Question

我有JPanel使用paintComponent方法执行某些绘图，然后当用户点击JPanel时，会在其上绘制一个字符串（或任何绘图）当用户将鼠标移到JPanel上方时，它会显示JPanel工具提示中的坐标。

1）问题是，当工具提示超过绘制的字符串时，它会删除它，但是这个工具文本对我在paintComponent方法中执行的绘图部分没有擦除效果。我无法理解为什么会这样。

2）当我在点击时绘制字符串然后最小化并恢复我的应用程序时，我绘制的字符串消失了。

希望你们都明白我的意思。

以下是代码：

@Override
public void paintComponent(Graphics graphics) {
    super.paintComponent(graphics);
    Graphics2D graphics2D = (Graphics2D) graphics;
    graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);

    drawBorder(graphics2D);
    drawGrid(graphics2D);
}

private void drawBorder(Graphics2D graphics2D) {
    graphics2D.setColor(Color.ORANGE);
    graphics2D.setStroke(new BasicStroke(borderStroke));
    graphics2D.drawRoundRect(panelStartLoc.x, panelStartLoc.y, panelBorder.width,
            panelBorder.height, borderRoundness, borderRoundness);
}

private void drawGrid(Graphics2D graphics2D) {
    graphics2D.setColor(Color.ORANGE);
    graphics2D.setStroke(new BasicStroke(gridCellStroke));

    for (int row = gridStartLoc.x; row < panelBorder.getWidth(); row += cellWidth + cellHorGap) {
        for (int col = gridStartLoc.y; col < panelBorder.getHeight(); col += cellHeight + cellVerGap) {
            graphics2D.drawRoundRect(row, col, cellWidth, cellHeight, cellRoundness, cellRoundness);
        }
    }
}

public void drawSubjectAtClickLoc(int subjectCode) {
    Color color = getBackground();
    String drawString = null;
    int subjectDrawXLoc = cellClickLoc.x + 4;
    int subjectDrawYLoc = (cellClickLoc.y + cellHeight) - 3;
    Graphics2D graphics2D = (Graphics2D) getGraphics();

    if (subjectCode == SUBJECT_CLEAR) {
        graphics2D.setColor(getBackground());
        graphics2D.fillRoundRect(cellClickLoc.x + 2, cellClickLoc.y + 2, cellWidth - 4, 
                cellHeight - 4, cellRoundness, cellRoundness);
        return;
    }
    if (subjectCode == SUBJECT_HUMAN) {
        color = Color.WHITE;
        drawString = "H";
    }
    if (subjectCode == SUBJECT_RESOURCE) {
        color = Color.GREEN;
        drawString = "R";
    }

    graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
    graphics2D.setFont(new Font(null, Font.BOLD, 26));
    graphics2D.setColor(color);
    graphics2D.drawString(drawString, subjectDrawXLoc, subjectDrawYLoc);
}

提前完成......

Answer 1

当您的屏幕被覆盖时，Java会调用paintComponent()来修复屏幕。如果您在paintComponent()方法之外绘制，那么当屏幕修复后，您的额外绘图将被删除。

所以不要这样做：在paintComponent()中完成所有绘图。当用户点击某处时，将要绘制的字符串和坐标添加到某种数据结构（即对象列表，每个对象包含一个字符串和一些坐标），然后调用repaint()。在paintComponent()方法中，查看该数据结构并绘制字符串。

工具提示文本擦除java中的面板绘图

1 个答案: