GuiScrollPane.java

package com.minestellar.core.gui.widget;

import java.awt.Dimension;
import java.awt.Rectangle;

import com.minestellar.utils.MathHelper;

public abstract class GuiScrollPane extends GuiWidget {
	protected int scrollclicky = -1;
	protected float scrollpercent;
	protected int scrollmousey;
	protected float percentscrolled;

	public int marginleft;
	public int margintop;
	public int marginright;
	public int marginbottom;

	public GuiScrollPane(int x, int y, int width, int height) {
		super(x, y, width, height);
	}

	public void setMargins(int left, int top, int right, int bottom) {
		marginleft = left;
		margintop = top;
		marginright = right;
		marginbottom = bottom;
	}

	public Rectangle windowBounds() {
		return new Rectangle(x + marginleft, y + margintop, width - marginleft - marginright, height - margintop - marginbottom);
	}

	public abstract int contentHeight();

	public Dimension scrollbarDim() {
		int h = (int) ((windowBounds().getHeight() / contentHeight()) * height);
		return new Dimension(5, h > height ? height : h < height / 15 ? height / 15 : h);
	}

	public Rectangle scrollbarBounds() {
		Dimension dim = scrollbarDim();
		return new Rectangle(x + width - dim.width, y + (int) ((height - dim.height) * percentscrolled + 0.4999), dim.width, dim.height);
	}

	public void scrollUp() {
		scroll(-5);
	}

	public void scrollDown() {
		scroll(5);
	}

	public void scroll(int i) {
		percentscrolled += i * height / (float) (2 * contentHeight());
		calculatePercentScrolled();
	}

	public void calculatePercentScrolled() {
		int barempty = height - scrollbarDim().height;
		if (isScrolling()) {
			int scrolldiff = scrollmousey - scrollclicky;
			percentscrolled = scrolldiff / (float) barempty + scrollpercent;
		}
		percentscrolled = (float) MathHelper.clip(percentscrolled, 0, 1);
	}

	public boolean isScrolling() {
		return scrollclicky >= 0;
	}

	public boolean hasScrollbar() {
		return contentHeight() > height;
	}

	/**
	 * @return -1 for left, 0 for none, 1 for right
	 */
	public int scrollbarGuideAlignment() {
		return -1;
	}

	public void showSlot(int sloty, int slotHeight) {
		Rectangle w = windowBounds();
		if (sloty + slotHeight > w.y + w.height) {
			int diff = sloty - (w.y + w.height - slotHeight);
			percentscrolled += diff / (double) (contentHeight() - w.height);
			calculatePercentScrolled();
		} else if (sloty < w.y) {
			int diff = w.y - sloty;
			percentscrolled -= diff / (double) (contentHeight() - w.height);
			calculatePercentScrolled();
		}
	}

	@Override
	public void mouseClicked(int mx, int my, int button) {
		Rectangle sbar = scrollbarBounds();
		Rectangle w = windowBounds();
		int barempty = height - sbar.height;

		if (button == 0 && sbar.height < height && // the scroll bar can move (not full length)
		mx >= sbar.x && mx <= sbar.x + sbar.width && my >= y && my <= y + height)// in the scroll pane
		{
			if (my < sbar.y) {
				percentscrolled = (my - y) / (float) barempty;
				calculatePercentScrolled();
			} else if (my > sbar.y + sbar.height) {
				percentscrolled = (my - y - sbar.height + 1) / (float) barempty;
				calculatePercentScrolled();
			} else {
				scrollclicky = my;
				scrollpercent = percentscrolled;
				scrollmousey = my;
			}
		} else if (w.contains(mx, my))
			slotDown(mx - w.x, my - w.y + scrolledPixels(), button);
	}

	/**
	 * Mouse down on slot area Coordinates relative to slot content area
	 */
	public void slotDown(int mx, int my, int button) {
	}

	/**
	 * Mouse up on slot area Coordinates relative to slot content area
	 */
	public void slotUp(int mx, int my, int button) {
	}

	@Override
	public void mouseMovedOrUp(int mx, int my, int button) {
		Rectangle w = windowBounds();
		if (isScrolling() && button == 0)// we were scrolling and we released mouse
			scrollclicky = -1;
		else if (w.contains(mx, my))
			slotUp(mx - w.x, my - w.y + scrolledPixels(), button);
	}

	@Override
	public void mouseDragged(int mousex, int mousey, int button, long time) {
		if (isScrolling()) {
			int scrolldiff = mousey - scrollclicky;
			int sbarh = scrollbarDim().height;
			int barupallowed = (int) ((height - sbarh) * scrollpercent + 0.5);
			int bardownallowed = (height - sbarh) - barupallowed;

			if (-scrolldiff > barupallowed)
				scrollmousey = scrollclicky - barupallowed;
			else if (scrolldiff > bardownallowed)
				scrollmousey = scrollclicky + bardownallowed;
			else
				scrollmousey = mousey;

			calculatePercentScrolled();
		}
	}

	public int scrolledPixels() {
		int scrolled = (int) ((contentHeight() - windowBounds().height) * percentscrolled + 0.5);
		if (scrolled < 0)
			scrolled = 0;
		return scrolled;
	}

	@Override
	public void draw(int mx, int my, float frame) {
		Rectangle w = windowBounds();
		drawBackground(frame);
		drawContent(mx - w.x, my + scrolledPixels() - w.y, frame);
		drawOverlay(frame);
		drawScrollbar(frame);
	}

	public void drawBackground(float frame) {
		drawRect(x, y, x + width, y + height, 0xff000000);
	}

	public abstract void drawContent(int mx, int my, float frame);

	public void drawOverlay(float frame) {
		// outlines
		drawRect(x, y - 1, x + width, y, 0xffa0a0a0);// top
		drawRect(x, y + height, x + width, y + height + 1, 0xffa0a0a0);// bottom
		drawRect(x - 1, y - 1, x, y + height + 1, 0xffa0a0a0);// left
		drawRect(x + width, y - 1, x + width + 1, y + height + 1, 0xffa0a0a0);// right
	}

	public void drawScrollbar(float frame) {
		Rectangle r = scrollbarBounds();

		drawRect(r.x, r.y, r.x + r.width, r.y + r.height, 0xFF8B8B8B);// corners
		drawRect(r.x, r.y, r.x + r.width - 1, r.y + r.height - 1, 0xFFF0F0F0);// topleft up
		drawRect(r.x + 1, r.y + 1, r.x + r.width, r.y + r.height, 0xFF555555);// bottom right down
		drawRect(r.x + 1, r.y + 1, r.x + r.width - 1, r.y + r.height - 1, 0xFFC6C6C6);// scrollbar

		int algn = scrollbarGuideAlignment();
		if (algn != 0)
			drawRect(algn > 0 ? r.x + r.width : r.x - 1, y, r.x, y + height, 0xFF808080);// lineguide
	}

}