GreetingLabelAction.java

package dev.simplified.tabsimile.header;

import com.intellij.openapi.actionSystem.ActionUpdateThread;
import com.intellij.openapi.actionSystem.AnAction;
import com.intellij.openapi.actionSystem.AnActionEvent;
import com.intellij.openapi.actionSystem.Presentation;
import com.intellij.openapi.actionSystem.ex.CustomComponentAction;
import com.intellij.openapi.project.DumbAware;
import com.intellij.ui.components.JBLabel;
import com.intellij.util.ui.JBUI;
import com.intellij.util.ui.UIUtil;
import org.jetbrains.annotations.NotNull;

import javax.swing.JComponent;

/**
 * Text label in the header, shown while {@link GreetingState} is on.
 *
 * <p>
 * Two things at once. That a header slot can hold arbitrary text rather than only
 * icon buttons, because an action toolbar renders whatever component a
 * {@link CustomComponentAction} hands it. And that such a component can be shown and
 * hidden at runtime - hiding is an ordinary {@code setEnabledAndVisible(false)} in
 * {@link #update}, and the toolbar drops the component on its next pass.
 */
public final class GreetingLabelAction extends AnAction implements CustomComponentAction, DumbAware {

    private static final String GREETING = "Hello!";

    /** Constructs the greeting label. */
    public GreetingLabelAction() {
        super(GREETING);
    }

    @Override
    public @NotNull JComponent createCustomComponent(@NotNull Presentation presentation, @NotNull String place) {
        JBLabel label = new JBLabel(GREETING);
        label.setForeground(UIUtil.getContextHelpForeground());
        label.setBorder(JBUI.Borders.empty(0, 8));
        return label;
    }

    @Override
    public void update(@NotNull AnActionEvent event) {
        event.getPresentation().setEnabledAndVisible(GreetingState.getInstance().isVisible());
    }

    @Override
    public @NotNull ActionUpdateThread getActionUpdateThread() {
        return ActionUpdateThread.BGT;
    }

    @Override
    public void actionPerformed(@NotNull AnActionEvent event) {
        // A readout, not a button.
    }
}