/*
 * Copyright 2020-2023 MicroEJ Corp. All rights reserved.
 * This library is provided in source code for use, modification and test, subject to license terms.
 * Any modification of the source code will break MicroEJ Corp. warranties on the whole library.
 */
package ej.mwt.render;

import ej.microui.display.Display;
import ej.microui.display.GraphicsContext;
import ej.mwt.Container;
import ej.mwt.Desktop;
import ej.mwt.Widget;

/**
 * This render policy keeps the initial order of the widgets. That means that when a widget is rendered, the widgets
 * after it in the hierarchy and that have an intersection with it, are also rendered.
 * <p>
 * When a widget is asked to be rendered, all the widgets that overlap it in the desktop hierarchy are also rendered. A
 * widget is considered to overlap another one if:
 * <ul>
 * <li>their bounds intersect,</li>
 * <li>it is after the other one when browsing the hierarchy following a depth-first algorithm.</li>
 * </ul>
 */
public class OverlapRenderPolicy extends DefaultRenderPolicy {

    /**
     * Creates an overlap render policy.
     *
     * @param desktop
     *            the desktop.
     */
    public OverlapRenderPolicy(Desktop desktop) {
        super(desktop);
    }

    @Override
    protected void renderWidget(Widget widget, int x, int y, int width, int height) {
        // reset translation and clip
        GraphicsContext g = Display.getDisplay().getGraphicsContext();
        g.resetTranslation();
        g.resetClip();
        // compute translation and clip
        setParentClip(widget, g);
        g.intersectClip(widget.getX() + x, widget.getY() + y, width, height);
        // Save clip to apply it for siblings.
        int translateX = g.getTranslationX();
        int translateY = g.getTranslationY();
        int clipX = g.getClipX();
        int clipY = g.getClipY();
        int clipWidth = g.getClipWidth();
        int clipHeight = g.getClipHeight();
        // render widget
        renderWidget(g, widget);
        renderSiblings(g, widget, translateX, translateY, clipX, clipY, clipWidth, clipHeight);
    }
}