design/designer-base/src/main/java/com/fr/design/mainframe/theme/TemplateThemePreviewPane.java

package com.fr.design.mainframe.theme;

import com.fr.base.chart.chartdata.CallbackEvent;
import com.fr.base.theme.TemplateTheme;
import com.fr.base.theme.settings.ThemeThumbnail;
import com.fr.design.mainframe.theme.preview.ThemePreviewed;
import com.fr.log.FineLoggerFactory;

import javax.swing.JPanel;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.Transparency;
import java.awt.image.BufferedImage;

/**
 * @author Starryi
 * @version 1.0
 * Created by Starryi on 2021/8/13
 */
public abstract class TemplateThemePreviewPane<T extends TemplateTheme> extends JPanel implements CallbackEvent, ThemePreviewed<T> {
    private JPanel parent;
    public static final int PREVIEW_WIDTH = 627;
    public static final int PREVIEW_HEIGHT = 532;

    public void setParent(JPanel parent) {
        this.parent = parent;
    }

    @Override
    public void callback() {
        if (parent != null) {
            parent.repaint();
        } else {
            this.repaint();
        }
    }

    protected Image createThumbnailImage() {
        BufferedImage image = null;

        int thumbnailWidth = ThemeThumbnail.WIDTH;
        int thumbnailHeight = ThemeThumbnail.HEIGHT;

        int width = getWidth();
        int height = getHeight();

        try {
            image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            Graphics2D g2d = image.createGraphics();
            // 创建一个支持透明背景的buffer image
            image = g2d.getDeviceConfiguration().createCompatibleImage(width, height, Transparency.TRANSLUCENT);
            g2d.dispose();
            g2d = image.createGraphics();

            g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g2d.clipRect(0, 0, width, height);

            paint(g2d);

        } catch (Exception e) {
            FineLoggerFactory.getLogger().error(e.getMessage(), e);
        }

        if (image != null) {
            return image.getScaledInstance(thumbnailWidth, thumbnailHeight, BufferedImage.SCALE_SMOOTH);
        }

        return null;
    }

    @Override
    public void paintComponent(Graphics g) {
        g.clearRect(0, 0, PREVIEW_WIDTH, PREVIEW_HEIGHT);
        // 添加个默认白色，否则因为上面的clearRect导致无背景时会出现黑色
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, PREVIEW_WIDTH, PREVIEW_HEIGHT);
        paintBackground((Graphics2D) g);
    }

    protected abstract void paintBackground(Graphics2D g);
}