谢！
我对您发布的代码做了一些修改。
- 我更改了 class
Grid，使其扩展 JPanel 而不是 JComponent，因为自定义绘画通常是在 JPanel 上完成的。
- 我将类型为
Grid 的实例成员变量 grid 添加到 class BuildGridGUI2 而不是创建一个并将其作为参数发送给方法 makeSideMenu.
这是经过我修改后的代码（以及我喜欢的编码风格）。它只是解决了您报告的问题，仅此而已。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BuildGridGUI2 {
static final int WIDTH_MIN = 100;
static final int WIDTH_MAX = 2000;
static final int WIDTH_INIT = 520;
static final int HEIGHT_MIN = 100;
static final int HEIGHT_MAX = 2000;
static final int HEIGHT_INIT = 300;
int widthOfFrames = 255;
int heightOfFrames = 255;
int numCols = 3;
int numFrames = 1;
Grid grid;
private final JComponent makeUI() {
JPanel p = new JPanel();
p.setLayout(new BorderLayout());
grid = new Grid();
JComponent j = makeSideMenu();
grid.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.red),
grid.getBorder()));
j.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.red),
j.getBorder()));
p.add(j, BorderLayout.EAST);
p.add(grid, BorderLayout.WEST);
return p;
}
private final JComponent makeSideMenu() {
JPanel p = new JPanel();
JLabel numColsSelectorLabel = new JLabel("Frames Per Column");
JSpinner numColsSelectorField = new JSpinner();
JLabel widthLabel = new JLabel("Width per Frame (Pixels)");
JSpinner widthSpinner = new JSpinner();
JSlider widthSlider = new JSlider(WIDTH_MIN, WIDTH_MAX, WIDTH_INIT);
JLabel heightLabel = new JLabel("Height per Frame (Pixels)");
JSpinner heightSpinner = new JSpinner();
JSlider heightSlider = new JSlider(BuildGridGUI2.HEIGHT_MIN,
BuildGridGUI2.HEIGHT_MAX,
BuildGridGUI2.HEIGHT_INIT);
JButton confirmButton = new JButton("Confirm");
numColsSelectorField.setEditor(new JSpinner.NumberEditor(numColsSelectorField));
numColsSelectorField.setMaximumSize(numColsSelectorField.getPreferredSize());
widthSlider.setMajorTickSpacing(300);
widthSlider.setMinorTickSpacing(20);
widthSlider.setPaintTicks(true);
widthSlider.setPaintLabels(true);
widthSpinner.setEditor(new JSpinner.NumberEditor(widthSpinner));
widthSpinner.setPreferredSize(new Dimension(70, 30));
widthSpinner.setMaximumSize(widthSpinner.getPreferredSize());
heightSlider.setMajorTickSpacing(300);
heightSlider.setMinorTickSpacing(20);
heightSlider.setPaintTicks(true);
heightSlider.setPaintLabels(true);
heightSpinner.setEditor(new JSpinner.NumberEditor(heightSpinner));
heightSpinner.setPreferredSize(new Dimension(70, 30));
heightSpinner.setMaximumSize(heightSpinner.getPreferredSize());
confirmButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
widthOfFrames = 200;
grid.refresh();
}
});
p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
p.setPreferredSize(new Dimension(300, 480));
p.setSize(new Dimension(300, 480));
numColsSelectorLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
numColsSelectorField.setAlignmentX(Component.CENTER_ALIGNMENT);
widthSlider.setAlignmentX(Component.CENTER_ALIGNMENT);
heightSlider.setAlignmentX(Component.CENTER_ALIGNMENT);
confirmButton.setAlignmentX(Component.CENTER_ALIGNMENT);
widthLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
heightLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
widthSpinner.setAlignmentX(Component.CENTER_ALIGNMENT);
heightSpinner.setAlignmentX(Component.CENTER_ALIGNMENT);
p.add(Box.createRigidArea(new Dimension(300, 30)));
p.add(numColsSelectorLabel);
p.add(Box.createRigidArea(new Dimension(300, 5)));
p.add(numColsSelectorField);
p.add(Box.createRigidArea(new Dimension(300, 25)));
p.add(widthLabel);
p.add(Box.createRigidArea(new Dimension(300, 3)));
p.add(widthSpinner);
p.add(widthSlider);
p.add(Box.createRigidArea(new Dimension(300, 25)));
p.add(heightLabel);
p.add(Box.createRigidArea(new Dimension(300, 3)));
p.add(heightSpinner);
p.add(heightSlider);
p.add(Box.createRigidArea(new Dimension(300, 45)));
p.add(confirmButton);
return p;
}
private static void createAndShowGUI() {
BuildGridGUI2 b = new BuildGridGUI2();
JFrame mainFrame = new JFrame("Grid Builder");
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setSize(940, 480);
mainFrame.getContentPane().add(b.makeUI());
mainFrame.setResizable(false);
mainFrame.setVisible(true);
}
public static void main(String... args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
}
class Grid extends JPanel {
static final int CANVAS_WIDTH = 640;
static final int CANVAS_HEIGHT = 480;
private final double conversionRatio = 4.0 / 9.0; // 1080p scaled down to 480p preview
private int squareHeight, squareWidth, numColumns, numRows;
public Grid() {
setOpaque(true);
setSize(CANVAS_WIDTH, CANVAS_HEIGHT); // trying to get the size to work properly.
setPreferredSize(new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT));
}
@Override
public Dimension getPreferredSize() {
return new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
updateVars();
int k;
for (k = 0; k < numColumns; k++) {
// @param: (x1, y1), (x2, y2)
g.drawLine(k * squareWidth, 0, k * squareWidth, CANVAS_HEIGHT);
}
for (k = 0; k < numRows; k++) {
g.drawLine(0, k * squareHeight, CANVAS_WIDTH, k * squareHeight);
}
}
public void refresh() {
// Attempting to set the repaint area to only the grid region
// because CTRL+F is free and parameters are not
repaint(0, 0, CANVAS_WIDTH, CANVAS_HEIGHT);
}
public void updateVars() {
this.squareWidth = (int) ((double) BuildGridGUI2.this.widthOfFrames * conversionRatio);
this.squareHeight = (int) ((double) BuildGridGUI2.this.heightOfFrames * conversionRatio);
this.numColumns = BuildGridGUI2.this.numCols;
this.numRows = (int) (((double) BuildGridGUI2.this.numFrames / numColumns) + 0.5);
}
}
}
一个提示：尝试使用 JComponent 的特定子 class 而不是 JComponent。例如，我建议将 return 类型的方法 makeSideMenu() 更改为 JPanel 而不是 JComponent 因为该方法实际上 return 是 JPanel.
All of the sidebar components get painted at the top-left corner, while still showing/functioning on the sidebar;
JComponent 是一个抽象 class，所有 Swing 组件都从中扩展。它没有默认的绘画逻辑。
因此调用 super.paintComponent(...) 并没有真正做任何事情。
特别是在进行自定义绘制之前不会清除组件的背景。这将导致您看到的绘画伪影。
任何时候你扩展 JComponent 你的逻辑应该是这样的：
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
// clear background
g.setColor( getBackground() );
g.fillRect(0, 0, getWidth(), getHeight());
// do custom painting
g.setColor( getForeground() );
...
}
注意：这就是 Abra 提到的许多人为简单的自定义绘画覆盖 JPanel 的原因。 JPanel的paintComponent(...)方法默认会清空背景
类似于
详情
计划的意图：
要显示 1920x1080 网格的预览（缩小到 640x480 以节省 space），在您更改每个正方形的高度、每个正方形的宽度以及它的列数时进行拉伸和收缩会有的（您首先指定要在网格中的总方块数，因此程序会推断出行数。）
结构：
- 一个顶级 JFrame。
- 包含两个 JPanel：Grid 和侧边栏，使用 BorderLayout 将它们对齐到东边和西边。
- 侧边栏是一个 JPanel，包含 Y 轴对齐的 BoxLayout 中的所有 JComponent。
- Grid 扩展 JComponent，并使用 Graphics.drawLine() 绘制网格。
- 边栏中的每个组件在更改时调用 Grid.repaint() 以更新网格。
Current UI, with the two main JPanels outlined in red.
问题
每当我更改任何组件并因此调用 Grid.repaint():
- 网格不清晰，导致出现多行；
- 所有侧边栏组件都绘制在左上角，同时仍然 showing/functioning 在侧边栏上；
- 出于某种原因，网格将自身调整为比正常情况更宽。
Current UI, but borked.
我尝试过的
- 将 repaint() 区域更改为仅覆盖网格的矩形，
- 检查文档以了解有关此的任何信息，
- Google,
- 问你们
代码
Reprex：（简化为“按下按钮重现”，同时仍然保留潜在问题区域的本质。）
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BuildGridGUI2
{
static final int WIDTH_MIN = 100;
static final int WIDTH_MAX = 2000;
static final int WIDTH_INIT = 520;
static final int HEIGHT_MIN = 100;
static final int HEIGHT_MAX = 2000;
static final int HEIGHT_INIT = 300;
int widthOfFrames = 255;
int heightOfFrames = 255;
int numCols = 3;
int numFrames = 1;
private final JComponent makeUI()
{
JPanel p = new JPanel();
p.setLayout(new BorderLayout());
Grid g = new Grid();
JComponent j = makeSideMenu(g);
g.setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createLineBorder(Color.red),
g.getBorder()));
j.setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createLineBorder(Color.red),
j.getBorder()));
p.add(j, BorderLayout.EAST);
p.add(g, BorderLayout.WEST);
return p;
}
private final JComponent makeSideMenu(Grid grid)
{
JPanel p = new JPanel();
JLabel numColsSelectorLabel = new JLabel("Frames Per Column");
JSpinner numColsSelectorField = new JSpinner();
JLabel widthLabel = new JLabel("Width per Frame (Pixels)");
JSpinner widthSpinner = new JSpinner();
JSlider widthSlider = new JSlider(WIDTH_MIN, WIDTH_MAX, WIDTH_INIT);
JLabel heightLabel = new JLabel("Height per Frame (Pixels)");
JSpinner heightSpinner = new JSpinner();
JSlider heightSlider = new JSlider(BuildGridGUI2.HEIGHT_MIN, BuildGridGUI2.HEIGHT_MAX, BuildGridGUI2.HEIGHT_INIT);
JButton confirmButton = new JButton("Confirm");
numColsSelectorField.setEditor(new JSpinner.NumberEditor(numColsSelectorField));
numColsSelectorField.setMaximumSize(numColsSelectorField.getPreferredSize());
widthSlider.setMajorTickSpacing(300);
widthSlider.setMinorTickSpacing(20);
widthSlider.setPaintTicks(true);
widthSlider.setPaintLabels(true);
widthSpinner.setEditor(new JSpinner.NumberEditor(widthSpinner));
widthSpinner.setPreferredSize(new Dimension(70, 30));
widthSpinner.setMaximumSize(widthSpinner.getPreferredSize());
heightSlider.setMajorTickSpacing(300);
heightSlider.setMinorTickSpacing(20);
heightSlider.setPaintTicks(true);
heightSlider.setPaintLabels(true);
heightSpinner.setEditor(new JSpinner.NumberEditor(heightSpinner));
heightSpinner.setPreferredSize(new Dimension(70, 30));
heightSpinner.setMaximumSize(heightSpinner.getPreferredSize());
confirmButton.addActionListener(new ActionListener() {
@Override public void actionPerformed(ActionEvent e)
{
widthOfFrames = 200;
grid.refresh();
}
});
p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
p.setPreferredSize(new Dimension(300, 480));
p.setSize(new Dimension(300, 480));
numColsSelectorLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
numColsSelectorField.setAlignmentX(Component.CENTER_ALIGNMENT);
widthSlider.setAlignmentX(Component.CENTER_ALIGNMENT);
heightSlider.setAlignmentX(Component.CENTER_ALIGNMENT);
confirmButton.setAlignmentX(Component.CENTER_ALIGNMENT);
widthLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
heightLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
widthSpinner.setAlignmentX(Component.CENTER_ALIGNMENT);
heightSpinner.setAlignmentX(Component.CENTER_ALIGNMENT);
p.add(Box.createRigidArea(new Dimension(300, 30)));
p.add(numColsSelectorLabel);
p.add(Box.createRigidArea(new Dimension(300, 5)));
p.add(numColsSelectorField);
p.add(Box.createRigidArea(new Dimension(300, 25)));
p.add(widthLabel);
p.add(Box.createRigidArea(new Dimension(300, 3)));
p.add(widthSpinner);
p.add(widthSlider);
p.add(Box.createRigidArea(new Dimension(300, 25)));
p.add(heightLabel);
p.add(Box.createRigidArea(new Dimension(300, 3)));
p.add(heightSpinner);
p.add(heightSlider);
p.add(Box.createRigidArea(new Dimension(300, 45)));
p.add(confirmButton);
return p;
}
private static void createAndShowGUI() {
BuildGridGUI2 b = new BuildGridGUI2();
JFrame mainFrame = new JFrame("Grid Builder");
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setSize(940, 480);
mainFrame.getContentPane().add(b.makeUI());
mainFrame.setResizable(false);
mainFrame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable() {
@Override public void run() {
createAndShowGUI();
}
});
}
class Grid extends JComponent
{
static final int CANVAS_WIDTH = 640;
static final int CANVAS_HEIGHT = 480;
private final double conversionRatio = 4.0/9.0; // 1080p scaled down to 480p preview
private int squareHeight, squareWidth, numColumns, numRows;
public Grid()
{
setOpaque(true);
setSize(CANVAS_WIDTH, CANVAS_HEIGHT); // trying to get the size to work properly.
setPreferredSize(new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT));
}
@Override
public Dimension getPreferredSize()
{
return new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT);
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
updateVars();
int k;
for (k = 0; k < numColumns; k++)
{
// @param: (x1, y1), (x2, y2)
g.drawLine(k * squareWidth, 0, k * squareWidth, CANVAS_HEIGHT);
}
for (k = 0; k < numRows; k++)
{
g.drawLine(0, k * squareHeight, CANVAS_WIDTH, k * squareHeight);
}
}
public void refresh()
{
// Attempting to set the repaint area to only the grid region
// because CTRL+F is free and parameters are not
repaint(0, 0, CANVAS_WIDTH, CANVAS_HEIGHT);
}
public void updateVars()
{
this.squareWidth = (int)(
(double)BuildGridGUI2.this.widthOfFrames
*
conversionRatio);
this.squareHeight = (int)(
(double)BuildGridGUI2.this.heightOfFrames
*
conversionRatio);
this.numColumns = BuildGridGUI2.this.numCols;
this.numRows = (int)(
(
(double)BuildGridGUI2.this.numFrames
/
numColumns
)
+ 0.5);
}
}
}
Actual Source Code (Not strictly relevant, but if you're in the mood for code review 那么我很想学习更好的编码约定。）
谢谢！
我对您发布的代码做了一些修改。
- 我更改了 class
Grid，使其扩展JPanel而不是JComponent，因为自定义绘画通常是在JPanel上完成的。 - 我将类型为
Grid的实例成员变量grid添加到 classBuildGridGUI2而不是创建一个并将其作为参数发送给方法makeSideMenu.
这是经过我修改后的代码（以及我喜欢的编码风格）。它只是解决了您报告的问题，仅此而已。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BuildGridGUI2 {
static final int WIDTH_MIN = 100;
static final int WIDTH_MAX = 2000;
static final int WIDTH_INIT = 520;
static final int HEIGHT_MIN = 100;
static final int HEIGHT_MAX = 2000;
static final int HEIGHT_INIT = 300;
int widthOfFrames = 255;
int heightOfFrames = 255;
int numCols = 3;
int numFrames = 1;
Grid grid;
private final JComponent makeUI() {
JPanel p = new JPanel();
p.setLayout(new BorderLayout());
grid = new Grid();
JComponent j = makeSideMenu();
grid.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.red),
grid.getBorder()));
j.setBorder(BorderFactory.createCompoundBorder(BorderFactory.createLineBorder(Color.red),
j.getBorder()));
p.add(j, BorderLayout.EAST);
p.add(grid, BorderLayout.WEST);
return p;
}
private final JComponent makeSideMenu() {
JPanel p = new JPanel();
JLabel numColsSelectorLabel = new JLabel("Frames Per Column");
JSpinner numColsSelectorField = new JSpinner();
JLabel widthLabel = new JLabel("Width per Frame (Pixels)");
JSpinner widthSpinner = new JSpinner();
JSlider widthSlider = new JSlider(WIDTH_MIN, WIDTH_MAX, WIDTH_INIT);
JLabel heightLabel = new JLabel("Height per Frame (Pixels)");
JSpinner heightSpinner = new JSpinner();
JSlider heightSlider = new JSlider(BuildGridGUI2.HEIGHT_MIN,
BuildGridGUI2.HEIGHT_MAX,
BuildGridGUI2.HEIGHT_INIT);
JButton confirmButton = new JButton("Confirm");
numColsSelectorField.setEditor(new JSpinner.NumberEditor(numColsSelectorField));
numColsSelectorField.setMaximumSize(numColsSelectorField.getPreferredSize());
widthSlider.setMajorTickSpacing(300);
widthSlider.setMinorTickSpacing(20);
widthSlider.setPaintTicks(true);
widthSlider.setPaintLabels(true);
widthSpinner.setEditor(new JSpinner.NumberEditor(widthSpinner));
widthSpinner.setPreferredSize(new Dimension(70, 30));
widthSpinner.setMaximumSize(widthSpinner.getPreferredSize());
heightSlider.setMajorTickSpacing(300);
heightSlider.setMinorTickSpacing(20);
heightSlider.setPaintTicks(true);
heightSlider.setPaintLabels(true);
heightSpinner.setEditor(new JSpinner.NumberEditor(heightSpinner));
heightSpinner.setPreferredSize(new Dimension(70, 30));
heightSpinner.setMaximumSize(heightSpinner.getPreferredSize());
confirmButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
widthOfFrames = 200;
grid.refresh();
}
});
p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
p.setPreferredSize(new Dimension(300, 480));
p.setSize(new Dimension(300, 480));
numColsSelectorLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
numColsSelectorField.setAlignmentX(Component.CENTER_ALIGNMENT);
widthSlider.setAlignmentX(Component.CENTER_ALIGNMENT);
heightSlider.setAlignmentX(Component.CENTER_ALIGNMENT);
confirmButton.setAlignmentX(Component.CENTER_ALIGNMENT);
widthLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
heightLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
widthSpinner.setAlignmentX(Component.CENTER_ALIGNMENT);
heightSpinner.setAlignmentX(Component.CENTER_ALIGNMENT);
p.add(Box.createRigidArea(new Dimension(300, 30)));
p.add(numColsSelectorLabel);
p.add(Box.createRigidArea(new Dimension(300, 5)));
p.add(numColsSelectorField);
p.add(Box.createRigidArea(new Dimension(300, 25)));
p.add(widthLabel);
p.add(Box.createRigidArea(new Dimension(300, 3)));
p.add(widthSpinner);
p.add(widthSlider);
p.add(Box.createRigidArea(new Dimension(300, 25)));
p.add(heightLabel);
p.add(Box.createRigidArea(new Dimension(300, 3)));
p.add(heightSpinner);
p.add(heightSlider);
p.add(Box.createRigidArea(new Dimension(300, 45)));
p.add(confirmButton);
return p;
}
private static void createAndShowGUI() {
BuildGridGUI2 b = new BuildGridGUI2();
JFrame mainFrame = new JFrame("Grid Builder");
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setSize(940, 480);
mainFrame.getContentPane().add(b.makeUI());
mainFrame.setResizable(false);
mainFrame.setVisible(true);
}
public static void main(String... args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
}
class Grid extends JPanel {
static final int CANVAS_WIDTH = 640;
static final int CANVAS_HEIGHT = 480;
private final double conversionRatio = 4.0 / 9.0; // 1080p scaled down to 480p preview
private int squareHeight, squareWidth, numColumns, numRows;
public Grid() {
setOpaque(true);
setSize(CANVAS_WIDTH, CANVAS_HEIGHT); // trying to get the size to work properly.
setPreferredSize(new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT));
}
@Override
public Dimension getPreferredSize() {
return new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
updateVars();
int k;
for (k = 0; k < numColumns; k++) {
// @param: (x1, y1), (x2, y2)
g.drawLine(k * squareWidth, 0, k * squareWidth, CANVAS_HEIGHT);
}
for (k = 0; k < numRows; k++) {
g.drawLine(0, k * squareHeight, CANVAS_WIDTH, k * squareHeight);
}
}
public void refresh() {
// Attempting to set the repaint area to only the grid region
// because CTRL+F is free and parameters are not
repaint(0, 0, CANVAS_WIDTH, CANVAS_HEIGHT);
}
public void updateVars() {
this.squareWidth = (int) ((double) BuildGridGUI2.this.widthOfFrames * conversionRatio);
this.squareHeight = (int) ((double) BuildGridGUI2.this.heightOfFrames * conversionRatio);
this.numColumns = BuildGridGUI2.this.numCols;
this.numRows = (int) (((double) BuildGridGUI2.this.numFrames / numColumns) + 0.5);
}
}
}
一个提示：尝试使用 JComponent 的特定子 class 而不是 JComponent。例如，我建议将 return 类型的方法 makeSideMenu() 更改为 JPanel 而不是 JComponent 因为该方法实际上 return 是 JPanel.
All of the sidebar components get painted at the top-left corner, while still showing/functioning on the sidebar;
JComponent 是一个抽象 class，所有 Swing 组件都从中扩展。它没有默认的绘画逻辑。
因此调用 super.paintComponent(...) 并没有真正做任何事情。
特别是在进行自定义绘制之前不会清除组件的背景。这将导致您看到的绘画伪影。
任何时候你扩展 JComponent 你的逻辑应该是这样的：
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
// clear background
g.setColor( getBackground() );
g.fillRect(0, 0, getWidth(), getHeight());
// do custom painting
g.setColor( getForeground() );
...
}
注意：这就是 Abra 提到的许多人为简单的自定义绘画覆盖 JPanel 的原因。 JPanel的paintComponent(...)方法默认会清空背景